TITLE OF THE PAPER (Arial, 14pct, Bold)

Transcription

No. 3/2014
ISSN 1453 – 7303
“HIDRAULICA” (No. 3/2014)
Magazine of Hydraulics, Pneumatics, Tribology, Ecology, Sensorics, Mechatronics
CONTENTS
•
5-6
EDITORIAL
Petrin DRUMEA
•
THE EXPERIMENTAL VERIFICATION OF EFFECT OF LUBRICATION ON
COEFFICIENT OF FRICTION IN ENDOPROSTHESIS OF HIP JOINT
7 - 12
Andrea HARINGOVÁ, Karol STRAČÁR, Karol PRIKKEL
•
THE USE OF BIOCHAR AS A MEANS OF SOIL REGENERATION
13 - 18
Sava ANGHEL, Alina Iolanda POPESCU
•
19 - 24
ELECTRONIC SCREENING
Justinian Laviniu CÎRSTEA, Dorel STOICA
•
TILLER HYDROSTATIC TRANSMISSION
25 - 30
Gheorghe IVAN, Radu CIUPERCA, Ioan GANEA
•
RAINFALL INDICES IN THE CITY OF BUCHAREST
31 - 35
Carmen Otilia RUSĂNESCU
•
STUDY OF THE FLUIDIZED BED HYDRODYNAMICS FROM THE ENERGETIC
BOILERS USING DIFFERENT TYPE OF SOLID PARTICLES
36 - 45
Daniela HOARĂ, Gheorghe LĂZĂROIU
•
GENERAL METHODOLOGY OF WORKING WITH HVOF INTEGRATED
TECHNOLOGICAL SYSTEM
46 - 51
Valeriu AVRAMESCU, Luminita Elena OLTEANU, Loredana Theodora PAUN,
Raluca Magdalena NITA, Daniel BOBE, Sebastian ROSULESCU, Marius MANEA
•
CABIN HEAT REMOVAL FROM PARKED CARS
52 - 58
Adrian CIOCANEA, Dorin Laurentiu BURETEA
•
INTEGRATED TECHNOLOGICAL SYSTEM FOR THERMAL SPRAYING
BY HVOF PROCESS
59 - 65
Theodora Loredana PAUN, Valeriu AVRAMESCU, Raluca Magdalena NITA, Daniel BOBE,
Sebastian ROSULESCU, Elena Luminita OLTEANU, Marius MANEA
•
THE PROCEDURE FOR DRYING PLANT PRODUCTS IN CONVECTIVE DRYERS
Iulian – Cezar GIRLEANU, Gabriela MATACHE
3
66 - 71
ISSN 1453 – 7303
MANAGER OF PUBLICATION
- PhD. Eng.Petrin DRUMEA - Hydraulics and Pneumatics Research Institute in Bucharest, Romania
CHIEF EDITOR
- PhD.Eng. Gabriela MATACHE - Hydraulics and Pneumatics Research Institute in Bucharest, Romania
EXECUTIVE EDITORS
- Valentin MIROIU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania
- Ana-Maria POPESCU - Hydraulics and Pneumatics Research Institute in Bucharest, Romania
SPECIALIZED REVIEWERS
- PhD. Eng. Heinrich THEISSEN – Scientific Director of Institute for Fluid Power Drives and Controls IFAS,
Aachen - Germany
- Prof. PhD. Eng. Henryk CHROSTOWSKI – Wroclaw University of Technology, Poland
- Prof. PhD. Eng. Pavel MACH – Czech Technical University in Prague, Czech Republic
- Prof. PhD. Eng.Alexandru MARIN – POLITEHNICA University of Bucharest, Romania
- Assoc.Prof. PhD. Eng. Constantin RANEA – POLITEHNICA University of Bucharest, Romania
- Lecturer PhD.Eng. Andrei DRUMEA – POLITEHNICA University of Bucharest, Romania
- PhD.Eng. Ion PIRNA - General Manager - National Institute Of Research - Development for Machines and
Installations Designed to Agriculture and Food Industry – INMA, Bucharest- Romania
- PhD.Eng. Gabriela MATACHE - Hydraulics & Pneumatics Research Institute in Bucharest, Romania
- Lecturer PhD.Eng. Lucian MARCU - Technical University of Cluj Napoca, ROMANIA
- PhD.Eng.Corneliu CRISTESCU - Hydraulics & Pneumatics Research Institute in Bucharest, Romania
- Prof.PhD.Eng. Dan OPRUTA - Technical University of Cluj Napoca, ROMANIA
Published by:
Hydraulics & Pneumatics Research Institute, Bucharest-Romania
Address: 14 Cuţitul de Argint, district 4, Bucharest, cod 040557, ROMANIA
Phone: +40 21 336 39 90; +40 21 336 39 91 ; Fax:+40 21 337 30 40 ;
E-mail: [email protected]
Web: www.ihp.ro
with support of:
National Professional Association of Hydraulics and Pneumatics in Romania - FLUIDAS
E-mail: [email protected]
Web: www.fluidas.ro
HIDRAULICA Magazine is indexed in the international databases:
HIDRAULICA Magazine is indexed in the Romanian Editorial Platform:
ISSN 1453 – 7303; ISSN – L 1453 – 7303
4
ISSN 1453 – 7303
EDITORIAL
DE CE HERVEX?
In perioada 5-7 noiembrie 2014 se desfasoara la CalimanestiCaciulata in judetul Valcea editia a 21-a a Conferintei si Expozitiei
Internationale de Hidraulica si Pneumatica “HERVEX”.
Incepand cu anul 2013 organizatorilor traditionali (INOE 2000-IHP
Bucuresti si CCIVL) li se alatura si o unitate de cercetare de prestigiu
din Polonia (Institutul de Tehnologie Miniera – KOMAG din Gliwice),
facand ca manifestarea sa se desfasoare alternativ in cele doua tari,
in anii impari in Polonia sub numele de CYLINDER, iar in anii pari in
Romania sub numele de HERVEX.
Dr.ing. Petrin DRUMEA
DIRECTOR DE PUBLICATIE
Intrucat conferinta, probabil cea mai importanta din domeniul hidraulicii si pneumaticii din Romania,
are in continuare rolul de platforma de prezentare a noutatilor, inovatiilor si tendintelor, ea reuseste
sa adune foarte multi specialisti romani pentru un schimb direct de idei.
Inca de la inceput organizatorii romani si-au pus intrebarea privind rolul si utilitatea acestui
simpozion. Initial HERVEX a avut un rol extrem de important in aducerea la aceeasi masa a
producatorilor, a proiectantilor, a profesorilor si a utilizatorilor romani de hidraulica si pneumatica
pentru a-si prezenta realizarile ultimilor ani. Astazi manifestarea, care intre timp a devenit
internationala, include cateva activitati interesante, utile si de mare interes pentru specialistii
domeniului.
Una dintre aceste actiuni este cea de a analiza si face unele recomandari profesorilor care
pregatesc pe viitorii specialisti ai domeniului, atat la nivel universitar cat si la nivelul perfectionarii
profesionale. Tot in acest sens, de mai multi ani se desfasoara un concurs tehnic pentru tinerii
specialisti, fie studenti, fie proaspat absolventi.
O alta activitate de perspectiva o constituie contactul cu specialistii si profesorii de hidraulica si
pneumatica din tari europene cu care Romania a stabilit legaturi si care prezinta realizarile lor
recente si mai ales tendintele dezvoltarii domeniului.
In acest an se va dezbate noul program european Orizont 2020 si se vor analiza posibilitatile
participarii in comun la realizarea unor proiecte de interes pentru tarile prezente la HERVEX 2014.
Acest lucru este favorizat si de participarea unor IMM-uri de profil sau interesate de domeniu.
De mare interes a fost in ultimii ani si prezentarea unor echipamente complexe cu actionare
hidraulica sau pneumatica utilizate in productia energiei, atat a celei clasice, dar mai ales a celei
bazate pe resurse regenerabile si, de asemenea, implicarea in sistemele care reduc, recupereaza
sau optimizeaza resursele si consumurile energetice.
5
ISSN 1453 – 7303
EDITORIAL
WHY HERVEX?
From 5th to 7th of November 2014 in Valcea county, at Calimanesti
Caciulata, will be organized the 21st edition of the International
Conference and Exhibition of Hydraulics and Pneumatics “HERVEX”.
Since 2013 a prestigious research entity in Poland (KOMAG Institute
of Mining Technology in Gliwice) joins the traditional organizers (INOE
2000-IHP Bucharest and CCIVL), determining the event to be held
alternately in both countries, in odd years in Poland, referred to as
CYLINDER, and in even years in Romania referred to as HERVEX.
Ph.D.Eng. Petrin DRUMEA
MANAGER OF PUBLICATION
Since the conference, perhaps the most important in the field of hydraulics and pneumatics in
Romania, continues to play the role of a platform for presenting news, innovations and trends, it
manages to gather a lot of Romanian specialists for a direct exchange of ideas.
Since its inception Romanian organizers have asked themselves the question on the role and
usefulness of this symposium. Originally HERVEX had a major role in gathering around the same
table the Romanian producers, designers, teachers and users of Hydraulics and Pneumatics for
them to present their achievements in recent years. Today the event, which has since become an
international one, includes several interesting activities, useful and of great interest to the
specialists in the field.
One of these activities is to analyze and make recommendations to professors who teach the
future specialists in the field, both at university level and in professional training. In the same
regard, for several editions there has been organized a technical contest for young professionals
either students or newly graduates.
Another prospect activity is the contact with specialists and professors of Hydraulics and
Pneumatics in European countries which Romania has established connections with, who come to
present their recent achievements and especially the development trends in the field.
This year there will be discussed the new European Programme Horizon 2020 and will be explored
the possibilities for joint participation in the implementation of projects of interest to the countries
attending HERVEX 2014. This is encouraged by the participation of SMEs active in the field or
interested in the field.
Of high interest there was in recent years also the presentation of complex equipment hydraulically
or pneumatically actuated used in energy production, both classical, and especially the one based
on renewable resources, and likewise the involvement in systems that reduce, recover and
optimize energy resources and consumption.
6
ISSN 1453 – 7303
THE EXPERIMENTAL VERIFICATION OF EFFECT OF LUBRICATION ON
COEFFICIENT OF FRICTION IN ENDOPROSTHESIS OF HIP JOINT
Andrea HARINGOVÁ1, Karol STRAČÁR 2, Karol PRIKKEL 3
1
Institute of chemical and hydraulic machines and equipment, STU in Bratislava, Slovak republic,
[email protected]
2
[email protected]
3
[email protected]
Abstract: The endoprosthesis of hip joint has overall lifetime up to 20 years. After this period the
patient has to submit the revision operation. The main problem of the failure of endoprosthesis of
hip joint are debris that comes from direct contact of head and socket pad and so called dry
friction. The paper deals with effect of additional lubricant on the value of coefficient of friction in
endoprosthesis of hip joint. As the testing fluid was selected the replacement of synovial fluid:
solution of hyaluronic acid.
Keywords: lubrication, coefficient of friction, endoprosthesis
1. Introduction
The endoprosthesis of hip joint is composed from 3 basic parts- stem with head and socket and
has overall lifetime 20 years. The lifetime is limited by debris that are caused by direct contact of
head and socket with absenting lubrication layer. The dry friction continuously reflects in mostly
polyethylene debris coming from the socket cup. These polyethylene debris are very harmful for
human body and causes infection and loosening of the endoprosthesis followed by the failure of
endoprosthesis (fig. 1).
Fig.1 Failed components of endoprosthesis
According to the [5] 55% cases of failure of primary total hip joint endoprosthesis are caused by
loosening of one of the components of the endoprosthesis. The amount of debris caused by dry
friction is 100 - 200 μm/year for endoprothetic pair ceramics/metal- polyethylene and the
polyethylene debris have irregular shape. In this article we would deal with the effect of lubrication
on coefficient of friction. The average coefficient of friction in endoprosthesis is 0,3 that is more
than 10 times higher as coefficient of friction in the healthy human joints (0,01 < f < 0,1 [2]).
2. Lubrication in hip joints
The fluid flow in endoprosthesis is described by Navier-Stokes equation that describes the
equilibrium between mass, pressure and viscose forces.
7
ISSN 1453 – 7303
∂v
p
+ v.gradv = − grad (U G + + ν .Δv)
∂t
ρ
(1)
The viscose forces are the basic benefit of fluid in the healthy hip joint gap and effects in
decrease of coefficient of friction. The lubrication fluid in hip joint is called the synovial fluid and
is captured in synovial membrane around the whole joint. The elementary component of
synovial fluid that is responsible for the excellent lubrication properties is hyaluronic acid. The
solution of hyaluronic acid is used also for viscosuplemantation- to add the absenting
lubrication layer in joint as the first solution of degenerative diseases. The solution of
hyaluronic acid would be used also in our experiment as testing lubrication fluid. Thy synovial
fluid behaves according to the shear rate as Newtonian or Non-Newtonian fluid.
The dynamic viscosity of synovial fluid is described:
μ0 − μ∞
μ p = μ∞ +
1 + AX + BX 2
X = ∂v1 / ∂h
(2)
(3)
where μ∞ - dynamic viscosity of synovial fluid for high shear rates, over 105 s-1;
μ0 - dynamic viscosity of synovial fluid for low shear rates;
X – shear rate ratio;
v1 – circumferential component of synovial velocity;
h – high of the gap;
A,B – empiric coefficients, for healthy joints A= 1,88307, B= 0,00458 and for
pathological joints A= 0,03349, B= 0,00131.
The character of lubrication in human joint is changing during the motion. According to the
Dowson (2001) and Medley (2001) is lubrication determined by coefficient λ that is derived
from following equation [3]:
λ=
hmin
Ra´´
(4)
where hmin minimum thickness of synovial fluid;
Ra’ composite roughness of endoprothetic pair.
According to the (4), it is determined the character of lubrication:
0,1 < λ < 1
critical lubrication,
1≤λ≤3
mixed lubrication,
λ>3
thin flow lubrication or hydrodynamic.
Critical lubrication means that the layer of fluid is so thin that there is a high risk of direct
contact of materials of joint. The thin layer lubrication is secured with minimum thickness of
lubrication layer 0,15 – 0,25 μm [3] and in this region we obtain the lowest value of coefficient
of friction as it is visible in fig.2.
8
ISSN 1453 – 7303
Fig.2 Stribeck´s curve of lubrication on joints[1]
3. Description of experiment
The stand for testing of endoprosthesis and their properties was designed in the
laboratories of Institute of chemical and hydraulic machines and equipment of Faculty of
Mechanical Engineering of STU in Bratislava. The stand is designed according to the standards
ISO 142 42 for stand for testing of endoprosthesis of hip joint and secures the prescribed value of
vertical load as well as the horizontak displacement value. The force and motional system is
secured by hydraulic components from company FESTO Slovakia s.r.o. and demanded limits are
set by the sensors: load cell, displacement sensor and magnetic sensor of position on the valve.
Fig.3 The stand for testing of effect of lubrication
As it was noted in the beginning the purpose of the measurements is the verification of the
effect of lubrication in endoprosthesis of hip joint on coefficient of friction. The measurement is
done in 2 steps-phases.
1. Phase A – simplified model of endoprosthesis of hip joint, with added lubrication layer
2. Phase B - simplified model of endoprosthesis of hip joint, dry friction, no lubrication layer
9
ISSN 1453 – 7303
Fig.4 Position of strain gages on hip joint
To capture the data from measurement we have used the following sensors:
- one-axis strain gage 1-LY11-1.5/120, sensitivity0,1 %, produced by HBM;
- subminiature stainless steel compression load cell LC 302-1K, measuring range 457 kg, accuracy
± 0,5 % from range, produced by OMEGA;
- inductive displacement transducer WA100, measuring range 0-100mm, produced by HBM;
- sensor of temperature ALMEMO 5690-2.
The evaluation of measured data was made with two softwares. Software CATMAN from company
HBM that help us to read the obtained data from QUANTUM MX 1615, and computational software
MATLAB for next evaluation of measured data.
Fig.5 Software for evaluation of measured data
The measurement properties from phases A and B are following:
Date of measurement: 17.6.-10.7. 2014
Place: STU SjF Bratislava,
Length of one cycle: 1,2s
The length of loading cycle: simulation of 2 days walk
Lubricant: solution of hyaluronic acid
4. Results
The results from the experiment are on the figures 6-9. From figures follows that addition of
lubrication layer causes decrease of coefficient of friction from maximum value captured in phase B
- dry friction 0,2062, to the value for phase A with added lubricant 0,0502.
10
ISSN 1453 – 7303
10
0.05
5
0.025
0
0
-5
-0.025
-10
-0.05
-15
-0.075
10
10.5
11
11.5
12
12.5
15
3500
10
3000
5
2500
0
2000
-5
1500
-10
1000
-15
500
-20
Vertikálne zaťaženie [N]
0.075
K o e fic ie n t tr e n ia [- ]
D r á h a v e r tik á ln e h o v a lc a - fle x ia a e x te n z ia c h ô d z e [m m ]
15
Dráha vertikálneho valca- flexia a extenzia chôdze [m m]
Fáza A: endoprotéza bez úpravy s mazaním hyaluronanom
0
10
13
10.5
11
11.5
12
12.5
Čas [s]
Čas [s]
Fig.6 Phase A, Horizontal loading and coeffiecient of fricton with respect to the time, Vertical and horizontal
loading with respect to time, endoprosthesis with added lubricant
0.04
0.03
Koeficient trenia[-]
0.02
0.01
0
-0.01
-0.02
-0.03
-0.04
-0.05
9.8
10
10.2
10.4
10.6
10.8
Čas [s]
Fig.7 Phase A, Coefficient of friction, endoprosthesis with added lubricant
Fáza B: endoprotéza bez úpravy, bez prídavného mazania
0.25
0.15
5
0.05
0
0
-5
K o e fic ie n t tr e n ia [-]
0.1
-0.05
-10
-0.1
-0.15
-15
333.5
334
334.5
335
335.5
336
-0.2
D r á h a v e r tik á ln e h o v a lc a - fle x ia a e x te n z ia c h ô d z e [ m m ]
D rá h a v e r tik á ln e h o v a lc a - fle x ia a e x te n z ia c h ô d z e [m m ]
0.2
10
15
3500
10
3000
5
2500
0
2000
-5
1500
-10
1000
-15
500
-20
Čas [s]
333.5
334
334.5
335
335.5
336
V e r tik á ln e z a ť a ž e n ie [N ]
Fáza B: endoprotéza bez úpravy, bez prídavného mazania
15
0
Čas [s]
Fig.8 Phase B, S Horizontal loading and coeffiecient of fricton with respect to the time, Vertical and
horizontal loading with respect to time, endoprosthesis with dry friction
Fáza B: endoprotéza bez úpravy, prídavného mazania
0.2
0.15
Koeficient trenia[-]
0.1
0.05
0
-0.05
-0.1
-0.15
332
332.1
332.2
332.3
332.4
332.5
332.6
332.7
332.8
332.9
Čas [s]
Fig.9 Phase B, Coefficient of friction, endoprosthesis with dry friction
11
ISSN 1453 – 7303
5. Conclusions
The addition of lubricant into the endoprosthesis gap is significant step in decreasing of coefficient
friction and we could derive that could also positively effect the lifetime of endoprosthesis. This
results would continue to the lifetime tests of endoprosthesis with simulation of one year walking,
representing 1 million of cycles.
Fig. 10 Resulting coefficient of friction
REFERENCES
[1]
COLES, J. M. – CHANG, D. P. – ZAUSCHER, S. 2010. Molecular mechanisms of
aquaeous
boundary lubrication by mucinus glycoproteins . In Current Opinion in Colloid & Interface Science, 2010.
Vol. 15, s. 406 – 416., ISSN 1359-0294
[2]
KLEINSTREUKRER, C. 2006. Biofluid Dynamics. Boca Raton: CRC Press
Taylor & Francis Group, 2006. 492 s. ISBN 0-8493-2221-9.
[3]
SEEBECK, P. 2009. Clinical and Technical Review: Hyaluronic acid (Hyaluronan).
TECOmedical Group, 2011. [online]. [cit.2012-02-12]. 24 s. Dostupné na:
http://www.tecomedical.com/downloads/pdf/Hyaluron%20%28e%29%20%28
10%29.pdf>.
[4]
MATTEI,L.-DI PUCCIO,F.-PICCIGALLO,B.-CIULLI,E., 2011, Lubrication and
wear modelling of artificial hip joints: A review, In Tribology International,
vol.44, 2011, s. 532-549, ISSN 0301-679X
[5]
NEČAS, L. a kol. 2009. Sloveský artroplastický register. Analýza 2003 – 2008.
Martin: SAR, 2009. [citovane 2011-01-24]. Dostupné na:
<http://sar.mfn.sk/file/subory/SAR_analyza_2003_2008.pdf>.
[6]
PRIKKEL, K.- HARINGOVA, A., 2012, Hip joint endoprosthesis. SK50222012 (U1)
[citovane 2014-08-25]. Dostupné na:
<http://worldwide.espacenet.com/publicationDetails/biblioDB=worldwide.espacenet.com&II=4&ND=3
&adjacent=true&locale=en_EP&FT=D&date=20120903&CC=SK&NR=50222012U1&KC=U1>.
[7]
PRIKKEL, K.- HARINGOVA, A., 2012, Hip joint endoprosthesis. SK50232012 (U1)
[citovane 2014-08-25]. Dostupné na:
<http://worldwide.espacenet.com/publicationDetails/biblioFT=D&date=20120903&DB=worldwide.esp
acenet.com&locale=en_EP&CC=SK&NR=50232012U1&KC=U1&ND=4>.
[8]
HARINGOVÁ, A. - PRIKKEL, K. - STRACÁR, K.: The lubrication in hip joint. In:
Hidraulica - ISSN 1453-7303. - No. 1 (2014), online, p. 26-31
[9]
HARINGOVÁ, A. - PRIKKEL, K.: The possibilities of modification of endoprosthesis of hip
joint
according to the usage of hydraulic components. In: Hidraulica. - ISSN 1453-7303. No. 3-4 (2011), p. 28-33
12
ISSN 1453 – 7303
THE USE OF BIOCHAR AS A MEANS OF SOIL REGENERATION
Dipl.Eng. Sava ANGHEL1, Dipl.Eng. Alina Iolanda POPESCU2
1, 2
INOE 2000 – IHP, [email protected]
Abstract: Intensive agriculture exploitations led to pronounced degradation of soil by altering soil
structure, affecting natural circuits of water, carbon and nitrogen by presence of poisonous
substances from pesticides family, of residues of harmful substances resulted by conducting crop
treatments. One way to remedy these soils, used worldwide, is the use of activated carbon as the
biochar. It copies the natural phenomenon of vegetation fires after which due to the resulting
carbon is gets to soil regeneration. Aim of the study is to increase production by regenerating the
soil as a result of using biochar and food fortification for targeted interventions, at poor households
around the world.
Keywords: biochar, greenhouse gases, biomass, pyrolysis, TLUD module
1. Introduction
In development perspective of sustainable agriculture is required efficient use of resources
to increase their energy independence of technological processes, to reduce the use of mineral
fertilizers in increasing the productive potential finality of agriculture. A relevant synthetic indicator
is energy balance of crops that can show which the level of energy independence is and how it
contributes to reducing the carbon concentration in the atmosphere.
Research in the use of biomass for energy production led to the conclusion that the plant
coal, called biochar, resulting from pyrolysis and gasification processes is a valuable amendment
for agriculture soils and an effective and very economical carbon sequestration.
Biochar is a product rich in carbon, created by thermochemical gasification of biomass with
air in slow substoichiometric regime. Biochar is produced organically, it increases crop yield,
improves the effectiveness of fertilizers, eliminates significantly the pesticides, reduces emissions
of methane and nitrous oxide (two aggressive greenhouse gases) and stores carbon atmospheric
in soil over a large period. It is widely highlighted as a method for reducing concentrations to
carbon dioxide (CO2) in the atmosphere, mitigating climate change dynamics. The exchange of
carbon between plants, soil and the atmosphere exceeds the exchange between ocean and the
atmosphere.
2. Methodology
Inorganic fertilizers used for growing crops produce on short-term intensive energy and
carbon. The use of these fertilizers in soils emits nitrous oxide, a powerful greenhouse gas
emission. Globally, fertilizer production is the largest source (38 %) of emissions from agriculture
(EPA, 2010). Reduced doses of inorganic fertilizer by incorporating biochar into soil would
therefore reduce CO2 emissions related to agricultural production.
Biochar is a very important element that participated in time, by accidental burning of
vegetation, at formation of productive layer of the present soil. A new biochar can be enriched with
nitrogen and used as a valuable agricultural amendment, as a substitute for chemical fertilizers
with nitrogen.
Internationally, there are known concerns in the use of production technologies of carbon
by controlled burning of plant materials.
Pyrolysis involves trade-offs between the production of biochar, bio-oil and gas, and the
process can be calibrated to maximize the output of different products, depending on economic
factors. This is illustrated in Table 1.
13
ISSN 1453 – 7303
Table 1: Typical product yields (dry wood basis) obtained by different modes of wood pyrolysis.
Mode
Conditions
Moderate temperatures (500°C) for 1
Fast
second
Intermediate
Moderate temperatures (500°C) for
10–20 seconds
Slow
Low temperature, (400°C), very long
(carbonisation)
solids residence time
Gasification
High temperature, 800°C, long
vapour residency time
Source: International Energy Agency 2007
Bio-oil
Biochar
Gas
75%
12%
13%
50%
20%
30%
30%
35%
35%
5%
10%
85%
There are known methodologies for obtaining coal by burning wood in covered pits, or in
stacks on the soil surface as shown below (Figure 1).
Fig.1 Methodologies for obtaining coal by burning wood in covered pits, or in stacks on the
soil surface
Another example is the establishment of an open-plan kitchen stove TLUD. The focus is on
the bottom of the stove where biomass burning occurs under the action of primary air that is
adjustable. The results from pyrolysis are biochar, heat energy and biogas. By the middle part
enters the secondary air, which burns the biogas at the top where one can cook.
14
ISSN 1453 – 7303
Fig. 2. Schematic of a top-lit updraft (TLUD) gasifier wood cook stove. (according to Brown
RC (2009) Biochar Production Technologies in Lehmann, J., & Joseph, S. (Eds.) Biochar for
Environmental Management: Science and Technology. London: Earthscan.)
Research has been conducted on effective use of biochar in soil obtained in controled field
in shifting cultivation and in field in shifting cultivation with biochar embedded in soil.
Fig.3 The effect of using biochar after five years of application
(- is more stable that any soil amendment (MRT 1,000-2,000 yrs);
- increases nutrient availability beyond a fertilizer effect;
-is more efficient at enhancing soil quality than any other organic soil amendment)
Data on biochar technology (fig.4) and functional diagram (fig.5) of a module type TLUD is
shown below.
15
ISSN 1453 – 7303
Fig.4 Biochar technology of a module type TLUD
Energy module type TLUD consists of a reactor which is filled with biomass and is
introduced in a case that has two adjustable air circuits. Gasification air enters through the bottom
and ensures the production of heat, oxidation and gasification of biomass, obtaining biochar and
gas produced by gas generator (gengas). The second circuit provides preheating of combustion air
which is mixed with the gas produced in the upper side and ensures burning of the gengas causing
heat.
Fig.5 Functional diagram of a module type TLUD
Functional block diagram of an energetic module type TLUD - Input values are: biomass,
air, task order, and output: biochar, heat, products of CO2 combustion.
If a source of carbon is added to the soil without sufficient nitrogen, microorganisms must
scavenge nitrogen from the soil environment, which can result in little nitrogen being available for
plants which can greatly limit crop growth. In general, an amendment needs to have a C:N ratio
that is no higher than about 30 to avoid nitrogen immobilization (the additional C is used for
maintenance respiration).
Biochars, which are mostly carbon, usually have very high C:N ratios on an elemental
composition basis; fortunately, nearly all of this carbon will not be available to microorganisms
meaning that the effective C:N ratio is much lower. If a biochar is not pyrolyzed sufficiently,
16
ISSN 1453 – 7303
however, some of the carbon may still be bioavailable and may cause nitrogen immobilization,
resulting in short-term negative effects on crop yield. Depending on magnitude of the carbon
overloading, the nitrogen in the microbial biomass will eventually become plant-available again as
microorganisms die off and the nitrogen is recycled, but by then (a few weeks to a few months
later), the plants may not be able to recover. An example of nitrogen immobilization is shown in
Figure 6. In this study, corn stover and carbonized corn stover (i.e. corn stover biochar) were used
as soil amendments in pots growing corn.
The third case is nitrogen immobilization due to a high ratio of available carbon to available
nitrogen in the biochar amendment. When they are actively growing (i.e. producing more biomass),
microorganisms need about 1 mole of nitrogen for every 5 to 10 moles of carbon that they
consume.
Both amendments had high C:N ratios but only the corn in the pots with the highest rates of
uncarbonized amendment showed signs of nitrogen immobilization (the stunted plant growth in
pots with 1.0 and 2.0% by weight of corn stover added).
Fig. 6. An example of nitrogen immobilization by microorganisms: the effect of soil
amendment bio-available C: N ratio on corn growth in a greenhouse study
Soils used in the study were amended with either corn stover (CS), which had a high
available C:N ratio, or carbonized corn stover (CCS), which had a much lower available C:N ratio
due to the carbonization process, at applications rates of 0.5, 1.0 or 2.0 wt% of soil. The corn
grown on soils amended with the higher amounts of corn stover (total C:N = 71) did worse than
that grown on soils amended with the carbonized crop residue (total C:N = 49). (Source: Christoph
Steiner, Biorefining and Carbon Cycling Center, University of Georgia, USA.)
Scientific innovation of the work results from biochar application in Romanian
agriculture, process known worldwide but at us only at the beginning
In Romania we know works in the field conducted at:
> Metallurgical Research Institute ICEM SA, in partnership with the Municipality of Motru,
SNLO Miami and IPROCHIM SA have under implementation, since July 2002, the project of
obtaining activated carbon by exploitation of xylose using clean technologies.
> the ICDP Maracineni, the project PC 51-008/14.09.2007- concerns regarding the use of
black coal in fruit growing.
Our institute has collaborated with partners such as Politehnica University of Bucharest,
INMA Bucharest in research works for obtaining active carbon as a byproduct of gas-producing
17
ISSN 1453 – 7303
and TLUD modules, developing in works under the national programmes RELANSIN and
PARTNERSHIPS.
> RELANSIN: motor pumps for irrigation, fueled by gas produced by gasification of plant
debris.
> RELANSIN: storage and distribution facility for gas produced by a generator.
> PARTNERSHIPS: Research on the use of corn crop as a source of biomass for thermal
energy production.
Food security, the challenge of ensuring the availability of safe, nutritional and accesible
food, took a new dimension in the light of increased global demand, environmental restrictions on
agricultural production and increased competition for soil quality and the means for obtaining it.
3. Conclusions
Modern experimental research demonstrates that biochar application can substantially
raise productivity of crops such as soybeans, sorghum, potatoes, maize, wheat, peas, oats, rice
and cowpeas.
Evidence suggests that significant productivity gains are possible at application rates as low
as 0.4 to 8 tonnes of carbon per ha, but at extremely high applications crop productivity may
actually drop due to nitrogen limitation.
Much synthetic fertilizer is currently produced by using natural gas to synthesis ammonia
using nitrogen from the air, but this releases one molecule of carbon dioxide for each molecule of
ammonia produced. Conventional urea-based fertilizers, made from this ammonia, also have other
adverse environmental impacts when used inappropriately. Combining ammonia, carbon dioxide
and water in the presence of biochar forms a solid, ammonium bicarbonate fertilizer, inside the
pores of the char. This nitrogen-enriched char can be incorporated into the soil, where it serves
three purposes: as a carbon store, as nitrogen fertilizer, and as a biologically active soil enhancer.
REFERENCES
[1] S. Anghel, C. Dumitrescu, Gh. Sovaiala, “Research study regarding the making of maize stalks
briquettes”, Wroclaw, 7-9 Oct. 2009, Conference Proceedings, pp. 349-353
[2] E. Murad, A. Culamet, G. Zamfiroiu, “Biochar- Economically and ecologically efficient technology for
carbon fixing”, International Symposium HERVEX-2011, Călimăneşti, 9-11 November 2011, Conference
Proceedings, ISSN 1454-8003, pp. 37-43
[3] E. Murad, A. Ciubucă, A. Culamet, Radu Marian, “Biochar produced from vine prunings organic soil
amendment for viticulture”, Symposium ICDVV, Valea Călugărescă, 12 June, 2012
[4] E. Murad, F. Dragomir, “Heat generators with TLUD gasifier for generating energy from biomass with a
negative balance of CO2”, International Conference HERVEX 2012, Călimăneşti, 7-9 November 2012,
Conference Proceedings, ISSN 1454-8003, pp. 440-447
[5] D. Sumedrea, C. Marin, E. Chiţu, C. Nicola, M. Sumedrea, V. Chiţu, M. Călinescu, M. Butac, “Preliminary
results regarding the influence of black charcoal application in apple orchards on chemical and
microbiological properties of the soil”, International Symposium, 2010, Annales of the University of
Craiova, vol. XV (XLXI), Publishing House Universitaria, Craiova, ISSN 1453-1275, pp. 534-543,
http://anucraiova.3x.ro, CNCSIS B+.
[6] P. Winsley, “Biochar and Bioenergy production for climate change mitigation”, International Energy
Agency, 2007, New Zealand Science Review, Vol.64. 1, 2007, pp. 5-10
18
ISSN 1453 – 7303
ELECTRONIC SCREENING
Ing. Justinian Laviniu CÎRSTEA, doc. Ing. Dorel STOICA 1
1
, University POLITEHNICA of Bucharest, Faculty of Biotechnical Engineering
[email protected] , [email protected]
Abstract: The article deals with the electronic screening of the commercial vehicles, which can be
done using mainline screening and ramp screening. Mainline screening allows vehicles to be
cleared without pulling into the station and has the advantages of a reduced traffic volume entering
the station facility and of a minimized delay for safe and legal vehicles, but also has the
disadvantage that the in-road equipment repairs on the mainline can be very costly and disruptive.
Ramp screening is performed at lower speeds within the confines of the station and approach
ramp. The purpose of the e-screening is to ensure a safe and optimal traffic.
Keywords: e-screening, CVISN, PrePass, NorPass.
1. INTRODUCTION
Commercial Vehicle Information Systems and Networks (CVISN) is the collection of state,
federal, and private sector information systems and communications networks that support
commercial vehicle operations. Electronic screening is one of the three key program areas in
CVISN Level 1.
WHAT IS ELECTRONIC SCREENING?
Screening is a selection mechanism to target high-risk operators and make efficient use of
weigh station and inspection resources. Electronic screening (e-screening) is the application of
technology to make more informed screening decisions. Properly implemented, electronic
screening results in improved traffic flow, focuses vehicle inspections and ultimately achieves the
goals of increased safety and reduced operating costs. In electronic screening:
• DSRC is used to identify the vehicle, store and transfer other screening data, and signal the
driver of the pull-in decision.
• Electronic Data Interchange (EDI) may be used to transmit safety and credentials history
(snapshot) data from the information infrastructure to the roadside systems to assist in the
screening decision.
The application of electronic screening will be affected by many constraints, including site
limitations, availability of support staff, and funding. Each roadside check station is likely to have a
unique design. Each station’s design is unique because of:
• State policy and practices
• Traffic flow, volume, and number of lanes
• Available site space
• Legacy system characteristics
• Existing proprietary solutions
• Vintage of roadside facilities and communications equipment
• Resources available for making changes.
19
ISSN 1453 – 7303
2. Technologies
There are a variety of technologies that can be applied to electronic screening in support of
the commercial vehicle weigh and inspection process. There are also a number of ways in which
these technologies can be applied. The purpose of this section is to briefly describe some of the
basic technologies used in electronic screening.
2.1 Dedicated Short Range Communications (DSRC)
DSRC is used to provide data communications between a moving vehicle and the roadside
equipment to support the screening process. This is accomplished by means of a transponder
(also known as a “tag”) mounted in the cab of the vehicle, and a reader and antenna mounted at
the roadside. The tag may contain identifiers specific to the vehicle (carrier and vehicle IDs), plus
optional prior screening event information. The transponder has audio and visual indicators that
may be used to signal the driver. The term Automated Vehicle Identification (AVI) is often used
when referring to DSRC systems. Strictly speaking, AVI is any technology, including DSRC, used
to identify vehicles. This category also includes optical, audio, and other Radio Frequency (RF)
identification systems.
2.2 Weigh In Motion (WIM)
WIM is used to measure approximate axle weights as a vehicle moves across the sensors,
and to determine the gross vehicle weight and classification based on the axle weights and
spacings. Although not as accurate as a static scale, WIM allows the weight of a vehicle to be
estimated for screening purposes while maintaining traffic flow.
2.3 Automatic Vehicle Classification (AVC)
Axle detectors are used to classify the various vehicle types. This information is necessary
at WIM-equipped sites because vehicle classification plays a role in the determination of legal
weight. AVC units are also used in compliance subsystems to detect vehicles bypassing the
station.
2.4 Vehicle Tracking Loops
Inductance loops may be used to track vehicle positions as they proceed through the site.
This information is required to synchronize lane signaling with the correct vehicles and to verify
compliance with these signals.
2.5 Automatic Signing
Lane signals and variable message signs should be automatically controlled by roadside
operations and coordinated with the detected location of the vehicle. Precise timing and control of
these signals is required in order to ensure that unambiguous direction is given to the intended
vehicle. Misdirection, confusion and ambiguity may result if signals intended for one vehicle are
visible to and misread by another.
3. Data Exchange
A critical component of the CVISN architecture is the standardization of two interfaces:
computer-to-computer exchanges using EDI and vehicle-to-roadside exchanges via DSRC. The
EDI interfaces are primarily used to transfer information between public agencies (e.g., state
government to state government) or between a public agency and private sector entity (e.g., state
20
ISSN 1453 – 7303
government to motor carrier). The computer-to-computer interfaces may evolve from the use of
EDI to the use of XML and other Web-based protocols.
Another component to standardization of data exchange between state and/or public systems
is the use of common data “snapshots.” Snapshots contain information that provide a quick picture
of carrier/vehicle/driver safety performance history and basic credentials information. Carrier and
vehicle snapshots exchange safety and credentials data between state and national systems. The
snapshots are used in conjunction with DSRC messages to support roadside operations as shown
in Figure 1.
Figure 1 shows the data flow among the various systems supporting electronic screening.
WHAT ALREADY EXISTS?
A large body of knowledge and experience already exists for deploying electronic screening
systems and technologies. Member states of two major multi-state electronic screening programs,
Heavy Vehicle Electronic License Plate (HELP) PrePass™ and North American Preclearance and
Safety System (NorPass), have deployed a number of sites that are currently in operation. The
CVISN pilot and prototype states have completed or are in the process of developing electronic
systems that meet CVISN Level 1 requirements. Software products and design documents,
developed for CVISN with FMCSA funds, are available in the public domain. These products
include the Roadside Operations Computer (ROC), Perryville Screening Computer, and the
Commercial Vehicle Information Exchange Window (CVIEW) systems.
4. Programs
Heavy Vehicle Electronic License Plate (HELP) PrePass™ is the largest North American
electronic screening program with operational sites in Alabama, Arizona, Arkansas, California,
Colorado, Florida, Illinois, Indiana, Iowa, Louisiana, Mississippi, Montana, Nebraska, Nevada, New
Mexico, Ohio, Oklahoma, Tennessee, West Virginia, and Wyoming. The PrePass™ Service Center
manages pre- and post-enrollment verification checks of carriers and provides transponders for
21
ISSN 1453 – 7303
vehicles. At the roadside station, transponder-equipped vehicles are checked against a preclearance list and weighed using WIM equipment.
North American Preclearance and Safety System (NorPass) was created in the merger
of Advantage CVO and Multi-jurisdictional Automated Preclearance System (MAPS). States that
have signed the NorPass agreement include: Kentucky, Georgia, Idaho, Utah, and Washington.
Information based on safety and credential records is passed to the roadside stations via an
enrolled vehicle list. Weight enforcement may be conducted using WIM or weight compliance
history.
Kentucky (KY) and Washington (WA), two CVISN pilot states that are also NorPass members, are
nearing completion of electronic screening sites that should meet the roadside CVISN Level 1
requirements.
Greenlight – Oregon has implemented an e-screening program called Greenlight and has
21 Greenlight sites. Oregon provides its own transponder administration. Carriers are free to use
the Oregon transponder in any or all other systems they choose. Oregon currently uses the carrier
safety fitness rating and SafeStat score for its safety bypass criteria. Oregon Greenlight sites can
only read the transponder ID code. If you are enrolled in Greenlight, the transponder ID will be
associated with a license plate.
Maryland (CVISN prototype state) has implemented electronic screening, based on the
CVISN architecture, at the Perryville, MD, inspection station. By successfully conducting several of
the CVISN interoperability tests, Maryland became the first state to meet the roadside CVISN Level
1 requirements.
5. Operational concepts and scenarios
The term “operational concept” generally means “how a system is used in various
operational scenarios.” “System” is used here in a broad sense to include people and manual
processes as well as automated information, sensors, and control systems. New operational
concepts are adopted in order to solve a problem in the current operations or to take advantage of
new knowledge or technology that enables improvements in current operations.
CVISN electronic screening operational concepts include necessary steps toward achieving
the goal of national interoperability among electronic screening systems. Realizing this goal will
promote seamless and safer movements, equitable treatment, increased productivity, and uniform
enforcement for the motor carrier community.
5.1. Operational Scenario
The e-screening system deployed at Perryville, Maryland, is described in this section along
with the associated operational scenario. This site is unique because it includes both mainline and
ramp screening systems. Due to cost, most electronic screening systems are either mainline-only
or ramp-only. Maryland has elected this dual-capability configuration in order to compare the
relative performance of the two methods.
The listed scenario describes the combined operation of the two subsystems and function of the
various components. The operational scenario for a ramp-only or mainline system can easily be
derived from the information presented.
5.1.1
Site Layout
Figure 2 illustrates the site layout for the e-screening system being deployed at Perryville,
MD. All major roadside equipment components are shown in the figure. The key features of this
layout are:
22
ISSN 1453 – 7303
• Mainline Piezo WIM/AVC in the right-hand southbound lane on I-95, approximately one mile
upstream of the station
• Over-height (OH) detector collocated with mainline WIM
• DSRC reader (Advance) collocated with mainline WIM
• DSRC reader (Notification) located approximately ¼ mile upstream of the ramp approach. The
location of the notification reader must allow sufficient time for the vehicle operator to receive the
bypass/pull-in signal via DSRC and safely remain on I-95 or pull onto the station ramp
• AVCs across all three south-bound lanes of I-95, downstream of the station ramp
• DSRC reader (Compliance) collocated with AVCs. The compliance readers shall cover only the
right-hand lanes on I-95. Trucks will be restricted to these lanes when bypassing the station
• Load-cell WIM in ramp lane
• DSRC reader (Ramp) on ramp, upstream of WIM
• Over-height detector installed near ramp reader
• Overhead signs directing traffic back to I-95 or onto the static scale
• DSRC reader (Static Scale) collocated with the station static scale
• Tracking loops installed as necessary.
5.1.2
E-Screening Operational Scenario
In the site layout shown in Figure 2, there are five DSRC readers along with both ramp and
mainline WIM. The five DSRC readers shown in this configuration are: advance reader, notification
reader, compliance reader, ramp reader and static-scale reader. The advance reader’s function is
to read the screening message, including the carrier and vehicle identifiers, and to send this
information to the screening computer for use in determining whether to clear the vehicle without
pulling into the station. The reader is located far enough ahead of the notification reader that the
mainline screening subsystem has time to complete all necessary processing as the vehicle
approaches. The advantages of screening on the mainline are to control traffic volume entering the
23
ISSN 1453 – 7303
station facility and to minimize the delay for safe and legal vehicles. The mainline WIM/AVC
provide vehicle weight estimates as input to the mainline screening decision. Gross vehicle weight
along with axle weights and spacing are available. Although not as accurate as either a static scale
or ramp WIM, the weight estimates are sufficient to clear a significant portion of the vehicle traffic.
At the notification reader, a signal is transmitted to the vehicle to convey the screening
decision status to the driver. Since a DSRC-equipped vehicle could be signaled to pull in, the
notification reader must be deployed far enough from the roadside check facility for the vehicle’s
driver to be able to react without endangering other vehicles on the roadway. Reaction time
budgets should account for slowing and turning off the mainline, as well as crossing lanes of traffic.
By the time the vehicle has passed the advance and notification readers, it has been
electronically cleared. However, it is also necessary to verify that vehicles are not illegally
bypassing a check station. Therefore, a compliance reader and an AVC system are located on the
mainline, past the entrance ramp to the station. The AVC identifies un-tagged commercial vehicles
that have illegally passed the station. The reader checks tagged vehicles to verify that the vehicle
was cleared to bypass the station. If a violation is detected, an indication is given to enforcement
personnel.
Vehicles entering the check facility ramp would fall into one of the following categories:
• DSRC-equipped, valid legal weight – the vehicle has been identified via DSRC, a valid weight
has been recorded, and an active screening decision has been made to stop the vehicle for some
type of closer review. This may be based on specifically identified problems or may be due to
random selection. Closer review may be limited to a visual check while on the static scale, or may
include an inspection based on the visual review, on data reported back in the screening process,
or on random selection.
• DSRC-equipped, invalid or over-weight – the vehicle has been identified via DSRC; however,
either the WIM failed to properly register the weight or the detected weight exceeded the criteria.
• DSRC-equipped, unrecognized – the vehicle is equipped with a transponder; however, the tag
may either be incompatible with or not valid for use at the site.
• No DSRC.
Upon entering the facility ramp, vehicles will be processed by the ramp WIM. The DSRC
ramp reader will interrogate the vehicle tag to retrieve the relevant identification data. A screening
decision will be made and the vehicle will be subsequently directed by visual lane signals. Cleared
vehicles will be signaled to return to the mainline. Vehicles receiving a pull-in decision on the ramp
will be directed to the static scale. The static-scale reader is used to identify transponder-equipped
vehicles that are on the scale. Snapshot-based safety and credential data for the vehicle will be
available to the static scale operator.
REFERENCES
1. Intelligent Transportation Society of America, Fair Information Principles for ITS/CVO.
2. JHU/APL, CVISN Electronic Screening Functional Specification for Southbound I-95 at
Perryville, MD, POR-01-7298 V1.0, January 2001.
3. JHU/APL, Delivery of Recommended Practices and System Specification Documents
for Enhanced Electronic Screening.
24
ISSN 1453 – 7303
TILLER HYDROSTATIC TRANSMISSION
Phd.eng. Gheorghe Ivan*, Phd.eng. Radu Ciuperca*, Phd.eng. Ganea Ioan*
*INMA Bucharest, [email protected]
Abstract: The article relates to a hydrostatic transmission intended for the tillers equipped with
internal combustion engines for continuous transmission of motion and power of the drive wheels
or to a device for digging soil. The state of the art transmission tillers operated internal combustion
engines using classical scheme consists of clutch, gearbox, control systems thereof etc. Chaining
these elements presents disadvantages, on the one hand because they are complicated, bulky and
heavy, requires a large number of control systems for drive and on the other hand that the
transmission of the movement is done in steps. The hydrostatic transmission we propose simplify
construction of tillers and control systems for its operation and will mount easily on the
transmission instead of classical combustion engine. This transmission is made up of a variable
displacement hydraulic pump which is connected to the internal combustion engine, an orbital
hydraulic motor to drive the wheels of the driving or digging the ground equipment, on which is
mounted a framework for the internal combustion engine, hydraulic pump and motor hydraulic
pipes connecting the hydraulic motor and hydraulic pump.
Keywords: tiller, hydrostatic transmission.
Introduction
A tiller is a self-propelled vehicle, usually having two drive wheels, internal combustion engine
through a gearbox and clutch, operated by a handlebar of a leader who walk. The engines full
power more than 15 kW and are powered by gasoline or diesel. The moving of tiller has different
speeds, forward or backward, gears and moving purposes are changed using control systems
located on the handlebars.
The tillers are used in horticulture and gardening soil processing using specific equipment
attachments (plough, milling unit, ridge plough, cultivator, digging canals for irrigation equipment,
digging pits equipment, equipment for crown shaped shrubs and trees, irrigation pump etc.). Also,
the some tillers can pull a trailer on two wheels, the driver sitting in a chair.
The tiller to replace the mechanical transmission with a hydrostatic transmission is type
produced by S.C. RURIS
Technical and functional characteristics of the tiller with mechanical transmission and
hydrostatic transmission are presented in Table 1.
Technical and functional characteristics of the tiller
Table 1
Technical and functional
characteristics
full power engine (net power)
maximum RPM engine
RPM drive wheels
maximum resistant torque, mrmax
clutch
gearbox
reducer
geometric volume hydraulic pump
Values
mechanical transmission
Values
hydrostatic transmission
5.5 kW (4.8 kW)
3600 rpm
40...125 rpm
30 daNm
dry single disc clutch
2 forward, 1back
-
25
7,08 cm3/rot
ISSN 1453 – 7303
theoretical flow of hydraulic pump
operating pressure
geometric volume hydraulic motor
oil flow of the hydraulic motor
metal wheels diameter
weight
65 kg
25,5 l/min to 3600 rpm
210 bar
125,7 cm3 / rot
5,6 ÷ 17,4 l / min
400 mm
42 kg
The mechanical transmission, consists of clutch, gearbox and reducer, is replaced with hydrostatic
transmission, consists of variable displacement hydraulic pump which is connected to the internal
combustion engine, an orbital hydraulic motor to drive the wheels of the driving or digging the
ground equipment, on which is mounted a framework for the internal combustion engine, hydraulic
pump and motor hydraulic pipes connecting the hydraulic motor and hydraulic pump. In Figure 1 is
presented the tiller with mechanical transmission.
Fig.1 Tiller with mechanical transmission
1. TILLER WITH HYDROSTATIC TRANSMISSION
The tiller with hydrostatic transmission is mainly composed of an internal combustion engine, a
flexible coupling, a variable hydraulic pump, two frames assembly, a hydraulic orbital motor with
two axes, hoses and fittings and pump control system [Fig. 2].
26
ISSN 1453 – 7303
Fig.2 Tiller with hydrostatic transmission
Calculation of hydrostatic transmission
Internal combustion engine torque diagram is presented in Figure 3.
Fig.3 Internal combustion engine torque diagram
27
ISSN 1453 – 7303
The tiller hydrostatic system will have variable flow hydraulic pump PMV0-07, driven by the
combustion engine at speed of np = 3000 rpm and an orbital hydraulic motor with two-axis output
MRB 125, to drive the wheels of the driving or digging the ground equipment.
Hydrostatic installation diagram is presented in Figure 4.
Fig.4 Hydrostatic installation diagram
The total efficiency of the hydraulic motor is calculated with relation 1 [1]:
ηtm = ηvm ηmm
(1)
where ηtm is total efficiency of the hydraulic motor;
ηvm – volumetric efficiency of the hydraulic motor, ηvm=0,9 ÷ 0,95; it is choose ηvm= 0,9;
ηmm – mechanical efficiency of the hydraulic motor; ηmm= 0,9.
Resulting: ηtm = 0,81…0,85. For the calculation it is chosen: ηtm = 0,81.
Geometrical calculation of the hydraulic motor is calculated with relation 2 [1]:
Vgm =
2π Mr max
102
(pn - pr ) ηmm
(2)
where Vgm is geometric volume of the hydraulic motor, in cm3/rot;
Mr max - maximum resisting moment, Mr max = 30 daNm;
pn – nominal pressure of the hydraulic motor, pn = 210 bar;
pr – the pressure in the return line; pr=4÷5bar;
ηmm - mechanical efficiency of the hydraulic motor, ηmm=0,9.
Resulting: Vgm =102,16 cm3/rot.
It is choose hydraulic motor MRB 125 from Motors Catalog [2], with the following characteristics:
- geometric volume: 125,7 cm3/rot;
- maximum speed: nmax= 475 rpm;
- maximum torque: Mmax = 30 daNm;
- torque on the shaft A: MA = 20 daNm;
- torque on the shaft B: MB = 20 daNm;
- pressure drop: Δp = 175 bar;
- maximum flow: Qm max = 60 l/min.
The oil flow of the hydraulic motor is calculated with relation 3 [1]:
Qm =
Vgmnmh
ηvm
10−3
(3)
where Qm is oil flow of hydraulic motor, in l/min;
28
ISSN 1453 – 7303
nmh - RPM motor hydraulic, nmh = 40÷125 rpm;
ηvm – volumetric efficiency of the hydraulic motor, ηvm= 0,9.
Resulting: Qm = 5,6 ÷ 17,4 l/min.
Total efficiency of hydraulic pump is calculated with the relation 4 [1]:
ηtp = ηvp ηmp
(4)
where ηtp is total efficiency of the hydraulic pump;
ηvp – volumetric efficiency of hydraulic pump, ηvm=0,9÷0,95; it is choose ηvp= 0,9;
ηmp – mecanichal efficiency of hydraulic pump; ηmp=0,9.
Resulting: ηtp = 0,81…0,85. For the calculation is chosen ηtp = 0,81.
Geometric volume calculation of the hydraulic pump is calculated with the relation 5 [1].
Vgp =
1000Qp
np ηvp
(5)
where Vgp is the geometric volume of the hydraulic pump, in cm3/rot;
Qp - assured flow of hydraulic pump Qp = Qm = 17,4 l/min.
np – RPM driving pump, np = 3000 rpm;
ηvp – volumetric efficiency of hydraulic pump, ηvp= 0,9.
Resulting: Vgp = 6,44 cm3/rot
Is chosen hydraulic pump PMV0 - 07 C1 M 00 A0 00 R from Poclain Hydraulic Catalog [3], with the
following characteristics:
-
geometric volume of the hydraulic pump: Vgp = 7,08 cm3/rot;
RPM driving: np = 700÷3600 rpm;
theoretical flow: 25,5 l/min, to 3600 rpm;
operating pressure: 210 bar;
maximum pressure: 300 bar;
inlet pressure: 0,8 bar;
mounting flange: SAE A;
setting: mechanical;
weight:7,5 kg (for setting mechanical).
The calculation of necessary power the hydraulic pump is made with relation 6 [1]
Pp =
Qp pmax
(6)
600 ηtp
Resulting: PP = 4,37 kW
The calculation of the torque consumed by the pump is made with relation 7:
Mp = 973,8
Pp
(7)
np
where Mp is the consumed torque by the pump, in daNm.
Resulting: Mp=1,42 daNm.
29
ISSN 1453 – 7303
3. CONCLUSIONS
Lately it tends to develop technical solutions to achieve tiller that allow much more control
over it safely and effectively, given that it is run and handled directly by the operator. More
specifically, it is the ability to control the speed, so the movement no load, but especially in the
work, knowing that a tiller can work with a very wide range of equipment.
From this point of view it required a much wider range of gear adapted to the work carried
out and the nature and state of the ground work, which is not possible with current versions of
tillers, they generally having only two working speeds, seldom three. To meet these requests,
otherwise justifiable, it was realized a tiller with hydrostatic transmission.
The hydrostatic transmission, with variable displacement hydraulic pump and an orbital
hydraulic motor, replace the mechanical transmission (clutch, gearbox and reducer), thus enabling
a very wide speed range.
An other advantages of the hydrostatic transmission we propose, simplify construction of
the tiller and for the control systems for its operation and will mount easily on the transmission
instead of classical combustion engine.
The disadvantage of the hydrostatic transmission is lower efficiency and higher costs.
REFERENCES
[1] P. Babiciu, V. Scripnic, Al. Fratila, "Hydraulic systems of tractors and agricultural machinery"
Ceres Publishing House, Bucharest, 1984 - pg.45, 239, 241;
[2] M+S Hydraulic-Spool Valve Hydraulic Motors Catalog / Lyra firm;
[3] Poclain Hydraulic Catalog - Variable Displacement Pump Closed Loop Circuit / Lyra firm;
30
ISSN 1453 – 7303
RAINFALL INDICES IN THE CITY OF BUCHAREST
Carmen Otilia RUSĂNESCU
1
University Polytechnic Bucharest, Biotechnical Faculty of Engineering, [email protected]
Abstract: In this paper is analyzed rainfall regime with rainfall indices: the amount of rainfall,
conventional balance of humidity (K), emberger rainfall coefficient.
Specific precipitation amounts are calculated analysis of the ecological factors that characterize
either the period of accumulation of biologically active water horizon (XI-III) or maximum biological
activity (VII-VIII). We performed conventional moisture balance. We calculated the average yearly
rainfall in 2009-2012. We calculated the eco-climatic indices for the city of Bucharest, a city with a
lot of vegetation, parks, and green spaces to highlight issues tend aridity of the region. According
to the data processed, the city of Bucharest has a temperate continental climate. Specific four
seasons, winter, spring, summer and autumn. Bucharest winters are very mild with little snow and
relatively high temperature, while in recent years are very hot summers, very hot with little
precipitation.
Keywords: indices of rainfall, rainfall, annual precipitation
1. Introduction
Bucharest is situated on the banks of Dambovita river that empties in Arges affluent of the Danube.
Several lakes stretch along the river Colentina, within the city, as Floreasca lake Tei and lake
Colentina, and in the center there is a lake in Cismigiu. This lake, former marsh the old medieval
city, is surrounded by gardens Cismigiu, inaugurated in 1847. Besides Cismigiu, there is a number
of large parks: Herastrau (the Village Museum) and the Botanical Gardens (the largest in Romania
and includes over 10,000 species of plants, including exotic) Youth Park, Park Alexandru Ioan
Cuza and more smaller parks and green spaces of the district municipalities [1] .
The climate and topography of the surroundings of Bucharest are very suitable for
agriculture. Growing grain, vegetables and fruit trees. In addition a number of plants growing wild,
damaging crops and which man tries to destroy them (weeds). The forests grow a wide variety of
fungi, ferns and moss. [2].
The meteorological concept of aridity has a temporal reference, is a phenomenon
characterized by low rainfall (period arid, arid year). Currently over a third of Earth's land is
affected by aridity. The main drivers of aridity are: rainfall, temperature, continental, albedo, etc.
[3]. Biogeographic point of view, the lack of water in the soil produces a growth deficit of plant
species and even create large discontinuities in the carpet vegetable.
And other authors have studied their works rainfall in different regions of the world [4,5].
2. Materials and methods
The amount of rainfall is monitored weather station. Technical specifications of precipitation sensor
it is a digital sensor. Measuring range: unlimited; maximum measuring range: 0 to 300 mm / h.
3. Results and discussion
Based on data recorded by the weather station 24 hours out of 24, we performed statistical
analysis, and calculated the amounts of precipitation analysis specific ecological factors
characterize either the period of accumulation of biologically active water horizon (XI-III) or
maximum biological activity (VII-VIII).
The period from November to March is a time of excess water in the soil, the accumulation
of which is very necessary but vegetation structure in the first two stages of vegetative
(germination and sprouting).
31
ISSN 1453 – 7303
High temperatures during this period leading to high values of actual evapotranspiration (Satmari,
2010). Due to the development of all the leaves, the plants are also needs maximum, which results
in the depletion of water from the soil [6].
For weather station in Bucharest, we performed calculations based on data recorded by
station and got the values shown in Figure 2.
Table 1 The amount of rainfall
The amount of rainfall recorded in the month XIX-III 2009
The amount of rainfall recorded in the month VII-VIII2009
319
221.6
185.6
211.2
95.4
128.4
130.3
The sum of precipitation during the cold season of the year represents the total water amount
resulted from both solid and liquid precipitation. The cold season is as important as the warm one
from the pluviometric point of view, as it ensures the water reserve in the soil that is then used
during the first phonological phases. The amounts registered during this interval represents about
35-40 percent of the annual mean, which is about 221.6 mm (2011).
. The highest value is 319 mm in 2009 (Table 1).
The sum of the precipitation amounts during the maximum consumption period represents
the precipitation amount corresponding to the interval July-August, when there are also registered
the highest thermal values. These amounts represent about 19 percent of the annual mean.
Generally, this interval is characterized by long and intensive drought periods. The highest values
are 211.2 mm in 2009 and the lowest values in 2010 of 95.4 mm.
The sum of precipitation during the cold season of the year represents the total water amount
resulted from both solid and liquid precipitation. The cold season is as important as the warm one
from the pluviometric point of view, as it ensures the water reserve in the soil that is then used
during the first phonological phases. The amounts registered during this interval represents about
35-40 percent of the annual mean, which is about 221.6 mm (2011).
The sum of the precipitation amounts during the maximum consumption period represents the
precipitation amount corresponding to the interval July-August, when there are also registered the
highest thermal values. These amounts represent about 19 percent of the annual mean. Generally,
this interval is characterized by long and intensive drought periods. Cele mai mari valori sunt in
anul 2009 de 211.2 mm iar cele mai mici valori in anul 2010 de 95.4 mm.
We perform conventional balance of humidity (K) [7].
P
∑ (T ≥ 10)
(5)
K=
∑T ≥ 10 C
∑ PIV − IX = = 16.8 + 59.4 + 97.2 + 143 + 68.2 + 67.6 = 3.58
=
∑T IV − IX 13.43 + 19.4 + 22.94 + 25.4 + 24.6 + 20.4
∑ PIV − IX = = 52.6 + 119.6 + 102.4 + 69.2 + 26.2 + 33.2 = 3.21
=
∑T IV − IX 13.48 + 21.27 + 20.52 + 24.57 + 26.75 + 19.134
∑ PIV − IX = = 36 + 137.4 + 79.8 + 74.2 + 54.2 + 0 = 3.09
=
∑T IV − IX 12.02 + 17.7 + 22.5 + 24.95 + 24.46 + 21.92
∑ PIV − IX = = 54.2 + 179.8 + 58.4 + 78.4 + 65.3 + 35.4 = 3.69
=
15.4 + 19.5 + 21.3 + 25 + 24.6 + 22.1
∑T IV − IX
0
K 2009
K 2010
K 2011
K 2010
Conventional balance of humidity is favorable climate for the degree of forest vegetation.
Conventional balance of moisture values calculated for 2009-2012 based on the values of air
temperature and rainfall recorded by the weather station, ranged between 3.09 and 3.69 so only
part of the storm water gets up in the soil. We calculated the amount of rainfall recorded based on
station in the years 2009 - 2012 and the maximum rainfall in the same period (figure 1 and 2).
32
ISSN 1453 – 7303
Conventional balance of moisture is favorable climates for the degree of forest vegetation.
Conventional balance of moisture values calculated for 2009-2012 based on the values of air
temperature and rainfall recorded by the weather station, ranged between 3.09 and 3.69 so only
part of the storm water gets up in the soil.
We calculated the amount of rainfall recorded based on station in the years 2009 - 2012
and the maximum rainfall in the same period.
Annual average amount of rainfall in 2009 is 708 [mm/year]
Annual average amount of rainfall in 2010 is 652.2 [mm/year]
The highest value of rainfall was recorded in 2009 by 708 [mm/year]
The smallest amount of rainfall was recorded in 2011 of 510.6 [mm/year]
The highest quantity of precipitation falls in May 2012 = 197.4 mm, 137.4 mm followed by
May 2011.
The least amount of precipitation falling in February 2011 = 12 mm
The maximum monthly = 40.8 mm in August 2009
Monthly Minimum quantity = 0 .4 mm in September and November 2011
250
The rainfall amount 2009, 2010,
2011, 2012
200
150
100
50
2010
2011
ob
er
No
ve
m
be
r
De
ce
m
be
r
Oc
t
Au
gu
s
Se
p
t
tem
be
r
Ju
ly
ay
M
2009
Ju
ne
Ap
ril
ar
ch
M
ry
ru
ar
y
Fe
b
Ja
nu
a
M
on
th
0
2012
45
40
35
30
25
20
15
10
5
2009
2011
be
r
be
r
em
D
ec
em
cto
O
No
v
be
r
t
Se
pt
em
be
r
Au
g
us
y
e
2010
Ju
l
Ju
n
M
ay
il
A
pr
M
ar
ch
ua
ry
Fe
br
Ja
n
M
on
ua
ry
0
th
The maximum amounts of rainfall calculated
for the years 2009-2012
Figure 1 The rainfall amount calculated for the 12 months of the years 2009, 2010, 2011, 2012
2012
Figure 2 The maximum amounts of rainfall calculated for the years 2009, 2010, 2011, 2012
Emberger rainfall coefficient
Q=
100 ⋅ P
M i2 − mi2
(6)
P – average annual rainfall
M – maximum average annual rainfall
m-minimum average annual rainfall
33
ISSN 1453 – 7303
Year
2009
2010
2011
2012
2013
Calculated values for Q
45,25
59,80
70,97
53,19
50,37
Figure 3 Maximum annual rainfall
Figure 4 The amount of rainfall in 2009-2013
Conclusions
We observed that annual average rainfall in 2012 is 721.9 [mm/year] with the highest value
in the range examined.
The smallest value in 2011 of 510.6 [mm/year] followed by the precipitation of 2010 to
510.6 [mm / year].
The highest value of rainfall was recorded in 2009 by 708 [mm/year].
The smallest amount of rainfall was recorded in 2011 of 510.6 [mm/year].
The highest quantity of precipitation falls in May 2012 = 197.4 mm, followed by May 2011, with the
value of 137.4 mm.
The least amount of precipitation falling in February 2011, = 12 [mm].
The maximum monthly = 40.8 [mm] in August 2009.
Monthly minimum quantity = 0 .4 [mm] in September and November 2011.
Maximum amount of rainfall in 24 hours is an important feature of rainfall in Bucharest. The high
frequency of these rainfall especially emphasizes the warm half of the continental climate of the
country. They are generated by a high absolute humidity of the air, the more intense frontal activity
and thermal convection, which stimulates the development of clouds and increase rainfall.
Number of days with precipitation> 0.1 mm during the year is not constant from month to
month. In general, he has a variation that resembles with the annual course of monthly
precipitation amounts. The months with the highest number of days with precipitation are May and
34
ISSN 1453 – 7303
August, and the fewest days is recorded in September and February. Frequency the average
yearly rainfall in the city of Bucharest exceed 110 days.
References
[1] Stănescu SV, Gavriloaie C. (2011) Aspects of the vegetation and fauna Colentina river route from
Bucharest Romanian Ecoterra 27
[2] Stângă IC, Minea I., (2005) Considerations droughts in the Moldavian Plain, Romanian Journal of
Climatology, 1 :367-377; Alexandru Ioan Cuza University Publishing Iaşi
[3] Minea I, Stângă IC., (2004) Analysis of spatial variability of indices for assesing drought risks and
disasters, Volume III :138-149 Book House Science, Cluj Napoca, ISSN 1584-5273
[4] Ghermec O., Ghermec C., Dubovan S., Rusănescu C.O. Improving the environmental performances of
iron powders carburizing process in a methane-bearing atmosphere; Environmental Engineering and
Management Journal October 2013, Vol.12, No. 10, 2019-2023
[5] Peel MC, Pegram GGS, McMahon TA. (2004) Global analysis of runs of annual precipitation and runoff
equal to or below the median: run length International Journal of Climatology, 24, 807–822
DOI: 10.1002/joc.1041
[6] Barbu I, Popa I., (2004) Temperature and precipitation regime in 2003 in the Romanian forests Magazine
forests, 4
[7] Vlăduţ A., (2010) Ecoclimatic indexes within the Oltenia plain Forum geographically. Studies and research
in geography and environmental protection 9 : 49-56 49
35
ISSN 1453 – 7303
STUDY OF THE FLUIDIZED BED HYDRODYNAMICS FROM THE
ENERGETIC BOILERS USING DIFFERENT TYPE OF SOLID PARTICLES
PhD Daniela HOARĂ1, Prof. Gheorghe LĂZĂROIU2
1
Power Engineer Faculty, University “Politehnica” of Bucharest, Romania, [email protected]
2
Power Engineer Faculty, University “Politehnica” of Bucharest, Romania
Abstract: This paper presents the determination manner of the pressure drop, the minimum
fluidization velocity and the floatation velocity of the solid particles in the fluidized beds, depending
on the type of material used and on the size of the solid particles, making a comparison between
the theoretical and experimentally determinations.
Keywords: fluidizing, fluidization minimum velocity, pressure drop in the bed, floatation velocity of
the particles
1. The fluidized bed - introductory notions
Definition
The fluidized bed is a system in which a gas, distributed by a distribution device (grid or jet
nozzles), is expelled, from bottom to top, through a bed of solid particles, so that the particles float
in the gas stream into a constant agitation.
Overview of fluidized bed combustion technology
The basic concept of the fluidized bed combustion technology consists in that in the combustion
chamber is realized a hot bed of solid particles (e.g., coal, coal ash, gypsum, dolomite, calcium
carbonate, silica sand, etc .) and is fluidized by an air flow which is introduced into the outbreak
over to the bottom, keeping the bed in a sustentation state. Due to the layer homogeneity, the fuel
particles are rapidly distributed in bed and are burned rapidly producing heat at elevated
temperatures to generate steam, to heat water or for other technological purposes. Solid particles
are continuously fed in layer and the ash which remains after burning is always removed to
maintain a constant volume of solids in bed. Due to the rapid mixing of the particles layer
respectively due to the higher combustion efficiency, the amount of unburned material layer is low.
For a proper functioning of the layer, it is maintained in the temperature range 750°C÷950°C, the
temperature at which the ash is soft and fine.
Fig. 1 The principle of fluidized bed combustion of the solid fuels
36
ISSN 1453 – 7303
2. Aspects of fluidized bed combustion process
It is assumed that the combustion in the fluidized bed takes place in the same way as the
combustion of a single particle because the carbon concentration in the fluidized bed combustion is
about 1÷2%.
The fluidized bed combustion process for a single particle is performed in four stages:
• heating and drying;
• release and combustion of the volatiles;
• primary fragmentation;
• fuel combustion, secondary fragmentation and abrasion.
The Figure 2 shows in a schematized form this burning process.
Fig. 2 The stages succession for combustion of solid fuel particles [4]
So, it is necessary to analyze the combustion of a single particle before getting an overview of
fluidized bed combustion process, after which may be quantified the results.
In literature there are many models for specific processes (hydrodynamics, heat and mass transfer,
combustion) occurring in steam generators with fluidized bed combustion technology, but their use
must be made with more caution.
3. The fluidized bed hydrodynamics
3.1 Determination of the pressure loss and of the minimum fluidization velocity
The fluidization state represents a biphasic dispersed system, one phase being constituted of solid
particles and gas flowing amongst the particles (dispersion) and a bubble phase, made up from the
gas phase and a small proportion of the solid particles found in sustentation, inside the bubbles. [5]
The fluidized bed, because of its structure and laws, is an intermediate state between two limit
regimes: fixed bed and pneumatic transport. For this reason, its study is approached for
particularizations on the two cases. There is a critical value of the velocity at which it starts to
produce the expansion of a solid phase fraction, while the majority of the particles are still fixed. In
37
ISSN 1453 – 7303
this case, the pressure loss of the gas in the layer is equal to the weight of the solid phase reported
to the surface of the fluidization grid:
∆p mf = (1 − ε mf ) ⋅ (ρ s − ρ g ) ⋅ g ⋅ H mf [Pa]
(1)
where: Hmf [m] is the height of the layer at incipient fluidization conditions;
εmf [-] is the bubbles fraction in the layer at incipient fluidization conditions;
ρs, ρg [kg/m³] represents the density of solid and gas;
g [m/s²] is the gravity acceleration.
In order to determine the pressure loss in a fixed bed with solid particles of diameter dp and
sphericity φs, it is used the Ergun's equation: [4]
∆p
(1 − ε) 2
w
1− ε
w2
= 150 ⋅
⋅η⋅
+ 1,75 ⋅ 3 ⋅ ρ g ⋅
H
φs ⋅ d p
ε3
ε
(φ s ⋅ d p ) 2
(2)
where: η [N⋅s /m²] is the dynamic viscosity of the gas;
w [m/s ] is the gas velocity.
Replacing ∆p/Hmf from (1) in (2) it obtained a criterial relationship from which it can determine the
minimum fluidization velocity:
Ar = 150 ⋅
where: Ar =
1 − ε mf
1
⋅ Re p + 1,75 ⋅
⋅ Re 2p
2
3
3
φ s ⋅ ε mf
φ s ⋅ ε mf
(3)
g ⋅ d 3p ρ s − ρ g
is the criterion of Archimedes;
⋅
ρg
ν g2
Re p =
w ⋅ dp
νg
is the criterion of Reynolds;
νg [m²/s] is the kinematic viscosity of the gas.
For small particles (Rep < 20) predominate the viscous forces, the equation (3) can be simplified,
resulting the minimum fluidization velocity:
w mf =
(φ s ⋅ d p ) 2 ρ s − ρ g
ε3
⋅
⋅ g ⋅ mf [m/s]
η
150
1 − ε mf
(3’)
For larger particles (Rep > 1000) predominate the kinetic energy losses, the minimum fluidization
velocity being approximated with:
w mf =
φs ⋅ d p ρs − ρg 3
⋅
⋅ ε mf ⋅ g [m/s]
1,75
ρg
38
(3”)
ISSN 1453 – 7303
If εmf or φs are unknown, can be made following approximations, valid for a variety of systems: [6]
1− ε
1
≅ 11
≅ 14 and 2 mf
3
φ s ⋅ ε 3mf
φ s ⋅ ε mf
(4)
After replacing in (3), (3’) and (3”) results:
w mf =
w mf =
d 2p ⋅ (ρ s − ρ g ) ⋅ g
1650 ⋅ η
[m/s], if Rep < 20
d p ⋅ (ρ s − ρ g ) ⋅ g
(5’)
[m/s], if Rep > 1000
24,5 ⋅ ρ g
(5”)
In order to calculate the minimum fluidization velocity are given many relationship in the literature
(See Table 1). [7]
Tab. 1 Calculation relationships of the minimum fluidization velocity obtained on the experimentally
way
Minimum fluidization
velocity, wmf [m/s]
No.
Authors
1
Baerg
2
Miller,
Logwinuk
3
Leva
4
Frantz
0,001065 ⋅
5
Davis,
Richardson
0,00078 ⋅
6
Pillai, Raya
Rao
0,000701 ⋅
7
Baeyens
0,361 ⋅
0,00125 ⋅
[d
⋅ ρ s ⋅ (1 − ε mf )
]
d 2p ⋅ (ρs − ρ g ) 0,9 ⋅ ρ 0g,1 ⋅ g
η
d1p, 68 ⋅ (ρs − ρ g ) 0,94
η0,88
d 2p ⋅ (ρs − ρ g ) ⋅ g
η
d 2p ⋅ (ρs − ρ g ) ⋅ g
η
d 2p ⋅ (ρs − ρ g ) ⋅ g
η
d1p,88 ⋅ (ρs − ρ g ) 0,934 ⋅ g 0,934
η0,87 ⋅ ρ 0g, 066
dp [µm]
Remf < 20
6 – 880
--
97 – 249
Remf < 10
51 – 970
Remf < 32
46 – 305
--
--
Remf < 20
58 – 1100
Remf < 10
--
1, 23
ρg
0,0079 ⋅
0,0009 ⋅
p
Validity
domain
3.2 The floatation velocity
The gas flow through the fluidized bed is limited on the one hand by the minimum fluidization
velocity, wmf, and on the other hand by the entrainment of solid particles. When the solid particles
are entrained in the layer, they must be recirculated or replaced with a fresh material to keep the
operation equilibrium. The upper limit of the gas velocity is approximated by the floatation velocity
or by the freefall velocity of the solid particles, which can be estimated from the equilibrium
equation between the gravity force and the particle resistance force at the displacement of the gas
stream:
39
ISSN 1453 – 7303
w pl =
4 ⋅ g ⋅ d p ⋅ (ρ s − ρ g )
3 ⋅ C x ⋅ ρg
[m/s]
(6)
In (6) the coefficient Cx is experimentally determined. An alternative variant for determining the
floatation velocity is to calculate the Cx coefficient for spherical particles, replacing in (6) and
applying some correction factors.
For calculation of the Cx coefficient exist a lot of variants, the most commonly used being the
method proposed by M. Leva: [3][8]
Cx =
18,5
24
for Re < 2; C x =
for 2 < Re < 500;
Re
Re 0, 6
C x = 0,44 for Re < 200.000
(7)
Kuni and Levenspiel propose the same method of calculation with small differences in formulas
and in validity domains: [7]
Cx =
24
10
for Re < 0,4; C x =
for 0,4 < Re < 500;
Re
Re 0,5
C x = 0,43 for Re < 200.000
(8)
4. Results
According to the theoretical method of determining the minimum fluidization velocity respectively
the pressure loss in layer, there were determined its values depending by the variation of the solid
particle diameter (Figures 3 and 4). There were taken into account several types of solid particles
with following densities:
Coal
ρs = 1545 kg/m³
Gypsum
ρs = 2320 kg/m³
Dolomite
ρs = 2872 kg/m³
CaCO3
ρs = 3320 kg/m³
40
ISSN 1453 – 7303
Minimum fluidization velocity [m/s
1,2
Coal
1,0
Gypsum
Dolomite
0,8
CaCO3
0,6
0,4
0,2
6
33
59
86
112
139
165
192
219
245
272
298
325
351
378
405
431
458
484
511
538
564
591
617
644
670
0,0
Particle diameter [µm]
Fig. 3 Variation of the minimum fluidization velocity (theoretically determined) depending by the
particle diameter
Conditions: ρg = 0,4 kg/m3, εmf = 0,45, ηg = 1,5×10-5 Ns/m2
700
Pressure loss [Pa]
600
500
400
300
200
100
6
33
59
86
112
139
165
192
219
245
272
298
325
351
378
405
431
458
484
511
538
564
591
617
644
670
0
Fig. 4 Variation of the pressure loss in layer depending by the particle diameter
Considering the calculation manner of the minimum fluidization velocity in the specific conditions of
fluidized bed combustion (shown in the Table 1), below, there were graphically presented its
values depending by the particle diameter modification, for each solid material taken into account.
41
ISSN 1453 – 7303
0,45
Baerg
Frantz
Davis, Richardson
Pillai, Raya, Rao
Baeyens
Leva
Miller, Logwinuk
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0,00
0
100
200
300
400
500
600
700
800
Fig. 5 Variation of the minimum fluidization velocity depending by the particle diameter, determined
with calculation relationships proposed by various authors
Conditions: ρs = 1545 kg/m3, ρg = 0,4 kg/m3, εmf = 0,45, ηg = 1,5×10-5 Ns/m2
0,45
Baerg
Frantz
Davis, Richardson
Pillai, Raya, Rao
Baeyens
Leva
Miller, Logwinuk
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0,00
0
100
200
300
400
500
600
700
800
42
ISSN 1453 – 7303
0,45
Baerg
Frantz
Davis, Richardson
Pillai, Raya, Rao
Baeyens
Leva
Miller, Logwinuk
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0,00
0
100
200
300
400
500
600
700
800
0,45
Baerg
Frantz
Davis, Richardson
Pillai, Raya, Rao
Baeyens
Leva
Miller, Logwinuk
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0,00
0
100
200
300
400
500
600
700
800
In the Figure 9 it shows the variation of the floatation velocity depending by the particle diameter, in
the specific conditions of the fluidized bed combustion, for the mentioned solids particles.
43
ISSN 1453 – 7303
6
Coal
5
Dolomite
CaCO3
4
3
2
Floatation velocity [m/s]
Gypsum
1
6
33
59
86
112
139
165
192
219
245
272
298
325
351
378
405
431
458
484
511
538
564
591
617
644
670
0
Fig. 9 Variation of the floatation velocity depending by the particle diameter
50
45
Coal
40
Gypsum
Dolomite
CaCO3
Reynolds number
35
30
25
20
15
10
5
6
33
59
86
112
139
165
192
219
245
272
298
325
351
378
405
431
458
484
511
538
564
591
617
644
670
0
Fig. 10 Variation of the Reynolds criterion depending by the particle diameter to determine the
floatation velocity
4. Conclusions
When determining the theoretical values of the minimum fluidization velocity respectively the
pressure loss in layer depending on the particle diameter, using several types of solid materials, it
resulted that: the minimum fluidization velocity values have an increasing trend with rising of the
particle diameter, and also when the material used has an increasingly larger density. In terms of
44
ISSN 1453 – 7303
pressure loss determined under the same conditions, its values increase in the same way as
minimum fluidization velocity values.
Given the results of the calculations of minimum fluidization velocity, shown in the Figures 5, 6, 7
and 8, it is noted that the minimum fluidization velocity has an upward trend with increasing of the
particle diameter. For the whole values range of the particle diameter, it recorded close values
between the curves of Frantz, Davids, Richardson and Pilai, Raza, which also have a pronounced
upward tendency. The curves of Baerg and Leva have maximum values and Baeyens have
minimum values for whole range of values. Since the material is different, it changes its density,
and thus, the minimum fluidization velocity is even higher with increasing of the used material
density. Considering the minimum fluidization velocities found on the experimentally and
theoretically way, for the considered solid materials, it appears that, for the experimentally
determination, the minimum fluidization velocity values are lower than the ones resulted by the
theoretical determination.
From the Figure 9 it is observed that the floatation velocities, calculated for different solid materials
depending on the particle diameter variation, have higher values with increasing of the particle
diameter and of solid material density, taking into account the values of the Reynolds criterion
determined by the particle dimension size (shown in Figure 10).
REFERENCES
[1] V. Athanasovici, "Tratat de inginerie termică – Alimentări cu căldură. Cogenerare”, Ed. Agir, Bucureşti,
2010
[2] C. Neaga, "Tratat de generatoare de abur", Vol 1, Ed. Agir, Bucureşti, 2001
[3] C. Mihăilă, “Procese termodinamice în sisteme gaz-solid şi aplicaţiile lor în industrie”, Ed. Tehnică,
Bucureşti, 1982
[4] Gh. Ivănuş, I. Todea, Al. Pop, S. Nicola, Gh. Damian, “Ingineria fluidizării”, Ed. Tehnică, Bucureşti, 1996
[5] P. Basu, S. Frasier, "CFB Boilers - Design and Operations", Butterworth-Heinemann, 1991
[6] D. Kunii, O. Levenspiel, "Fluidization Engineering", John Wiley&Sons Inc., 1969
[7] S. N. Oka, "Fluidized bed combustion", Marcel Dekker Inc., New York, SUA, 2004
[8] V. Stojkovski, Z. Kostic, A. Nospal, “Determination of the terminal velocity for non-spherical particles”,
Termotehnika nr. 4, Belgrad, 1997
List of notations:
Notation
NOx
SF
Δpmf
εmf
ρs
ρg
g
Hmf
dp
φs
η
w
Ar
Re
νg
Description
UM
Nitrogen oxides
Fluidized bed
Pressure drop of the gas layer
Pa
Bubble fraction in the layer under the incipient fluidization conditions
Density of solids
kg/m³
Density of gas
kg/m³
Gravitational acceleration
m/s²
Layer height under the incipient fluidization conditions
m
Particle diameter
m
Particle sphericity
The dynamic viscosity of the gas
Ns/m²
The gas velocity
m/s
Archimedes criterion
Reynolds criterion
Gas viscosity
m²/s
45
ISSN 1453 – 7303
GENERAL METHODOLOGY OF WORKING WITH HVOF
INTEGRATED TECHNOLOGICAL SYSTEM
Eng. Valeriu AVRAMESCU1, Phd. Eng. Luminita Elena OLTEANU1,
Phd. Eng. Loredana Theodora PAUN1, Phd. Eng. Raluca Magdalena NITA1,
Eng. Daniel BOBE1, Eng. Sebastian ROSULESCU1, Phd. Student Marius MANEA1
1
S.C. ICTCM S.A. – Mechanical Engineering and Research Institute
[email protected]
Abstract: Article "General methodology of working with HVOF integrated technological system"
aims to present some information about the thermal spraying process and all major stages of
working with the integrated technological system for thermal spraying, created in the SC ICTCM Mechanical Engineering and Research Institute, both in the case of metallic coatings for new
pieces and general methodology for working with this system
Keywords: HVOF installation, integrated technological system, thermal spraying process,
spraying parameters, process structure of thermal spraying
1. Introduction
In S.C. ICTCM – Mechanical Engineering and Research Institute - SA by project no. 614 SMIS
code/NSRF: 12537 "Applied researches, technology and technological equipment for high
strength thermal spraying by HVOF process used in industrial and medical applications", cofunded by the Regional Development European Fund, under the contract financing 270/
27.10.2010, in the Operational Programme " Increasing Economic Competitiveness " (SOP IEC),
Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2- „High
scientific level R&D Projects attended by specialists from abroad" with the participation of foreign
experts was conducted an integrated technology system for thermal spraying by HVOF
2. HVOF thermal spraying process.
Thermal spraying consists of a group of processes for making thin layers in which fine powders,
metal or non-metal, is deposited in the molten state to form a coating layer with properties required
of the of the applicability field. The process consists in continuously introducing a mixture of
metallic powder and the axial high pressure gas in a combustion chamber. Thus, in the combustion
chamber, result a high pressure to the combustion of the mixture of the flue gas – oxygen and
especially through the expansion in the combustion nozzle located at the output, resulting a highspeed gas jet. As a result, the metal powder particles are accelerated to very high speeds which
leads to layers of particles deposited with high density and very good adhesion.
Characteristics of the HVOF thermal spraying process are briefly the following:
¾ energy source is the gaseous oxygen and the fuel gas is ethylene, propylene or propane,
and the liquid is kerosene;
¾ flame has the temperature of up to 2700 C and speeds up to 1600 m/s;
¾ the deposited material is powder with particle size of 5-45 μm;
¾ type of powder for deposition: generally are carbides with matrix of metal alloys
¾ speed of particles during deposition: 400-800 m/s;
¾ spray distance: 150 – 300 mm;
The features of layers deposited by HVOF process include superior characteristics to those
deposited by other processes thermal deposition. They are:
¾ high density: normally are obtained porosities lower than 2% and in special conditions,
porosity of 0.2%;
46
ISSN 1453 – 7303
¾ high degree of adhesion to the base material; e.g. typical deposition of carbides such as the
¾
¾
¾
¾
¾
¾
HVOF have the adhesion over 82 MPa, and the materials deposited by this process have
significantly higher adhesion values than the same materials deposited by other thermal
deposition methods in the atmosphere, such as plasma deposition;
high hardness; e.g. a carbide with wolfram and cobalt, with 12% wolfram has typical
microhardness 1100 ... 1350 DHP300;
good fatigue resistance; depending on the chemical composition, the low temperatures of the
deposited material by HVOF may produce coatings with good wearing resistance with
excellent resistance to impact;
greater thickness of layer; HVOF coatings have the thickness of coated layer greater than
plasma coatings, by combustion or by wire to the same material, due to the effect of
flattening the previously deposited layer by increased particle impact at high speed; thus, the
thickness of layers of wolfram carbides can be up to 6.4 mm;
excellent wear resistance; HVOF deposition are resistant to the wear caused by sliding
friction, friction, erosion or cavitation depending on the material and the parameters of
selected process;
superior corrosion resistance; high density and metallurgical properties of layers deposited
by HVOF confer resistance to corrosion effects, including hot corrosion, oxidation and
corrosion of acid and alkaline environments;
very good finishing of the covered surface; HVOF coated surfaces are smooth and can be
used as such in many applications, can also be machined, grinding, lapping, honing or
super-finished to applications that require precise tolerances and very good surface quality.
3. The general structure of a HVOF coating technological process
In general, a metal coating is in one of two situations: applied in the mass production for new parts
or used in the reconditioning process of existing parts.
In the first case all necessary technological parameters are known to meet the technical
requirements of respective pieces, the carried activities being only those of process control.
If it is necessary the development of a new application, in which are known only to the quality
requirements of the future piece are needed research/development activities on both materials that
can be used to cover and parameters of the technological process used. This is the case of this
project, in which is necessary to conduct researches to achieve coatings by HVOF process to meet
the requirements of each application separately.
In figure 3.1 is presented the methodology of research/development of new metallization
applications, valid for HVOF process.
In general, the structure of a thermal coating technology process through HVOF process (High
Velocity Oxygen Fuel) is:
• Prepare surfaces for coating; techniques commonly used for this are the following:
- cleaning the surface;
- formation of the substrate;
- activating the surface;
- masking.
• HVOF deposition of the material layer on the support material;
• Apply treatments/technological operations after depositing material layer; techniques commonly
used for this are the following:
- thermal treatment, which can be:
- electro-magnetic treatment;
- treatment in an oven;
- hot isostatic pressing (HIP);
- remelting with flame;
- impregnation, which can be:
- coating of the surface/seal with organic substances;
- coating of the surface/seal with inorganic substances;
47
ISSN 1453 – 7303
- finishing, which can be:
- grinding;
- polishing and lapping;
Fig. 3.1 – Methodology for the elaboration of new coatings
4. General Methodology of working with the HVOF technological integrated system
In the HVOF technological process one of the most important steps is cleaning the workpiece
surface to remove impurities such as rust, paint residues. This step is performed using a blasting
booth. Blasting is the process of cleaning or finishing through blowing abrasive of metal surfaces.
One of the materials used to blasted is corundum, which is blown by means of a jet compressed
air. Corundum is a mineral classified as hardness 9, second after diamond on the Mohs scale,
because the Moissanite mineral with hardness 9.25 (very rare in nature) is not considered. From
the point of view of the chemical composition is an aluminum oxide with the formula Al2O3. Color is
very varied depending on the existing impurities in the crystal.
The steps of the blasting operation are the following:
- is started the compressor's dryer and is waiting until the indicator reaches on green zone of the
scale;
- is adjusted the compressor’s working pressure from 6 to 7 bars;
- is started the compressor and is waiting until the operating pressure is reached in the
compressed air system;
- is supplied the blasting booth with air and is adjusted the working pressure at 6 bar from the
resident air regulator;
- is started the blasting booth, the pieces to be blasted are putted in the cabin, is pushed the
compressed air filling pedal and is blowed the corundum over the pieces surfaces until they
become cleaned;
48
ISSN 1453 – 7303
- are visually inspected the blasted pieces and is measured the surface’s roughness;
- if the blasted surface quality is adequate, the air supply is interrupted and blasting booth is
stopped;
After preparing the pieces through the blasting process, the thermal spraying process is achieved
by the HVOF process.
For this, perform the following operations:
- pieces for spraying are fixed in clamping brackets mounted in handling devices for pieces with
horizontal shaft (type lathe - between centering peaks mounted in the universal headstock and in
tailstock) and vertical (rotary table – with clamps on the plateau with T channels);
- is started the electrical installation for driving the manipulation devices, is switching on the type
of device used and is started adjusting the corresponding speed to the type of HVOF coverage;
is checked the centering of the fixed pieces in the handling device in question; if the operation is
properly is stoped the handling devices;
- is established on the mobile console of the robot FANUC (teach pendant) the moving program
properly for sprayed pieces, including movement speed and number of passes properly for
thickness layer which will provide, and spray distance specified; is checked the program in
operation mode T1 and AUTO (closes the spray booth door which will be locks by the safety
module "open door");
- is started the PLC control cabinet;
- is started the feeding/dosing powder system and are filled the two cans of the system with
adequate powder properly for cover, in equal amounts (weighed with a precision analytical
balance) depending on the specific consumption/min (tested depending on the speeds dosage
discs from prescription of spray);
- is started the pistol cooling system, is checked the level and is adjusted the temperature of the
cooling water; are opened the water valves flow/return;
- are opened the cylinders of oxygen and nitrogen:
¾ is adjusts the working pressure 20 bar on the oxygen supply system regulator
¾ is adjusts the working pressure 6 bar on the nitrogen supply system regulator
- is ensured sufficient kerosene in the recipient;
- is adjusted to 6 bar pressure for the compressed air used for cooling sprayed parts from the air
regulator found in the gas control cabinet.
After all the above steps have been performed, can be started the HVOF operators console
command:
- is unlocked the emergency stop button on the front panel of the console;
- is inserted the key and turn the power switch on the control panel to the ON position and is
waiting for the computer to start the process and to display the startup menu display command
console;
- the red button "fault" for errors on display will flash warning that there are some errors;
- is setting the program language (ie English), and are admitted errors using the touchscreen
"acknowledge".
- are checking on the display the parameters of the cooling gun system, supply kerosene, supply
oxygen, nitrogen, compressed air and possible gas leaks and kerosene;
- are established the technological parameters of the specific spray recipe: the pressure and the
flow rate of oxygen, nitrogen, kerosene, type of powder used, feeding/dosing powder system’s
speed; the spray recipe is saved with a specific name;
- is pressed the button „Power On”;
- is closed the spray booth door and press the button "Door locked"; lights the lamp "Door locked"
and the door is locked by the user’s safety system module;
- is pressed the button "User safety" and if module safety system is activated, will light the
indicator "Customer safety";
- is started the emissions filter system from the button with three positions on its switchboard (1
emissions filtration installation + inside air introduction system, 2 emissions filtration installation,
3-OFF;
- is started from the specific menu, the compressed air supply of pieces' cooling nozzle;
- is pressed the button "Ignition" and is primed the flame of the spray gun;
49
ISSN 1453 – 7303
- is checked the priming mode (no failures), color (should be blue), focus and continuity of the
flame (flame must be continuous without interruption);
- is pressed the button "Powder Start" then the button "START" and the jet is primed and is
checking the focus (jet must be focused and otherwise modify the flow of nitrogen from two feed
powder) and its continuity (jet must be continuous without interruption);
- is started appropriately handling device and adjust the speed required;
- is started the robot program in operation mode AUTO;
- after spraying is pressed the button "Stop Powder", "STOP";
- is waiting about 15 min for cooling pieces then is stopped the feeding of cooling nozzles and
emissions filtration system;
- is stopped the device for handling pieces, from the electrical installation of drive devices;
- is pressed the button "Door unlocked" and can enter in the spray booth;
- is rotated the key in the power switch on the control panel to the OFF position;
- are removed the pieces from the handling device and are controlled the parameters of the
sprayed layer: thickness, hardness, adhesion, porosity, metallographic structure.
5. Methods of characterization and control of HVOF deposited layer
In general the HVOF deposited layers are characterized by strong links with the base and a good
quality and porosity of the surface. Thus, for wolfram carbide can be achieved resistances to
separation of 90 MPa with porosity of less than 1%.
The characterization of deposited layers by metal coatings is important for: research/development
activities for a new product or quality control in production. The easiest way to control the quality of
the surface is a careful visual observation of it. Such a method allows the detection of defects such
as incomplete coverage of the entire surface or superficial cracks.
More advanced methods for the surface investigation are those of analysis of the microstructures
that are made by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron
microscopy by transmission (TEM), porosimetry by inclusion of mercury (MIP) or other techniques.
The properties of the metal coating cause its behavior during use. The best test is done under
conditions that simulate actual conditions of use of the piece. The mechanical properties such as
microhardness, tensile strength and modulus of elasticity, wear-resistance are often determined.
Thermophysical properties and in particular the thermal conductivity, usually determined by
measuring the expansion to 300 K, specific heat and diffusivity are frequently tested. These tests
are frequently accompanied by tests of resistance to thermal shock. Magnetic and electrical
properties of the coating are frequently tested. Non-destructive tests such as the use of thermal or
acoustic waves have been introduced to characterize the quality of the coating. Finally many
properties are closely interlinked so it is possible to measure a property by determining another.
An example for determining of a property by another's measuring is correlation between anisotropy
of NiCr coatings, electrical conductivity and modulus of elasticity. These properties interlinked
helps to reduce the number of tests required.
The methods for characterization of metal coatings are the following:
1) Methods for characterization of the microstructure: chemical analysis; crystallographic analysis;
analyzes of the microstructure;
2) Methods for characterization of mechanical properties: determination of the adhesion;
determination of the hardness and microhardness; determination the modulus of elasticity,
friction resistance, ductility; properties related to fracture mechanics of the metal coatings;
determination of the resistance to friction and wear; determination of residual stresses;
3) Methods for characterization of physical properties: determining the thickness, porosity and
density; determining thermophysical properties; determining resistance to thermal shock;
4) Methods for characterization of electrical properties: determination of electrical conductivity;
determination of dielectrics properties; determination of electron emission from surfaces;
determination of wet corrosion; determining gaseous corrosion (hot gas);
5) Methods for characterization the quality of the metal coatings: acoustic methods; thermal
methods.
50
ISSN 1453 – 7303
6. Hydraulic and pneumatic applications
HVOF process has extensive applications in highly various domains, but it is important to specify
the particular applicability of the HVOF deposition both in the domains of the hydraulic components
and the pneumatic. Special properties required by the environment and operating conditions are
ensured by HVOF process for the components of hydraulic or pneumatic cylinders, valves, pumps,
taps and other hydraulic/pneumatic components which can equip building machinery, forestry
machinery, agricultural machinery, equipment and industrial installations etc.
In the case of a hydraulic or pneumatic cylinder, there are surfaces that can be deposited in
different ways to obtain the functional properties of the cylinder - deposits can be specific for rod or
pipe, or piston, or cap but their combination and the final result provide getting a high quality
product with very good durability, extremely reliable in operation.
The HVOF depositions give them specific properties both at the manufacturing stage, as new
product, but and as reconditioning able to provide at least the initial quality of the remanufactured
parts. Increased service life, is a considerable advantage but and the providing of special
tribological properties, or adherence or porosity and wear resistance are equally important.
Finally, an important aspect is the opportunity to research obtaining of a specific deposition, a
specific requirement, or a plurality of requests, the process can be optimized.
7. Conclusions
By the project "Applied researches, technology and technological equipment for high strength
thermal spraying by HVOF process used in industrial and medical applications", was developed a
technological system - prototype - technological equipment and laboratory equipments - which
allows performing of the applied researches to achieve high mechanical strength metal coatings,
thermal, anticorrosive on materials used industrial or medical applications using HVOF process
(High Velocity Oxygen Fuel). Also the conditions of market access were created for the new
technological system by conducting theoretical and applied researches of the optimal technological
parameters for solving practical requirements of industry and the production of medical equipment.
Characteristics of the HVOF thermal spraying process are briefly the following:
¾ energy source is the gaseous oxygen and the fuel gas is ethylene, propylene or propane,
and the liquid is kerosene;
¾ flame has the temperature of up to 2700 C and speeds up to 1600 m/s;
¾ the deposited material is powder with particle size of 5-45 μm;
¾ type of powder for deposition: generally are carbides with matrix of metal alloys
¾ speed of particles during deposition: 400-800 m/s;
REFERENCES
[1] Technical Documentation GTV Coating System HVOF-MF-K 1000, Project ICTCM, 662.013
[2] "Study regarding the theoretical determination of specific technological parameters for HVOF process on application"
project no. 614 SMIS code/NSRF: 12537, contract no.: 270 / 27.10.2010, project "Applied researches, technology and
technological equipment for high strength thermal spraying by HVOF process used in industrial and medical applications
-“TEHVOF” ", Sectoral Operational Programme " Increasing Economic Competitiveness ", Priority Axis 2,Operation 2.1.2„High scientific level R&D Projects attended by specialists from abroad”, co-funded by the Regional Development
European Fund,
[3] “Research on identifying applications and parameters specific to HVOF process - Study on the determination of spray
materials used in each case”, project no. 614 SMIS code/NSRF: 12537, contract no.: 270 / 27.10.2010, project "Applied
researches, technology and technological equipment for high strength thermal spraying by HVOF process used in
industrial and medical applications -“TEHVOF” ", Sectoral Operational Programme " Increasing Economic
Competitiveness ", Priority Axis 2,Operation 2.1.2- „High scientific level R&D Projects attended by specialists from
abroad”, co-funded by the Regional Development European Fund,
[4] *** Thermal spray materials guide, SULZER – METCO
[5] *** Surface technology, H.C.STARK
[6] *** HVOF and thermal spray powders, DELOR
51
ISSN 1453 – 7303
CABIN HEAT REMOVAL FROM PARKED CARS
Assoc. Prof. Ph.D. Adrian CIOCANEA 1 , Lect. Ph.D. Dorin Laurenţiu BUREŢEA 1
1
University Politehnica Bucharest, [email protected]
Abstract:The paper presents a solution for designing an intelligent and modular solar energy
system for heat removal from parked car cabins. We propose a ventilation system composed of
two pairs of cross flow fans, one placed under the car roof cabin between the steel plate and the
indoor insulation and the second under the rear shelf of the back seats. The cabin was exposed to
the sun radiation (600-800 W/m2) with no wind. Indoor temperature and humidity were measured
with no ventilation. The data was used to design the cross flow fans. The air flow rate needed for
an efficient ventilation was calculated at 0.02 m3/s, a value compatible with other results in the
literature.
Keywords: car ventilation, solar energy, cross flow fan
1. Introduction
The increase of the air temperature inside car cabins, especially when parked under
intense solar radiation, has some negative impact such as: low thermal comfort and some health
risk for the passengers, increased fuel consumption when restarting the air conditioning for
reducing the indoor temperature and lowering the quality of the cabin materials like plastics, foams
or artificial leather, rubber, synthetic fiber etc.
Concerning the health risk for the passengers, research was performed in order to highlight
the risk of human exposure to volatile organic compounds (VOC) especially in the case of new
cars [1]. Even if some studies state that “the smell of the new car”wears off in a matter of weeks or
months [2], the process of VOC elimination, also responsible for the indoor air quality, is not
confirmed. For example, the toluene and xylene concentration inside cars declines from 200 to 60
μg/m3 and from 250 to 30 μg/m3 respectively in 20 days but these VOCremain present [3]. Also,
research shows that for some VOC the concentration varies in time and is dependent on indoor
temperature, humidity, ventilation efficiency, age of the car (where poor sealing allows exhaust
gases to enter the cabin)and other conditions such asclimate etc. In close relation with the above,
we know that in an automobile of 1000 kg weight, about 100 kg consists of plastics –50% of the
total internal components including safety subsystems, doors and seat assemblies. Also, 13 types
of polymers are used in an automobile - 66% of these are polypropylene (32%), polyurethane
(17%) and PVC (16%) [4]. Statistics estimate that people spend about 7% of their day commuting
between home and workplace [5], or even more if vehicle’s cabinis in fact their workplace(the case
of professional drivers). Hence automobile drivers are exposed to organic hydrocarbons.
Concentrations reported in the passenger cabins are about 13 to 560 μg/m3 for benzene, 33 to 258
μg/m3 for xylene and 3 to 23 μg/m3 for trimethylbenzene [3]. The
μg/m3 for toluene, 20 to 250
accepted values for the environment are 2–150 μg/m3 for toluene and 5–20 μg/m3 for benzene
(European Chemicals Bureau, 2003 a,b; World Health Organization, 2000). For new cars, studies
[6-7] report average concentrations values of 11.8 μg/m3, 82,7μg/m3, 21,2 μg/m3 and 89,5 μg/m3
for BTX - benzene, toluene, o-xylene and m,p-xylene respectively. In used cars, BTX concentration
values are higher and relevant deterioration of data was reported for more than 11.000 km.
Concerning the passenger thermal comfort, some research was performed in order to
evaluate the interaction between the human body and indoor cabin conditions. For this, a “human
body defragmentation”in 16 static elements was proposed [9] for which mass and heat exchange
was measured between these elements and cabin components. It was reported that nonuniform air
and temperature distribution are the cause for local high discomfort for passengers. Other studies
propose intelligent ventilation of the cabin when the car is parked [10]. For some case studies
52
ISSN 1453 – 7303
windshields are consideredas the main gate for solar radiation access and for this hypothesis
some extreme heat surfaces were identified in order to be first/intensely ventilated. Still, existing
studies do not provide clear results regarding efficient solutions for cabin ventilation, since
experimental results are not convergent with theoretical models [11].
Concerning the fuel consumption it is known that when restarting the air conditioning
system over a parked period under high solar radiation, the car engine will request more fuel than
under normal conditions (related to rated engine temperature). Hence high engine fuel
consumption will be registered untilindoor conditions becomesuitable for passenger comfort. The
above reasons constitute a good motivation for studying an efficient ventilation system also for
reducing house effect in the cabin.
According to the above assumptions, we propose an original solution for cabin heat
removal from parked cars by using an intelligent solar modulated system equipped with crossflow
fans.
2. The ventilation system
For the ventilation of passenger cabins some solutions propose independent units with
simple structuresuch as lateral windows fans [12-14] or roof window fans [15] powered by solar
photovoltaic panels. Another solution is given by considering complex ventilation systems
included in the ventilation structure of the cabin. For example some systems are placed on the
roof of the car [16-17] in the exterior as shown in figure nr. 1 a, b or inside the car [7-9] as shown
in figure nr. 2 a,b,c; the case “c”pictures a ventilation through the car trunk.
The solutions for ventilation systems are only to some extent compatible with theoretical
results as presented in the first chapter. This is because most of the ventilation solutions are
focused just on exhausting the heat air form the car cabin neglecting the indoor region where
temperature is rising excessively–for example the front shelf. On the other hand, theoretical
studies depend on some special border conditions in order to provide numerical solutions –for
example the sun azimuth. Due to such a hypothesis, some theoretical results are not suitable to
be used for selecting practical solutions –for example some studies consider the high
temperature region to be on front shelf, other results consider this region as between the front
and back seats.
a.
a. b.
Fig. 1 External vehicle ventilation units
Top window cabin unit [16]; b. Air extraction unit [17]
53
ISSN 1453 – 7303
a.
b.
Fig. 2 Internal vehicle ventilation systems
a.b. Top cabin system [18-20]; c. Trunk system [21]
c.
According to these conclusions one has to decide the optimum position and size of the fans
and to design the ventilation system in terms of electrical and operating demands.
The present paper presents a solution to these problems by considering that the best method
to remove the car cabin heat is to avoid, as much as possible, the rise of the indoor temperature.
Hence one propose a modular ventilation system. Two cross flow fans are to be positioned on the
top front of the cabin–under the car roof cabin between the steel plate and the indoor insulation and the other two under the rear shelf of the back seats. The main idea is to avoid temperature rise
by ventilating the car roof - which is the highest surface exposed to the sun –and at the same time
to remove the indoor heat through the rear of the cabin using the trunk in the same conditions as
before. The positions of the fans and the system are presented in figure nr. 3. A Ford Mondeo
cabin was considered for the preliminary experimental research i.e. monitoring the indoor
parameters –temperature and humidity–and outdoor parameters –air temperature and external car
roof temperature.
a.
54
ISSN 1453 – 7303
b.
c.
d.
e.
Fig. 3 The proposed ventilation system
a.
Structure of the ventilation system; b. Front cross flow fan (A); c. Roof cabin
extraction unit (B);d.Rear cross flow fan (C); e. The trunk extraction unit (D)
3. Experimental research
The cabin was exposed to the sun radiation –600-800 W/m2- with no wind. Indoor
temperature and humidity were measured with no ventilation. In the cabin, the temperature and
humidity were measured at the level of the driver; the outdoor thermometer for measuring the
temperature of the steel roof was positioned at 5mm distance from it. The measurements had a 15
min frequency. Table nr. 1 shows the results. The data corresponds to the values of the indoor
temperature provided by the literature –(60-65) 0C –which is reached in about 70 min. after the
moment of parking the vehicle. The gap between indoor, outdoor and roof steel temperature is
presented in figure nr. 4.
Table 1.
Temperature and humidity inside the car cabin
Time
T out
[0C]
Tin
[0C]
Tsteel
[0C]
urel
[%]
H
[W/m2]
1230
40.0
32.8
40.0
35.0
728
12
45
40.2
34.9
46.6
31.3
738
13
00
40.6
45.2
66.0
22.4
746
13
15
40.8
51.5
66.0
18.1
788
13
30
40.9
56.5
61.0
15.5
785
55
ISSN 1453 – 7303
1345
41.5
59.1
62.5
14.6
790
1400
42.7
61.0
64.3
14.1
780
1415
42.7
61.0
62.7
13.8
752
1430
43.4
64.3
63.6
13.6
747
1445
43.6
64.8
64.6
13.4
727
1500
45.1
65.6
66.3
13.4
714
1515
45.8
65.9
66.3
13.4
704
1530
46.7
65.8
66.3
14.0
688
Fig.4 The gap between tindoor , toutdoor and tsteel
It can be observed that after 60 minutes the gap is 4.5 0C and after 90 minutes the gap remains
constant at about 2-3 0C. It is also clear that the ventilation system must start after about 25 min
after parking the car.
In order to design the cross flow fan it is necessary to evaluate the air velocity in the
channel (see figure 3.b). Using the average values of the data presented in table nr. 1 we consider
that all the heat transferred from the roof to the channel is removed through section B. As the
physical model is similar with that of plane solar heat collectors one can use the same
mathematical approach: the roof channel describes a plain solar heat collector with internal flow.
The dimensions are L x l x b = (1,3 x 1 x 0,03) m, where “b”is the diameter of the fan rotor and has
to meet the ventilation requirements. If the efficiency of the installation is⎜c = 0,5, assuming a good
evacuation of the heat, velocity value and the air flow through section B can be calculated. Using
the classical formula for the heat flux:
Q = ©air xcpair l x b x v x (t in - tout)
and:
⎜c = Q/ (L x l x H),
1
2
we obtain the value for air velocity “v”. For the present case study, if average values are H = 750
W/m2and (t in - tout) = 200 C, the velocity average value is v = 0,65 m/s and the air flow rate is 0,02
m3/s. The obtained values are compatible with recent theoretical research [21] where the authors
obtained an air flow rate of 0,023 m3/s for the case of heat removing from a car cabin by using a
numerical method (thesestudies were performed between the same time of the day). As the
results are similar both for the roof channel (experimental) and cabin (theoretical from the
literature) we propose the same dimensions for the rear cross flow fans of the cabin.
56
ISSN 1453 – 7303
Figure nr. 5 shows an example of an available the cross flow fans. The technical solution for the
case study consists in two pairs of fans with a single motor for each pair.
Fig. 5 Cross flow fan
(drotor=30 mm; A=160 mm; B=170 mm; C = 194 mm; Rated voltage =12 V; Rated current = 0,2 A; Speed
=3,200 RPM; Max. Pressure = 1.5 nnH2O; Air Flow = 0.8 m2/min; Noise = 37 dB; Weight = 230 g)
The fans are selected for parallel operation, doubling the available flow rate. If longer rotors
(A) are used, more air flow can be obtained. The two ventilation modules are powered by solar
photovoltaic cells positioned on the roof of the auto vehicle and assisted by an automation system
–as presented in figure nr. 6 -providing variable rotating speed for the fans according with the
indoor temperature and the external temperature of the steel roof –related with the solar radiation.
Fig. nr. 6 Automation system
1. Photovoltaic cells; 2. DC to DC Converter – Switched Mode; 3.Temperaturesensors; 4.Humidity
sensors; 5.Car Battery; 6.Automation Unit; 6.1.Measurement Unit; 6.2.Microcontroller Unit;
6.3.SMPS
(Switched Mode Power Supply) Variable Speed Fan Motor Driver; 7. Fan Motor 1; 8. Fan Motor 2.
As the humidity is decreasing in the cabin car during the parked period, a method for
improving the passenger comfort after restarting air conditioning is needed. Further research will
be focused on controlling humidity vs. temperature in the cabin car.
The presented system has low economic impact on vehicle price. From an economic point
of view, the cost of the system is approx. 250 Euro since the double cross flow fans cost is 100
Euro.
57
ISSN 1453 – 7303
Conclusions
The paper presents a solution for designing an intelligent and modular solar energy system
for heat removal from parked car cabins. We propose a ventilation system composed of two pairs
of cross flow fans, one placed under the car roof cabin between the steel plate and the indoor
insulation and the second under the rear shelf of the back seats. The cabin was exposed to the
sun radiation with no wind. Indoor temperature and humidity were measured with no ventilation.
For a 750 W/m2 average solar radiation the air flow rate needed for an efficient ventilation was
calculated at 0,02 m3/s, a value compatible with other results in the literature.From an economic
point of view, the cost of the system is approx. 250 Euro since the double cross flow fans cost is
100 Euro. Further research will be focused on controlling humidity vs. temperature in the cabin car.
REFERENCES
[1] Mandalakis M., Stephanou E. G., Horii Y., Kannan K., 2008. Emerging contaminants in car interiors:
Evaluating the impact of airborne PBDEs and PBDD/Fs. Environmental Science and Technology,
42(17): 6431–6436.
[2] Johansson I., 1999. The role of volatile organic compounds in the assessment of indoor air quality.Ph.D
thesis.Institute of Environmental Medicine, KarolinskaInstitutet, Stockholm.
[3] Schupp T., Bolt H. M., Jaeckh R, Hengstler J G, 2006. Benzene and its methyl-derivatives: Derivation of
maximum exposure levels in automobiles. Toxicology Letters, 160(2): 93–104.
[4] http://www.plasticsconverters.eu/organisation/division / automotive -cit. on 30.4.2010
[5] Kadiyala A., Kumar A., 2012. Development and application of a methodology to identify and rank the
important factors affecting in-vehicle particulate matter.Journal of Hazardous Materials, 213-214: 140–
146.
[6] Moriske, H.-J., 2002. Luftqualitaet in Innenraeumen von Verkehrsmitteln. Bundesgesundheitsbl
Gesundheitsforsch Gesundheitsschutz 45, 722–727.
[7] Faber, J., Brodzik, K., Golda-Kopek, A., Lomankiewicz, D., 2013, Benzene, toluene and xylenes levels in
new and used vehicles of the same model. Journal of Environmental Sciences 2013, 25(11) 2324–2330.
[8]World Health Organization, 2000.Air Quality Guidelines for Europe.WHO regional publications,
European series, No. 91, ISSN 0378- 2255.
[9] Kaynakli, O., Kilic, M., 2005, An investigation of thermal comfort inside an automobile during the heating
period, Applied Ergonomics 36 (2005), pp. 301–312.
[10] Huang, K.D., Tzeng S-C, Ma, W-P, Wu, M-F, 2005, Intelligent solar-powered automobile-ventilation
system, Applied Energy 80 (2005) 141–154.
[11] Marcos, D., Pino, F.J., Bordons, C., Guerra, J.J., 2014, The development and validation of a thermal
model for the cabin of a vehicle, Applied Thermal Engineering 66 (2014), pp. 646-656.
[12] Wolfe, R.P., Callaghan, J.K., Pidgoen, S., 1990, Solar Powered Ventilator, U.S. Patent 4,899,645.
[13] Biancone, M.R., 2002, Ventalation system for an interior of the motor vehicle, U.S. Patent 6,435,961.
[14] Lesle, M.J., 2011, Through glass ventialtion, US 2011/0151761 A1.
[15] Fermont, R., 1989, Ventilation device, U.S. Patent 4,800,803.
[16] Smith, M.A., Smith, C.Y., 2007, Vehicle roof mounted air extraction unit, GB 2429518 A.
[17] Amrhein, W., Scharf, F., Bauer, W., 1988, Device for ventilating vehicle compartments ,EP 0256313 A2.
[18] Clenet, A.J.-M., 1992, Vehicle vent, U.S. Patent 5,081,912.
[19] Snow, C.E., 2004, Solar powered heating and ventilation system for vehicle, US 6,692,130 b1.
[20] Cui, Z., 2012, Vehicle parking idling solar air intercharger, CN 201220435932.
[21] Leong, J.C., Tseng, C.-Y., Tsai, B.-D., Hsiao, Y.-F., 2010, Cabin Heat Removal from an Electric Car,
World Electric Vehicle Journal Vol. 4 - ISSN 2032-6653.
58
ISSN 1453 – 7303
INTEGRATED TECHNOLOGICAL SYSTEM FOR THERMAL SPRAYING
BY HVOF PROCESS
Phd. Eng. Theodora Loredana PAUN1, Eng. Valeriu AVRAMESCU1,
Phd. Eng. Raluca Magdalena NITA1, Eng. Daniel BOBE1, Eng. Sebastian ROSULESCU1,
Phd. Eng. Elena Luminita OLTEANU1, Phd. Student Marius MANEA1
1
SC ICTCM – MECHANICAL ENGINEERING AND RESEARCH INSTITUTE,
[email protected]
Abstract: The paper "Integrated Technological System for thermal spraying by HVOF process"
presents technological system aims, system that includes both technological equipment and
laboratory equipment. It can thus perform applied research to achieve high strength metal
coatings, thermal, corrosion on materials used in both industrial and medical applications using
HVOF process. It is also possible to create the conditions of market access for new technological
system by conducting theoretical and applied research of the optimal technological parameters for
solving practical requirements of industry and the production of medical equipment.
Keywords: HVOF, technological system, technological parameters, thermal spraying, industrial
robot
1. Introduction.
In S.C. ICTCM – Mechanical Engineering and Research Institute - SA by project no. 614 SMIS
code / NSRF: 12537 "Applied researches, technology and technological equipment for high
strength thermal spraying by HVOF process used in industrial and medical applications", cofunded by the Regional Development European Fund, under the contract financing 270 /
27.10.2010, in the Operational Programme " Increasing Economic Competitiveness " (SOP IEC),
Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2- „High
scientific level R&D Projects attended by specialists from abroad" with the participation of foreign
experts was conducted an integrated technology system for thermal spraying by HVOF process.
2. HVOF thermal spray process.
Thermal spraying is made up of a group of processes for making thin layers in which fine powders,
metal or non-metal, is deposited in the molten state to form a coating layer with properties required
of the user. The method includes continuously introducing a mixture of metallic powder and axial
gas pressure in a combustion chamber. In the combustion chamber results a high pressure from
the combustion of a mixture from gas - oxygen, and by expansion in the combustion, which is
located at the output, results the high speeds of the gas flow. As a result, the metal particles from
the powder are accelerated at a high speed which results in layers of particles made with high
density and good adhesion.
The characteristics of HVOF thermal spray process are briefly the following:
¾ energy source is oxygen in gaseous form and the fuel gas is ethylene, propylene or
propane, and the liquid is kerosene;
¾ the flame has a temperature of up to 2700 C and the speeds up to 1600 m / s;
¾ the deposited material is a powder with particle size of 5-45 μm;
¾ type of the deposited powder is: carbide with metal alloys matrix;
¾ particle velocity during deposition: 400-800 m/s;
Charasterics of the deposited layers by HVOF process are superior characteristics toward to those
deposited by other processes of thermal deposition. They are:
59
ISSN 1453 – 7303
¾ high density: is obtained, generally less than 2% porosity and special conditions up to 0.2%
porosity;
¾ high adhesion with the base material; for example, the fuel HVOF deposition are typically
above 82 MPa adhesion, and other materials made by this process have significantly higher
adhesion values than the same materials made by other methods of thermal deposition
atmosphere, such as plasma deposition;
¾ high hardness; eg tungsten and cobalt carbide, with 12% tungsten has a typical
microhardness about 1100 ... 1350 DHP300;
¾ good fatigue resistance; depending on the chemical composition, the low temperatures may
cause a good wearing resistance and a high impact resistance of the deposited material by HVOF
process;
¾ it has a greater thickness; the layers coated by HVOF process hahavea greater thikness than
plasma coatings by combustion or by wire to the same material, due to the effect of flattening the
rule previously filed by increased particle impact at high speed; thus, the thickness of layers of
tungsten carbides can be up to 6.4 mm;
¾ excellent wear resistance; HVOF coatings are resistant to the wear caused by sliding friction,
abrasion, erosion or cavitation depending on the material selected and the process parameters;
¾ superior corrosion resistance; due to the high density and metallurgical properties of coatings
deposited by HVOF confer resistance to corrosion effects, including hot corrosion, oxidation and
corrosion of acid and alkaline environments;
¾ good finish surface covered; HVOF coated surfaces are smooth and can be used as such in
many applications, can also be machined, ground, lapping, honing, lapping or super-finished for
applications that require precise tolerances and a high quality surface.
3. HVOF laboratory. Main components: features and functionality
The laboratory is a technological system - prototype - which allows applied research in order to
achieve high strength metal coatings, thermal, corrosion on used materials, industrial and medical
applications using HVOF process, for which they were provided the following equipment and
accessories: blasting cabin, compressor, thermic spray cabin, parts handling devices (horizontal
axis and vertical axis connected to the exhaust system and exhaust filter) FANUC robot M-20i
model, a filtration system exhaust and ventilation ducts, technical gases and distribution networks,
security system for containers and HVOF accessories, thermal spray equipment.
3.1 Vacuum Sandblaster acquired by ICTCM is a FERVI-0687 and has the following
characteristics and equipments:
• Chamber dimensions ………………………………………… 1200x600x600 mm;
• Operating pressure …………………………………………… 6,5-7,5 bar;
• Air consumption………………………………………………. 630 l/min;
• Ø gun nozzles (mm)………………………………………….. 6-7 mm;
• Filtration rate …………………………………………………. 5 micron;
• Operating power ……………………………………………… 1200 W/230 V;
• Power supply …………………………………………………. 230v/ 50 Hz;
• Mass……………………………………………………………. 147 kg;
• External dimensions …………………………………………. LxlxH=1220x910x1740 mm;
• Sandblasting gun with sand jet;
• Side doors an both parts and access on the superior part;
• Illuminating system at the inside with blasting protection;
• Exhausting system and residual dust filtering;
• Closed system with retrieving, filtering and recycling of the abrasive material;
• Separatinf filter for water;
• Pedal with pneumatic command;
60
ISSN 1453 – 7303
Fig. 3.1 Integrated technological system for thermal spraying by HVOF process
The surfaces of parts that will be coated by HVOF process, thay are blasted in order to remove
oxides, slag, and to obtain rough to ensure good adhesion of deposited dust layer. The
sandblasting consists of shelling the surface with abrasive particles (corundum) of various grain
sizes, driven by compressed air produced by a compressor.
The sandblasting cabin and the compressor are located (in order to reduce the compressed air
routes) in the room adjacent to that in which they are spray equipment.
3.2
Screw air compressor is ESM 7TK type and has the following technical and functional
parameters:
• Lifting pressure …………………………………………..................... 7,5 bar;
• Operating pressure ……………………………………………………. 7 bar;
• Effective discharge ……………………………………………………. 1320 l/ min;
• Tank capacity …………………………………………........................ 270 l;
• Nominal Motor rating …………………………………………………. 7,5 kw;
• Total absorbed power at operating pleasure ………………………. 9,58 kw;
• Total absorbed power without charge ………………………………. 3,1 kw;
• Voltage (frequency) …………………………………………. 400 VCA- triphased 50 Hz.
The screw air compressor is dotted with drying machine air system by refrigerating, with the
following characteristics:
• Dew point ……………………………………………………… +3°C;
• Voltage ………………………………………………………… 220VCA monophased-50 Hz;
61
ISSN 1453 – 7303
•
•
Consumed power …………………………………………….. 0,28 Kw;
Cooling agent …………………………………………………. R134A.
3.3
In the spraying cabin are placed the working piece manipulations and the robot on witch
arm is mount the spaying gun. It has the following features.
• Working space ……………………………………..... L x l x h = 4300 x 3550 x 2500 mm;
• Access through a door in 2 leafs…………………… L x l = 2500 x 2000 mm;
• It is dotted with two windows with thermo glasses for watching the process and for interior
illuminating with two fluorescent lamps;
• Walls of 100 mm thickness from galvanised sheet and sound absorbing material sandwich.
On the cabin ceiling it is mount an air recirculation system with the following characteristics:
• Ventilation System………………………………………………BOX BV12/12 2,2 kw;
• Flow ………………………… 5100 mc/ hour (with an initial pressure falling 45 daPa)
• Electric supply…………………………………………………. 400VCA- triphased-50 Hz
• Ventilation piping and dispersion from galvanised sheet, filter G Class
The sparying cabin is designed to protect personnel from the noise, nuisance and high
temperatures that emit during the thermal spraying operation and is located inside the laboratory
HVOF of ICTCM. Inside there are the handling devices and the robot that on its arm is fixed the
sparying gun. The spraying cabin dimensions are LxWxH = 4300x3550x2500 mm. The cabin is
fitted with an access door in two leaves, which are mounted sensors do not allow the operation of
the spray and the robot when the door is open.
Also, the cabin is equipped with two double glazed windows through which operators can track the
process.
3.4 The handling device of parts with horizontal axis is used for parts with maximum diameter
of 300 mm and maximum length of 1200 mm. They get at the head of a universal right and the left
in a rotating top. The universal is driven to the right speed by a worm gear.
3.5 The handling device of parts with vertical axis is used for parts with maximum diameter of
500 mm and maximum length of 1000mm. It consists of a tilting rotary table driven by an electric
motor mounted on a stand.
3.6 Fanuc Robot, model m-20I A
• Type…………………………………………………………….. articulated
• Number of controlled axes …………………………………… 6;
• Repeatability…………………………………………………… ±0,8 mm;
• Working load …………………………………………………. 20 kg;
• Working area …………………………………………………. 1811 mm;
• Montage………………………………………………………….Vertical, on the ground
Robot controller:
• Command cabinet equipped with programming and command functions for the manipulator,
programming console;
• Mobile console for programming for the operator;
• Safety/blocking system for open door of the spraying cabin;
• Collision detection module;
• Electric supply ……………………………………….. 200-230 VCA +10% -15% 50 Hz;
• Medium consumption power ……………………….. 1 kw.
The robot is necessary for handling system of a thermal spray equipment by HVOF process (High
Velocity Oxygen Fuel). The robot operates in a cabin in which there take place the HVOF
deposition process, and on the robot’s arm is fixed the sparying gun for metallization and supply
hoses following specific process gas and liquid: oxygen, kerosene, metallizing powder mixed with
nitrogen, cooling water . The robot’s task is to handle the the gun, as a program, for a wide the
wide range of geometrical configurations and sizes there of: cylindrical, rectangular, etc. The robot
is located and mounted so as to include in its work space handling devices with vertical axis and
horizontal axis (rotary table) that are set pieces that will be covered by metallization.
3.7 Exhaust gases filtering system and evacuation pipes system
• Integrated ventilation system…………………………………………… ART 502 7,5 kw;
62
ISSN 1453 – 7303
•
•
•
•
•
•
•
Flow 5500 mc/hour at a pressure of …………………………………. 275 daPa;
Filtering cartridge THERMO-WEB/ limit temperature ………………. 1350°C, 12 pieces;
Total filtering surface…………………………………………………….. 168 mp;
Cleaning system with cartridges for compressed air.....pressure bar, flow rate 16,2 mc/hour;
Electric supply …………………………………………………… ……… 400VCA/50 hz;
Discharge of the contaminant elements:……………………………… 2 containers x 60 litres;
Piping from sheet metal zincked SPIRO helical fold for increasing rigidity: ……………Ø300
mm x 0,5 mm deeph;
• Flexible pipes Ø300 mm x 0,085 mm deep of the wall formed by a steel wire covered with
inlayed bronze pasted with adhesive in multiple laminated layers, from aluminium sheet;
• Normal running temperature ………………………………………….. -30/+140°C;
• Maximum speed for the air ……………………………………………. 30 m/sec;
• Maximum pressure …………………………………………………….. 2500 Pa.
The exhaust filtration system is necessary for the collection, disposal and filtration of flue, dust and
fumes resulting from thermal spray technological process by HVOF (High Velocity Oxygen Fuel)
with liquid fuel (kerosene). The evacuation are made by two horizontal and vertical handling
devices that are included in the integrated technology system for thermal spraying by HVOF
process. The two devices are equipped with suctions hood and they are located in a spray cabin
where the process HVOF takes place. The emissions evacuation is achieved by a pipe that
branching in two parts and on the one hand it make contact with the two suctions hood and on the
other hand, after passing out of the spray cabin by HVOF laboratory at a distance of approx. 6800
mm and connected to the filter unit installed in the outside of the building laboratory. The dust from
filtering is stored in two containers attached to the evacuation appliance. There is also an air
reintroduction system into the spray cabin in order to rebalance the pressure form the inside, that is
consisting of: fan, two filter with pockets - G4 class filter, duct airflow ventilation and dispersion.
From a functional perspective, the exhaust filtration system consists of: emissions filter appliance;
reinseration air system into cabin; exhaust pipe.
3.7 Technical gases and distribution networks. For the spray process is necessary 1200 liters /
min at 20 bars of oxygen and 30 l / min at 6 bars of nitrogen. The oxygen is stored in two batteries
each with 16 bottles of 50 liter and the storage pressure in cylinder is 200 barr. The nitrogen is
stored in two cylinders, each having 50 liters at a pressure of 200 bars. The gas flow from the gas
bottle to the gase locker of the spraying appliance through distribution networks.
Oxygen distributions pipes comprise the following elements:
• Coil pipe, 2 metres……………………………………………………… 2 pieces;
• Distribution ramp with one entering and 2 exits …………………….. 1 piece;
• Reducer ………………………………………………………………… 1 piece;
• Pneumatic valve;
• Pipelines from cooper
Distributions pipes for nitrogen it is composed by:
• Serpentine, 2 meters ………………………………………………….. 1 piece;
• Pressure regulator........ ………………………………………............ 1 piece;
• Silicone flexible pipe
3.8 Security system of the holders and HVOF accesories. The batteries with oxygen cylinders,
nitrogen cylinders and exhaust filtration plant are located outside the building next to where the
spray plant are. Also, outside building, on the wall there are the elements of the distribution are
networks, except for portions of the pipe and hose that enter into the control gase cabin of the
spray plant. They are protected from access by unauthorized personnel, and also from the rays
sunlight by closing into a security system. It has a roof of corrugated and galvanized sheets, side
closures with access doors with frame made by pipe on that are welded nets. In addition to the
wire guard is caught a protection netting that restrain the sunlight and also ensuring a good
ventilation. The security system includes an uncovered locking for the air filter that is placed
outside the building. This is equipped with doors that allow the cleaning of the filtering cartridges
and access to the switchboard of the installation of filtering emissions.
63
ISSN 1453 – 7303
3.9 Thermal spraying equipment
GTV K2 torch for HVOF thermal spaying
Combustion chamber
Pressure box for the combustion chamber
Water jacket
⎯ Fuel: …………………………………..……………..
Exxsol D 60 (kerosene)
⎯ Minimum caloric power……………………….………. 250 kW (10 kW per litre kerosene)
⎯ Minimum speed for the spraying jet: ………………………………
2000 m/s
⎯ Maximum temperature of the spaying jet: ………………..………
2800 ºC
⎯ Maximum quantity for the (WC-Co) sprayed powder: ……….…… 10 kg/h
⎯ Combustion temperature: …………………………………………..
38 MJ/l
⎯ (λ) (oxygen quantity/ kerosene quantity) ratio for the maximum temperature:……....2,9
(λ) (oxygen quantity/ kerosene quantity) ratio for the neutral flame: ………………. 3,4
⎯ Pressure in the combustion chamber: …………………………………….
max. 10 bar
GTV K2 torch assures forming of the incandescent jet which transports the melted powder at the
deposit zone, the moving being assured by the robot on which arm it is mounted.
GTV Controler for gases (O2/ Air/ N2)
⎯ O2 Delivery:
Entering pressure: …………………………………… 20 bar
Maximum flow: ……………………………………….. 1000 l/min
⎯ N2 Delivery:
Entering pressure: …………………………..……….. 6 bar
Maximum flow: ……………………………..…………. 30 l/min
⎯ Compressed air delivery:
Entering pressure: …………………………..……….. 6 bar
Minimum flow: ……………………………..………….. 1000 l/min
Assures the control and delivery of the gases and the compressed air to the torch where is
formed the spraying jet which transports the powder for the HVOF spraying.
GTV Unit for kerosene pumping
⎯ Kerosene Delivery (Exxsol D 60)
Pressure: ……………………………………………… 25 bar
Flow …………………………………………………… 30 l/min
Assures the control and distribution of the kerosene to the spraying torch where is formed the
spraying jet which transports the powder for the HVOF spraying.
GTV PLC control unit with robot interface
Consumption power: ……………………………..….. 2 kW
Electric supply: ……………………………….. 400V C.A. – triphased – 50 Hz – 3A
Assure a biunique link with the Fanuc robot.
GTV HVOF – Control console of operators (HMI)
Allows control and selection of process parameters including real-time monitoring of their.
Feed system GTV / power measuring
⎯ Powder supply:
2 canisters x 1,5 l
Powder mixer speed ………………….…………........0 – 100%
Metering disc speed ……………………….……….... 0 – 10 rot/min
Used power: ……………………………….…............. 2 kW
Electrical supply ………………………….……........... 230 V – monophase – 50 Hz –
max 10 A
GTV powder feeder type PF is a system that stores, supplies and distribute controlled with powder.
The power supply consists essentially from a container of powder (unit dose) and a base, which
incorporates the powder container, and also including the control and operation of Siemens S7.
The powder container is a separate module and can therefore be put to different bases and is
special designed according to customer requirements.
64
ISSN 1453 – 7303
Standardized 1, 2, 3 or 4 powder canisters can be driven parallel (PF 2/1, PF 2/2, PF 3/3, PF 4/3 or
PF 4/4). Furthermore to have the possibility, every powder canister with a weighing system to
equip (PF 1/1W, PF 2/2W = scale).
The device is a powder feeder for thermal spraying, laser welding or PTA hard facing. The device
is used exclusively for the promotion of powdered materials. On the gas side the unit operates with
argon/nitrogen or helium only. Oxygen and hydrogen and other flammable gases are not permitted
under any circumstances!
Gun cooling system (heat exchanger)
⎯ Cooling water supply
Cooling capacity ……………………….……………....... 87,6 kW
Ambient temperature ...……………………………......... +10 ... +420 C
Maximum pressure ………………………….…………… 42 barr
Refrigerant ………………………………………….......... R410A
Used power ……………………………..….……............. 43,2 kW
Power supply ……………………………………. 400V C.A. – triphase -50 Hz – 78A
4. Conclusions
In terms of materials that can be used for specific applications of the project, there are the following
conclusions:
¾ For industrial applications, materials have been indicated for the following applications: pomps
for high pressue that are used in plant for water jet cutting; molds for glass; molds for plastic
deformation of metals, hydraulic and pneumatic components - cylinders, pumps, valves, taps.
Materials that can be used to cover by using HVOF process are the following two types:
a. Carbides such as WC-Co or WC-Co-Cr based on the type of application;
b. Nickel alloys such as NiCrBSi;
c. Oxides, such as Al2O3 can be used but HVOF process is less used for coating such material.
¾ For medical applications were given materials for the following applications: surgical
instruments; electrostatic coating for surgical parascopic. Mainly, materials that can be used to
cover by using HVOF process are the following two types:
a. Carbides WC-Co or WC-Co-Cr for surgical instruments;
b. Oxides, such as Al2O3 for isolating electrostatically - HVOF process is less used for coating
such material.
REFERENCES
[1] Technical Documentation GTV Coating System HVOF-MF-K 1000, Project ICTCM, 662.013
[2] "Study regarding the theoretical determination of specific technological parameters for HVOF process on application"
project no. 614 SMIS code / CNRS: 12537, contract no .: 270 / 27.10.2010, project "Applied researches, technology
and technological equipment for high strength thermal spraying by HVOF process used in industrial and medical
applications", co-funded by the Regional Development European Fund, under the contract financing 270 /
27.10.2010, in the Operational Programme "Increasing Economic Competitiveness" (SOP IEC), Priority Axis 2
Research, Technological Development and Innovation, Operation 2.1.2- „High scientific level R&D Projects
attended by specialists from abroad" .
[3] “Research on identifying applications and parameters specific to HVOF process - Study on the determination of spray
materials used in each case”, project no. 614 SMIS code / CNRS: 12537, contract no.: 270 / 27.10.2010, project
"Applied researches, technology and technological equipment for high strength thermal spraying by HVOF process
used in industrial and medical applications", co-funded by the Regional Development European Fund, under the
contract financing 270 / 27.10.2010, in the Operational Programme "Increasing Economic Competitiveness" (SOP
IEC), Priority Axis 2 Research, Technological Development and Innovation, Operation 2.1.2 - „High scientific level
R&D Projects attended by specialists from abroad".
[4]. Arash Ghabchi, Tommi Varis, Erja Turunen, Tomi Suhonen, Xuwen Liu, S.-P. Hannula„Behavior of HVOF WC10Co4Cr Coatings with Different Carbide Size in Fine and Coarse Particle Abrasion”, Journal of Thermal Spray
Technology, January 2010
[5]. Brandl W., G. Marginean, D. Utu, D. Maghet, “High Performance Coatings for Protection of Components Against
High Temperature Corrosion”, Advanced Materials, pp. 57-64, Timisoara, Romania, 2004;
[6]. Brandl W , Utu D., Marginean G., Cartis I., Serban V.A., “Morphology and Phase Modification of HVOF-Sprayed
McrAlY-Coatings Remelted by electron Beam Irradiation”, Vacuum 77/4, pp. 451-455, 2004
65
ISSN 1453 – 7303
THE PROCEDURE FOR DRYING PLANT PRODUCTS
IN CONVECTIVE DRYERS
PhD.s. Eng. Iulian – Cezar GIRLEANU, PhD. Eng. Gabriela MATACHE
INOE 2000-IHP, [email protected]
Abstract: This paper shows the advantages of using convective dryers and their performance in
terms of energy. These are meant for dehydration of vegetal products, in line with the global trend
concerning conservation through the thermohydric technology of enzyme inactivation
(dehydration).
In the paper two concepts are promoted which are strictly up-to-date in the present context of
deepening of energy and food crisis at global level: the concept of energy independence and the
concept of food security and safety for consumers.
Keywords: convective dryers, plant products, dehydration, energy independence, food security
and safety
1. Introduction
Convective drying remains, also nowadays, the best known and widespread process of removing
moisture from the material, both due to the simplicity of the process, and especially due to the
numerous opportunities to obtain, at low cost, high quality of drying in a short period of time.
Drying is a complex operation involving transient heat and mass transfer along with various
processes, such as physical and chemical changes which, in turn, can cause changes in the
quality of the product just like the mass and heat transfer mechanisms. Physical changes that may
occur are: contracting, swelling, crystallization, glass transformation. In some cases, there may be
chemical or biochemical reactions desirable or not which can affect the color, texture, smell, or
other properties of the solid product.
In intensive drying processes it is intended to accomplish a uniform contact between the thermal
agent and the biomaterial granules which is done in relatively homogeneous layer structures. This
challenge is imposed by the fact that in the heat treatment of biomaterials there could occur
significant degradation of the quality of the final product.
Drying is one of the traditional ways and yet always modern for storing on extended periods of time
vegetables and fruits for direct consumption or for industrial processing without addition of
preservatives and low power consumption for storage and reprocessing. Convective drying is an
intensive thermal energy technology, which in many cases makes it dependent on the heat
sources which are as cheap as possible, one reason for super concentration of drying plants.
Rapid price decline in automation devices, the development of the automated management
software and also the development of machine building technology have led to a decentralization
of processing fruits and vegetables by drying, to the displacement of drying facilities at the place of
harvest of the products to be dried. This makes the use of mobile dryers dependent on the use of
diesel oil and LPG, which are fuels with high energy density, but sources of pollution through the
emission of CO2.
Vegetables and fruits throughout the history of humanity were the basic elements of food, due to
their content in proteins, fat and carbohydrates, minerals such as potassium, sodium or
magnesium etc., their use throughout the year being good for health. Pedoclimatic and relief
conditions in Romania have made it possible that on this territory to be grown a variety of
vegetables and fruit, of great importance, divided into more than 15 botanical families. However,
these products are seasonal, have relatively short harvesting periods, and the perishable nature of
66
ISSN 1453 – 7303
most of them is very high or medium, making their use as fresh products be possible only as a
result of exquisite storage, which significantly increases costs.
2. The main advantages of vegetables and fruit preserved by drying
Drying of fruit and vegetables is the healthiest solution for long time preservation. Another
advantage of the dehydrated fruits and vegetables is that they have a validity term greater than
frozen or canned ones. Actually, dried and stored in optimal conditions, fruits and vegetables can
be eaten even after several years.
An important economic aspect of dehydrated vegetables and fruits is that their storage does not
pose serious problems because their volume is reduced significantly after the drying process. For
example, two kilograms of raw fruit after drying will be a quarter of the initial volume.
There can be dehydrated almost all fruits and vegetables, with the exception of the vegetal fat-rich
ones because they can become greasy. Grapes, plums, apples, pears, peaches, apricots,
pineapple, bananas, tomatoes, carrots and herbs are best suited for this operation.
Dehydration can be done by simply placing the fruits and vegetables in the sun, as it was done
hundreds of years ago; however the dehydration plant is the best solution, because the drying
process in the drying facility will shorten significantly the time of dehydration of fruits and
vegetables. In Moldavia, a grid called “lojniţă” is used for dehydrating apples, pears and plums,
often resorting also to cold smoke. In this case, the process is called smoking (plums, apples and
pears are preferred). There are used varieties that are not very sweet, because there is a risk after
dehydration for resulting juice to leak.
3. The drying of vegetal products in convective dryers using warm currents and facilities for
this type of drying
Convective drying remains, also nowadays, the best known and widespread process of removing
moisture from the material, both due to the simplicity of the process, and especially due to the
numerous opportunities to obtain, at low cost, high quality of drying in a short period of time.
The wet material gets into contact with the drying agent - hot air or combustion gases – receiving
from it, by convection, 80-90% of the total quantity of heat necessary for the drying process. The
parameters (speed, temperature, relative humidity, etc.) of the drying agent, as well as the
connection between humidity and material determine the heat and mass transfer in the drying
process. In the process, the drying agent changes its temperature, relative humidity and even
circulation speed, and the wet material changes its density, specific heat, thermal conductivity and
even dimensions. The drying process is a complex process during which many parameters
(coefficients of heat and mass transfer, the viscosity of the water, surface tension, etc.) change, so
that for exact knowledge of the development of the process there is necessary a correlation
between the known theoretical results and the direct experimental research carried out for each
material.
Experimentally, the peculiarities of the drying process of wet material are given by the drying
curves (which show the change in humidity over time), the drying speed curves (which show the
variation of drying rate with moisture or over time), the variation of material temperature and drying
agent over time etc.
From the point of view of heat transmission in order to eliminate moisture the drying can be:
Convective drying - heat transfer by convection from air or other gases to the material
subjected to drying;
Conductive drying - heat transfer by conduction, by means of a heat transfer surface;
Dielectric drying - dielectric heating of the material in a HFC (high frequency currents) field;
Radiant drying - heat transfer by radiation.
67
ISSN 1453 – 7303
4. The general functional diagram of a convective dryer
The component parts of a dryer type chamber with trolleys and shelves are: 1- the dryer chamber;
2- trolleys (carriages) with racks or shelves; 3- fan; 4- external radiator for heating the mixture of
air; 5,6- internal radiators for intermediate heating of drying agent; 7- choke for the adjustment of
exhaust air recirculation.
Its operation is an elementary one; ambient air is introduced into the drying plant after initially was
passed through a heat exchanger. This one is meant to provide the introduced fresh air with the
temperature necessary to the drying process for that phase. The air is then passed on in the
installation to a system of choke valves, which is intended to control the flow of thermal agent
introduced into the drying chamber, thus being achieved in a simple manner the dosing of hot air;
this one, taken by a fan, is sent through a pipe system to the drying chamber where there are
previously placed the vegetal products that are to be subjected to the drying process.
Fig. 1 The general functional diagram of a convective dryer
type chamber with trolleys and shelves.
After going through the entire chamber, the air is already moist, because it has taken over part of
the moisture of vegetable products, following that part from that one to be discharged, and the
other part be recirculated, thus reducing the amount of fuel used for heating the air.
This diagram focuses on energy saving and promotion of work processes as profitable as possible
in terms of energy, important features in the field of convective dryers.
68
ISSN 1453 – 7303
5. Types of drying
Batch drying:
Fig. 2 Diagram of a convective dryer with circulation through layer panels
Fig. 3 Diagram of a convective dryer with tangential circulation panels
69
ISSN 1453 – 7303
The advantages of this type of drying are:
- material to be dried is spread evenly across panels that are stacked on trolleys or slideways;
- hot air is introduced with an automatically controlled temperature, constant, or greater at the
beginning and lower at the end of drying;
- temperature and humidity at the output are measured and there is calculated the average
temperature at the material surface;
- there is adjusted the ratio external air/thermal agent recirculated in order to control the surface
temperature of the material to be dried;
- if constructively possible, there is changed periodically the direction of travel of drying agent in
order to obtain even drying.
Semi-continuous drying:
-
material to be dried is spread evenly across panels that are stacked on trolleys which are
inserted and pulled out periodically;
hot air is introduced with an automatically controlled temperature;
temperature and humidity of drying agent at the output are measured and there is calculated
the average temperature at the material surface;
there is adjusted the ratio external air/thermal agent recirculated in order to control the surface
temperature of the material to be dried;
circulation of the drying agent and the trolleys is done: in co-current, counter-current or mixed
flow.
Fig. 4. Fruit and vegetable dryer tunnel type - functional diagram
6. Conclusions
One of the easiest ways to keep the quality of fruits and vegetables is their preservation by drying
or dehydration. While drying is performed based on natural heat transfer of water from vegetal
70
ISSN 1453 – 7303
products to the outside, dehydration assumes that the same transfer is performed under strict
human control, by using adequate technical equipment.
Industrial scale dehydration of food products, characterized by relatively high production costs, is
widely used as the final products have low weight and volume and, through strict control of
technological operations, there is ensured compliance with the current regulations on hygiene and
food safety.
Convective drying is the most common method of removing moisture from fruit and vegetables,
both due to the simplicity of the process, and especially due to the numerous opportunities to
obtain, at low cost, high quality of drying in a short period of time.
REFERENCES
[1] Arun S. Mujumdar and Sakamon Devahastin: "Principii fundamentale ale uscarii"/"Fundamentals of
drying";
[2] Erol Murad, Aurelian Crăciunescu, Georgeta Haraga, Uscatoare mobile pentru zona montana cu impact
ecologic redus/ Mobile dryers for mountain areas with low environmental impact, Politehnica University
of Bucharest;
[3] Erol Murad, David Ladislau, Victor Safta, Gabriela Balacianu "Uscarea convectiva a produselor
agricole-forma moderna si economica de pastrare si valorificare"/"Convective drying of agricultural
products - modern and economical way for storage and valorification", Politehnica University of
Bucharest 2006
[4] Andreea Lavinia R.I. MARIN, “Cercetari privind optimizarea energetică a procesului de conservare prin
uscare a fructelor si legumelor”/ “Research on optimizing energy in the conservation process by drying
fruits and vegetables”, Brasov 2012;
[5] Rasenescu L.: "Operatii si utilaje in Industria Alimentara"/ "Operations and equipment in food industry",
Vol II, Technical Publishing House, Bucharest, 1972;
[6] Ţane, N., Gaceu, L.: "Maşini, instalaţii şi utilaje pentru produse de origine vegetală"/"Machines,
installations and tools for plant products", Publisher University "Transilvania" of Brasov, 2000;
*** http://www.agenda.ro/o-metoda-naturala-de-conservare/--"Deshidratarea fuctelor si legumelor"/
"Dehydration of fruits and vegetables", September 16, 2009
71
http://hidraulica.fluidas.ro

TITLE OF THE PAPER (Arial, 14pct, Bold)

Transcription

Similar documents

Sun Hydraulics` First Publication in pdf format

Customised hydraulic systems

tipper applications - Hydreco Hydraulics

cylinder training

AVENTICS: AgIlE, foCuSEd, ANd wITh pASSIoN for Tomorrow`S

Catalog - OPS Ltd.

j - Revista HIDRAULICA | HIDRAULICA Magazine

Haul Master - Prairie Sky Equipment Ltd.

PRESS RELEASE - STEINEXPO 2014 After a long

Flyer - Neale Consulting Engineers