Development of a Sampling Train for Motorcycle Exhaust PM 2.5

Development of a Sampling Train for Motorcycle Exhaust PM 2.5

A sampling and measurement system
for motorcycle exhaust PM2.5
Ji-Ying Lai, Chih-Wei Lin, Chia-Wei Hsu, Shen-Hsiu
Hung, and Chih-Chieh Chen
National Taiwan University
Huei-Sheng Cheng
The Environmental Analysis Laboratory, Taiwan EPA
1
Introduction and Aim
Introduction
• Motorcycle was an important transportation tool in tropical and
subtropical countries.
• It becomes even more popular nowadays because of convenience,
mobility and economy.
• In 2014, Taiwan had more than 14 million motorcycles,
accounting for 64.7% of all motor vehicles.
Taipei
Kaohsiung
United photo
2
Introduction and Aim
Introduction
Many studies have been conducted to
measure the regulated air pollutants such as
CO, HC and NOx from motorcycles (Chen et al.,
2003; Tsai et al., 2001).
In addition to these regulated air pollutants,
the unregulated constituents can be
significant because of particulate matter
formation in urban areas and their potential
health effects on human.
3
Aim
Hence, the main objective of the present study
was to develop a sampling and measurement
system for PM2.5 emission from motorcycles.
For Taiwan EPA inspectors?
4
Material and methods
Table1. List of operating parameters
Parameter
Variable
Engine
Carburetor vs Electronic injection
Speed (rpm)
2000 - 4000
Relative humidity(%)
20 - 90
Dehumidification unit
Diluter (2~10 dilution ratio), Nafion dryer,
Ice bath
Flow rate of PM2.5 cyclone (L/min)
3, 16.7
Instrument
SMPS, FMPS, CPC, microAeth AE51,
BE-2000 Gas analyzer, Dusttrak, Opacity
meter
5
Fuel
Engine
Sampling
chamber
Dynamometer
Clean air
Diluter
Nafion dryer
RH meter
0.3 L/min
Filtered Air
Q dry
MFC
MFC
DMA1
Constant output
(Nacl solution)
Silica gel
humidifier
Q wet
Mixing
chamber
RH meter
0.3 L/min
DMA2
Sheath air
RH adjusting
module
CPC
6
Fig.1. Schematics of the experimental setup of the Tandem Differential Mobility Analyzer (TDMA).
NaCl & PST solution
Generator (Ultrasonic atomizer + Constant output)
Filtered air
Am-241
Homemade
PM2.5 cyclone
APS
Nafion dryer
SMPS
Diluter
APS
Fig.2. Diagram of the experimental system set up for aerosol penetration test of
diluter, Nafion dryer and PM2.5 cyclone.
7
Dynamometer
with engine
Sampling chamber
48~52 ℃
RH:100 %
Motorcycle exhaust
Dehumidification
Diluter
Size fractionation
Measurement
Filter
Nafion dryer
PM2.5 cyclone
Mixing chamber
SMPS
PM2.5 cyclone in ice bath
FMPS
Dusttrak
RH and temperature meter
CPC
microAeth
AE51
Opacity
meter
Gas
analyzer
Fig. 3. Schematic diagram of the experimental system setup of the dynamometer
and motorcycle.
8
Results and Discussion
9
(b) Motorcycle exhaust
(a) NaCl particles
1.2
NaCl
D0: 53 nm
2.2
4-stroke exhaust
1750 rpm
D0: 32, 51, 156 nm
Growth factor (Dp / D0)
Growth factor (Dp / D0)
2.4
1.1
2.0
1.8
1.0
1.6
1.4
nm
0.9
1.2
32
51
156
1.0
0.8
0.8
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Relative Humidity, %
Fig.4. Hygroscopic growth of particles emitted from the motorcycle engine and NaCl particles.
10
14
12
Xw, %(V/V)
10
8
6
Moisture content, %
SVP at 20℃ : 2.1
SVP at 30℃ : 4.2
4
2
0
1500
2000
2500
3000
3500
4000
4500
Engine speed, rpm
Fig. 5. Water contents of motorcycle exhaust at different engine speed.
11
Q total
Q dilution
Q sample
Dilution ratio
16.7
16.7
16.7
16.7
15.03
13.92
12.53
8.35
1.67
2.78
4.17
8.35
10
6
4
2
Dilution factor
10
6
4
2
1
0.05
0.1
0.5
1
3
5
Particle diameter, µm
Fig. 6. Test of dilution ratio on diluter.
12
120
120
Sampling zone: 68℃
100
100
80
80
60
60
Temperature
40
40
20
20
0
0
0
2
4
RH,%
o
Temperature, C
RH
6
8
10
12
Dilution factor
Fig. 7. Dehumidification performance of the diluter at different flow rate .
13
Aerosol penetration, %
100
Modified
Original
115
Front
View
10
Cross
section
view
38.2
113.7
1.5 Modified nafion dryer
3.0
6.0
12.0
16.7
20.0
3.0 Original
16.7
113.7
Unit: mm
1
0.01
Flow rate, L/ min
0.1
1
10
Diameter, µm
Fig.8. Aerosol penetration of Nafion dryer at different flow rate.
14
Relative humidity of dowmstream, %
100
80
Flow rate, L/min
20
60
16.7
12
40
6
20
3
1.5
0
0
200
400
600
800
Response time, sec
Fig. 9. Dehumidification performance of Nafion dryer at different flow rate .
15
120
16.7 L/min
3 L/min
EPA-PM2.5
Aerosol penetration, %
100
80
60
40
20
0
1
2
3
4
5
Aerodynamic diameter, µm
6
Fig.10. PM2.5 cyclone penetration curve.
7
8
9 10
16
100
70
Tem. & RH of Downstream
60
Sampling
chamber
Motorcycle
exhaust
90
50
Ice & water
80
40
RH
30
70
20
Temperature
60
10
0
Relative humidity of downstream, %
Temperature of downstream, oC
80
50
Sampling
chamber
Homemade PM2.5
cyclone at 3 L/ min
Homemade PM2.5
cyclone at 16.7 L/min
Fig.11. Colling and dehumidification Efficiency of ice bath for motorcycle exhaust
17
Table 2. Comparison of three dehumidification unit.
Type
Advantage
Weakness
Applicability
Diluter
1. Easy to use
2. Low cost
1. Lower concentration
Good
Nafion
dryer
1. High dehumidification
performance
2. No dilution effect
1.When flow rate is increase, and the
dehumidification performance is
decrease.
2.Nafion membrane damage
3.Expensive
Good
Ice-bath
1. Easy to use
2. Low cost
3. Efficiently decreased the
temperature and humidity
4. No dilution effect
1. Must pay attention to the ice
temperature changes
Better
18
Dynamometer
with engine
Sampling chamber
48~52 ℃
RH:100 %
Motorcycle exhaust
Diluter
Nafion dryer
PM2.5 cyclone in ice bath
PM2.5 cyclone
Mixing chamber
Filter
SMPS
FMPS
Dusttrak
RH and temperature meter
CPC
microAeth
AE51
Opacity
meter
Gas
analyzer
Fig. 3. Schematic diagram of the experimental system setup of the dynamometer and motorcycle.
19
1e+8
1e+7
Electronic injection (8)
Number concentration:1.2x105 #/cm3
Carburetor (19)
Number concentration: 2x106 #/cm3
SMPS
Number concentration, #/cm3
1e+6
1e+5
1e+4
1e+3
1e+2
1e+1
1e+0
1e-1
1e+8
1e+7
10
100
10
100
100
10
100
FMPS
1e+6
1e+5
1e+4
1e+3
1e+2
1e+1
1e+0
1e-1
10
Diameter, nm
Fig.12. Size distribution of motorcycle exhaust.
20
12 hr
24 hr
36 hr
48 hr
60 hr
72 hr
180
160
140
Weight, µg
28%
120
42%
100
57%
80
64%
60
69%
71%
40
20
0
10
20
30
40
50
60
70
80
Time, hour
Fig.13. Filter sample weight decreased with time
21
10000
10000
SMPS
y = 0.9806x + 146.67
r =0.785
1000
Carburetor
100
10
Electronic
injection
engines
1
Mass concentration, µg/m3
Mass concentration, µg/m3
FMPS
0.1
y = 0.9922x + 141.8
r =0.764
1000
100
10
1
0.1
0.1
1
10
100
1000
10000
0.1
Mass concentration of filter, µg/m
3
10
100
1000
10000
Mass concentration of filter, µg/m
3
10000
1e+8
AE51
CPC
y = 6634.9x – 682053
r= 0.698
1e+7
1e+6
3
Mass concentration, µg/m
Number concentration, # /cm3
1
1e+5
1e+4
1e+3
1e+2
1e+1
y = 0.0508x - 5.6158
r =0.9618
1000
100
10
1
0.1
0.1
1
10
100
1000
Mass concentration of filter, µg/m3
10000
0.1
1
10
100
1000
10000
Mass concentration of filter, µg/m3
Fig. 14. Filter sample weight vs instrument reading for motorcycle exhaust PM2.5 .
22
Conclusions
The results indicated that the engine emission at idle
mode (1750 rpm) had a CMD of 5 nm, GSD of 1.8,
and number concentration of 104~106 #/cm3.
The particles generated from motorcycle engine did
not growth even if the RH was up to 95 %.
The ice bath: low cost and easy operation
It efficiently decreased the temperature and humidity of the
motorcycle exhaust.
The separation efficiency curve of the cyclone had a
good fit to the US EPA PM2.5 sampling convention.
23
Conclusions
The mass and number concentrations of 19 carburetor
engines were 730.4 μg/m3 and 2×106 #/cm3, respectively.
For 8 electronic injection engines, the mass and number
concentrations were 139.6 μg/m3 and 1.2×105 #/cm3,
respectively .
The weight of filter samples decreased with time because of
the loss of semi-volatile. The loss decreased if the filter
holder was heated. There was still a 10% loss even the filter
holder was heated up to 90 C.
The regression analysis showed that the correlation
coefficients of the filtered mass against FMPS, SMPS, CPC
and AE51 measurements were 0.785, 0.764, 0.698 and
0.961, respectively.
24
Conclusions
Therefore, the combination of an ice bath, a cyclone,
and the black carbon aerosol monitor (AE51)
appeared to be most ideal system for motorcycle
exhaust PM2.5 measurements.
25
Acknowlegements
This study was sponsored
by Taiwan EPA
Thanks for listening!
26
Mass concentration of filter, µg/m3
1000
Electronic injection + Carburetor
r=0.9618
Carburetor
y = 23.916x + 85.675
100
Electronic injection
y = 59.315x + 32.699
10
0.1
1
10
100
Mass concentration of AE51, µg/m3
Carburetor (9)
Electronic injection (4)
Mean ± SD
Mean ± SD
Filter mass (μg/m3)
285.2±147.4
128.67±68.88
Black carbon (μg/m3)
11.17±10.55
1.61±1.15
27
Fig. 15. Filter weighing vs AE51 measurement instrument for motorcycle exhaust
PM2.5 .
100
25
80
20
60
15
40
10
20
5
0
0
50
100
150
Attenuation, %
Aerosol weight , µg
30
200
Time, min
Fig. 16. The relationship of black carbon(attenuation) and aerosol weight at different time.
28
• The attenuation of light (ATN) from an LED source
and transmitted through a filter that is loaded by the
aerosols is measured.
The ATN is defined as:
I 0 : the intensities of light that is transmitted through a reference blank spot
I : the intensities of light that is transmitted through the spot of aerosol on the filter
30
80
Q: 3 L/ min
RHchamber: 35 %
RHadjust: 40, 60, 80 %
T: 21 oC
∆ mass, µg
60
Glass fiber
40
20
PTFE
0
30
40
50
60
70
80
Relative humidity, %
Figure 10. Effect of humidity on the filter weighing
90