Two simplified manikins for indoor environment assessment

Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
Two simplified manikins for indoor environment assessment
Tengfei (Tim) Zhang, Ping You, Fei Sun, Zongshan Wang
School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian, China
Corresponding email: [email protected]
ABSTRACT
As a quick, objective and accurate research method, thermal manikins have been widely used
to assess indoor environment. Advanced thermal manikins that even can simulate human
breathing and sweating have been applied to assess indoor environment. Although such
advanced manikins are very precise and accurate, they are very expensive so they cannot be
widely used, especially in large spaces where many manikins may require. This makes
necessary to develop a simplified manikin both in physical and numerical form but still holds
significant accuracy.
This investigation has designed two simplified manikins at relatively low cost and tested their
performance. One was fabricated by four painted metal boxes with lighting bulbs and fans
inside to generate heat. The other was modified from a fashion manikin available from market
by winding electrically heated wires on the body and then dressed with clothing. These two
manikins together with a typical adult were put to an indoor environmental chamber served by
underfloor displacement ventilation to do test. Performances of the manikins were evaluated
in terms of geometric profile, surface temperature, ambient air velocity and temperature by
comparing with the test adult. Finally, two corresponding numerical manikin models were
created with computational fluid dynamics (CFD) modeling to extensively explore their
performance.
This study finds although the manikin made by metal boxes has more uniform surface
temperature, the geometric profile is apart from a realistic human shape and the agreement for
measured ambient air velocity and temperature is poorer than the thermal fashion manikin.
The simulation for numerical manikins has also confirmed better performance of the clothed
fashion manikin. Hence, with a closer geometric profile and comprehensively better ambient
air velocity and temperature distribution, the clothed, thermal fashion manikin both in
physical and numerical form is recommended for indoor environment assessment.
INTRODUCTION
A thermal manikin is a heated blockage with geometric profiles close to a human body to
represent a person in occasions where human beings are difficult to employ. Three main
disciplines have been identified for the application of manikins, including clothing, HVAC
(heating, ventilating, and air conditioning), and thermal physiology [1], although in recent
years tendency is towards to carrying on a multidisciplinary study. Thermal manikins were
originated in clothing industry in 1940s upon the demand in determining thermal insulation of
whole clothing ensembles [2]. Later in 1980s, thermal manikins were firstly used as a tool to
evaluate the microclimate conditions in the HVAC discipline [3]. Since then, as a quick,
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
objective, accurate and highly reproducible research method, thermal manikins have been
widely used to assess indoor environment.
Thermal manikins used in indoor environment range from different complexity and
sophistication. Simplified manikins may be like just one or several simple, rectangular heated
boxes [4], or heated boxes covered by cloth bags [5], or composed by several painted metal
boxes with lighting bulbs inside to mimic metabolic heat generation [6]. Such manikins are
cheap and easy for duplication but have limited accuracy, though Topp et al. [4] claimed it is
sufficient for indoor global airflow study. With the recent increasing attention on very
detailed microenvironment around a human body, more précised thermal manikins are
necessary. The development of modern technology makes it possible to manufacture complex
and sophisticated thermal manikins for research and high-end testing. One example is the selfcontained sweating thermal manikin – ADAM (ADvanced Automotive Manikin) that even
can breathe [7] by the US NREL (National Renewable Energy Laboratory). However, such
sophisticated manikins are very expensive, which prohibits them to be applied extensively,
especially in large space where many manikins may have to be employed.
This investigation aims to develop two simplified manikins and their corresponding numerical
counterparts that are easy to duplicate but hold significant accuracy. Performance of these
manikins in representing a human body to respond indoor environmental conditions will be
evaluated. The following briefs our efforts towards to the above objectives.
METHODS
Many international attempts have been carried out to construct hundreds of thermal manikins
in different precision around the world. This makes necessary to establish internationally
recognized standards to guide the manikin production to aid comparison and reproduction of
results, as recommended by some scholars [8, 9]. For example, Melikov [9] suggested a series
of requirements on design and characteristics of a manikin, in which the most important
include body size and shape, posture, surface temperature, control mode, etc. This study is
therefore intended to evaluate manikin performance in terms of geometry profile, surface
temperature, and the ambient air velocity and temperature around the manikin bodies when
they are positioned in the nearly stagnant indoor environment.
Two types of sedentarily seated manikins were built. One was fabricated by four painted
metal boxes with lighting bulbs and fans inside to generate heat as shown in Figure 1 a). This
manikin was designed to simulate a typical adult whose total surface area is around 1.8 m2
and sitting height of 1.25 m. There are no arms, nor are the two legs separated. The total
power input was tuned by a voltage regulator into 75 W, which coincides with the sensible
heat generation from a sedentary adult. The heat release from the top box was around 12 W,
and 21 W for each of the other three boxes.
The other was modified from a naked female fashion manikin available from market as shown
in Figure 1 b), whose sitting height is also around 1.25 m. The manikin was manufactured by
the glass reinforced plastic (GRP) and thus can sustain high temperature on surface. To mimic
metabolic heat generation, the fashion manikin was evenly wound with electrically heated
wires and then dressed with medium clothing as shown in Figure 1 (c). Again, the total power
input was tuned into 75 W by the voltage regulator.
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
a)
b)
c)
Figure 1. Two simplified thermal manikins. a) the metal box manikin, b) the naked female
fashion manikin, c) the clothed, thermal fashion manikin.
Corresponding to the physical manikins, two numerical manikin models applying
computational fluid dynamics (CFD) were also created to extensively explore the
performance of the two simplified manikins. Figure 2 a) shows the numerical box-shaped
manikin model created by a commercial CFD software, which held the same shape and
dimensions with the physical counterpart. The shape and dimensions for the clothed fashion
manikin when creating the numerical model (Figure 2 b)) were tailored slightly due to very
complicated details in the physical manikin. It is very challenging to draw the realistic
geometric profile of a human body in CFD simulation. Nevertheless, the numerical fashion
manikin model created in this investigation is more or less close to the physical one in
geometric appearance.
Line 2
Line 3
Line 3
Line 4
Line 1
Line 1
Line 2
Line 4
Line 5
Line 5
Line 2
Line 4
a)
b)
Figure 2. Numerical manikin models. a) the metal box manikin, b) the clothed, fashion
manikin.
In order to evaluate the performance of both manikins in representing human bodies, these
two manikins were put to an indoor environmental chamber served by underfloor
displacement ventilation as illustrated in Figure 3, where very weak indoor flow was created.
This is to observe the natural convection flow around manikins generated by thermal plume
and also to minimize the influence from the outside momentum sources such as air supply
diffusers since they are very hard to maintain stable. There are four square underfloor air
supply openings (0.6m by 0.6m) and two rectangular ceiling exhausts to extract the inside air.
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
Four fluorescent lightings were mounted against the ceiling to provide illumination. There
was no other furnishing or appliance but a sedentary manikin seated quietly on a chair. This
was to create a simple indoor environment that was easy to repeat at different runs to aid
comparison between manikins. The air supply rate was 0.025 m3/s and temperature of 23 oC.
Underfloor air
supply opening
Exhaust
Lighting
Manikin
Manikin
Chair
Chair
Underfloor air supply opening
a)
b)
Figure 3. Evaluation of manikin performance in an underfloor displacement ventilation. a) test
site, b) schematics of the testing case.
In addition, we selected a female adult with similar geometric shape with the fashion manikin
as an evaluation gauge for comparison between manikins. Surface temperature for both
manikins and the test adult was taken using an infrared thermo-image camera (type B2; FLIR
Systems, US), whose accuracy is within ±2 oC. Ambient air velocity and temperature were
measured with a thermo-anemometer (type 20T35; Dantec Dynamics, Denmark), whose
accuracy for velocity is under ±0.02 m/s and for temperature ±0.2 oC. Sampling spots for air
velocity and temperature were along line 1 to line 5 as highlighted in Figure 2, where these
lines are apart from the manikin or body surface with 5 cm.
RESULTS
This section outlines the comparison of measurement data for both manikins with the test
adult and then the simulation results for both numerical manikins.
Measurement results for both manikins
Figure 4 shows comparison of surface temperatures on both manikins with the test adult.
Generally, temperature distribution is highly non-uniform. The head part of the box manikin
holds high temperature evenly (Figure 4 a), d)), whereas the head part of the fashion manikin
holds low temperature (Figure 4 b), e)), which are somehow different from the test adult that
presents higher temperature on the forehead (Figure 4 c)) and face (Figure 4 f)) but low
temperature on the rest part. Temperature of the upper trunk for the box manikin is lower than
the fashion manikin and the test adult. Otherwise, the box manikin exhibits relatively uniform
surface temperature. Both the box and fashion manikins have higher temperature on legs near
the ankles and feet. The reason why the test adult holds lower temperature is that relatively
loose trousers on lower legs wearing and good insulation of shoes. Although the fashion
manikin cannot match exactly with the test adult and also has temperature wiggles on surface,
the fashion manikin shows somewhat closer temperature distribution and better geometric
characteristics with the test adult.
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
a)
b)
c)
d)
e)
f)
Figure 4. Surface temperatures on manikins and the test adult. a) box manikin from the front
view, b) fashion manikin from the front view, c) test adult from the front view, d) box
manikin from the side view, e) fashion manikin from the side view, f) test adult from the side
view.
Figure 5 shows the ambient velocity and temperature profiles around manikins, where the
horizontal coordinate represents velocity magnitude or temperature, while the vertical
coordinate represents measurement spot locations. These profiles were measured on line 1 to
line 5 as highlighted in Figure 2. Since the manikins or the test adult are seated on chairs, it is
not very convenient to apply the actual vertical height at sitting posture to express the
measurement spot. We therefore still use the standing height, H, as the vertical coordinate in
Figure 5. Due to limited space available in this paper, only profiles on line 1 to line 3 have
been listed out although we have measured and compared on lines 4 and 5.
Figure 5 a), b) and c) show the natural convection flow velocity is generally maintained in
very low level within 0.2 m/s and increases slightly with the standing height. Velocity reaches
peak at around the standing height of 1.3 m, which is at the upper trunk. On line 1 both
manikins match well with the test adult, while on line 2 and line 3 the fashion manikin agrees
better with the test adult.
Temperature stratifies along the three lines as shown in Figure 5 d), e) and f), which conforms
to the temperature characteristics in underfloor displacement ventilation. On line 1, measured
temperature from the fashion manikin is more or less close to the test adult, whereas the box
manikin holds a little lower temperature although the deviation is within 1 oC, which should
not be very meaningful. On line 2 within the leg section, the three temperatures are almost the
same, while within the trunk section, difference exists among them. Temperatures from both
the fashion manikin and the test adult reduce with the height but contrarily the box manikin
increases. It is in reason of different body profile geometry that leads to difference. Such is
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
also reflected on line 3 that makes it very hard to conclude temperature profile characteristics.
However, temperature profile for the box manikin seems to exhibit the increasing tendency
with the height, though it may not conform to the realistic human being.
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d)
e)
f)
Figure 5. Measure ambient velocity and temperature around both manikins and the test adult
(black squares for the box manikin, blue triangles for the fashion manikin, red circles for the
test adult). a) velocity on line 1, b) velocity on line 2, c) velocity on line 3, d) temperature on
line 1, e) temperature on line 2, f) temperature on line 3.
Simulation results for both numerical manikins
The purpose of this study is not just constructing physical manikins for testing use but also
investigating corresponding numerical manikin models that can be applied for CFD
simulation. The RANS (by solving the Reynolds-averaged Navier-Stokes equations) CFD
modeling was applied in this study. CFD solves the transport equations for mass continuity,
momentum, energy, turbulent kinetic energy, and its dissipation rate equations, because
indoor air flows are turbulent. The turbulence model employed was the Re-Normalization
Group (RNG) k-ε model. CFD simulation requires a set of boundary conditions provided. All
boundary conditions taken during measurement were employed. Temperature boundary
conditions for all solid surfaces exposed to indoor air including manikin surfaces, were
specified with the sampled measurement temperatures. Since manikin surface temperatures
are highly non-uniform, only averaged temperatures after dividing the body surface into
segment by segment from Figure 4, were inputted into CFD simulation.
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
Similar to Figure 5, Figure 6 shows simulated ambient velocities and temperatures from both
numerical manikins on 1ine 1 to line 3. To aid comparison, the measured values from the test
adult were also given in the same figures. Again, simulated velocities as shown in Figure 6 a),
b) and c) were in very low level. On line 1, the numerical fashion manikin matches slightly
better with the test adult although the box manikin is not too bad. On line 2, both velocities
within the trunk section are significantly different from the test adult. The simulated peak
velocity for the numerical fashion manikin was shifted to around H=1.5 m, which does not
conform to the measurement results for the fashion manikin as shown in Figure 5 b). On line
3, simulation obtains a peak velocity for the fashion manikin at around H=1.5 m. The position
is also slightly higher than its measurement counterpart. Nevertheless, simulated velocities are
still within acceptably close range with the measurement under reasonable discrepancy.
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d)
e)
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Figure 6. Comparison of the simulated ambient velocity and temperature around both
manikins with the measurement data for the test adult (black squares for the box manikin,
blue triangles for the fashion manikin, red circles for the tested adult). a) velocity on line 1, b)
velocity on line 2, c) velocity on line 3, d) temperature on line 1, e) temperature on line 2, f)
temperature on line 3.
Figure 6 d), e) and f) presents simulated temperature profiles. On line 1 both manikins show
temperature wiggles with the height, which is not in consistency with the test adult, although
temperature deviation is maintained within 1 oC. On line 2 and line 3, the numerical fashion
manikin agrees better than the box manikin. The reason underlying is that the numerical
Zhang, T., You, P., Sun, F., Wang, Z. 2009. Proceedings of the 11th International Conference on Air
Distribution in Rooms (RoomVent 2009), pp. 1285-1292, Busan, Korea.
fashion manikin is in benefit of its closer geometric profile with the test adult that leads to
better performance.
CONCLUSIONS
This paper has designed and investigated two simplified manikins both in physical and
numerical forms. The fabricated clothed, thermal fashion manikin has closer geometric profile
with a realistic human being and shows better agreement in surface temperature distribution,
measured ambient air velocity and temperature with the test adult. The simulation for their
numerical counterparts using CFD modeling has also confirmed better performance of the
clothed, fashion manikin. The reason underlying is that the fashion manikin is in benefit of its
closer geometric profile with a realistic adult. Hence, the clothed, thermal fashion manikin
winding with electrically heated wires and the corresponding numerical model created with
CFD is recommended for possible use in indoor environment assessment.
DISCUSSION
The authors would like to remind that the test adult applied in this investigation does not
necessarily mean all manikin models should conform to her but instead in intent of
convincing the direction and potentials that simplified manikin models can be improved
towards to representing the realistic human beings.
ACKNOWLEDGEMENT
This research is co-supported by the Dalian University of Technology (DUT) of research
funding for young investigators and the DUT undergraduate innovation research project. The
authors are grateful for their financial support.
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