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Heat loss from a thermal manikin during wet tests with walking simulation
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Kalev Kuklane
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7th International Thermal Manikin and Modelling Meeting - University of Coimbra, September 2008
HEAT LOSS FROM A THERMAL MANIKIN DURING WET TESTS WITH WALKING
SIMULATION
Kalev Kuklane
Lund University, Dept. of Design Sciences, EAT, Thermal Environment Laboratory
Sölvegatan 26, Box 118, HS 69, SE-22100 Lund, Sweden
email: kalev.kuklane@design.lth.se
http://wwwold.eat.lth.se/Research/Thermal/
Summary: The walking tests with a thermal manikin TORE were carried out with THERMPROTECT WP2
clothing. The test conditions simulated the human tests of the same work package, including ambient conditions
(10 and 25 °C), clothing (impermeable and permeable), wetting of cotton underwear (wet and dry) and setting the
walking speed to approximately the same level. Additional tests in homogenous conditions (Ta=Tsk=34 °C) were
carried out. The results agree with previous studies and form a good basis for further analysis together with
human test results.
Keywords: walking manikin, wet underwear, heat loss, evaporation, evaporative efficiency
Category: Sweating manikins and moving manikins
1 Introduction
EU-project THERMPROTECT did extensively study heat
and mass transfer through textile materials and clothing
ensembles [1]. However, throughout whole project the
walking manikin tests were not carried out and that left a
gap in explaining and comparing walking subjects’ tests
[2] based on manikin measurements. In order to catch up
and exploit the available THERMPROTECT data from
the subject tests a test series were carried out on a
walking manikin TORE. The conditions were chosen to
get as close to the actual subject test conditions as
possible. This paper describes the walking manikin tests
and compares them with values collected during static
measurements reported before [3].
2 Methods
The conditions were chosen to follow a subject series of
THERMPROTECT WP 2 Moisture [2]. Additional
conditions were chosen for testing in order to gather
needed background information as described by [3].
Thermal manikin Tore was used for testing. Detailed
information on the manikin parameters is available in [4].
Both standing and walking tests were carried out,
however, only walking results are given in this paper.
During THERMPROTECT tests on Tore a thin plastic
film was wrapped around manikin surface. During these
tests the film was skipped in order to reduce the errors.
Walking of the manikin was simulated with pneumatic
system and was adjusted by frequency and step length
as close as possible to the walking speed of the subjects
(4.5 km/h). During walking tests at 10 °C several zones
had maximum heat losses and surface temperature
dropped below 34 °C.
THERMPROTECT permeable (PERM) and impermeable
(IMP) coverall together with wet or dry cotton underwear
were used for testing. Material properties of these
clothing pieces are available in [3]. The same socks
(Ullfrotté, material 400 g/m2) and shoes (sports shoes
from Arbesko AB) as the subjects had, were also used on
manikin. For wet tests the cotton underwear was put
through a short rinsing (4 minutes) and centrifuging (8
seconds) cycle. After the procedure underwear held in
average 1034±35 g of moisture.
Air velocity in the chamber was set to 0.35±0.10 m/s.
Tests were carried out at 3 ambient temperatures: 10, 25
and 34 °C. Two first conditions were used according to
subject tests and the third one was carried out for
defining wet heat loss in homogenous conditions
(manikin surface temperature was kept at 34 °C). The
relative humidity in the chamber was set to 80, 31, and
18 % humidity for 10, 25 and 34 °C respectively in order
to achieve an ambient water vapour pressure of 1000 Pa.
Fig. 1. Heat loss components from manikin areas that were fully covered by wet underwear (head, hands and feet excluded).
7th International Thermal Manikin and Modelling Meeting - University of Coimbra, September 2008
3 Results and discussion
The heat loss pattern (Figure 1) followed the results
described by Havenith [3]. The walking resulted in higher
heat losses. This effect compared to static tests was
expected.
Evaporative cooling potential (Emass) and apparent
evaporative heat loss (Eapp, Figure 2) showed similar
patterns as observed by Havenith [3]. Even similar peak
in Emass for PERM at 25 °C was observed as by Havenith
[3] at 20 °C. Although, the clothing weight was corrected
for evaporation during dressing, this peak might have
been caused by measuring uncertainties related to
dressing and undressing, and weighting the clothing
before and after the tests.
The apparent evaporative efficiency (ηapp) for PERM
stayed just around 1 for all walking tests, while for IMP it
almost doubled compared to [3], and reached close to 7
at 10 °C (Figure 3). It could be in a way expected as the
walking should increase both internal (pumping) and
external convection and thus also the effectiveness of the
heat pipe effect. On the other hand, ηapp values for 20 or
25 °C expected from the curves in both studies did not
differ very much when considering somewhat different
measuring conditions and setups. The values of real
evaporative efficiency (ηreal, Figure 3) for PERM differed
to some extent compared to Havenith [3], while for IMP
ηreal was much lower for walking and the difference
increased with increasing temperature. A reason for this
may be correcting clothing weight for moisture losses
during dressing. From IMP evaporation was low, and not
correcting or wrong correction could have had a large
influence on final results.
Finally, these results need to be analysed further in
combination with static tests with the same setup.
Further, the walking manikin data need to be analysed in
combination with the subject results [2].
Fig. 2. Evaporative cooling potential and apparent evaporative
heat loss from the manikin (excluding head, hands and feet).
a)
b)
Fig. 3. Apparent evaporative cooling efficiency and apparent latent heat of evaporation (a), and real evaporative cooling efficiency (b).
Acknowledgements
The study was supported by SCA Hygiene Products AB,
Sweden.
References
[1] Havenith, G., Holmér, I., Meinander, H, den Hartog,
E., Richards, M., Bröde, P., Candas, V., 2006, Final
technical report. THERMPROTECT, Assessment of
Thermal Properties of Protective Clothing and Their Use.
EU-project, contract G6RD-CT-2002-00846.
[2] Kuklane, K., Gao, C., Holmér, I., Bröde, P., Candas,
V., den Hartog, E., Meinander, H., Nocker, W., Richards,
M. and Havenith, G. 2007. Physiological responses at 10
and 25 °C in wet and dry underwear in permeable and
impermeable coveralls. In: Mekjavic, I. B., Kounalakis, S.
N., Taylor N. A. S. Environmental Ergonomics XII,
Proceedings of the 12th International Conference on
Environmental Ergonomics (ICEE 2007), August 19-24,
2007, Grand Hotel Bernardin, Piran, Slovenia.
[3] Havenith, G.; Richards, M.G.; Wang, X.; Bröde, P.;
Candas, V.; den Hartog, E.; Holmér, I.; Kuklane, K.;
Meinander, H.; Nocker, W. 2008. Apparent latent heat of
evaporation from clothing: attenuation and "heat pipe"
effects. Journal of Applied Physiology 104(1), 142-149
[4] Kuklane, K., Heidmets, S. and Johansson, T. 2006.
Improving thermal comfort in an orthopaedic aid: better
boston brace for scoliosis patients. The 6th International
7th International Thermal Manikin and Modelling Meeting - University of Coimbra, September 2008
Thermal Manikin and Modeling Meeting (6I3M), 16 - 18
October 2006, The Hong Kong Polytechnic University,
Hong Kong SAR.
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