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Title: Non-evaporative effects of a wet mid layer on heat transfer through protective clothing
Authors: Broede, Peter
Havenith, George
Wang, Xiaoxin
Candas, Victor
den Hartog, Emiel A.
Griefahn, Barbara
Holmer, Ingvar
Kuklane, Kalev
Meinander, Harriet
Nocker, Wolfgang
Richards, Mark
Keywords: Moisture
Clothing insulation
Conduction
Skin temperature
Sweating
Issue Date: 2008
Publisher: © Springer Verlag
Citation: BRODE, P....et al., 2008. Non-evaporative effects of a wet mid layer on heat transfer through protective clothing. European Journal of Applied Physiology, 2008, 104(2), pp.341 - 349
Abstract: In order to assess the non-evaporative components of the reduced thermal insulation of wet clothing, experiments were performed with a manikin and with human subjects in which two layers of underwear separated by an impermeable barrier were worn under an impermeable overgarment at 20 °C, 80% RH and 0.5 ms-1 air velocity. By comparing manikin measurements with dry and wetted mid underwear layer, the increase in heat loss caused by a wet layer kept away from the skin was determined, which turned out to be small (5-6 Wm-2), irrespective of the inner underwear layer being dry or wetted, and was only one third of the evaporative heat loss calculated from weight change, i.e. evaporative cooling efficiency was far below unity. In the experiments with 8 males, each subject participated in two sessions with the mid underwear layer either dry or wetted, where they stood still for the first 30 minutes and then performed treadmill work for 60 minutes. Reduced heat strain due to lower insulation with the wetted mid layer was observed with decreased microclimate and skin temperatures, lowered sweat loss and cardiac strain. Accordingly, total clothing insulation calculated over the walking period from heat balance equations was reduced by 0.02 m2 °C W-1 (16%), while for the standing period the same decrease in insulation, representing 9% reduction only showed up after allowing for the lower evaporative cooling efficiency in the calculations. As evaporation to the environment and inside the clothing was restricted, the observed small alterations may be attributed to the wet mid layer’s increased conductivity, which, however, appears to be of minor importance compared to the evaporative effects in the assessment of the thermal properties of wet clothing.
Description: The final publication is available at http://dx.doi.org/10.1007/s00421-007-0629-y
Version: Accepted for publication
DOI: 10.1007/s00421-007-0629-y
URI: https://dspace.lboro.ac.uk/2134/9295
Publisher Link: http://dx.doi.org/10.1007/s00421-007-0629-y
ISSN: 1439-6319
Appears in Collections:Published Articles (Design School)

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