A STUDY OF THE INFLUENCE OF FOG ON HEAT LOSS THROUGH CLOTHING

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Authors
  1. Farley, R.
  2. Farnworth, B.
  3. Sibbald, R.
  4. Uglene, W.
Corporate Authors
Mustang Engineered Technical Apparel Research Inc, Richmond BC (CAN);Defence Research Establishment Ottawa, Ottawa ONT (CAN)
Abstract
Fog is often perceived to increase heat loss in already cold environments. The physical process responsible for the increase in heat loss is not completely clear. However, the following explanation serves as a method of defining the process involved, and quantifying heat loss increases due to the presence of fog. In a cold environment, fog particles penetrating clothing or impinging on bare skin will evaporate upon reaching (or nearing) the higher temperature surfaces. Since evaporation is endothermic, the phase change from liquid to vapor removes a calculatable amount of heat from the surface. Thus, the heat of vaporization of the mass of water reaching the higher temperature surfaces should be equal to the incrfease in heat loss due to fog, if any increases are actually observed. Bare skin was emulated using the surface of a sweating hot plate covered with filter paper. Heat losses were measured with and without the presence of fog. The bare skin tests showed high correlation between increases in fog density and increased heat loss. Next, experiments were performed using an air and vapour permeable aramid fabric (Nomex (TRADEMARK) III), an air impermeable and vapor permeable fabric (Gore-Tex (TRADEMARK) Type I), and single faced fleece (a fabric widely used for thermal insultation). TRUNCATED.
Report Number
DREO-CR-93-600 — Contractor Report (Final)
Date of publication
01 Dec 1992
Number of Pages
15
DSTKIM No
95-00907
CANDIS No
148592
Format(s):
Hardcopy;Document Image stored on Optical Disk

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