Spacer Systems for Cooling by Natural Convection Inside Clothing
Abstract
The amount of air movement which can be obtained by natural convection depends on the difference in density between the air in the environment and saturated air at skin temperature. This means that there is a range of combinations of vapor pressure and temperature for which there will be little or no movement, but with air temperatures as much as 5 degrees Celsius (9 degrees F) below body temperature, and vapor pressure differences of 25 sufficient movement is obtained to give 150/Kg cal m2 hr of cooling. Channel size or clearance is the most critical clothing design factor in securing cooling. Clearances of two inches are as effective as no cover at all, (or even somewhat better, with a relatively long chimney); one inch is nearly as good, but with the channel reduced to half an inch clearance there is considerable loss of cooling. Increase of channel length lowers the average rate of cooling, but gain from greater length exceeds the loss in effectiveness of the upper parts of the channel. Extra length is much more effective in channels with one inch clearance than in half inch channels. Laboratory tests of motion of the "body" inside the spacer show a decrease of cooling, compared with undisturbed natural convection, or a small gain, when a flexible diaphragm is used to make the motion produce flow in and out instead of merely mixing the air inside the spacer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1960
- Accession Number
- ADA392772
Entities
People
- Lyman Fourt