The Effect of Bellows Action on Heat Transfer in Clothing System Part1 The Effect of Size of Air Space and Air Permeability of Clothing

Abstract

Bellows action is one of effective mechanisms to exchange air and heat inside clothing. To study the effect of bellows action on heat transfer in clothing system, experiments were done by using a simulated skin (hot plate) and a clothing material plate which was shuttled up and down over a hot plate to simulate a bellows action of clothing. The effect of bellows action on heat transfer has been expected being affected by both air permeability of clothing material and the size of air space in clothing. Unexpectedly, the effect of air permeability was small. The main route of heat transfer was the opening of clothing. On the other hand, the effect of size of air space was remarkable. When the size of air space “s” was set from 5mm to 10mm, the effect of bellows action on heat transfer in clothing was largest. Contrarily, when “s” was 20mm, bellows action did not always increase heat transfer. A simple theoretical analysis was made to explain the heat transfer phenomena in clothing during bellows action. It was found that when a material plate was shuttled up, a pressure difference in the air space of clothing became minus that caused penetration flow from environment and when a plate was shuttled down, a pressure difference became plus thus a air in the space blew away to environment. The nearer the distance from opening was, the larger the magnitude of velocity and thus effect of bellows action was.