Convective heat transfer area of the human body

Abstract

In order to clarify the heat transfer area involved in convective heat exchange for the human body, the total body surface area of six healthy subjects was measured, and the non-convective heat transfer area and floor and chair contact areas for the following nine common body positions were measured: standing, sitting on a chair, sitting in the seiza position, sitting cross-legged, sitting sideways, sitting with both knees erect, sitting with a leg out, and the lateral and supine positions. The main non-convective heat transfer areas were: the armpits (contact between the upper arm and trunk regions), contact between the two legs, contacts between the fingers and toes, and contact between the hands and the body surface. Also, when sitting on the floor with some degree of leg contact (sitting in the seiza position, cross-legged, or sideways), there was a large non-convective heat transfer area on the thighs and legs. Even when standing or sitting in a chair, about 6-8% of the body surface did not transfer heat by convection. The results showed that the effective thermal convective area factor for the naked whole body in the standing position was 0.942. While sitting in a chair this factor was 0.860, while sitting in a chair but excluding the chair contact area it was 0.918, when sitting in the seiza position 0.818, when sitting cross-legged 0.843, in the sideways sitting position 0.855, when sitting with both knees erect 0.887, in the leg-out sitting position 0.906, while in the lateral position it was 0.877 and the supine position 0.844. For all body positions, the effective thermal convective area factor was greater than the effective thermal radiation area factor, but smaller than the total body surface area.

Convective heat transfer coefficient relating to evaluation of thermal environment of infant

“…Kurazumi et al. (2003 , 2004 , 2008c) stated that 10–20% of the body surface area did not function to the convective heat transfer area even in the standing and seated positions. Therefore, in reality, the convective heat exchange is expected to be less than this.…”

“…However, Kurazumi et al. (2003 , 2004 , 2008c) stated that 10–20% of the body surface area did not function to the convective heat transfer area even in the standing and seated positions. In this study, 1.0 was used for the convective heat transfer area factor because, as described later, the experimental method is to open the infant thermal manikin, which does not touch the body surface, to the air.…”

Prediction of human thermophysiological responses during shower bathing

“…(ASHRAE 2005) The surface area of the skin in contact with the floor during the standing shower, and on contact with the chair during the sitting shower, is not considered in the calculation. This is because the contact area is comparatively small, i.e., about 1-2% of the total surface area in the sitting posture and less than 1% in the standing posture (Kurazumi et al 2004). Additionally, the thermal conductivity of the chair (made from plastic) is sufficiently small to ignore.…”