Abstract
This study aimed to clarify the body heat balance between the human body and its sleep environment. However, because heat transfer coefficients of sleeping positions have not been sufficiently studied, body heat balance of its positions cannot be accurately assessed. Therefore, the purpose of this paper is to propose the radiative heat transfer coefficient of the whole body and the empirical formula of convective heat transfer coefficient of the whole body in natural convection, with focus on the convective heat transfer area of the human body. Measurements were carried out with a thermal mannequin. Experimental posture was supine (floor contact) position. Thermal sensors directly measuring the heat flux and thermal radiation were employed. Experiments were conducted under the following conditions in an artificial climate chamber. Air temperature was set to six cases (ta=16, 18, 20, 22, 24, 26℃). Wall, floor and ceiling temperatures were set to equal air temperature (mrt=ta). Relative humidity and air velocity were kept constant level of 50% and less than 0.2m/s. The following results were obtained. The radiative heat transfer coefficient with supine (floor contact) posture was 3.235W/(m^2・K). The empirical formula of the convective heat transfer coefficient of the whole body with supine (floor contact) posture was represented hc=0.881ΔT^<0.368>[W/(m^2・K)] where the power of the difference between the mean skin temperature corrected by convective heat transfer area and air temperature (ΔT[K]).
