CONVECTIVE AND RADIATIVE HEAT-TRANSFER COEFFICIENTS FOR INDIVIDUAL HUMAN-BODY SEGMENTS

Human thermal physiological and comfort models will soon be able to si mulate both transient and spatial inhomogeneities in the thermal envir onment. With this increasing detail comes the need for anatomically sp ecific convective and radiative heat transfer coefficients for the hum an body. The present study used an articulated thermal manikin with 16 body segments (head, chest, back, upper arms, forearms, hands, pelvis , upper legs, lower legs, feet) to generate radiative heat transfer co efficients as well as natural- and forced-mode convective coefficients . The tests were conducted across a range of wind speeds from still ai r to 5.0 m/s, representing atmospheric conditions typical of both indo ors and outdoors. Both standing and seated postures were investigated, as were eight different wind azimuth angles. The radiative heat trans fer coefficient measured for the whole-body was 4.5 W/m(2) per K for b oth the seated and standing cases, closely matching the generally acce pted whole-body value of 4.7 W/m(2) per K. Similarly, the whole-body n atural convection coefficient for the manikin fell within the mid-rang e of previously published values at 3.4 and 3.3 W/m(2) per K when stan ding and seated respectively. In the forced convective regime, hear tr ansfer coefficients were higher for hands, feet and peripheral limbs c ompared to the central torso region. Wind direction had little effect on convective heat transfers from individual body segments. A general- purpose forced convection equation suitable for application to both se ated and standing postures indoors was h(c)=10.3 nu(0.6) for the whole -body. Similar equations were generated for individual body segments i n both seated and standing postures.