Analysis of sensible heat exchanges from a thermal manikin

Abstract

The present work is dedicated to the analysis of dry heat exchanges as measured by a thermal manikin placed in still air. We believe that the understanding of some fundamental aspects governing fluid flow and heat transfer around three-dimensional bodies such as human beings deserves appropriate attention. This should be of great significance for improving physiological models concerned with thermal exposures. The potential interest of such work can be directed towards quite distinct targets such as working conditions, sports, the military, or healthcare personnel and patients. In the present study, we made use of a climate chamber and an articulated thermal manikin of the Pernille type, with 16 body parts. The most common occidental postures (standing, sitting and lying) were studied. In order to separate heat losses due to radiation and convection, the radiative heat losses of the manikin were significantly reduced by means of a shiny aluminium coating, which was carefully applied to the artificial skin. The air temperature within the test chamber was varied between 13 degrees C and 29 degrees C. The corresponding mean differences between the skin and the operative temperatures changed from 3.8 degrees C up to 15.8 degrees C. The whole-body heat transfer coefficients by radiation and convection for both standing and sitting postures are in good agreement with those in the published literature. The lying posture appears to be more efficient for losing heat by convection. This is confirmed when the heat losses of each individual part are considered. The proposed correlations for the whole body suggest that natural convection is mainly laminar.

Personal protective clothing and safety of firefighters near a high intensity fire front

“…The convective heat transfer phenomenon is simulated using empirical relations derived from thermal manikin experiments by Quintela et al [20] for natural convection and from Havenith et al [18] and ISO 7730 [21] for forced convection. The radiation components Rad1 and Rad2, on each human body segment, are determined automatically by the program by approximated relations.…”

Theoretical analysis of the effects of human movement on the combined free-forced convection

“…Since the advent of thermal manikin in 1940s, researchers have already conducted several experiments to investigate the detailed knowledge of the heat exchanges between the human body and the environment [2][3][4][5][6][7][8], among which it can be speculated that the environment and the posture of the human body affect more for the convective heat transfer than the radiative heat transfer. During the last decade, experimental researches have been focused on the effects of wind speed, wind direction angle, temperature difference, body posture and limbs swing on the convective heat transfer coefficient [9][10][11][12][13][14]. One of the most noted study was by de Dear et al [15], who measured the convective heat transfer coefficients of the human body under different wind speeds and wind direction angles in the wind tunnel, and correlated the convective heat transfer coefficients as a power exponent function of the wind speed.…”

A correlation linking the predicted mean vote and the mean thermal vote based on an investigation on the human thermal comfort in short-haul domestic flights

“…The equivalent temperature, which integrates the independent effects of the thermal exchange for convection and radiation from the human body, is an objective index that does not take into account the human perception and sensation or other subjective aspects. Many studies have analysed the thermal comfort in vehicles by assessing the equivalent temperature by means of multi-segmented manikins or heated sensors (Wyon, 1989;Wyon et al, 1989;Nilsson et al, 1997;Gameiro da Silva, 2002;Nilsson et al, 2003;Quintela et al, 2004;Nilsson, 2007). The total and local heat fluxes from the thermal manikins were determined for different climatic conditions and compared with the thermal sensation votes of subjects exposed to the same conditions.…”