Study On Human Skin Temperature During Step-change In Non-uniform Thermal Environment

Skin temperature plays an important role in human thermal comfort research. As an important physiological parameter reflecting heat exchange between human body and the environment, study on skin temperature can be used to explore the formation mechanism of thermal sensation. As an input variable of the thermal comfort evaluation model, study on skin temperature provides theoretical foundation for design and operational control of air conditioning systems. As a reference, skin temperature database in different thermal environment can provide effective data for building human thermoregulatory models and studying thermal manikins. In uniform thermal environment, many studies on skin temperature have been systematically done. However, in non-uniform thermal environment and transitional thermal environment, studies on skin temperature are still badly lacking, which include the effect of environmental parameters on skin temperature, creation of reference databases of skin temperature, and the effect of skin temperature on thermal sensation.In this thesis, human skin temperature during step-change in non-uniform thermal environment was studied using subject experiments. First, skin temperature’s changing rules during step-change in non-uniform thermal environment created by the workstation with local ventilation and the ambient environment was investigated and the steady skin temperature both in uniform thermal environment (ambient environment) and in non-uniform thermal environment (workstation with local ventilation) was measured. Then, the effect of supply-air temperature, supply-air velocity and the stimulated body segment on skin temperature and the effect of skin temperature on human thermal sensation during step-change were analyzed. Last, predictive models for skin temperature of the stimulated body segment in summer non-uniform thermal environment were developed using correlation analysis and regression analysis.After step-change into workstation, as the temperature difference between ambient air and supply air increased, more body parts were affected by local ventilation, and the body part closer to supply air was affected earlier; When there existed temperature difference, hand was more sensitive but less thermal-conductive to local ventilation than head and chest; while there existed no temperature difference, three stimulated body segments (head, chest and hand) almost had the same sensitivity and conductivity to local ventilation.During step-change between ambient environment and workstation where the supply-air temperature was at least10℃higher than that of ambient air, thermal sensation and skin temperature of the stimulated body segment, overall thermal sensation and mean skin temperature changed, and the variation tendency of skin temperature was almost the same as that of thermal sensation. In such circumstances, thermal sensation of the stimulated body segment can be predicted by using skin temperature of the stimulated body segment, and overall thermal sensation can be predicted by using mean skin temperature. During step-change between ambient environment and workstation where the supply-air temperature was at most3℃lower than that of ambient air, skin temperature and thermal sensation of the stimulated body segment and overall thermal sensation changed, while mean skin temperature didn’t change. In this case, overall thermal sensation can not be predicted by using mean skin temperature. Besides, the variation tendency of stimulated body segment’s skin temperature and thermal sensation are different after step-change from ambient environment to workstation and almost same after step-change from workstation to ambient. That is, thermal sensation of the stimulated body segment can be predicted by using skin temperature of the stimulated body segment after step-change from workstation to ambient and can not be predicted by using skin temperature of the stimulated body segment after step-change from ambient environment to workstation.The results of correlation analysis indicated that after step-change from ambient environment to workstation, both supply-air temperature and supply-air velocity were linearly correlated with skin temperature of the stimulated body segment remarkably. Through regression analysis, predictive models for skin temperature of the stimulated body segment in summer non-uniform thermal environment were built with supply-air temperature and supply-air velocity as independent variables. From these models, the effect of environmental parameter on skin temperature can be predicted.