Experimental Research On Individual Thermal Comfort Based On Thermoelectric Cooling

In the summer of 2022,heat waves rapidly spread across the globe,increasing temperatures faster than even the peaks of climate prediction models.In the coming decades,extreme heat will approach the critical tolerance threshold of labor production and human health more frequently,and the resulting heat stress will reduce the physical,cognitive and psychomotor performance of railway workers,outdoor power maintenance personnel,and road traffic officers.Therefore,it is very important to ensure the occupational health of workers in high temperature environment.In recent years,many scholars at home and abroad have carried out a series of studies on human body thermal comfort in high temperature environment.The rising demand for energy conservation and diversified thermal management has prompted the industry to develop a variety of thermoelectric refrigeration units.However,at present,most scholars at home and abroad only analyze the thermal comfort mechanism of human body in high temperature environment by using thermoelectric refrigeration devices from the two perspectives of skin surface temperature and thermal comfort vote changes,and the number of physiological parameters and subjective feeling indicators is small.In addition,with the intensification of global warming trend,the research on the individual thermal comfort system of outdoor workers in high temperature environment is not deep enough,and the thermal comfort evaluation index of thermal environment has not been able to meet the changeable environmental conditions.As a potential site for local cooling,the back still lacks a lot of experimental research.From the perspective of quantifying physiological parameters and subjective feelings of personnel,this paper analyzes the changes of physiological parameters,such as core temperature,local skin temperature,local sweating rate and heart rate,and psychological indicators,such as thermal sensation,thermal comfort,thermal preference,wet sensation and sweating degree,before the use of thermoelectric refrigeration device for back cooling under different ambient temperatures and different activity levels.The main research conclusions are as follows:(1)Female subjects reached peak core temperature later than males.When the exercise rate was 6 km/h,the core temperature of female subjects was proportional to the ambient temperature;when the ambient temperature was 37°C,the core temperature of male and female subjects was proportional to the exercise rate.(2)The effect of exercise rate on the skin temperature of the back of male subjects was greater than that of ambient temperature.At lower ambient temperatures,the effect of exercise rate on the back skin temperature of female subjects was greater than that of ambient temperature;at higher ambient temperatures,the effect of exercise rate and ambient temperature on the back skin temperature of female subjects was not significantly different.(3)Regardless of the changes in ambient temperature and exercise rate,the skin temperature of the lower back near the midline of the spine was higher than that of the paravertebral area in both male and female subjects,and the heart rate of female subjects was higher than that of male subjects overall.35°C may be the most appropriate high ambient temperature for prolonged light activity,and its effect on heart rate was relatively smaller compared to 33°C and 37°C.(4)Sweating in all areas of the back increased with the intensity of activity in both males and females,with male subjects sweating more overall and in all areas of the back than females.(5)There was a delayed effect of overall heat sensation in female subjects compared to male subjects,and the overall level of heat sensation increased as the ambient temperature increased and the intensity of activity increased.Female subjects were more heat-resistant than males in a hot and humid environment,and their overall comfort level was higher than that of males.(6)There was a significant correlation between thermal preference and environmental temperature in male and female subjects,but not with exercise rate.There was a significant correlation between wet sensation and ambient temperature and exercise rate for both male and female subjects.However,the wet sensation was relatively weaker in female subjects compared to males.(7)At an exercise rate of 6 km/h and ambient temperatures of 33°C and 35°C,respectively,there was a significant difference in core temperature and heart rate before and after local cooling in male subjects;this significant difference was not significant when the ambient temperature increased to 37°C.The heart rate of male subjects before and after local cooling increased with increasing ambient temperature and with increasing exercise rate.