Study On The Effect Of Heating Area Distribution Of Electrically Heated Clothing On Human Thermal Comfort

In cold environments,the human body must to wear cold-proof clothing to prevent heat loss and maintain body temperature.Electrically heated clothing has been widely used in recent years because it can actively heat the human body,is light to wear and consumes less energy.The human body has local differences in hot and cold sensation,and the reasonable design of heating area distribution of electrically heated clothing can improve human thermal comfort,enhance heating efficiency,and save energy.Therefore,this paper focuses on the influence of heating area distribution on human thermal comfort,systematically investigates the thermal comfort performance of electrically heated clothing under different temperature conditions and different heating area distribution conditions through real-life experiments,and establishes a thermal comfort model for electric heating clothes.Firstly,the electric heating materials and their performance were compared and analyzed to determine the electric heating materials used in this study.Several representative electric heating pads were selected for performance testing.The performance was comprehensively analyzed in terms of heating speed and heating uniformity,and finally,the carbon nanotube electric heating pad with better performance was selected as the heating element.Secondly,the influence of heating area distribution of electrically heated clothing on human thermal comfort was systematically studied through real-life wearing experiments.Two low-temperature environmental conditions(ambient temperature of 5 °C and 0 °C;relative humidity of 50%)were simulated using an artificial climate chamber.The subjects conducted comfort experiments with three heating area distributions.The effects of the distribution of heating area distribution on the human skin temperature and subjective perception of the electrically heated clothing were compared at 5 °C with low and high-grade heating,and at 0 °C with high-grade heating only.The experimental results showed that the mean torso temperature was significantly increased when the heating area of the electric heating suit was concentrated in the torso position at 5 °C in low-grade heating and 0 °C in high-grade heating.Still,it was not sufficient to maintain the temperature of the hands and legs,resulting in the mean skin temperature decreasing to below 33 °C during the experiment.The mean skin temperature could be maintained at about 33 °C when the torso was heated centrally in high-grade at 5 °C.Distributing the heating area to the torso,legs and arms in low-grade at 5 °C could bring the mean skin temperature up to the level of centrally distributed heating in the torso at high-grade.The torso,thighs and calves had 100% thermal comfort satisfaction and the highest thermal acceptability when the heating area was distributed in high-grade heating.Finally,based on the results of the experimental study,a model of the relationship between local thermal sensation and thermal comfort,a model of local and overall body thermal sensation,and a model of local and overall body thermal comfort were established for the electrically heated clothing.There is a quadratic nonlinear correlation between local thermal sensation and thermal comfort of the arm,and there is a cubic nonlinear correlation between local thermal sensation and thermal comfort of other bodies.To summarize,the distribution of heating areas of electrically heated clothing has different effects on human thermal comfort.Choosing a suitable heating area can lead to a higher level of thermal comfort.The research results of this topic can provide a relevant basis for the design and development of electric heating clothing and the research of human thermal comfort,but also provides a reference for the design and development of other functional clothing,which has important theoretical and practical application value.