Evaluation On Performance Of Electrically Heated Garments

In the cold environmental conditions,electrically heated garments improve human wear thermal comfort by supplying active heating.This paper chooses carbon fiber and graphene electrically heated garments as the research object.Comparing the heating mechanisms and taking performance evaluation,which can help a wearer to improve the functionality of the electrically heated garments.It makes sense for smart costumes.First of all,electric performance and insulation are investigated for heating fabrics.Which include thermal stability,strength density,temperature changes and heat coefficients.Both fabrics have better thermal stability and insulation,and graphene are about twice as dense as carbon fiber.Graphene heat response time shorter and warmer than carbon fiber,and the heat uniformity is better than carbon fiber.Second,a thermal manikin is used to investigate the effects on the heating efficiency of an electrically heated garment.Where air temperature is 15℃,carbon fiber suit A(8W)the highest heat efficiency is 28.9%,graphene suit A(10W)the highest heating efficiency is 30.1%,Where air temperature is-5℃,carbon fiber suit B(13W)the highest heating efficiency is 21%,graphene suit B(10W)the highest heating efficiency is 20.5%.Where air temperature is 15℃ to 10℃,the thermal insulation of heating suit A has little change,while 5℃ to-5℃ the thermal insulation of heating suit B change a lot.When Temperature is 5℃ and air velocity is 1m/s,the thermal insulation of heating suit is affected seriously,carbon fiber garments(heating area ratio 1.2%,2%)can not keep warmer than no-heating suit,while heating area ratio 3.2% has better thermal performance.Graphene garments(heating area ratio 1.2%)plays well,because of good heating performance.Based on the level of metabolism,people can adjust the heating power to against cold stress and keep comfort conditions.When air temperature is 15℃ or 10℃,the body metabolism between 80~100W/m2,carbon fiber suit A(heating area ratio 1.2%,power 5W),graphene suit A(heating area ratio 1.2%,power 4W).when air temperature ia 5℃,the body metabolism about100W/m2,carbon fiber suit B(heating area ratio 1.2%,power 5W),graphene suit B(heating area ratio 1.2%,power 4W).when air temperature is-5℃,the body metabolism about 140W/m2,carbon fiber suit B(heating area ratio 3.2%,power 13W),graphene suit B(heating area ratio1.2%,power 10W).Which are the appropriate configuration to people to improve human wear comfortable in different cold conditions.Finally,the paper concludes the physiological indicators and human subjective thermal feeling through the wearing trial and the methods of subjective and objective evaluation.Wearing trial are divided into two parts,sitting and walking.The measurement data include the skin temperature and clothing microclimate on chest,back,waist and abdomen four points.Heat increases back’s temperature and clothing microclimate obviously,higher skin temperatures improved thermal sensations of the whole body.The closer to the heat fabrics,the higher of skin temperature and clothing microclimate.This paper analyzes the wearability of electrically heated garment and provides scientific guidance for consumers.