Design Of Electric Heating Gloves And Ergonomic Evaluation Under The Cold Environment

In the winter,warmth maintenance has always been a hot issue.Not only that every individual needs warmth in daily life,but in particular,the workers engaged in cold environment outdoor jobs and the enthusiasts participating in outdoor recreations requires special protection to withstand coldness.The low temperature will reduce the blood flow in the human's body,lower the flexibility of their fingers,and hinder their work.Electrical heating gloves have been used with heating technologies that provide heat to the hands and reduce the thickness of the gloves.This increases the flexibility of the fingers while keeping warm.This thesis is aiming to provide a systematic study of wearable heating materials including metallic wire(MWs)and carbon nanotube(CNT)films,which can be integrated into the active heating gloves.First,we studied the appearance,elemental composition and thermoelectric performance of MWs and CNT films.It is found that both the MWs and the CNT films have good heating properties,for example,their heating rates are fast when the voltage is switched on.However,a sudden jump of the temperature of the CNT films is outstanding as the voltage is switched on and off,which is not observed in the MWs.We analyzed the behaviour of MWs and CNT films with Newton's cooling law,where the evolution of the temperature during the heating and cooling process fits well with our simulation.Moreover,we show the relationship between thermal conductivity,mass and specific heat capacity of electric heating materials.To implement the sudden change of the temperature for CNT films during voltage switching,we employ the electrocaloric effect to modify our model based on the Newton's cooling law.Second,we presented realistic prototypes of the electrical heating gloves using MWs and nonwoven fabric,CNT film and polyester cloth adhesive respectively.According to the flexible hand shape and features of the target,we optimized the parameters of the electric heating material,such as length and area.We also designed the adjustable three-gear MW electric heating element and four-gear CNT film electric heating element based on the current stable-control principle.The maximum temperature changes of the two kinds of electric heating elements under different modes were calculated theoretically,and the heating effect of electric heating elements was tested with the infrared thermal imager.We found that the theoretical values are higher than the measured results,which is due to that there is a gap between the temperature measuring point and the heating material.Finally,we conducted human ergonomic experiments to test the real performance under an extreme working environment.The MW and the CNT film electric heating elements are placed on the back of the hand and sandwiched by a shaking fleecy insulation inner layer and a PU polyester textile for the outer layer which are resistant to water and wind.Then,the temperature-controlled MW electric heating glove and the CNT film electric heating glove were prepared.Using infrared thermal imager,we observed two kinds of electric heating gloves in hand before and after wearing the most upscale when heating affect.At the same time,we carried out the nut assembly efficiency experiment under extremely cold environment of-30?.We compared the performance of subjects with and without the heating condition applied,with the evaluation of their subjective thermal comfort and number of finished nut assembly.The results show that during the test time of 20 minutes,the working efficiency with MW electric heating gloves is increased,and the effect of keeping warm is significant.The effect of CNT film electric heating gloves on resisting cold is significant in the first 10 minutes but weakened in the last 10 minutes.