Study On Personal Cooling Garment Based On Phase Change Materials And Its Cooling Performance

High temperature operations are widespread in many industries in industrial production,such as coal mining,steel production,papermaking,plastic production,cement production and so on,but high temperature seriously affects the work efficiency and personal safety of workers.In addition,with the global warming,extremely hot weather in summer continues to increase,leading to high incidence of heat stroke,dehydration and other diseases in summer,personal cooling garment is one of the most effective means to alleviate high temperature heat effects.Phase change material cooling garment has many advantages,such as good cooling effect,low cost and convenient wearing.It has been widely applied,but there are also some shortcomings such as heavier wetting feeling and non-adjustable temperature.In this paper,a new type of cooling garment is studies,which is combined with phase change cooling and miniature fan cooling.Based on the thermal comfort and thermal balance of human body under high temperature environment as the theoretical basis,this paper establishes the heat balance model of human body when wearing cooling garment by discussing the mechanism of heat generation,heat dissipation and the influence factors of human body thermal comfort under high temperature environment.The parameters in the model are simplified and calculated,and the calculation formula of the amount of phase change materials is obtained.The phase change materials used for cooling were selected,determine the paraffin wax as the phase charge thermal storage module and improve its performance.Adding aluminum powder,graphite and expanded graphite to paraffin wax to enhance its thermal conductivity,and get the perfect combination of expanded graphite and paraffin.The 5%expanded graphite can increase its melting time by 39.4%without material leakage,Set up a water circulation heating experiment table to explore the influence of heat insulation cloth and packaging bags of different materials on the temperature rising characteristics of PCM.Obtained that the heat insulation cloth can prolong the effective service time of phase change material for an average of 30min and the phase change material encapsulated in the thermal insulation bag has a 20-40min longer effective time than the phase change material encapsulated in the aluminum foil bag.With safety ergonomics,fashion design,occupational health and hygiene as the theory,combined with the actual measurement,the new type of cooling garment is designed and produced.In the high temperature and high humidity microclimate room and the summer hot environment,testing and evaluating the effect of garment by the way of people dressing,and the results are as follows:First,the new cooling clothing can rapidly reduce the temperature and humidity in various parts of the skin and microclimate zone,keep it in a comfortable range for a long time,effectively improve the heat stress of human body without affecting body temperature.Second,the temperature of the microclimate zone in the chest,shoulder blade and waist is kept at the comfort temperature of below 330Cfor a long time after wearing the cooling garment.The cooling effect is obvious within 10±4 minutes of the fan’s opening,and the temperature of the area not covered by the phase change material of the cooling garment is still suitable,the cooling range of the garment is comprehensive.Third,the new type of cooling garment can make the average humidity of skin and microclimate zone of the torso decrease by 15.8%and 14.6%maximally,significantly improve the body’s humidity.Fourth,within 100 minutes of wearing a cooling suit test,the body’s thermal sensation,thermal comfort,and humid feeling were evaluated well;the evaluation value of thermal sensation was under 2(slightly hot),the thermal comfort evaluation value and the humid feeling evaluation value were under 1(slightly uncomfortably)and 1(slightly wet)most of the time.The new type of cooling suit designed in this paper has a reasonable structure,long cooling duration,obvious cooling dehumidification effect,easy to wear.Especially the combination of phase change cooling and fan cooling and dehumidification not only makes the temperature suitable,but also overcomes the shortcomings of phase change cooling garment,such as poor moisture permeability and unadjustable temperature,which makes the effect of cooling garment more optimized.