Study On The Heat Dissipation Intensity Of Human Sweat Evaporation In Wet Clothing

A good thermal and humid environment can help to create a comfortable and healthy working environment,improve work efficiency,reduce occupational diseases,and also ensure the thermal comfort of the human body.In sweating state,the comfort of the human body is also a part we need to consider.Based on the heat exchange between the human body and the surrounding environment,this paper analyzes and compares the proportion of heat dissipation in different environments.The research in this paper is mainly divided into three parts:The first part studies the effects of individual factors(ambient temperature,relative humidity,wind speed and garment surface temperature)on heat dissipation;The second part studies the comprehensive effects of four factors on the total heat dissipation ratio of evaporative heat dissipation in the full humidity state,and fits the relationship between the proportion of evaporation heat dissipation and the influencing factors;The third part studies the influence of fabric on heat dissipation and the comprehensive influence of evaporation and heat dissipation on the total heat dissipation ratio under the semi-wet state,and fits the relationship between evaporation heat dissipation ratio and influencing factors.The four influencing factors of this experiment were set at five levels,and the ambient temperature was 10°C,16°C,22°C,28°C,and 34°C,and the relative humidity was 60%,69%,78%,87%,and 96%,wind speeds of 0,1 m/s,2 m/s,3 m/s and 4 m/s,garment surface temperatures of 31°C,32.5°C,34°C,35.5°C and 37°C.In the single factor experiment,20 groups of experiments are needed for each factor,including 10 groups of dry clothing state and 10 groups of wet clothing state.In the comprehensive experiment,50 groups of experiments are needed by using orthogonal analysis method,including 25 groups of dry clothing state and 25 groups of wet clothing state.The influence of pure cotton,polyester cotton and polyester on heat dissipation is tested in fabric analysis.The above experiments are about 15 minutes for each group when the thermal manikin is stable.The stable 10 minutes are taken for analysis.The experimental conditions in semi-humid state are consistent with the comprehensive experiment,but the experimental time is set to 4-7 minutes because of the limitation of conditions.The experimental results show that the ambient temperature has a great influence on the heat dissipation.When the surface temperature of the human body is less than or equal to the ambient temperature,evaporative heat dissipation is the most effective way to dissipate heat;Under the condition of dry clothing,the effect of relative humidity of air on heat dissipation is not obvious,but under the condition of wet clothing,with the increase of relative humidity of environment,evaporative heat dissipation will decrease relatively with the increase of equivalent humidity;Under normal indoor conditions,when there is wind and the wind speed increases,the evaporative heat dissipation per minute is close to the sum of radiative heat dissipation and convective heat dissipation;among the factors affecting the proportion of evaporative heat dissipation to total heat dissipation,the influence of clothing external surface temperature on the proportion is less obvious than other factors.The influence of four factors on evaporative heat dissipation ratio under total humidity is as follows: ambient temperature > wind speed > relative humidity > clothing surface temperature;the influence of clothing fabrics on heat dissipation power mainly depends on clothing thermal resistance and wet resistance.The proportion of evaporative heat dissipation affected by four factors in semi-humid state is: ambient temperature > wind speed > relative humidity = clothing surface temperature,and the proportion of evaporative heat dissipation in semi-humid state is smaller than that in full-humid state.According to the experimental results and analysis,it can be concluded that the proportion of ambient temperature to evaporative heat dissipation is the largest,indicating that in sweating state,to maintain human thermal comfort and change ambient temperature is the most effective method,which also provides a method for manual workers to improve work efficiency and reduce occupational diseases.It also provides theoretical basis for the cold / hot comfort of personnel in special working environment.