液冷背心冰水比例对人体热湿舒适性的影响

Effects of the proportion of ice and water on the performance of liquid-cooling vests

为探究液冷服进水口温度对制冷效果及人体热舒适的影响,文章采用不同比例冰水混合物(2 kg水、0.5 kg冰加1.5 kg水、1 kg冰加1 kg水)作为冷源,通过真人着装实验,测试了皮肤温度、出汗量等客观指标及主观感受,研究了高温环境下(温度为32℃和36℃、湿度为50%)液冷服的降温效果。研究结果表明,本实验条件下,32℃时冰水比例为1︰3即可满足人体热舒适需求,36℃时冰水比例需要达到1︰1;液冷服设计时应加强肩胛部位的降温。

When people work in a high-temperature environment,the body’s heat dissipation is inhibited and the physiological burden on workers increases.Heat stroke may be triggered and heat cramps and pyrexia may occur when the body’s heat burden exceeds the body’s ability to self-regulate,causing life-threatening conditions in severe cases.At the same time,high temperature workers are prone to anxiety and distraction,reducing work efficiency.In recent years,flexible and portable cooling clothes are increasingly used in high-temperature operating environments.Among them,the liquid-cooling garment has the advantages of good cooling effect,wide range of applicable environments,and easy replacement of cold sources.Power and functional equipment of the liquid-cooling garments has become miniaturized and the cost has been reduced,which provides the possibility for liquid-cooling garments to be used in daily life for human cooling.Ice and water are the most commonly used cold sources for the liquid-cooling garments,and the ratio of ice to water has an important effect on its cooling effect.However,there are few experiments exploring the effect of ice and water ratio on human thermophysiological response and subjective comfort.Therefore,the effect of liquid-cooling garments on human thermal response under different ice to water ratios was investigated through human wearing experiments.Ten subjects were recruited to sit still in 32℃and 36℃environments to simulate office conditions with and without wearing the liquid-cooling vest.When they wore the liquid-cooling vest,the cold source was set up at three kinds of ice and water ratios:2 kg water,0.5 kg ice&1.5 kg water,and 1 kg ice&1 kg water.Objective parameters including the skin temperature,sweat production,and sweat evaporation of the subjects were measured.The subjective feelings of the subjects were obtained,including heat sensation,thermal comfort,and wetness.In addition,the inlet and outlet temperatures of the liquid-cooled suit were measured and the differences between them were calculated.The results show that the increase in ice ratio prolongs the sustained decrease in torso skin temperature and delays the increase in mean skin temperature.Under the present experimental conditions,continuous decrease in torso temperature can last for over 50 min when a 1︰1 ice to water ratio is adopted.But the temperature difference on the human surface exceeds 11℃.To further improve the comfort,the area covered by the water-cooling garment should be increased.The use of a liquid cooling vest to cool the torso can not only reduce the heat sensation of the covered area,but also reduce the whole body heat sensation and lower body heat sensation,and therefore improving the whole body thermal comfort.The increase of ice ratio also reduces the wet sensation of the body,mainly due to the decrease of sweating.Under the present experimental conditions,it is appropriate to take a 1︰3 ice to water ratio to meet the thermal comfort demand at 32℃.Under the 36℃environment,the ice to water ratio must reach 1︰1.In this experiment,the cooling degree of different parts of the torso is different for the liquid-cooling vest,which is highest at abdomen followed by chest,posterior waist,and scapula.The cooling effect at the scapular area should be enhanced to improve the overall cooling performance of the suit.The liquid-cooling garment can save energy by cooling the micro climate under the clothing to meet the thermal needs of the human body,and has an outstanding cooling capacity.Promoting the development of liquid-cooling clothing is conducive to maintaining the physical and mental health of workers.