Experimental Research On The Local Cooling Of The Back Of Thermoelectric Refrigerator Based On Thermal Manikin

With the rapid development of society and economy,people have higher and higher requirements for daily life and working environment.However,workers engaged in manual labor in high-temperature working environments,such as railway workers,outdoor power maintenance personnel,road traffic personnel,etc.,Due to the loss of a large amount of body fluids,the physical energy will be consumed too quickly,the cardiovascular and cerebrovascular functions will be reduced,and the heat stress response will be caused.When the ambient temperature exceeds 42°C and other extreme high-temperature environments,it may also cause heat stroke and shock or even death of workers.In these high-temperature working environments,it is impossible to achieve cooling measures for the overall environment.However,studies have shown that local cooling of key parts of the human body can improve the thermal comfort of the human body,but local cooling on the back of a real person has higher requirements for the cooling temperature of the body surface and the thermal comfort of the human body.In addition,the experimental results are greatly affected by individual differences,so it is necessary to use the thermal manikin to study the temperature distribution change law of the local cooling of the human back under high temperature environment.This paper summarizes the research and application of local cooling methods of human body,thermal manikin and local thermal comfort.Aiming at the local cooling of the human back,thermoelectric cooling technology is used to make a cooling device with a fan and fins in the heat dissipation method,and a local cooling test platform for a thermal manikin that simulates different metabolism of the human body is built.Firstly,test the cooling effect of the local cooling device through a human experiment.Under the working conditions of the ambient temperature of 30℃,34℃ and the running speed of 2,4,and 6km/h,6 volunteers were subjected to local cooling tests to study the temperature distribution and thermal comfort and thermal sensation voting value of the human back under different cooling powers.Secondly,under the same experimental conditions,the thermal manikin was used to perform a local cooling test to obtain the temperature of the thermal manikin’s back,and the actual test data was used to verify the experimental data of the thermal manikin.Finally,under the working conditions that the ambient temperature is 30-34℃ and the metabolic rate simulated by the manikin is 150,280,360 W,by changing the cooling power and cooling area,the surface temperature distribution of the thermoelectric cooling end and the temperature distribution of the back of the manikin are studied.Using the method of combining real-person experiments and thermal manikin experiments to study the local cooling of the human back,the main conclusions are as follows:(1)The results of real-person experiments show that the local cooling of the back significantly improves the thermal comfort of the human body.As the cooling input power increases,the skin surface temperature on the back of the human body continues to drop,but the skin temperature measurement values of other parts of the body do not change much.The local cooling of the back improved the overall thermal sensation and thermal comfort of the subjects and the chest to a certain extent,but it had no significant effect on the thermal sensation and thermal comfort of the head.The local thermal sensation and thermal comfort improvement effect on the back is the most obvious,which can make the back reach a comfortable state.At a running speed of 2-6km/h,when the room temperature is 30℃,the comfortable temperature range of the human back is 28-30℃,and when the room temperature is 34℃,the comfortable temperature range of the human back is 27-29°C.(2)The verification results of the real person experiment and the thermal manikin experiment show that the thermal manikin and the real person’s skin temperature and the local cooling temperature of the back are very close.The error of the skin surface temperature between the thermal manikin and the real person is less than 1°C,especially the error on the back is the smallest,within0.3°C.The overall downward trend of back temperature obtained from the local cooling experiment on the back of the manikin and the real person is similar,and the average temperature error is about0.36°C.When the indoor environment temperature is 30°C and 34°C,the temperature range of the back of the manikin when the human body feels comfortable is 28-30°C and 27-29.5°C,respectively.(3)The results of local cooling experiments on the back of the thermal manikin show that the greater the input power of the local cooling device,the lower the average temperature of the back of the manikin,the cold end temperature of the cooling device and the average temperature of the cooling aluminum plate,but as the ambient temperature rises,the local temperature of the back of the thermal dummy under the same input power is rising.In the case of the same metabolic rate,the higher the ambient temperature,the worse the cooling effect,and the lower the back temperature drop.When the ambient temperature is the same,the back temperature drop has no obvious correlation with the metabolic rate.Comparing the cooling effects with a cooling area of 10×10cm and 15×15cm,it is concluded that a cooling device with a cooling area of 15×15cm can produce a larger range and better cooling effect with better comfort.