| Extremely high temperature working conditions exist in many fields.However,due to the limitations of working scenarios or conditions,workers in these fields often cannot be equipped with cooling systems such as air conditioning,and they have to suffer from the threat of high temperature.On the other hand,with global warming and the increase of extremely hot summer days,people are more and more concerned about personal thermal protection and thermal comfort.The development and research of liquid cooling garments(LCGs)have important practical significance to maintain human health and thermal comfort who working in high temperatures.In recent years,with the civilian-oriented development of liquid cooling garments,the needs of portability,comfort have been put forward.Therefore,this dissertation mainly focuses on the heat dissipation characteristics and thermal comfort optimization design of the portable LCG.The main research contents and innovation points are as follows:1)A theoretical heat transfer model was built for human-LCG-environment system.For engineering application,the heat transfer model was simplified,and focused on the design parameters of LCG on the heat dissipation performance.The heat transfer process of humanLCG-environment system was analyzed along with the heat transfer path,and the corresponding thermal resistance was determined.Finally,a theoretical heat transfer model was built by solving the energy conservation equations of the tube model.The experiments show that the error of this model is less than 10%.2)The index of "time ratio of thermal discomfort" was proposed to evaluate the thermal comfort performance of LCG in the test.The test apparatus was built based on a modified thermal manikin method.A series of tests were conducted by orthogonal test method to investigate the influence of parameters on the working performance and thermal comfort of a portable LCG that utilized ice as cool source.The experiments show that the duration working time was 82.77 mins,while the uncomfortable time ratio was too large,up to 57.6%.The statistical analysis shows that the mass of ice is the most significant factor affecting thermal comfort because it has a direct influence on the change of water temperature.3)A thermal comfort model for LCG was established.To obtain the physiological effect and thermal comfort evaluation of human body dressed in LCG,a series of volunteer experiments were conducted,and thus the influences of different parameters on the thermal comfort were investigated.The results show that water temperature can reflect the real-time thermal comfort of human body better than the physiological indexes such as skin temperature and core temperature.Then,the dataset collected in these experiments was used as the training dataset of machine learning to establish the thermal comfort model for LCG.After verification,the accuracy of the model reaches 92.47%,which can be used for the intelligent control of the thermal comfort of human body in the LCG.4)A portable LCG system with comfortable cooling,high-efficiency and intelligent temperature control has been developed.To solve the problem that the water temperature cannot be controlled,the whole system and structures were improved,and a smart water temperature-regulating system was added.By controlling the mixing process of coolants with high and low temperature,the precise control of water temperature was realized with the supporting control algorithm.At the same time,the experimental results show that the working time of the system is prolonged by 37.2% due to the improved utilization efficiency of the cold source.To meet the thermal comfort of different people,a mobile phone applet was designed.Users can set the target temperature through the applet to meet the individual preferences. |
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