液冷背心冷却效果影响因素研究

Study on influencing factors of the cooling effect of a liquid-cooling vest

针对战斗机飞行员低空大速度飞行时存在的热应激问题,文章研制了一款液冷背心。采用暖体假人实验对液冷背心的入口水温、换热管路参数及排布方式进行研究,探究入口水温、换热管路的排布密度、横纵向排布、管径大小对液冷服装制冷性能的影响。实验结果表明,液冷背心冷却能力随入口水温的降低而显著增加;换热管路排布密度显著影响液冷背心冷却效果;换热管路内外径、横纵向排布对液冷背心的冷却效果的影响不显著,但换热管路为3×5 mm、换热管路横向排布的液冷背心具有较优制冷能力;换热管路组合设计的液冷背心具有更好的冷却效果。研究结果可为液冷背心的科学设计提供参考。

In the field of modern aviation, the cockpit temperature is too high due to solar radiation heat, avionics heat generation and aerodynamics heat of aircraft surface, and the cooling capacity of the cockpit environmental control system(ECS) of Chinese fighter aircraft cannot meet the requirements of human thermal comfort. The long-term heat stress of flight personnel not only affects the operational efficiency, but also becomes one of the important causes of plane crash. The improvement of cockpit environmental control system requires expensive cost and time, and is restricted by a variety of factors. Developing individual cooling suits for pilots is a cost-effective way to solve the problem of heat stress. Therefore, domestic and foreign scholars are developing individual cooling suits.A liquid-cooling vest for fighter pilots was developed to solve thermal stress problems in the scenarios of low altitude and high speed flights. Based on the garment ergonomics principle, factors were considered from the perspectives of cooling technology selection, design of the cooling capacity, cooling cover selection, basic properties of the surface and auxiliary materials, parameters of the heat exchange tube, loop number and arrangement, clothing style and structure and other aspects. The sweating thermal manikin tests were used to analyze the parameters and arrangement of heat exchange tubes of the liquid-cooling vest. The experiment was carried out in the artificial climate room, the ambient temperature was(34±0.2) ℃, the relative humidity was(40±5)%, the skin temperature of the sweating thermal manikin was set at 34 ℃, and the sweat volume was set at 800 mL/(h · m~2). Based on the four-loop design of the heat exchange tube circuit, the influence of the inlet water temperature, heat exchange tube layout density, horizontal and vertical arrangement and pipe diameter on the cooling performance of the liquid cooling vest was explored. The experimental results of the sweating thermal manikin show that the lower the inlet water temperature is, the greater heat loss and cooling power of the liquid-cooling vests with different tube circuit designs are. Therefore, the decrease of the inlet water temperature can significantly improve the cooling capacity of the liquid-cooling vests. The cooling effect of the liquid cooling vest is significantly affected by the layout density of heat exchange tubes. The cooling capacity of the liquid cooling vest with dense arrangement of heat exchange tubes is significantly better than that with parallel arrangement of heat exchange tubes. The heat exchange tube with a size of 3×5 mm or 4×6 mm has no significant effect on the cooling capacity, while the cooling vest with a 3×5 mm heat exchange tube has slightly higher cooling capacity. The horizontal or vertical arrangement of the heat exchange tube has no significant effects on the liquid cooling vest, while the liquid cooling vest with horizontal arrangement of the heat exchange tube exhibits better cooling ability. The liquid cooling vests with different heat exchange tube layouts have different cooling capacities at the same part of the human torso, so the liquid cooling vests with the combination design of a heat exchange tube have better cooling effect. Specifically, the cooling capacity of the liquid cooling vest with dense arrangement of heat exchange tubes is significantly better than that with parallel arrangement in all parts of the body. The liquid cooling vest with horizontal arrangement of heat exchange tubes has higher cooling capacity in the middle back and lower back, and the liquid cooling vest with vertical arrangement of heat exchange tubes has better cooling capacity in the upper chest and waist.The liquid-cooling vest developed in this paper uses the combination design and four-loop of the heat exchange tube, exhibits better cooling effect and can improve the thermal comfort of human body in high temperature environments. The research findings will enrich the practical research of liquid cooling equipment in the flight field and provide reference for the scientific design and application of liquid cooling clothing.