微通道低温换热器流动传热性能

Flow heat transfer performance of microchannel low temperature heat exchanger

基于微通道换热器占地小、换热效率高等优点和在微电子领域、工业冷藏、电动汽车空调等领域应用广泛的现状,建立了微通道低温换热器的物理模型和数学模型,并对模型进行了求解。针对水力直径小于1 mm的微通道低温换热器的流动换热性能,研究了在改变入口流速以及不同宽高比的情况下,对换热器沿程的阻力压降、壁面温度、通道出口流体温度、摩擦因数的影响。研究结果表明,不同宽高比对以上各种参数都有明显的影响。微通道压降随着流速的增大而增大,而且压降增大趋势逐渐加大。壁面温度、通道流体出口温度、摩擦因数等都随着流速的增大而减小,最后都是趋向于稳定。宽高比为4的通道的参数值比宽高比为1的各项参数值普遍偏大,宽高比对微通道换热器的换热性能有着较大的影响。

Based on the perfomance of small volume and high heat exchange efficiency for the microchannel heat exchanger and widely use in the fields of microelectronics,industrial refrigeration,electric vehicle air conditioning and so on,the physical model and mathematical model of microchannel low temperature heat exchanger are established and solved in the paper.To reveal the flow and heat transfer performance of microchannel low-temperature heat exchanger with hydraulic diameter less than 1 mm,the effects of changing inlet velocity and different aspect ratio on the resistance pressure drop,wall temperature,channel outlet fluid temperature and friction coefficient of the heat exchanger are studied.The results show that the above parameters were obviously effected by different aspect ratios.The microchannel pressure drop increases with the increase of flow velocity,and the increasing trend of pressure drop increases.The wall temperature,channel fluid outlet temperature and friction coefficient decrease with the increase of flow velocity,and finally tend to be stable.The parameter values of the channel with aspect ratio of 4 are generally larger than those of the channel with aspect ratio of 1.The aspect ratio has a great impact on the heat transfer performance of the microchannel heat exchanger.