在高空低气压环境模拟舱内对平直翅片管换热器的传热传质特性进行了实验，研究了不同环境压力下刘易斯因子的变化规律和影响因素，并引入了压力修正因子用来预测不同环境压力下的刘易斯因子。实验结果表明：当环境压力从101.3 kPa下降到40 kPa，刘易斯因子变化显著，最大降幅为22.2%，最大增幅为53.7%；当换热器翅片表面为部分湿工况时，入口空气含湿量对刘易斯因子影响较大，全湿工况下入口空气含湿量影响不明显；随环境压力的下降，翅片表面发生部分湿工况到全湿工况的转变，转变前刘易斯因子随环境压力下降而减小，转变后刘易斯因子随环境压力的下降而增大；引入压力修正因子后关联式能较好地预测不同环境压力下刘易斯因子，关联式和99%实验数据点的相对误差在±20%以内。

The heat and mass transfer characteristics of a flatly and straightly finned tube heat exchanger were tested in a simulation cabin with an environment having a high altitude and low atmospheric pressure to investigate the variation law of the Lewis factor and its influencing factors at various ambient pressures.On this basis,a pressure correction factor was introduced to predict the Lewis factors at various ambient pressures.The test results indicate that when the ambient pressure drops from 101.3 kPa to 40 kPa,the Lewis factor will vary notably,the maximum decrement hitting 22.2% and the maximum increment reaching 53.7%.When the surface of fins on the tubes of the heat exchanger is partially wet,the moisture content of air at the inlet will have a relatively big influence on the Lewis factor.When the surface of fins on the tubes of the heat exchanger is wholly wet,the moisture content of air at the inlet will have an inconspicuous influence on the Lewis factor.With a drop of the ambient pressure,the surface of the fins on the tubes of the heat exchanger will transit from the partial wet to the wholly wet.Before the transition,the Lewis factor will decrease with a drop of the ambient pressure and after the transition,the Lewis factor will increase with a drop of the ambient pressure.After a pressure correction factor had been introduced,the correlation formula can predict relatively well the Lewis factor at various ambient pressures and the relative errors between the values calculated by using the correlation formula and 99% of the test data are within a range of ±20%.

TK172

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