低温风洞管翅式换热器上水室排空残留水层干燥速率试验研究

Experimental study on the drying rate of the residual water layer in the upper water chamber evacuation of a cryogenic temperature wind tunnel tube and fin heat exchanger

为解决低温风洞内管翅式换热器自重排水后上水室残留5 mm水层在风洞低温工况下的冻结问题,在管内、管外热风温度均为40~70℃、入口风速为2.78~10.56 m/s的条件下,对椭圆管和铝扁管两种管翅式换热器自重排水后上水室残留水层进行干燥试验研究,对比分析了管内热风与管外热风干燥方法对两种换热器干燥速率的影响。结果表明:铝扁管换热器干燥速率更快,管外热风干燥方法干燥速率更快,换热器干燥时间随着入口风速的增加而缩短,入口风速10.56 m/s相比2.78 m/s,干燥时间节约50.75%。通过试验数据拟合干燥速率经验关系式,其拟合结果与试验测量值平均误差小于6.1%,对低温风洞内管翅式换热器热风干燥速率有较好的预测能力。

In order This study aims to solve the freezing problem of the 5 mm water layer remaining in the upper water chamber after self-weight drainage of the tube and fin heat exchanger in the low-temperature wind tunnel under low-temperature operating conditions.Under the conditions that the hot air temperature inside and outside the tube are 40—70℃and the inlet air speed is 2.78—10.56 m/s,two types of tube(elliptical tube and aluminum flat tube)and fin heat exchangers are tested and studied for drying the water layer remaining in the upper water chamber after self-weight drainage.The influence of the hot air inside and hot air outside the tube drying methods on the drying rate of the two heat exchangers are compared and analyzed.The results show that:the drying rate of aluminum flat tube heat exchanger is faster,so as the drying rate of the hot air outside the tube drying method is faster,;the heat exchanger drying time decrease with the increase of the inlet air speed and the drying time savings of saves 50.75%at the inlet air and shorten the inlet air speed of 10.56 m/s compared to 2.78 m/s.The empirical relationship equation for the drying rate was fitted by the experimental data,and the average error between the fitted results and the experimental measurements was less than 6.1%,which has a good prediction capability for the hot air drying rate of the tube-fin heat exchanger in the low-temperature wind tunnel.