数据中心冷却用丁胞型扁管内冷凝传热和压降特性试验研究

xperiment on condensation heat transfer and pressure drop characteristics in dimpled flat duct for data center cooling

针对丁胞型扁管内的冷凝传热和压降特性开展试验研究,分析干度、质量流速、饱和温度和热流密度对表面传热系数和摩擦压力梯度的影响。结果表明:在不同运行工况下,R245fa的表面传热系数均随干度的增大而增大;增大质量流速有利于提高表面传热系数,尤其是对于高干度区域;饱和温度改变对低干度区域的表面传热系数影响较小,但是当干度大于0.4时,饱和温度升高会导致表面传热系数略微下降;在整个干度区域内,不同热流密度对表面传热系数基本没有影响;质量流速和热流密度对摩擦压力梯度的影响与其对表面传热系数的影响相似,但是饱和温度升高会导致压降明显下降;丁胞型扁管的表面传热系数为常规流道的1.7~2.9倍,摩擦压力梯度为常规流道的4.3~10.9倍。

An experimental study on the condensation heat transfer and pressure drop characteristics in a dimpled flat duct is conducted.The influences of vapor quality,mass flux,saturation temperature and heat flux on the surface heat transfer coefficient and frictional pressure gradient are analyzed.The results indicate that under different operation conditions,the surface heat transfer coefficient of R245fa increases with the increase of vapor quality.Increasing mass flux is conducive to the increase of surface heat transfer coefficient,especially for the high vapor quality region.The change of saturation temperature affects the surface heat transfer coefficient little in the low vapor quality region,but when the vapor quality is higher than 0.4,the increase of saturation temperature leads to a slight decrease of the surface heat transfer coefficient.Meanwhile,in the whole vapor quality region,different heat fluxes basically affect the surface heat transfer coefficients little.The influences of mass flux and heat flux on friction pressure gradient are similar to those on surface heat transfer coefficient,but the pressure drop decreases obviously with the increase of saturation temperature.Compared with conventional flow paths,the surface heat transfer coefficient and friction pressure gradient of dimpled flat duct are increased to 1.7-2.9 times and 4.3-10.9 times,respectively.