摘要
分别以蒸馏水和无水乙醇为工质在闭式循环喷雾冷却系统上研究了喷雾流量、表面结构、喷雾工质对传热性能的影响。从对流换热和相变换热比例关系的角度对实验数据进行了整理。结果表明:随喷雾流量的增加,热流密度增加、相变换热份额降低。当水喷雾流量为227.1 g/min、表面温度为74.32℃时,热流密度达到6.8×105W/m2;表面温度对换热有较大影响,温度越高换热性能愈强,无水乙醇的换热始终强于蒸馏水,特别是表面温度较高时,强化换热效果更为明显;其相变份额同样始终大于蒸馏水,表面温度为50℃、流量同为27.52 g/min时,蒸馏水的相变换热份额仅为20.4%,而无水乙醇的达到55.5%。微结构表面虽然减弱了对流换热能力,但减薄了液膜厚度,增强相变换热能力,使换热效果大幅提升。给出了反映表面温度影响的无量纲准则方程。
With distilled water and anhydrous alcohol serving as the working medium respectively,studied was the influence of the atomization flow rate,surface structure and atomization working medium on the heat transfer performance in a closed type cycle atomization and cooling system.For the first time from the viewpoint of convection-based heat exchange and phase-change heat exchange proportions,the authors trimmed and analyzed the test data.It has been found that with an increase of the atomization flow rate,the heat flux density will increase while the phase-change heat exchange proportion will decrease.When the water atomization flow rate is 227.1 g/min and temperature on the surface is 74.32℃,the heat flux density will hit 6.8×10~5 W/m^2.The temperature on the surface has a relatively big influence on the heat exchange.The higher the temperature,the better the heat exchange performance.The heat exchange of anhydrous alcohol is always superior to that of distilled water,especially when the temperature on the surface is relatively high,the intensified heat exchange effectiveness will be more evident.The phase-change heat exchange proportion of the anhydrous alcohol is also invariably higher than that of distilled water.When the temperature on the surface is 50℃ and both flow rates are concurrently 27.52 g/min,the phase-change heat exchange proportion of distilled water is only 20.4% but that of anhydrous alcohol reaches 55.5%.Although the micro-structure surface weakens the convection-based heat exchange capacity,it thins the liquid film thickness and enhances the phase-change heat exchange capacity,thus greatly upgrading the heat exchange effectiveness.A non-dimensional criterion equation reflecting the influence of the temperature on the surface was given.
出处
《热能动力工程》
CAS
CSCD
北大核心
2012年第4期429-433,513-514,共5页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金资助项目(51176205)
山东省自然科学基金资助项目(Y2008F42)
山东省中青年科学家科研奖励基金资助项目(Y2009CL017)
关键词
喷雾冷却
喷雾流量
热流密度
相变换热份额
atomization cooling,atomization flow rate,heat flux density,phase-change heat exchange proportion
