【摘要】 结合沸腾传热问题,通过凝练并设计实验系统,研究有机工质R245fa在高效蒸发换热管Turbo-EHP管外流动沸腾传热的性能,分析有"孔穴"结构的表面强化管的强化机理。实验中通过改变热源流量、温度以及工质流量等参数,研究其与局部以及平均沸腾换热系数之间的关系。实验结果表明,Turbo-EHP型管前、中、末3段的强化效果不同,在前段气泡热阻对换热性能有一定的影响,中段换热效果达到最优,末段由核态沸腾转为气与壁面的对流换热,换热效果减弱;且随着工质流量的增大,沸腾性能显著增强。更多还原

【Abstract】 An experimental system to study the efficiency of organic working fluid R245 fa in the evaporator tubes wassetup. Turbo-EHP tube flow boiling heat transfer performance was analyzed and the mechanism of the tube with "cavities" reinforcing surface structure was studied. By changing the heat flow,temperature and the working fluid flowand other parameters,the relationship between these parameters and boiling heat transfer coefficients were studied.Experimental results showed that,the reinforcing effect of Turbo-EHP type is different in three sections. On the head ofthe tube bubble resistance have an impact on the heat transfer performance,optimal heat transfer performance on themiddle section,on the last section the nucleate boiling change to convective heat transfer between gas and the wall,heattransfer weakened. And with increase of the working fluid flow rate,the boiling performance is significantly strengthened.更多还原