微尺度水平单管内流动沸腾特性实验研究

The Experimental Study of Flow Boiling in Microtube

对非共沸混合工质R134a/R32(75/25)在水平微尺度管道内的流动沸腾换热实验结果进行了分析和讨论,以探究微细通道内流动沸腾换热的主导机制。对影响其换热的多种因素(热流密度、质量流量和质量干度)进行了分析,实验得出,当质量干度较低时,热流密度和质量流量共同控制着微尺度管内的换热方式,当热流密度的影响占主导地位时,管道内的换热以核态沸腾为主;当质量流量的影响占主导地位时,管道内的换热以强制对流为主。

In order to investigate the flow boiling heat transfer mechanism in mierotube, the experiment of azeotropic mixtures R134a/R32 （mass fraction 75/25） boiling heat transfer flowing in microtube was conducted and the experimental results were discussed. The various factors influencing heat transfer （including heat flux, mass flux, quality） were analyzed. According the experimental results, at low quality region the heat transfer is strongly dependent on mass flux and heat flux. When heat flux is dominant, nucleate boiling heat transfer is the main contribution. When mass flux is dominant, convective evaporation is the main contribution.