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研究非共沸混合工质R32/R134a(质量比,25%/75%)在水平微尺度通道内流动沸腾换热规律。在各种工况下进行了非共沸混合工质R32/R134a在水平微尺度管道内流动沸腾换热的实验,考察了质量流量G、热流密度q、质量干度x对微尺度通道内流动沸腾换热系数的影响。研究表明:在热流密度、质量流量都较低的区域,对细管道,换热系数与热流密度的关联度较大;而对微管道,换热系数受影响的因素比较多,并在干度为0.6时出现“干涸”现象,使得换热系数急剧下降。在质量流量高的区域,对细管道,热流密度对换热系数的影响很小;而对微尺度管道,当干度为0.06时换热系数发生转变,随质量干度的增加先减小后增大,热流密度增大到一定的阶段后,换热系数不再随热流密度变化。
The flow boiling heat transfer of non-azeotropic mixture R32 / R134a (mass ratio, 25% / 75%) in horizontal micro-scale channels was studied. Experiments were carried out to study the boiling heat transfer of non-azeotropic refrigerant R32 / R134a in horizontal micro-scale pipes under various operating conditions. The effects of mass flow rate G, heat flux density q and mass dryness x on the flow in micro-scale channels Effect of boiling heat transfer coefficient. The results show that in the areas with low heat flux and mass flow, the correlation between the heat transfer coefficient and the heat flux of the thin pipe is large. However, there are many factors affecting the heat transfer coefficient of the micro pipe, 0.6 when the phenomenon of “dry up ”, making the heat transfer coefficient dropped sharply. In the area with high mass flow, the effect of heat flux density on the heat transfer coefficient is very small. For the microscale pipe, when the degree of dryness is 0.06, the heat transfer coefficient changes and then decreases with the increase of mass dryness Increases, the heat flux increases to a certain stage, the heat transfer coefficient no longer changes with the heat flux density.