再循环重力供液制冷系统换热性能可视化研究

建立了再循环重力供液制冷系统可视化试验台,在不同工况下对制冷系统进行实验研究,观察玻璃蒸发管内制冷剂的沸腾换热流动状态,研究分析重力供液蒸发器的传热特性。试验表明:再循环重力供液蒸发器内,制冷剂的沸腾换热出现了气泡流、气塞流、气弹流、分层流、波状分层流等流型。通过编程计算得到,经过修正的J.Chawla关联式和Kandlikar关系式分别在低温及高温工况下对沸腾换热系数有较好的预测,计算结果与试验值的偏差均在12.5%以内,采用两种关联式相结合的方法能较好地对重力供液蒸发器管内沸腾换热进行预测。

Visualization Research on the Heat Transfer Performance of the Gravity Feeding Recirculation Refrigeration System

A visualization test bench of the gravity feeding recirculation refrigeration system was established in this paper.Through Experimental studied on the refrigeration system under different conditions,observing the boiling heat transfer flow state of the refrigerant in glass evaporation tube and analyzing the heat transfer characteristics of the gravity feeding evaporator.The experiment indicates that in the gravity feeding recirculation evaporator,the refrigerant appeared bubble flow,gas plug flow,gas bomb flow,stratified flow and wavy stratified flow pattern.By programming calculation,finding that the corrected J.Chawla correlation fits well to the boiling heat transfer coefficient at lower temperatures,and so does the corrected Kandlikar relation at higher temperatures.The deviations between calculation results and the experimental values are all less than 12.5%.Combining of the two relations could accurately forecast the boiling heat transfer of the gravity feeding evaporator.