摘要
在水平强化管内R134a的冷凝换热实验中,对试验工况中管内流型进行计算预测,使用关联式对管内传热系数进行预测,以校核实验数据的可靠性,以质量流量、冷凝温度为变量,以总传热系数K、冷冻水传热系数h_w、制冷剂传热系数h_r为衡量指标,对强化管换热热阻进行研究。实验结果表明:总传热系数K、制冷剂传热系数h_r均随质量流量的增加而增大,且对应冷凝温度越低其值越大,而冷冻水传热系数h_w随质量流量的增加而稍有降低,冷凝温度对其值影响并不大。此外,随着质量流量的增加,冷冻水热阻占总热阻比值逐渐增加,但制冷剂热阻总是小于冷冻水热阻,且冷凝温度越低,两者的差值越大。换热管内外热阻比重IOR随着质量流量的增加而降低,随着冷凝温度的升高而增大。
In the experiment of condensation heat transfer of R134 a in the horizontal enhanced tubes, firstly in order to calculate and predict the flow pattern inside the tube under test conditions,and then correlations were used to predict the heat transfer coefficient inside the tube to check the reliability of experimental data, finally, mass flux and condensation temperature were selected as the variables, the total heat transfer coefficient K、the water heat transfer coefficient h_w、the refrigerant heat transfer coefficient h_r were seen as performance evaluation index to study the heat resistance of the enhanced tube. The experimental results show that the total heat transfer coefficient K and the refrigerant heat transfer coefficient hr increase with the increasing mass flux and the decreasing corresponding condensation temperature, but the chilled water heat transfer coefficient hw slightly decreases with increasing mass flux, and condensation temperature has a small influence on it. In addition, as the mass flow rate increases,the thermal resistance ratio of the chilled water gains in the total resistance, but the thermal resistance of the refrigerant side is less than the chilled water side, and the lower the condensation temperature the greater the difference. Furthermore, the inside and outside ratio IOR decreases with increasing mass flow and increaseswith increasing condensation temperature.
作者
杨卫芳
桂超
Yang Weifang;Gui Chao(School of Civil Engineering and Architecture,Xinxiang University,Xinxiang 453003,China;School of Energy and Power Engineering,Shanghai University for Science and Technology,Shanghai 200093,China)
出处
《低温与超导》
CAS
北大核心
2019年第11期77-81,96,共6页
Cryogenics and Superconductivity
关键词
冷凝换热
热阻分析
冷冻水热阻、制冷剂热阻
Condensation heat transfer
Thermal resistance analysis
Water thermal resistance
Refrigerant thermal resistance
