| 摘要: |
| 对流体R1234ze在内径2 mm 的水平光滑圆管内的冷凝换热特性进行了实验研究，设定流体饱和温度为35 ℃、40 ℃，质量流量为100~400 kg/(m2?s)，热流密度为4~22 kW/m2。实验获得了R1234ze在不同工况下的冷凝换热系数和摩擦压降。发现R1234ze的冷凝换热系数范围在1.5到8 kW/(m2?K)之间，且随干度的增加而增加，随质量流量的增大而增大，随饱和温度的升高而降低，比在相同工况下R134a 、R32的换热系数分别平均低约22%和31%。R1234ze的摩擦压降随质量流量增加而增大，随饱和温度的升高而降低，高于相同工况下R32的摩擦压降。并将本次实验值与其它经典换热模型和压降模型进行了对比分析，发现Baird等人的模型对本次实验的换热系数预测较好，对其它文献中的相似数据点预测也较好。Müller- Heck模型对摩擦压降预测最好。 |
| 关键词: 制冷剂 R1234ze 冷凝换热系数 摩擦压降 水平光滑管 |
| DOI： |
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| 基金项目:国家自然科学基金（51176133）资助项目。 |
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| Heat transfer Characteristics for Condensation of R1234ze in a Horizontal Small Tube |
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Li Minxia, Yang Yingying, Gu Haoxiang, Ma Yitai
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| (Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, MOE, School of Mechanical Engineering, Tianjin University) |
| Abstract: |
| The condensation heat transfer coefficients of R1234ze in a single circular minitube of 2mm inner diameter were investigated experimentally. The experiment are conducted at saturation temperature of 35 ℃ and 40 ℃, mass flux of 100~400 kg/(m2?s) and heat flux of 4~22 kW/m. The test results showed that the range of heat transfer coefficients is 1.5~8 kW/(m2?K). Both the heat transfer coefficients and frictional pressure drop of R1234ze increase with the rise of mass flux, and decrease with the rise of saturation temperature. Compared with R134a and R32, the heat transfer coefficient of R1234ze is relatively low (22% lower than R134a and 31% lower than R32), and the frictional pressure drop of R32 is higher than R1234ze. After comparing the results with several typical predicted correlations, it is shown that Baird model can predict the experimental heat transfer coefficients well and Müller- Heck model can predict the experimental frictional pressure drop with best accuracy. |
| Key words: refrigerant R1234ze condensation heat transfer coefficients frictional pressure drop horizontal small tube |
