Flow boiling heat transfer characteristics and pressure drop of ammonia-lithium nitrate solution in a smooth horizontal tube
Flow boiling heat transfer characteristics and pressure drop of ammonia-lithium nitrate solution in a smooth horizontal tube
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DOI：
10.1016/j.ijheatmasstransfer.2016.12.004
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发表时间：
2017-05
影响因子：
5.2
通讯作者：
Jingkai Jiang;G. He;Yilin Liu;Yue Liu;Dehua Cai
中科院分区：
文献类型：
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作者：
Jingkai Jiang;G. He;Yilin Liu;Yue Liu;Dehua Cai
根据氨/硝酸锂溶液吸收式制冷系统的实际工况选择了实验条件，对氨/硝酸锂溶液在直径为10 mm的水平光滑管内流动沸腾换热系数进行了实验研究。试验段入口处溶液的氨浓度约为45.5wt%。溶液的质量流速和沸腾温度分别在20-55 kg/h和76.7-93.2° C的范围内。研究了热通量、质量通量和出口干度对蒸发器性能的影响。最大流动沸腾换热系数达到2100 W· m-2K-1。结果表明，热流密度对沸腾传热系数有显着影响。在测试过程中发现核沸腾占主导地位。并将实验结果与已有的NH3/LiNO 3溶液流动沸腾传热系数及文献中的关联式进行了比较。Kandlikar关联式适用于描述实验沸腾传热系数，平均偏差为± 12.56%。还测量了不同工况下溶液侧的压降。研究结果对氨/硝酸锂溶液吸收式制冷机组发生器的设计和优化具有重要意义。
This paper presents experimental results of flow boiling heat transfer coefficient of ammonia/lithium nitrate solution in a smooth horizontal tube with diameter of 10 mm. The test conditions are selected based on practical working conditions of absorption refrigeration system with ammonia/lithium nitrate solution. The ammonia concentration of the solution at the inlet of test section is around 45.5 wt%. The mass flow rate and boiling temperature of the solution are in the ranges of 20–55 kg/h and 76.7–93.2° C, respectively. The effects of the heat flux, mass flux and exit vapor quality has been investigated. The maximum flow boiling heat transfer coefficient reaches 2100 W· m-2 K-1. Results show that heat fluxes have significant influence on boiling heat transfer coefficients (HTCs). Nucleate boiling is found to be predominant during the tests. The experimental results are also compared with the available flow boiling heat transfer coefficients of NH 3/LiNO 3 solution and predicting correlations in literature. Kandlikar’s correlation is appropriate to characterize the experimental boiling heat transfer coefficients with a mean deviation of±12.56%. Pressure drops in the solution side are also measured under different working conditions. The results of the present study will be of great significance to the design and optimization of generators in the absorption refrigeration units using ammonia/lithium nitrate solution.