Numerical Study on Flow Heat Transfer Characteristics of Horizontal Tube Falling-Film Evaporator  

作　　者：XU Bo JIANG Chun CHEN Zhenqian 

机构地区：[1]School of Energy and Environment,Southeast University,Nanjing 210096,China [2]Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology,School of Energy and Environment,Southeast University,Nanjing 210096,China [3]Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education,School of Energy and Environment,Southeast University,Nanjing 210096,China

出　　处：《Journal of Thermal Science》2021年第4期1302-1317,共16页热科学学报（英文版）

基　　金：financially supported by National Natural Science Foundation of China (No. 52006031);international cooperation project of China Manned Space Program (6903001173)。

摘　　要：As an efficient and energy-saving heat exchange technology, horizontal tube falling film evaporation has a great application prospect in refrigeration and air conditioning. The three-dimensional models of falling film flow evaporation outside horizontal single tube and inside evaporator were established, and the accuracy of flow and heat transfer simulation process was verified by comparison. For horizontal single tube, the results showed that total heat transfer coefficient was low and increased with larger spray density and evaporation temperature. The thickness of liquid film outside tube decreased gradually with the increase of tube diameter, and the total heat transfer coefficient of small tube diameter was significantly greater than that of the large tube diameter. The total heat transfer coefficient presented an increasing trend with larger liquid distribution height and density. In addition, the fluctuation of tube axial liquid film thickness distribution decreased with larger liquid distribution density. For evaporator, the results indicated that part of liquid refrigerant was carried into the vapor outlet. The temperature of tube wall and fluid presented a gradually rising trend in vertical downward direction, while tube wall temperature within the same horizontal and transverse row had little difference. The high-temperature zone on the outer wall of heat exchange tube moved towards the inlet and gradually decreased, and the outlet temperature of water in the tube also gradually decreased with the increase of refrigerant spray density. The local heat transfer coefficient of heat exchanger tube in the vertical direction presented a downward trend which was more obvious with the smaller spray density and it was obviously higher located in the middle of upper tube row and both sides of lower tube row for horizontal tube rows.

关 键 词：horizontal single tube EVAPORATOR falling film numerical simulation heat transfer 

分 类 号：TB657.5[一般工业技术—制冷工程]