摘要
本文通过数值模拟Fluent软件,建立二维模型,利用体积函数模型研究水平管降膜蒸发器管外气液两相的降膜流动,通过对比不同的换热管的形状、布液高度及制冷剂,分析了换热管外成膜情况、液膜的流动情况和成膜厚度。结果表明:采用同一种制冷剂时,3种管形的液膜厚度在0°~180°呈先下降后上升的趋势,液膜厚度最小值均在90°附近,且水平方向圆管的液膜厚度分别为0.349 mm和0.343 mm,大于另外2种换热管;蛋形管的成膜效果好于圆管和滴形管;在不同的制冷剂下,蛋形管管外液膜厚度在水平方向分别为0.346 mm和0.334 mm,制冷剂R1234ze(E)的成膜效果优于制冷剂R134a;当采用制冷剂R134a且流速一定时,蛋形管的液膜厚度在上半周随布液高度的影响增大而减小,下半周则与之相反。
A two-dimensional model is established by numerical simulation Fluent software in this paper.The volume of fluid model is used to study the falling film flow of gas-liquid two-phase outside the horizontal tube falling film evaporator.By comparing different heat exchange tube shapes,liquid distribution heights and refrigerants,the film formation outside the heat exchange tube,the flow of the liquid film and the thickness of the film are analyzed.The results show that when the same refrigerant is used,the liquid film thickness of the three tubes decreases initially and then increases from 0°to 180°.The minimum liquid film thickness is near 90°,and the liquid film thickness of the horizontal circular tube is 0.349 mm and 0.343 mm,respectively,which is larger than that of the other two tube types.The film-forming effect of egg-shaped tube is better than those of round tube and drop-shaped tube.Under different refrigerants,the thickness of the liquid film outside the egg-shaped tube is 0.346 mm and 0.334 mm in the horizontal direction,respectively.The film forming effect of refrigerant R1234ze(E)is better than that of refrigerant R134a;when the refrigerant R134a is used and the flow rate is constant,the liquid film thickness of the egg-shaped tube decreases with the increase of the liquid distribution height in the first half of the cycle,which is opposite in the second half of the cycle.
作者
张君怡
杨丽
吴兆娣
ZHANG Junyi;YANG Li;WU Zhaodi(School of Thermal Engineering,Shandong Jianzhu University,Jinan 250100,Shandong,China;Liaocheng Xinao Gas Co.,Ltd.,Liaocheng 252000,Shandong,China)
出处
《制冷技术》
2025年第3期16-21,共6页
Chinese Journal of Refrigeration Technology
关键词
降膜蒸发器
数值模拟
异形管
布液高度
Falling film evaporator
Numerical simulation
Special pipe
Distribution height
