水平波纹管外降膜蒸发的液膜流动与换热特性分析  

Liquid film flow and heat transfer characteristics of falling film evaporation on horizontal corrugated tube

作　　者：王迎慧[1] 邢聪骢 刘建停 WANG Yinghui;XING Congcong;LIU Jianting(School of Energy and Power Engineering,Jiangsu University,Zhenjiang,Jiangsu 212013,China)

机构地区：[1]江苏大学能源与动力工程学院,江苏镇江212013

出　　处：《江苏大学学报（自然科学版）》2023年第1期89-95,共7页Journal of Jiangsu University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51576091)。

摘　　要：针对低温制冷剂R134a(C2H2F4)在水平管外存在降膜蒸发问题,运用流体体积(volume of fluid, VOF)模型与用户自定义函数(user-defined functions, UDF)数值模拟管外液膜流动与换热特性,包括液膜沿换热管(波纹管与光管)的轴向和圆周方向的流动、液膜厚度分布、液膜内气泡成核及分布等.计算结果表明:在恒热流(qw=2×104W·m-2)的波纹管与光管外壁上,R134a液膜在轴向和周向上的流动与换热均存在一定差异,波纹管外液膜在轴向上的铺展速度比光管快2.0 ms,而在周向上铺展较为均衡,且铺展速度稍慢于光管;波纹管外液膜平均厚度为0.120 mm,比光管薄7.00%,其中迎面区液膜厚度为0.119 mm,较光管薄13.14%;与光管相比,波纹管外液膜内气泡成核的起始时间提早2.6 ms,成核点数多15.32%,且分布较广,多见于周向角为55°~135°的区域;波纹管外平均换热系数比光管提高10.17%,迎面区换热系数为背面区的3.53倍.To investigate the falling film evaporation process of R134 a(C2H2F4) on horizontal tube, the volume of fluid(VOF) model and the user-defined functions(UDF) were used to numerically simulate the flow and heat transfer characteristics of the liquid film on tubes, including the flow of liquid film along the axial direction and circumferential direction of cross section of heat exchange tubes(corrugated tubes and smooth tubes), the thickness and distribution of liquid film and the bubbles nucleation and distribution in liquid film. The calculation results show that when the heat flux on the wall is 2×10~4 W·m-2, both flow and heat transfer of the R134 a liquid film have differences between corrugated tube and smooth tube in the axial and circumferential direction. Along the axial direction, the spreading speed of the liquid film on corrugated tube is 2.0 ms faster than that on smooth tube, while along the circumferential direction, the liquid film spreads more uniformly and slowly than that on smooth tube. The average thickness of the liquid film on corrugated tube is 0.120 mm, which is 7.00% thinner than that on smooth tube. The thickness of liquid film on the front area of tube is 0.119 mm, which is 13.14% thinner than that on smooth tube. Compared with smooth tube, the first bubble nucleation in the liquid film on corrugated tube occurs 2.6 ms earlier, and the number of bubble nucleation is 15.32% more than that on smooth tube, while the range of bubble nucleation is larger with more bubble nucleation occurring at circumferential angles of 55°-135°. The average heat transfer coefficient on corrugated tube is 10.17% higher than that on smooth tube, and the heat transfer coefficient on the front area is 3.53 times bigger than that on the back area.

关 键 词：波纹管 降膜蒸发 液膜流动 气泡成核 传热 

分 类 号：TK124[动力工程及工程热物理—工程热物理]