椭圆横管外降膜流动和换热特性分析  

Analysis of Falling Film Flow and Heat Transfer Characteristics outside the Elliptical Horizontal Tube

作　　者：谭起滨 蒋斌[1] 

机构地区：[1]西南科技大学土木工程与建筑学院,四川绵阳621010

出　　处：《热能动力工程》2017年第9期20-25,114,共7页Journal of Engineering for Thermal Energy and Power

基　　金：国家自然科学基金项目(51306156);西南科技大学博士基金项目(11zx7106)

摘　　要：本研究基于VOF算法编写用户UDF(自定义函数),采用FLUENT软件建立了椭圆横管外降膜流动和换热的计算模型。根据CFD(计算流体力学)模型计算和分析了在不同长短轴比下管外降膜速度分布、压力分布、液膜内温度分布和管外换热分布的变化规律。研究结果表明:长短轴比的变化影响了管外液膜速度分布、压力分布和膜内温度分布;相比圆管,椭圆管的管外膜内液体流速更快。壁面压力沿周向逐渐减少并在X=0.9附近快速回升;随长短轴比e的增加,周向压力最小值位置逐渐向后推移。局部Nu数分布与压力分布在趋势上存在一致性。当e=1.65附近时,椭圆的换热性能最优;最后,通过对管形的研究分析,提出横管的传热分区模型。Based on VOF algorithm and UDF(user defined function),a physical model was established for elliptical transverse tube falling film flow and heat transfer by FLUENT. According to the CFD model,the velocity distribution of falling film outside tube,pressure distribution,temperature distribution inside the liquid film and the change of the distribution of heat transfer were calculated and analyzed under different ratio of long and short axes. The data of simulation were consistent with the experimental data. The results showed that the velocity distribution,pressure distribution and temperature distribution of the liquid film are affected by the change in the ratio of long and short axes.Compared to the circular tube,the liquid flow rate in the elliptical tube is faster. Wall pressure gradually decreases along the circumferential direction and has rapid recovery at X = 0. 9. With the increase in the ratio of long andshort axes,the position of the minimum circumferential pressure is gradually increased. The local Nu reaches the minimum value at X = 0. 9. The local Nu distribution is consistent with the pressure distribution in term of trend.When the ratio of long and short axes is 1. 65,the heat transfer performance of ellipse is optimal. At last,the heat transfer model for horizontal tube was presented in this paper through the study and analysis of the tube shape.

关 键 词：降膜流动 椭圆管 结构优化 传热传质 传热模型 

分 类 号：TK172[动力工程及工程热物理—热能工程]