水平肋片管外自然凝结传热特性研究  

Research on natural condensation heat transfer characteristics on horizontal finned tube

作　　者：李慧君[1] 董楠[1] 王炯[1] 

机构地区：[1]华北电力大学能源动力与机械工程学院动力工程系,河北保定071003

出　　处：《热科学与技术》2015年第2期94-100,共7页Journal of Thermal Science and Technology

摘　　要：基于Nusselt凝结传热理论,沿肋片管圆周方向划分有限个微元角,建立了每个微元角内肋侧壁、肋间基管及肋顶三个区域的凝结传热模型,通过求解非淹没区和淹没区总传热量,推导管外平均传热系数计算式。计算不同肋片高度、肋密度时,R134a饱和蒸汽的管外平均凝结传热系数。结果表明:随肋密度的增加,平均传热系数先增大后减小,肋密度为25fpi时传热最佳;高肋片管的平均凝结传热系数大于低肋片管的,肋片高度达到一定值时,平均传热系数几乎不随肋高增加而增加。当R134a饱和蒸汽为20℃时,两种不同翅片密度的管外平均凝结传热系数随温差的增大而减小,并通过所建模型得到的计算值与Beatty-Kate模型进行了比较,平均误差分别为约16.1%和8.3%,故所建模型基本反映肋片管外蒸汽凝结传热机理。Presents an analytical model to calculate the condensation heat transfer coefficient on horizontal finned tube based on the Nusselt condensation heat transfer theory.The employs an elemental calculation by dividing the tube wall into finite elements to establish the condensate heat transfer model of the fin flank,the channel between fins and the fin tip in the small annular element. The model can predict the mean condensation heat transfer coefficient outside finned tubes by calculating the total heat transfer.The average condensation heat transfer coefficient of the saturated steam R134a outside the pipe versus fin heights ,fin densities were then calculated.The results show that the average heat transfer coefficient first increases and then decreases with the increase of fin density.The optimum fin density is 25 fpi an the average condensation heat transfer coefficient of the higher finned tube is greater than that of lower finned tube.The average heat transfer coefficient hardly increased with the increase of fin height until it reaches a certain value.Compared with the Beatty-Kate model,at the saturation temperature of 20 ℃,the mean condensation heat transfer coefficient of the tubes with two different fin densities shows mean deviations of 16.1% and 8.3%, respectively;and it decreases versus the temperature difference.The model reflects the mechanism of condensation heat transfer on horizontal finned tubes.

关 键 词：凝结 数值分析 传热系数 肋片管优化 理论模型 

分 类 号：TK124[动力工程及工程热物理—工程热物理]