Study of Variable Turbulent Prandtl Number Model for Heat Transfer to Supercritical Fluids in Vertical Tubes  

作　　者：TIAN Ran DAI Xiaoye WANG Dabiao SHI Lin 

机构地区：[1]Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University [2]Department of Chemical Engineering, Tsinghua University

出　　处：《Journal of Thermal Science》2018年第3期213-222,共10页热科学学报（英文版）

基　　金：financially supported by the National Key Research and Development Program of China under Grant No.2016YFB0901405;the State Key Program of the National Natural Science Foundation of China(Grant No.51236004);the Science Fund for Creative Research Groups(No.51621062)

摘　　要：In order to improve the prediction performance of the numerical simulations for heat transfer of supercritical pressure fluids, a variable turbulent Prandtl number(Pr_t) model for vertical upward flow at supercritical pressures was developed in this study. The effects of Pr_t on the numerical simulation were analyzed, especially for the heat transfer deterioration conditions. Based on the analyses, the turbulent Prandtl number was modeled as a function of the turbulent viscosity ratio and molecular Prandtl number. The model was evaluated using experimental heat transfer data of CO_2, water and Freon. The wall temperatures, including the heat transfer deterioration cases, were more accurately predicted by this model than by traditional numerical calculations with a constant Pr_t. By analyzing the predicted results with and without the variable Pr_t model, it was found that the predicted velocity distribution and turbulent mixing characteristics with the variable Pr_t model are quite different from that predicted by a constant Pr_t. When heat transfer deterioration occurs, the radial velocity profile deviates from the log-law profile and the restrained turbulent mixing then leads to the deteriorated heat transfer.

关 键 词：Turbulent Prandtl Number Supercritical Fluid Heat Transfer 

分 类 号：TK124[动力工程及工程热物理—工程热物理]