Heat Transfer Enhancement of Supercritical Nitrogen Flowing Downward in a Small Vertical Tube:Evaluation of System Parameter Effects

作     者：ZHU Xiaojing LYU Zhihao YU Xiao LI Qiang CAO Maoguo REN Yongxiang ZHU Xiaojing;LYU Zhihao;YU Xiao;LI Qiang;CAO Maoguo;REN Yongxiang

作者机构：Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of EducationDalian University of TechnologyDalian 116024China Shenyang Aeroengine Research InstituteAero Engine Corporation of ChinaShenyang 110015China 

出 版 物：《Journal of Thermal Science》 (热科学学报（英文版）)

年 卷 期：2020年第29卷第6期

页      面：1487-1503页

核心收录：

学科分类：080701[工学-工程热物理] 08[工学] 0807[工学-动力工程及工程热物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：financially sponsored by the National Natural Science Foundation of China(No.51876024 and No.51976204) Science and Technology on Reactor System Design Technology Laboratory 

主　　题：supercritical nitrogen heat transfer enhancement(THE) numerical simulation vertically downward flow system parameter evaluation 

摘      要：In this paper,the heat transfer enhancement(HTE)of supercritical nitrogen flowing downward in a vertical small tube(diameter 2 mm)is studied using the commercial software CFX of Ansys16.1,to provide theoretical guidance on the design of high-performance heat transfer *** effective numerical simulation method,which employs the SSG Reynolds stress model with enhanced wall treatment,is applied to study the heat transfer of supercritical nitrogen under typical working *** objective is to evaluate the effect of the main parameters taking into account the buoyancy and flow acceleration *** results are compared with results calculated from three well-known empirical correlations and the applicability of empirical correlation is discussed in *** is discovered that the Watts and Chou correlation accurately fits the simulation results of supercritical nitrogen and the Dittus-Boelter and Jackson correlations can only be used for high-pressure *** HTE of supercritical nitrogen is closely related to the laminar sub-layer and buffer layer of a boundary *** buoyancy effect on the HTE should be considered at low mass flux conditions,and thermal acceleration can be completely ignored for the cases *** special HTE featured by the increment in heat transfer coefficient with increasing heat flux is discovered at low pressure,and simulation results proved that this HTE is caused by the combined actions of buoyancy as well as significant variations in specific heat and viscosity.