超临界CO_2水平细微管内层流流动与换热的数值模拟  

Numerical solution of mixed convective heat transfer of supercritical carbon dioxide in horizontal mini tubes

作　　者：饶政华[1] 廖胜明[1] 

机构地区：[1]中南大学制冷空调研究所,湖南长沙410075

出　　处：《热科学与技术》2005年第2期113-117,共5页Journal of Thermal Science and Technology

基　　金：国家自然科学基金资助项目 (5 980 60 0 2 )

摘　　要：对超临界CO2 在水平细微管内层流流动与换热进行了数值模拟。给出了冷却和加热条件下,细微管(d<1 .0 mm)内有代表性的速度、温度剖面,以及Nusselt数随流体温度的变化。研究表明:超临界CO2 在水平细微管内层流流动时,由于流体热物性随温度剧烈变化,浮升力的影响非常显著,加强了管内换热;且由于流体强变物性特点,只要流体和壁面存在温差,速度及无量纲温度分布就不断变化,充分发展流不可能达到。研究结果对超临界CO2Investigation of laminar flow and convective heat transfer of supercritical carbon dioxide in horizontal miniature tubes was carried out numerically. The flow patterns and isotherms in typical cross sections with tube diameters less than 1.0 mm under both cooling and heating conditions with and/or without gravity were presented. The variations of Nusselt numbers with bulk temperature were also obtained. The results indicate that the buoyancy effects are significant for all cases considered due to the sharply varied physical properties of the fluid. The velocities and nondimensional temperatures keep changing and fully developed flows can never be reached unless the fluid and tube wall are under thermal equilibrium condition. The results of this work are of significance for the design of high efficiency compact heat exchangers of supercritical carbon dioxide.

关 键 词：超临界CO2 层流流动 数值模拟 水平 NUSSELT数 无量纲温度分布 紧凑式换热器 流体热物性 加热条件 温度剖面 流体温度 管内换热 充分发展 研究结果 代表性 浮升力 变物性 速度 壁面 

分 类 号：TK124[动力工程及工程热物理—工程热物理] TQ028.32[动力工程及工程热物理—热能工程]