细蛇形管内超临界压力CO_2层流对流换热数值研究

Numerical Investigation on Laminar Convection of Supercritical Pressure CO_2 in a Mini Serpentine Tube

本文对超临界压力CO2在微细蛇形管内层流对流换热开展了数值模拟研究。研究的蛇形管内径0.5 mm,弯曲半径2 mm,入口雷诺数200500,压力9 MPa。分析了变物性、浮升力和离心力的影响,对特征截面温度与速度分布进行了详细分析。结果表明:向上流动时,截面温度和速度呈对称分布,水平流动时,对称性消失;截面上两对涡的分布在向上和水平流动时呈现不同特性,换热强化和减弱区域不同。

This paper presents numerical investigation on the laminar convection heat transfer of supercritical pressure CO_2 in a serpentine tube with inner diameter of 0.5 mm and curve radius of2 mm.The inlet Reynolds number varies from 200 to 500 under pressure 9 MPa.The effects of properties variations,buoyancy force and centrifugal force are analyzed with providing the detail analysis of the temperature and velocity distribution on the characteristic cross-sections.The results show that the temperature and velocity distributions on the cross-sections are symmetrical when flowing vertically but this symmetry disappears when flowing horizontally.The distribution of two pairs of vortexes on the cross-sections varies in the different flowing directions with the corresponding improved heat transfer area or weakened heat transfer area.