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本文对超临界压力CO_2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200~500,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。
In this paper, numerical simulation of convective heat transfer in laminar flow of supercritical pressure CO_2 in a fine serpentine tube was carried out. The diameter of the serpentine tube studied is 0.5 mm, the radius of curvature is 2 mm, the inlet Reynolds number is 200 ~ 500 and the pressure is 9 MPa. The influence of variable physical properties, buoyancy force and centrifugal force were analyzed. The temperature and velocity distributions of the characteristic cross sections were analyzed in detail. The results show that the temperature and the velocity of the cross section are symmetrical and the symmetry disappears when the flow is upward. The distribution of the two pairs of vortices shows different characteristics when the flow is upward and horizontal, and the regions of heat enhancement and weakening are different.