中文摘要：

建立了内径为2 mm的三叶管三维模型,使用ANSYS Fluent软件对超临界二氧化碳在三叶管内的对流换热特性进行了研究,分析了流动方向、进口雷诺数、壁面热流密度和冷却压力等因素对局部换热系数的影响,结果表明：在本文研究的范围内,流动方向对超临界二氧化碳在三叶管内局部换热系数的影响较小,可以忽略,进口雷诺数、壁面热流密度和冷却压力对局部换热系数的影响较大;二氧化碳进口雷诺数越高,对应的局部对流换热系数也越高,壁面热流密度的大小对局部换热系数出现峰值位置有较大影响,对其大小影响不大;超临界二氧化碳冷却压力越高,对应的局部对流换热系数的峰值也越大;局部对流换热系数峰值所对应的温度只与冷却压力下的临界温度有关。

英文摘要：

Three-dimensional model of trefoil tube with diameter of 2ram is established in this paper. Using ANSYS Fluent software, the heat transfer characteristics of supercritical carbon dioxide in the trefoil tube is studied, and the effects of direction of the flow, inlet Reynolds number, wall heat flux and cooling pressure on local heat transfer coefficient are analyzed. The results showed that： in the scope of this study, the effect of flow direction on heat transfer coefficient of supercritical carbon dioxide in trefoil tube is smaller, and could be ignored; influence of inlet Reynolds number and the cooling pressure on the local heat transfer coeff~cients are greatly. The higher the inlets Reynolds number of supercritical carbon dioxide, the larger the local convection heat transfer coefficient. The wall heat flux has great influence on the peak position of the local heat transfer coefficient, and has little effect on its value. The higher the cooling pressures of supercritical carbon dioxide, the larger the peak of the local convection heat transfer coefficient. The temperature of local convection heat transfer coefficient peak only corresponding to the critical temperature under the cooling pressure.