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采用RNG k-ε湍流模型对超临界CO2流体在内径为4 mm,长度2000 mm,节距为10 mm,曲率为0.1的水平螺旋管内的冷却换热进行了数值模拟.研究了质量流量、热流量以及压力对换热系数的影响,并和超临界CO2在水平直管内的冷却换热进行了对比.研究结果表明,超临界CO2在水平螺旋管内流动产生的二次流强于水平直管内的二次流,前者的换热系数大于后者;换热系数随质量流量的增加而增大;在似气体区,换热系数随着热流量的增加而增大,而在似液体区,热流量对换热系数几乎没有影响;换热系数峰值点随着压力的升高而下降,并向高温区偏移.
The RNG k-ε turbulence model was used to simulate the cooling heat transfer of supercritical CO2 fluid in a horizontal spiral tube with an inner diameter of 4 mm, a length of 2000 mm, a pitch of 10 mm and a curvature of 0.1. The effects of mass flow rate, Flow and pressure on the heat transfer coefficient were compared with that of supercritical CO2 in horizontal straight pipe.The results show that the supercritical CO2 flow in the horizontal spiral pipe is stronger than that in horizontal straight pipe In the gas-like zone, the heat transfer coefficient increases with the increase of the heat flux, while in the liquid-like zone, the heat transfer coefficient is larger than that of the latter. The heat transfer coefficient increases with the increase of mass flow rate. The flow rate has almost no effect on the heat transfer coefficient; the peak value of the heat transfer coefficient decreases with increasing pressure and shifts to the high temperature range.