竖直圆管内跨临界压力区水对流传热数值模拟研究

Numerical Simulation on Convective Heat Transfer to Transcritical Pressure Water in Vertical Heated Tube

应用CFD方法对跨临界压力区竖直圆管内水的对流传热进行了数值模拟研究。通过与实验结果比较,分析了浮升力因素的影响机理。研究结果表明,采用浮升力修正的k-ε两方程湍流模型可准确预测跨临界压力区正常对流传热现象。当流体温度达到拟临界点,尽管该模型可预测传热恶化现象,但与实验数据偏差较大,在水热物性及数值模型等方面有待进行更深入研究。

Numerical investigations on flow and heat transfer were conducted for transcritical pressure fluid. A three-dimensional numerical method was developed by modeling upward water in a uniformly heated tube with inside diameter of 6.07 cm. Numerical results based on the buoyancy-corrected k-epsilon turbulence model are in good agreement with the experimental data under normal heat transfer conditions. The flow pattern and wall temperature distribution indicate heat transfer deterioration when temperature range experiences the pseudocritical point. Buoyancy plays a significant role in the occurrence of heat transfer impairment, though clear discrepancy is found mainly due to physical model＇s inadequate prediction. Further recommendations were made for numerical applications to transcritical flow and heat transfer.