Abstract:

Based on the boundary layer theory，a new simple numerical model is proposed by taking into account the effect of variable physical properties.Numerical simulations are carried out to investigate the turbulent convective heat transfer of water in tubes at the supercritical pressure（SCP）.The comparison of the simulation with experiment data shows that the proposed model gives correct results about the effects of pressure，mass flux and wall heat flux on the heat transfer for variable-property flow at the SCP and saves considerable computation time.Two low Reynolds number k-ε turbulence models by Jones and Launder（JL）to predict heat transfer of water at the SCP are evaluated.The JL1 model(c1=1.55)agrees well with the constant-property flow but greatly underestimates the heat transfer coefficient under the SCP condition.The JL2 model(c1=1.45)〖JP〗significantly overestimates the heat transfer coefficient for the constant-property flow，but it exhibits a good prediction in a wide range of parameters under the SCP condition.

Key words:

超临界, 对流换热, 变物性, 低Reynolds数k-ε模型

摘要：

基于边界层理论，针对管内变物性湍流流动，建立了一种简单的数值模型，对超临界压力下水在直管内的湍流强制对流换热进行了数值研究。计算结果与实验数据比较表明，该数值模型不仅能正确地反映超临界工况下压力、质量流速和壁面热通量等参数对传热系数的影响，而且整个计算过程简洁而高效;计算中分别应用了两种均由Jones和Launder提出的低Reynolds数k-ε湍流模型（JL模型），发现JL1模型（c1=1.55）适用于常物性管流，但在模拟超临界工况时计算值比实验值偏低很多;JL2模型（c1=1.45)明显高估了常物性管流的传热系数，但在模拟超临界工况时在大部分参数范围内有着良好的预测精度。

关键词:

超临界, 对流换热, 变物性, 低Reynolds数k-ε模型