流体变物性对带肋套管内耦合换热的影响

Numerical Simulation of Variable Fluid Properties' Influence on Conjugated Heat Transfer in a Concentric Tube Recuperator with Longitudinal Fins

数值模拟了变物性带均布纵肋的同心套管换热芯的导热和对流换热耦合问题三维温度场和流场以及Nu数,与常物性下的结果进行了对比。对微型燃气轮机回热器,必须考虑物性的变化对流动和传热的影响。在相同质量流量和几何条件下,考虑物性变化时的平均Nu与常物性时要小很多。变物性对摩擦系数影响非常大,温度升高摩擦阻力也增大。在相同的Re下,变物性和常物性时的平均Nu相差很小,其比值在0.97～0.99之间,因此在常物性时所得的平均Nu,仍具有参考价值。

In the paper, 3D temperature and fluid flow fields were numerically simulated in three-split concentric tube recuperator with longitudinal fins on conjugated heat transfer. The rules of the Nusselt number for both of the constant thermo-physical property parameters and the variable gas fluid flow were found, by comparison, the difference between them is very large at the same mass rate, so the variable has remarkable influence on Nusselt number, which must be considered, so is it to the friction coefficient of them. At the same Reynolds number, the mean Nusselt number is almost the same, the ratio of the variable and the constant is about 0.97～0.99, then the mean Nusselt number for the constant thermo-physical property parameters is also valuable for the variable.