太阳能集热管内熔盐流动传热特性数值模拟

Numerical Simulation Study on the Heat Transfer of Molten Salt in Solar Receiver Tube

建立太阳能集热管物理模型,采用RNG κ-ε模型,基于CFD方法在不同热流边界条件下熔盐入口温度300℃,速度0.6~3.6 m/s,平均热流密度180 k W/m2参数范围内,对外径20 mm,壁厚2 mm的集热管内熔盐传热特性进行数值模拟研究。分析了集热管管壁温度分布规律和熔盐传热性能,对比了不同热流边界下管壁周向温度不均匀分布特性。研究结果表明:不同热流条件下集热管管壁温度分布规律差异较大,管内熔盐温度也存在较大差异;集热管内Nu随Re增大而升高,周向热流分布对Nu影响较大;非均匀热流边界下集热管壁温周向分布不均匀,周向热流越不均匀,壁面温差越大。

A physical model of solar receiver tube of which the inner diameter is 16 mm and wall thick- ness is 2 ram, was built to numerically investigate the heat transfer of molten salt in the receiver tube. The numerical investigation was performed within the range of inlet velocity from 0.6 to 3.6 m/s, and the molten salt temperature is 300%, average heat flux is 180 kW/m2. The present study uses CFD to reveal the temperature distribution and transfer characteristics by using the RNG κ -ε model. The results show that the temperature distribution of molten salt and tube wall was difference under the uniform and non - uniform heat flux. The Nusslet number increases with Reynolds number in the receiver tube,the circular heat flux have a great influence on Nusselt number. The temperatures at tube wall are non - uniformity on the circumference under the non - uniform heat flux. The great uneven of circular heat flux induces a great difference of the temperature at tube wall.