热流对考虑自然对流吸热管内熔盐对流传热影响

Effect of heat flux on convective heat transfer with natural convection in a receiver tube

以熔盐为传热工质,对考虑自然对流条件下吸热管内熔盐的流动与传热进行了数值研究。结果表明:均匀热流下自然对流促进管内下侧和熔盐向管中心流动,弱化管内上侧熔盐向管中心流动;吸热管内下侧Nu数大于上侧Nu数,管内最大Nu数出现在底部,最小Nu数出现在顶部,吸热管内下侧Nu数与上侧Nu数的差值随着Re数增大而减小,但其平均Nu数变化较小,且其平均Nu数与不考虑自然对流影响的管内平均Nu数基本相等。非均匀热流下吸热管加热的上下位置对吸热管内单侧Nu数影响较大,但对平均Nu数无影响。同一Re数,吸热管上侧Nu数随着热流增高而最小。

The effect of molten salts natural convection on flow and heat transfer in a receiver tube has been simulated.The simulated results showed that the natural convection promoted downside part molten salts flow to the central,but weakened upside part.The Nusselt number of receiver tube downside part was higher than that of upside part,and the maximum Nusselt number appeared the bottom,the minimum Nusselt number appeared the top,the value difference of Nusselt number downside part to upside part decreased gradually with increasing Reynolds number at uniform heat flux.The average Nusselt number with and without considering natural convection in receiver tube was almost equal.The unilateral Nusselt number was remarkable influenced by the heated position with nonuniform heat flux,but very little influenced to the average Nusselt number.The Nusselt number of receiver tube upside part was reduced with heat flux increased at the same Reynolds number.