翅片管熔盐对流传热特性研究

高温熔盐在熔盐堆和太阳能等能源领域有广泛的应用前景。为研究熔盐在强化换热管中的强化传热效果,本文基于三元硝酸盐KNO_3-NaNO_2-NaNO_3(摩尔分数比为53%-40%-7%)与导热油的对流传热实验装置,根据相似理论使用导热油代替熔盐,对翅片换热管湍流区的对流传热特性开展了测量,流体雷诺数(Re)变化范围10 000-60 000。通过威尔逊分离法获得翅片管中湍流区的对流传热系数(ho)和努赛尔数(Nu),基于实验数据与Dittus-Boelter公式,拟合翅片管湍流区的对流传热关联式,实验数据与拟合公式的误差在-7.1%-7.5%之间。与传统对流传热关联式Dittus-Boelter公式对比进行强化传热效果评估,结果表明,翅片管的强化传热效果为光滑管的2.32-3.63倍。

Heat transfer characteristics of molten salt in finned tube

Background: High-temperature molten salt has been considered as medium for heat transfer in molten salt reactors and energy storage in solar power due to its excellent thermal physical properties.Purpose:This study aims at the heat transfer characteristics of molten salt and the enhanced heat transfer effect in finned tube.Methods: Based on the convective heat transfer experimental apparatus of KNO3-NaNO2-NaNO3 (53%-40%-7%) molten salt and heat transfer oil, the heat transfer characteristics of turbulent region in finned tube was studied. The convective heat transfer characteristics of molten salt in finned tube were analyzed on the basis of experimental data, and a new correlation was proposed by the least squares fitting method. Furthermore, the effect of enhanced heat transfer of finned tube was discussed based on above analysis.Results andConclusion: The error between the experimental data and the fitting formular is in the range of?7.1% and 7.5%. The Dittus-Boelter convective heat transfer correlation is used to evaluate the effect of heat transfer, and it shows that the enhanced convective heat transfer effect of the finned tube is 2.32?3.63 times of that of smooth tube.