考虑对流换热的水平套管式蓄热体数值模拟

在考虑对流传热作用的基础上,采用数值传热方法建立了十水硫酸钠蓄热材料的凝固/熔化模型,并应用焓法对水平放置的同心套管蓄热体进行了数值模拟,分析了相变传热过程中不同时刻套管内相变材料的速度场和温度场分布,考察了对流换热对传热的影响。研究结果表明,随着蓄热过程的进行,对流换热对传热的影响越来越强烈,不可忽略。对两种可增强对流换热效应的偏心套管式蓄热体和非均匀内纵翅片套管式蓄热体进行了研究,结果表明两种新结构都能较大幅度提高蓄热体性能,缩短放热时间,而且非均匀内纵翅片套管性能更优。研究结果对该类蓄热体在工程实际中的应用具有一定的参考价值。

Numerical Study of Horizontal Double-pipe Thermal Accumulating Units Considering Heat Convection

The solidification and liquefaction model of the phase change material-sal glaubera was set up via numerical heat transfer method,considering the heat convection.Firstly,the enthalpy method was employed to simulate the horizontal coaxial double-pipe thermal accumulating unit and the distribution of temperature and velocity fields was analyzed at the different time to estimate the influence of the heat convection.The calculating result indicates the heat convection can not be ignored due to the stronger and stronger affection caused by the heat convection when the time elapses.Hence,two enhanced new accumulating units,eccentric double-pipe and coaxial double-pipe with asymmetrical internal longitudinal fins,were studied.The simulation shows these new structures are able to increase the performance and reduce the liberating time of phase change material.The coaxial double-pipe with asymmetrical internal longitudinal fins is better than the eccentric double-pipe.The results presented in this paper could guide the practical design of the double-pipe thermal accumulating units.