水平壳管式相变蓄能单元传热机理研究

Heat transfer mechanism of horizontal shell-and-tube latent thermal energy storage units

以水平壳管式相变蓄能单元为研究对象,建立了考虑相变的流动传热耦合数学模型,对蓄能单元熔化/凝固过程的传热机理进行了研究。结果表明:熔化过程传热机理为从以导热主导到以自然对流主导再恢复到以导热主导;而凝固过程,传热机理为全程以导热主导;自然对流对熔化过程影响较大,可以强化传热,减少总的熔化时间,而对凝固过程影响很小;由于自然对流的强化传热效果,熔化过程蓄热速率会在快速下降后经历一个先上升再缓慢下降直至熔化结束的过程;凝固过程释热速率呈现快速下降后再缓慢下降直至凝固结束;熔化和凝固过程热量的吸收与释放均以潜热为主。

Taking the horizontal shell-and-tube latent thermal energy storage unit as the research object,establishes a mathematical model of coupled flow and heat transfer considering phase change,and studies the heat transfer mechanism of the melting/solidification process of the unit.The results show that the heat transfer mechanism in the melting process is from heat conduction to natural convection and then to heat conduction again,while in the solidification process,the heat transfer mechanism is dominated by heat conduction throughout the whole process.Natural convection has a great influence on the melting process,can strengthen heat transfer and reduce the total melting time,but has little influence on the solidification process.Due to the enhanced heat transfer effect of natural convection,the heat storage rate in the melting process will experience a process from rapid declining to rising and then to slowly falling until the end of the melting process.The heat release rate in the solidification process first rapidly decreases and then slowly decreases until the end of the solidification process.The absorption and release of heat during melting and solidification processes are dominated by latent heat.