肋片布置对相变蓄冷用冷藏车蓄冷板充冷过程的影响

The effect of fins arrangement on the charging process of cold panel with phase change material in a refrigerated truck

为量化充冷管道外添加肋片对采用相变蓄冷技术的城市冷链配送小型冷藏车用蓄冷板充/补冷过程的影响,以相变材料(PCM)RT5 HC作为蓄冷介质,对PCM凝固过程进行计算,分析充冷管道上肋片数量、肋片形状、肋片厚度及相邻管道上肋片布置方式对充冷时间及蓄冷效率的影响。结果表明,充冷管道上设置肋片,蓄冷板充冷过程中液态和部分凝固的PCM被分隔为多个小区域,小区域内自然对流得到强化,同时相界面延长,传热面增大,冷量传递加快;与充冷管道上无肋片的蓄冷板相比,设置肋片使充冷时间大大降低,蓄冷效率ε得到极大的提升,而蓄冷量略有降低;当肋片数量由4条依次增加至6,8条时,对应的ε及肋片效率ε_(f)增长速率升高,而由8条增加至10条时,ε及ε_(f)增长速率下降;对比肋片截面形状,矩形肋片效率最高,为3.19;肋片厚度t增大对蓄冷效率的提升作用较小;相邻充冷管道上不同肋片布置方式对充冷过程影响较小。研究结果为蓄冷板内充冷管道设计提供参考。

In order to quantify the influence of adding fins outside tube on charging/replenishing process for cold panel with phase change material(PCM)in a refrigerated truck for urban cold chain logistics,the solidification process of RT5 HC was numerically analyzed.The effects of the numbers of fins,fin shape,fin thickness and fins arrangement of adjacent tubes of tube bank in cold panel on charging time and charging efficiency were discussed.The calculation results show that,when setting up fins on the charging tube,the liquid and partially solidified PCM were divided into several small areas,in which the natural convection is strengthened,meanwhile,the phase interface was extended,resulting in the increase of heat transfer area and acceleration of energy transfer.Compared with unfinned tubes in cold panel,the finned tubes shortened the charging time and improved charging efficiency considerably,meanwhile,cold storage capacity slightly decreased.When the number of fins increases from 4 to 6 and 8,the growth rate of ε and ε_(f) improves.While number of fins changes from 8 to 10,and the growth rate of ε and ε_(f) decreases.The fins with rectangle-section,by contrast,display higher fin efficiency and the value is 3.19.Larger fins thickness causes marginal promotion for charging efficiency;and fins arrangement of adjacent tubes of tube bank in cold panel has little influence on changing process.The above conclusions provide a reference for the design of tubes in cold panel filled with PCM.