不同结构金属翅片对石蜡相变传热的影响

分别将两种金属翅片(翅片1、翅片2)加入纯相变材料(石蜡),制备复合相变材料1、复合相变材料2。容纳石蜡的方腔长×宽×高为20 mm×10 mm×20 mm,翅片1的长×宽×高为15 mm×10 mm×1 mm,翅片2是在翅片1的基础上增加6个直径为3 mm通孔，金属翅片设置在方腔内部，垂直于左壁面平行布置。石蜡的初始温度为298.15 K,相变开始之前石蜡为固态。方腔左壁面为加热面，温度恒定为338.15 K,其余各面为绝热面。采用有限元软件COMSOL Multiphysics模拟方腔内石蜡的相变过程，分析加热过程中纯相变材料、复合相变材料的液相率分布、液相率随时间变化、速度场分布。纯相变材料内，在导热和对流换热的共同作用下，石蜡从左上角开始熔化直至右下角石蜡完全熔化。方腔内金属翅片的加入可改善熔化过程的均匀性，缩短了熔化时间。纯相变材料、复合相变材料1、复合相变材料2石蜡完全熔化时间分别为302、106、90 s,复合相变材料1、2比纯相变材料完全熔化时间缩短了约64%、70%,复合相变材料2比复合相变材料1完全熔化时间缩短了约15%。在石蜡熔化初期，主要以导热为主，复合相变材料...

Effect of Metal Fins with Different Structures on Phase-change Heat Transfer of Paraffin

Two kinds of metal fins(fin 1 and fin 2)were added to pure phase-change material(paraffin)to prepare composite phase-change material 1 and composite phase-change material 2.The length×width×height of the square cavity containing paraffin was 20 mm×10 mm×20 mm,the length×width×height of the fin 1 was 15 mm×10 mm×1 mm,and 6 through holes with a diameter of 3 mm were added to the fin 2 on the basis of the fin 1.The metal fins were arranged inside the square cavity and were arranged perpendicular to the left wall in parallel.The initial temperature of the paraffin was 298.15 K,and the paraffin was solid before the phase change started.The left wall of the square cavity was the heating surface,the temperature was constant at 338.15 K,and the other surfaces were adiabatic surfaces.The finite element software COMSOL Multiphysics was used to simulate the phase change process of paraffin in the square cavity,and the liquid phase ratio distribution,liquid phase ratio change with time and velocity field distribution of pure phase-change material and composite phase-change materials during the heating process were analyzed.In the pure phase-change material,under the combined effect of heat conduction and convection heat transfer,the paraffin started to melt from the left wall until the paraffin in the lower right corner was completely melted.The addition of metal fins in the square cavity can improve the uniformity of the melting process and shorten the melting time.The complete melting time of paraffin in pure phase-change material,composite phase-change material 1 and composite phase-change material 2 was 302 s,106 s and 90 s,respectively.The complete melting time of paraffin in composite phase-change materials 1 and 2 was about 64%and 70%shorter than that in pure phase change material,and the complete melting time of paraffin in composite phase-change material 2 was about 15%shorter than that in composite phase-change material 1.In the initial stage of paraffin melting,it was mainly heat conduction.The liquid phase ratio of composite phase-change material 1 was higher than that of composite phase-change material 2.With the melting of paraffin,the natural convection effect gradually appeared,and the liquid phase ratio of composite phase-change material 2 was gradually higher than that of composite phase-change material 1.During the melting of the pure phase-change material,the flow of paraffin was mainly concentrated on the heating wall and the phase change interface,and the keratinization phenomenon was obvious.In the composite phase-change material 1,the flow of paraffin was close to the top of the fin and the upper and lower walls close to the heating wall,which showing a partial flow.The circular flow trend in composite phase-change material 2 was more obvious than that of paraffin in composite phase-change material 1,and the natural convection heat transfer effect was stronger.