孔隙分布对分形泡沫金属基相变材料传热特性的影响
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摘要
基于分形理论,采用Sierpinski分形结构来模拟分形泡沫金属的孔隙结构。以泡沫金属为基体,孔隙中填充相变材料,通过数值计算比较了相同孔隙率和分形维数但不同孔隙结构分布规律的泡沫金属基相变材料在恒热流边界条件下的传热特性差异,得到了在传热过程中相变材料的相变率随时间变化及其相场分布情况云图。结果表明:当泡沫金属存在开口孔且所在位置处于热流边界时,孔隙中相变材料的传热速率明显大于不存在任何孔隙处于热流边界的情况;当泡沫金属不存在孔隙处于热流边界时,随着泡沫金属比表面积的增大,孔隙中相变材料传热速率增大;且分形体的分形级数越高,孔隙分布规律对其传热性能的影响程度越大。
The heat transfer model of porous metal foam filled with phase change material by Sierpinski fractal is developed and numerically analyzed. The phase field of phase change material inside porous metal foam is presented, and the effect of the pore structure on the heat transfer characteristics is analyzed. The results indicate that, if there are some open pores connected with the thermal boundary of the foam metal, the heat transfer rate of the phase change material will be higher than that without pores. For the latter case, the heat transfer rate increases with the specific surface of the metal foam. In addition, the higher the fractal order of the fractal model, the greater the influence of the pore structure on the heat transfer characteristics.
The heat transfer model of porous metal foam filled with phase change material by Sierpinski fractal is developed and numerically analyzed. The phase field of phase change material inside porous metal foam is presented, and the effect of the pore structure on the heat transfer characteristics is analyzed. The results indicate that, if there are some open pores connected with the thermal boundary of the foam metal, the heat transfer rate of the phase change material will be higher than that without pores. For the latter case, the heat transfer rate increases with the specific surface of the metal foam. In addition, the higher the fractal order of the fractal model, the greater the influence of the pore structure on the heat transfer characteristics.
引文
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[3]谢望平,汪南,朱冬生,等.相变材料强化传热研究进展[J].化工进展,2008,27(2):190-195.XIE W P,WANG N,ZHU D S,et al.Review of heat transfer enhancement of the PCMs[J].Chemical Industry and Engineering Progress,2008,27(2):190-195.
[4]WANG T Y,WANG S F,GENG L X,et al.Enhancement on thermal properties of paraffin/calcium carbonate phase change microcapsules with carbon network[J].Applied Energy,2016,179:601-608.
[5]LIN C P,RAO Z H.Thermal conductivity enhancement of paraffin by adding boron nitride nanostructures:a molecular dynamics study[J].Applied Thermal Engineering,2017,110:1411-1419.
[6]CHEN J Q,YANG D H,JIANG J H,et al.Research progress of phase change materials(PCMs)embedded with metal foam(a review)[J].Procedia Materials Science,2014,4:389-394.
[7]盛强,邢玉明,王泽.泡沫金属复合相变材料的制备与性能分析[J].化工学报,2013,64(10):3565-3570.SHENG Q,XING Y M,WANG Z.Preparation and performance analysis of metal foam composite phase change material[J].CIESC J.,2013,64(10):3565-3570.
[8]SUNDARRAM S S,LI W.The effect of pore size and porosity on thermal management performance of phase change material infiltrated microcellular metal foams[J].Applied Thermal Engineering,2014,64(1/2):147-154.
[9]YANG J L,YANG L J,XU C,et al.Numerical analysis on thermal behavior of solid-liquid phase change within copper foam with varying porosity[J].International Journal of Heat and Mass Transfer,2015,84:1008-1018.
[10]DI GIORGIO P,IASIELLO M,VIGLIONE A,et al.Numerical analysis of a paraffin/metal foam composite for thermal storage[J].Journal of Physics:Conference Series.IOP Publishing,2017,796(1):012032.
[11]FENG S S,SHI M,LI Y F,et al.Pore-scale and volume-averaged numerical simulations of melting phase change heat transfer in finned metal foam[J].Int.J.Heat Mass Tran.,2015,90:838-847.
[12]杲东彦,陈振乾,孙东科,等.泡沫金属内相变材料融化的格子Boltzmann方法孔隙尺度模拟研究[J].工程热物理学报,2016,37(2):385-389.GAO D Y,CHEN Z Q,SUN D K,et al.Lattice Boltzmann simulation of melting of phase change materials in metal foams at pore scale[J].J.Eng.Thermophys-Rus.,2016,37(2):385-389.
[13]郁伯铭.多孔介质输运性质的分形分析研究进展[J].力学进展,2003,33(3):333-346.YU B M.Advances of fractal analysis of transport properties for porous media[J].Advances in Mechanics,2003,33(3):333-346.
[14]WEI W,CAI J C,HU X Y,et al.A numerical study on fractal dimensions of current streamlines in two-dimensional and three-dimensional pore fractal models of porous media[J].Fractals,2015,23(1):1540012.
[15]XU P,LI C H,QIU S X,et al.A fractal network model for fractured porous media[J].Fractals,2016,24(2):1650018.
[16]DENG Z L,LIU X D,ZHANG C B,et al.Melting behaviors of PCM in porous metal foam characterized by fractal geometry[J].Int.J.Heat Mass Tran.,2017,113:1031-1042.
[17]ZHANG C B,WU L Y,CHEN Y P.Study on solidification of phase change material in fractal porous metal foam[J].Fractals,2015,23(1):1540003.