蓄热单元尺寸对融化传热增强作用的数值研究

Numerical Investigation of Melting Heat Transfer Enhancement of Enclosure Geometry

为提高板式相变蓄热单元融化过程的传热速率,本文在传统矩形单元的基础上改变装置尺寸得到楔形截面蓄热装置。利用焓法模型分析了单元结构尺寸(包括高宽比,上下边长比)对蓄热过程材料融化及传热特性的影响。结果显示,蓄热单元高度(热源面积)一定时,装置上下边长比、高宽比均对其热性能有显著影响。具体表现为:减小矩形单元的高宽比有利于强化传热;采用上下边长比大于1的楔形单元可在一定程度上消除蓄热过程的融化死角,蓄热时间最大缩短32.8%;蓄热单元的最优上下边长比与高宽比存在对应关系。

The method of improving thermal storage unit geometry was proposed to enhance heat transfer, and the wedge-shaped unit was obtained on base of the traditional rectangular unit. An enthalpy based mathematical model was employed to calculate effect of the enclosure aspect ratio as well as length ratio between the top and bottom side on melting and heat transfer. The results indicate that both aspect ratio and length ratio between the top and bottom has significant effect on thermal performance of the unit that based on a fixed enclosure height（heating area）. The results can be expressed as the smaller the aspect ratio, the larger the heat transfer enhancement for rectangular unit. Changing unit length ratio between the top and bottom side to less than 1 can be used as an effective method to enhance melting heat transfer and the maximum thermal storage time reduced can be 32.8%. The optimal length ratio between top and bottom corresponds to enclosure＇s aspect ratio.