ABSTRACT

In this study, the flow and heat transfer characteristics of microencapsulated phase change material (MPCM) slurry were experimentally investigated using a newly designed helical coil heat transfer device. The conventional helical coil has been structurally modified with passive enhancement features aiming to further promote fluid mixing. Specifically, 360° plastic tubing with or without wire coil inserts was added after each 180° of the main helical loop to enhance fluid mixing and improve the overall thermal performance of the device. Pressure drop and heat transfer experiments with MPCM slurry were conducted under turbulent flow and constant heat flux conditions. A new friction factor and Nusselt number correlations for MPCM slurry in helical coils with reversed loops and wire coil inserts are proposed. Experimental results show that the structural modifications did enhance the heat transfer performance of MPCM slurry. The experimental results revealed that the phase change process of MPCM considerably enhanced the heat transfer rate of MPCM slurry. Furthermore, the use of reversed loops and wire coil inserts led to better fluid mixing within the coil, resulting in improved convective heat transfer of the MPCM slurry.

摘要

在这项研究中，使用新设计的螺旋线圈传热装置对微囊相变材料（MPCM）浆料的流动和传热特性进行了实验研究。传统的螺旋线圈已在结构上进行了改进，具有旨在进一步促进流体混合的被动增强功能。具体来说，在主螺旋环的每 180° 之后添加 360° 塑料管，带或不带线圈插件，以增强流体混合并改善设备的整体热性能。MPCM浆料的压降和传热实验是在湍流和恒定热通量条件下进行的。提出了一种新的摩擦系数和努塞尔数相关性，用于具有反向环和线圈插入物的螺旋线圈中的 MPCM 浆料。实验结果表明，结构改性确实提高了 MPCM 浆料的传热性能。实验结果表明，MPCM 的相变过程显着提高了 MPCM 浆料的传热速率。此外，使用反向回路和线圈插入件可以更好地在线圈内混合流体，从而改善 MPCM 浆料的对流热传递。