Optimization of microencapsulated phase change material slurry-based porous heat exchanger

Abstract

Microencapsulated phase change material (MPCM) is one of the promising methods for thermal energy storage systems. However, the feasibility of their implementation in different systems, especially heat exchangers, is still questionable. In this study, the MPCM slurry flow within a porous double-pipe heat exchanger is evaluated and optimized. To have a better understanding of characteristic parameters impact, including Reynolds number, Darcy number, MPCM mass concentration and inlet temperature difference, on the performance of the heat exchanger, response surface methodology is applied. The effectiveness and Performance Evaluation Criterion (PEC) with three levels are selected as the response variables. The results showed that the simultaneous use of MPCM and a porous medium is not reasonable in terms of pressure losses inside the pipes. However, increasing the permeability of porous media can increment and decrement the PEC and effectiveness by 83 and 5.2 %, respectively, at any MPCM mass concentration. Also, MPCM can improve the cost-effectiveness at lower PEC which demands finding optimum values depending on the application. Increasing the mass concentration of MPCM has shown a high negative impact on PEC at high Reynolds numbers in which up to 13 % reduction is observed by changing the mass concentration from 5 to 15 %.