Development of microfluidic based graphene/micro-capsulated phase change materials for thermal management application

Abstract

Phase change materials (PCMs) are commonly used for heat storage, but they face challenges such as leakage, corrosion, and low thermal conductivity. In this project, microencapsulation packaging is employed to address these issues before using PCMs for energy storage and thermal management. Additionally, graphene-based materials are incorporated to enhance the heat transfer of the microencapsulated phase change materials (MEPCMs).The formation, breakup, and phase change mechanism of low melting point alloy (LMPA) PCM particles in a microfluidic channel are numerically studied. The effects of flow rate, interfacial tension, perturbation flow Weber number, and oscillating frequencies on droplet dynamics are being investigated. Furthermore, experimental synthesis is carried out in a needle-based microfluidic device to synthesize MEPCMs and graphene-decorated MEPCMs. The results demonstrate a smooth surface and spherical shape of the microcapsules with a relative size change in the MEPCM particles within 5%. These microcapsules exhibit good phase transition and thermal storage performance, with the shell material providing effective protection for the PCM material. The addition of graphene significantly improves heat conductivity as the mass ratio increases from 0.1 to 2 wt%. Finally, the thermal performance and pressure drop of various microchannel designs and coolants are compared. Structure C proves to have the best PEC performance, reaching 1.43 at Re=600. Geometric shapes of micro pin fins minimally affect thermal resistance, but triangular fins cause the highest pressure drop. Circular pins exhibit the highest PEC, surpassing hexagonal pins by over 8% in certain Re ranges. Micro pin fin spacing influences outlet temperature distribution and PEC optimization, with 0.3 mm spacing achieving a peak PEC of 1.57 at Re=600. GO/MEPCM slurry in microchannels shows higher pressure drop and thermal resistance compared to water. The PEC peaks at 3.79 with 0.4wt% GO content at Re=100, outperforming Al2O3 nanofluid by 84% at Re=400.

Date of Award	Oct 2024
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Yong Ren (Supervisor)