Numerical study on forced convection of water-based suspensions of nanoencapsulated PCM particles/Al2O3 nanoparticles in a mini-channel heat sink

Abstract

The contributions of Al2O3 nanoparticles and nanoencapsulated PCM particles for enhancing the heat transfer in the rectangular mini-channel heat sink are compared in this work. A three-dimensional numerical method is used to simulate the forced convection heat dissipation of water-based suspensions of nanoencapsulated PCM particles/Al2O3 nanoparticles in the mini-channel heat sink. A homogenous mixture formulation by means of the pseudo-vorticity-velocity formulation together with the energy equation is adopted to evaluate the cooling characteristics. Several important factors in the system such as the friction factor, the thermal resistance, the figure of merit, and the average heat transfer coefficient ratio are investigated at various concentrations of Al2O3 nanoparticles and nanoencapsulated PCM particles, flow Reynolds numbers, and heat fluxes. The numerical results clearly reveal that the maximum thermal resistance reduction of 1.2% and 6.9% can be observed by adding the nanoencapsulated PCM suspension with the concentrations of 2% and 10%, respectively. For the case of water-based suspension of Al2O3 nanoparticles, the heat transfer coefficient ratios are larger than unity for all values of heat flux and Reynolds number. The usage of Al2O3 nanoparticles provides better cooling performance as compared with the case of nanoencapsulated PCM particles. As a result, the beneficial effect of Al2O3 nanoparticles is much greater as compared with that of nanoencapsulated PCM particles.