Forced convection heat transfer of Nano-Encapsulated Phase Change Material (NEPCM) suspension in a mini-channel heatsink

Abstract

In the present experimental study, Nano-Encapsulated Phase Change Material (NEPCM) nanoparticles with particle sizes in the range of 250–350 nm are synthesized. The core of nanoparticles is made of eicosane and can undergo liquid-solid phase change by absorbing/releasing latent heat. The eicosane core of the NEPCM particles is enclosed in a formaldehyde shell, and the particles are suspended in the water as the base fluid. The synthesized NEPCM-water suspension is employed as the working-fluid for heat removal from a microchannel heatsink. The heatsink is made of red-copper, and it consists of eight rectangular microchannels with an aspect ratio of 1.5 and a hydraulic diameter of 1.2 mm. Under the heatsink, a heating plate is embedded, which produces a uniform heat flux. The working-fluid, NEPCM-water, enters the microchannel and absorbs the heat from the microchannel walls in the form of sensible and latent heat. The impact of the nanoparticle's concentration, the heating-power, and the flow rate is investigated on the channel wall temperature, Nusselt number, convection ratio, performance index, and coefficient of performance. The results show that the presence of NECPM-particles improves heat transfer and the index of performance up to 70% and 45%, respectively. The observed enhancement of heat transfer is particularly notable at low Reynolds numbers. However, at the high Reynolds numbers, the presence of NECPM particles may reduce the convection ratio and performance index, which is mainly due to the increase of the viscosity and reduction of the sensible heat of the working-fluid in the presence of NEPCM nanoparticles.