Experimental study on thermal performance of water-based nano-PCM emulsion flow in multichannel heat sinks with parallel and divergent rectangular mini-channels

Abstract

In this work, an experimental study is arranged to investigate the cooling efficacies of water-based nano-PCM emulsion flow in the multi-channel heat sinks with parallel and divergent rectangular mini-channels. N-eicosane particles with size of 130 nm are considered as the phase change material (PCM) nanoparticles. Two multi-channel heat sinks with eight parallel and divergent mini-channels are fabricated. The divergent channel has a divergent angle of 2.06°. The effects of different parameters including volumetric flow rate of working fluid (60 cm3/min <Q̇ < 600 cm3/min), heat flux (3.2 W/cm2 <qh′′ < 4.8 W/cm2), Reynolds number (100 < Re < 1000), and mass fraction of PCM nanoparticles (0% <ωPCM < 10%) on the dimensionless wall temperature, the Nusselt number, the cost of performance (COP), and the pressure drop are investigated. The experimental results show that the nano-PCM emulsion can improve heat transfer in both parallel and divergent mini-channel heat sinks as compared with the pure water. At Rebf = 965 and qh′′ = 3.21 W/cm2, the average Nusselt number in the parallel mini-channel heat sink improves about 15.2% by adding the PCM nanoparticles with mass fraction of 10% to the base fluid. This enhancement is up to 13.8% in the divergent mini-channel heat sink at Rebf = 295 and qh′′ = 3.21 W/cm2. Moreover, the divergent mini-channel heat sinks provide a higher Nusselt number along with lower pressure drop as compared with the parallel ones. Accordingly, the value of COP increases by diverging the mini-channel.