Cooling performance of mini-channel heat sink with water-based nano-PCM emulsion-An experimental study

Abstract

In this investigation, the cooling characteristics of mini-channel heat sink with the water-based nano-phase change material emulsions are examined experimentally. The n-eicosane nanoparticles and the pure water are considered as the as the phase change material and base fluid, respectively. The fluid flow and convection heat transfer in the mini channel heat sink are studied at different parameter ranges: the volumetric flow rate varied from Q˙ = 60 cm3 min−1 to 600 cm3 min−1, three values of the heat flux imposed on the bottom wall of the heat sinks including qh″ = 3.2 W cm−2, 3.95 W cm−2, and 4.78 W cm−2, and the mass fraction of n-eicosane nanoparticles varied from ωpcm = 0%–10%. The influences of these parameters on the friction factor, wall temperature, heat transfer effectiveness, Nusselt number, figure of merit, coefficient of performance, and thermal resistances are investigated. It is concluded that for the low volumetric flow rate and the heat fluxes of heat flux of 3.20 W cm−2, 3.95 W cm−2, and 4.78 W cm−2, using the n-eicosane nanoparticles with larger values of mass fraction is more proper to decrease the wall temperature. For low value of heat flux, the value of the convective heat transfer effectiveness is larger than unity for most values of Reynolds number. The maximum figure of merit index of 1.098 can be achieved at the Reynolds number of 1381, the heat flux of 4.78 W cm−2, and the mass fraction of 2%. The figure of merit index is decreased with boosting the mass fraction of n–eicosane particles. The figure of merit index is decreased about 44% with boosting the mass fraction of n–eicosane particles from 2% to 10% for the heat flux of 3.20 W cm−2. The usage of n-eicosane nanoparticles with the concentration of 2% results in the lower thermal resistances in comparison to the case of pure water. The difference between the thermal resistances for various mass fractions of n-eicosane nanoparticles decreases as the heat flux increases.