Numerical Investigation on Heat Transfer and Fluid Flow Characteristics in Minichannel Heat Sinks Using nano-PCM-Based Coolant

In this era of ever reducing electronic component sizing, thermal management using Nano-encapsulated Phase Change Materials (nano-PCM) is gaining attention. This cooling technique utilizes latent heat absorption due to melting of nano-sized paraffin particles dispersed in a base-fluid. In the present study, a numerical model is developed based on Volume of Fluid multiphase model coupled with Enthalpy-Porosity model for analyzing forced convection cooling and melting characteristics of nano-PCM-based coolant in a Minichannel heat sink. Numerical simulations are performed to determine the effect of nano-PCM concentration and flow velocity on heat transfer and pressure drop in a rectangular minichannel heat sink of hydraulic diameter 2.383 mm with water as the base-fluid. The maximum improvement in heat transfer coefficient is found to be 36% (compared to pure water) by employing 1% concentration of nano-PCM in water. Although increasing the concentration of nano-PCM has been shown to enhance heat transfer performance, the corresponding rise in pumping power requirement due to the presence of nano-PCM particles is found to offset these benefits, particularly at higher concentrations. The study gives insight into the importance of optimizing flow velocity and particle concentration using the Figure of Merit parameter. It is evident from the simulations that at flow Reynolds number of 100 or above, the reduced residence time of particles inside the minichannel results in Figure of Merit dropping below that of water.