Numerical Study of Heat Transfer Enhancement Using Nano-encapsulated Phase Change Slurries (NPCS) in Wavy Microchannel Heat Sinks


Author/Creator ORCID




Mechanical Engineering


Engineering, Mechanical

Citation of Original Publication


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In past decades, researchers have attempted to further improve the heat transfer performance of mini/microchannel heat sinks by dispersing nano-encapsulated phase change slurry (NPCS) materials in the base coolant. In this study, the performance of wavy microchannels with the mixture of nano-encapsulated phase change material and water as the coolant is studied. It is observed that NPCS flow in the wavy channel can enhance greater heat transfer performance than that in the straight channel under the same operating conditions due to the Dean?s vortices on a plane normal to the direction of the streamline. Although wavy channels increase pressure drop and cost more pumping power, evaluation of the overall transfer performance factor (TPF) shows a better performance in wavy channels than that in straight channels. We use a discrete Lagrangian model to investigate particle deposition and transport in straight and wavy channels considering multiple forces exerted on a nano-sized particle. Particle deposition in the wavy channel is nearly two times higher than in the straight channel; however, most particles deposit on the sidewall, and the impact of deposition on heat transfer is less severe than fouling on the bottom surface. It is observed that particle distribution in the straight channel is nearly uniform; however, the motion of particles subjected to the Dean?s vortices in the wavy channel causes particle concentration to vary near the channel wall. Further, the variation of particle concentration is more pronounced at higher inlet velocity. A single-phase fluid model is employed to study the heat transfer performance of wavy channels with either varying amplitude or wavelength using 10 vol.% NPCS over the velocity range of 0.3 m/s to 0.5 m/s. Changing the aspect ratio from 0.2 to 0.588 increases the curvature of the wavy channel and strengthens the Dean?s vortices, leading to enhanced Nusselt number, large optimal heat fluxes, high pressure drop, and good overall thermal performance factor. In addition, the effect of increased aspect ratio is more apparent at higher inlet velocities.