Numerical investigation of liquid flow with phase change nanoparticles in microchannels

A numerical solution is introduced to investigate the effect of laminar flow with a suspension of phase change material nanoparticles (PCMs) in a microchannel. The nanoparticle suspension consisting of lauric acid nanoparticles in water is introduced into a microchannel of 50 mu m height and 35 mm length, where a constant heat flux is applied to the bottom wall. Mass, momentum and energy equations are solved simultaneously using a fluid with effective thermo-physical properties. The effect of various parameters including mass flow rate (1 x 10(-5)-4 x 10(-5) kg/s), heat flux (8000-20,000 W/m(2)) and particle volume concentrations (0-10%) on the thermal performance is investigated using effectiveness ratio, performance index, and Merit number. The study is extended to include the optimum channel length for improved thermal performance. For a given particle concentration, an optimum heat flux to mass flow rate ratio exists that leads to the maximum effectiveness ratio of 2.75, performance index of 1.37 and Merit number of 0.64. Such a study facilitates understanding the parametric space to optimize heat transfer in microchannels for applications such as thermal management and energy conversion devices. (C) 2012 Elsevier Inc. All rights reserved.