Numerical investigation of channel dimension effects on the performance of a cross flow micro heat exchanger for chip cooling applications

In this paper, we developed a basic 3D numerical model for a cross-flow micro heat exchanger considering a crossflow module formed by two plates having 34 microchannels each for cold and hot fluid transfer. The simplified model implemented with Finite Element Method (FEM) based Comsol Multiphysics software doesn't take into accounts the flow maldistribution effects. The dynamic viscosity and density of water (the working fluid) are assumed to be different in different channels and also gradually increasing/decreasing along the heat exchange part of each channel. We considered in this study three different dimensions for the channel plates, having the depth b and width c at the values of: 100 and 200 μm, 125 and 160 μm, 80 and 250 μm. Fluid flow and heat transfer investigations for the models with different channel geometries revealed that the model with b = 125 gm and c = 160 gm presented the most compact temperature gradient along the hot and cold plate and the highest value for figure of merit (FoM) coefficient at the lowest values of friction factor for hot and cold channels, considering different laminar flow regimes with Reynolds number Re between 133 and 562.