Numerical investigation of a radial microchannel heat exchanger with varying cross-sectional channels

This paper investigates the heat transfer performance of a radial microchannel heat exchanger with varying cross-sectional-area channels. The thermal performance of axially varying cross-sectional-area channels is compared with uniform cross-sectional-area channels. The first model is a one-dimensional thermal-resistance based model, and the second model is a three-dimensional conjugate computational fluid dynamics analysis using FLUENT software. The heat sink has a footprint area of 3.5 cm(2) and the fluid flows radially inward. The inlet aspect ratio is varied from 0.4 to 1.0, and the outlet aspect ratio is fixed at 0.5. Inclusion of axial conduction effects are found to be imperative for accurate modeling of a radial configuration using the one-dimensional thermal-resistance model. The analysis shows that when constrained by a fixed channel-outlet area, increasing the channel-inlet area will improve the thermal performance. At low pumping powers, the present scheme is found to have thermal performance that is equivalent to or better than the performances with other experimentally and numerically investigated microchannel heat sink designs.