Optimization and design guidelines for high flux micro-channel heat sinks for liquid and gaseous single-phase flow

Abstract

A numerical optimization tool is used to optimize forced convection micro-channel heat sinks for minimum pump power at high heat fluxes. Results gained with the optimization tool are generalized and optimum configurations are illustrated on design charts. Physical trends are illustrated analytically using the underlying relations. Investigations are done for air and water in single-phase flow with no phase transition; with hydraulic diameters of the micro-channels ranging from about 1 micron to 80 mm. Optimization is shown to have a tremendous effect. It can reduce pump power by several orders of magnitude, especially for high heat flux devices. Using water and air as coolants, designs for heat fluxes of >10 kW/cm/sup 2/ and >100 W/cm/sup 2/ respectively with pump/fan power expenses less than 1% are easily found with the optimization tool. It appears that large aspect ratios for the flow channels are favorable for high heat fluxes in micro heat sinks. For each design, there exists an optimum fin height and ratio of fin thickness to channel width. The design space investigation also suggests that short channels in multiple parallel units are a key feature of compact high heat flux heat sinks. Practical design examples underline the feasibility of the results and general design guidelines are derived.