Experimental study of heat transfer and pressure drop in micro-channel based heat sinks with tip clearance

This article presents an experimental study on the optimisation of micro-heat sink configurations when both thermal effects and pressure drop are accounted for. The interest of the latter is that the practical engineering viability of some of these systems also depends on the required pumping power. The working fluid was water and, according to typical power dissipation and system size requirements, the considered fluid regime was either laminar or transitional, and not fully developed from the hydrodynamics point of view. Five configurations were considered: a reference geometry (selected for comparison purposes) made up of square section micro-channels, and four alternative configurations that involved the presence of a variable tip clearance in the design. The performance of the different configurations was compared with regard to both cooling efficiency and pressure drop. Finally, we also provide some practical guidelines for the engineering design of these types of systems.