Enhancing Convective Heat Transfer Using Flow Unsteadiness for Micro Scale Electronics Cooling

Description Background – Given the increasingly stringent cooling demands in mid to high-end electronic packages, there is a need for high cooling power density yet robust cooling solutions. Convective liquid cooling using micro-channel heat sinks in single-or two-phase operation has received a lot of attention in recent research. Whereas single-phase cooling is simpler and more robust, two-phase cooling potentially offers much higher cooling performance yet at a cost of reduced robustness and compactness. However preliminary research has indicated that single-phase heat transfer performance can be significantly improved by using unsteady pulsating flow [1]. There is no general agreement in the literature on the governing mechanisms explaining the effect of flow unsteadiness. Only a limited number of theoretical/analytical, numerical and experimental studies have been performed, reporting in some cases small reductions [2] and significant improvements in heat transfer rate [3]. This trend has been partially confirmed by initial experiments [1], yet there is a need for further investigation in a wider range of parameters, and with better control of the boundary conditions. Aims – The project aims to investigate the potential for enhancing single-phase liquid convective cooling in micro-channel heat sinks by pulsating flow. The project will assess the costs and benefits of applying these techniques, in terms of heat transfer performance (thermal resistance and thermal gradients), external work input (pumping power), manufacturability and unit cost. Methodology – A fully functional experimental facility is available for this investigation [1]. Minor adaptations should be designed and manufactured to e.g. investigate the effect of the inlet and outlet flow conditions. The approach is largely experimental since modelling transient flow is not straightforward. However steady state flow simulations using a commercial computational fluid dynamics package would be beneficial for understanding the flow field inside the micro channel heat sink, and determine the existence of secondary vortical flow structures and separation regions. This joint numerical and experimental approach can give useful insights in the underlying