Open manifold microchannel heat sink for high heat flux electronic cooling with a reduced pressure drop

Abstract

To meet the intensifying demands of electronics cooling the current study proposes an open manifold microchannel heat sink, which substantially reduces the pressure drop of a conventional manifold microchannel heat sink while retaining a low thermal resistance, thin profile (< 2 mm) and planar geometry suited to microfabrication. The open heat sink achieves this by eliminating ineffective nozzle constrictions, specifically by removing channel walls beneath the slot nozzle. Two three-dimensional conjugate heat transfer models are used, including a single microchannel or a single manifold channel pair with hundreds of interconnecting microchannels. The performance of the open geometry is compared to an unmodified baseline geometry. In the microchannel model, the open case showed ideal pressure drop reductions of 45 % to 75 % with a negligible change to thermal resistance, at flow rates between 0.2 L/min and 1.0 L/min. Chamfering the tips of the microchannel walls show similar trends, although to a lesser degree. In the manifold model, the open case showed pressure drop reductions of 25 %, with thermal resistance slightly decreasing at flow rates below 0.58 L/min (-4 % to 1 %) and increasing at flow rates above 0.70 L/min (11 % to 21 %). These changes in thermal resistance were attributed to flow maldistribution, which may be alleviated through optimisation of the manifold convergence profile. At a flow rate of 1.32 L/min, the open geometry achieved a thermal resistance of 0.120 cm2K/W with a pressure drop of 10.3 kPa.