Heat Dissipation Beyond 1 kW/cm~2 with Low Pressure Drop and High Heat Transfer Coefficient for Flow Boiling using Open Microchannels with Tapered Manifold

摘要

Heat dissipation beyond 1 kW/cm~2 accompanied with high heat transfer coefficient and low pressure drpp using water has been a long-standing goal in the flow boiling research directed toward electronic cooling application. In the present work, three approaches are combined to reach this goal: (a) a microchannel with a manifold to increase critical heat flux (CHF) and heat transfer coefficient (HTC), (b) a tapered manifold to reduce the pressure drop, and (c) high flow rates for further enhancing CHF from liquid inertia forces. A CHF of 1.07 kW/cm~2 was achieved with a heat transfer coefficient of 295 kW/m~2°C with a pressure drop of 30 kPa. Effect of flow rate on CHF and HTC is investigated. High speed visualization to understand the underlying bubble dynamics responsible for low pressure drop and high CHF is also presented.