Flow Patterns of an Open Microchannel and Jet Impingement Hybrid Cooling Scheme

In last several decades, there are great development in electronic technology, which needs high performance cooling schemes urgently. Recently, an enhanced flow boiling of open micro-channel and jet impingement hybrid cooling scheme by separating liquid-vapor pathways is proposed with a critical heat flux of 546 W/cm(2). Nevertheless, due to the introduction of jet impingement, the bubbles generated in channel are compelled to migrate to the fins top to gather and grow. Consequently, a new series of bubbles behavior and flow patterns were observed. In order to have a further understand of flow patterns and the transition mechanism, visualization experiments are conducted with the deionized water, inlet temperature is 16 - 19 degrees C, and volumetric flow rate for micro-channel and jet impingement is 50 ml/min respectively. Subsequently, a new phenomenon was observed, where the bubbles owned the various critical motion diameters in different flow regions. Finally, based on the force balance of a bubble on fin tops, a prediction model of critical motion diameter is also proposed. The maximum error is 20%. These findings have an impact on the further development of efficient cooling technology.