Experimental study on pin-fin shapes for bubble growth and heat transfer in microchannel heat exchangers

The microchannel heat exchangers (MCHXs) with pin-fin array using electronic fluoride liquid have become one of the promising solutions for dissipating excessive localised heat flux due to the continuous advancement in computing capabilities and the miniaturisation of electronic devices. However, the detailed mechanisms by which pin-fin shape influences microscale flow patterns and thermal behaviour remain insufficiently understood, necessitating further in-depth investigation. This study experimentally evaluates the performance of the MCHXs with circular, diamond, and drop pin-fins. A high-speed camera is used to visualise the bubble growth process and investigate the flow regimes variation under different heat fluxes and flow rates. The results show that, at a heat flux of 90 kW/m 2 , the maximum equivalent bubble diameters for diamond, circular, and drop are 4.6 mm, 4.1 mm and 3.9 mm, respectively, leading to the lowest pressure drop for the MCHX with drop shapes.