Experimental investigation on heat transfer performance and temperature uniformity of two-phase cooling in microchannels with different cross-section geometries

With the continuous increase of heat flux in power electronic devices, conventional cooling technologies can no longer satisfy the demand for efficient thermal management. Microchannel two-phase cooling has attracted considerable attention due to its high heat transfer capability and compact structure; however, systematic investigations on the effects of channel cross-sectional geometries on temperature uniformity and critical heat flux (CHF) are still lacking. To address these gaps, this study establishes a multi-heat-source IGBT microchannel cooling platform, focusing on three representative channel cross-sections: circle, droplet, and diamond. Infrared thermography, combined with multi-point thermocouple measurements, was employed to examine heat-transfer and pressure-drop characteristics under flow rates of 0.6–1.4 g/s and inlet temperatures ranging from 10 °C to 40 °C. The droplet-shaped microchannel achieved a 15% higher heat-transfer coefficient and a 25% lower maximum temperature difference compared with the diamond geometry. This work introduces temperature uniformity as a key performance metric in evaluating microchannel cooling, and infrared visualisation is utilised to reveal hot-spot formation and temperature distribution. The outcomes of this work not only enrich the experimental database for microchannel geometry optimisation but also provide new insights and guidelines for the thermal management of multi-heat-source power electronic devices.