Performance Evaluation of Boiling Chamber with Microchannel Chip and Taper Microgap

The increasing trend of power densities in high-performance computing, driven by artificial intelligence (AI), machine learning (ML), and cloud computing, necessitates advanced thermal management solutions to maintain operational stability and energy efficiency. This study examines the effectiveness of cooling a 1.5U simulated copper microchannel chip compared to a plain chip. Both chip types were tested with and without configurations for dual taper microgaps to enhance the heat transfer performance of a boiling chamber. Experimental investigation was conducted using 500 µm wide × 400 µm deep microchannels separated by 200 µm fins. Varying inlet gaps (0.5 mm – 4 mm) and taper lengths (8.25 mm and 16.5 mm) with a taper angle of 3° were employed in dual taper configuration. Their impact on critical heat flux (CHF) and subcooled boiling dynamics was investigated. Microchannels provided considerable performance enhancement over a plain surface with or without the taper mirogap. It is seen that smaller inlet gaps (0.5 mm – 1 mm) and longer taper manifold lengths (16.5 mm) significantly enhance nucleate boiling. These configurations improve vapor escape and delay CHF through subcooled boiling and submerged condensation. However, a lower CHF was noted due to vapor agglomeration within the microgap. The 80% fill ratio microchannel chip exhibited the highest CHF as subcooled boiling increased liquid replenishment and prevented vapor stagnation. Similarly, lower coolant temperatures (20°C–30°C) enhanced boiling performance, where submerged condensation accelerated bubble collapse and improved heat dissipation efficiency in lower surface temperatures.