High-Heat-Flux Rack Level Direct-to-Chip Cooling

This technical report presents an experimental comparison of two refrigerants, R134a and R1336mzz(Z), in a direct-to-chip two-phase cooling system designed for high-heat-flux applications in data centers. The study addresses the increasing power densities in data centers, driven by advancements in technologies such as artificial intelligence and machine learning, which challenge traditional air cooling methods. The report details the experimental setup, including a thermal test vehicle developed for testing sleds with CPUs, and outlines the performance metrics measured during the tests. Results indicate that while R134a outperformed R1336mzz(Z) in thermal resistance across various power levels, R1336mzz(Z) still demonstrated adequate cooling capabilities suitable for high-performance CPUs and potential next-generation GPUs. The report emphasizes the importance of considering R1336mzz(Z) as a more sustainable alternative due to its significantly lower global warming potential, suggesting further optimization of cooling systems specifically for this refrigerant.