Performance Comparison of R1233zd(E) and R515B Refrigerants

This technical report presents a performance comparison between two refrigerants, R1233zd(E) and R515B, used in two-phase direct-to-chip (2P DTC) cooling systems. The study addresses the increasing cooling demands in data centers driven by high-performance processors and artificial intelligence applications. It details experiments conducted with thermal test vehicles representing a CPU and GPU, analyzing the thermohydraulic characteristics of both refrigerants under varying conditions. The findings indicate that R515B exhibits lower thermal resistance for the CPU while maintaining similar performance for the GPU compared to R1233zd(E). Additionally, R515B demonstrates a lower pressure drop across the quick-disconnect coupling. Conversely, R1233zd(E) is noted for its significantly lower global warming potential and reduced mechanical requirements, making it favorable for environmental considerations. The report aims to assist data center operators in selecting appropriate refrigerants based on their specific cooling needs and environmental priorities.