From water to dielectric fluids: Pool boiling research under pressure and subcooling for next-generation cooling

초록

The rapid growth of data-intensive technologies in renewable energy systems has increased the demand for efficient thermal management of high-performance power electronics in data centers and battery energy storage systems (ESS). Dielectric fluids are attractive working fluids for immersion cooling owing to their electrical insulation, chemical stability, and low boiling temperatures. However, their relatively low critical heat flux (CHF) and heat transfer coefficient (HTC) compared with water remain major limitations. While prior studies have largely focused on surface engineering to enhance boiling performance, this review instead synthesizes existing experimental data and predictive correlations for CHF and HTC of dielectric fluids, with particular emphasis on the effects of system pressure and liquid subcooling. Owing to their distinct thermophysical properties, such as low surface tension and latent heat, dielectric fluids exhibit fundamentally different dimensionless parameters and sensitivities to pressure and subcooling compared with water, making universal boiling correlations inapplicable. By critically reviewing correlation performance across operating conditions, this work clarifies their applicability and limitations for dielectric fluids. A qualitative techno-economic discussion is also provided to link boiling performance trends to potential system-level energy and cost benefits. Overall, this review highlights the potential of pressure- and subcooling-based strategies for improving boiling performance in dielectric fluids and identifies key knowledge gaps that must be addressed to establish robust and generalizable predictive frameworks.

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