Pool Boiling Heat Transfer Performance of a Dielectric Fluid With Low Global Warming Potential

Abstract

Due to growing concerns over anthropogenic effects on the climate, there is increasing need to replace engineered fluids of high global warming potentials (GWPs), such as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), with more environmentally friendly alternatives in thermal management systems. This article presents experimental data and compares various correlations for predicting the pool boiling heat transfer coefficient of a new low-GWP fluid, FK-649. Using a pressurized boiling facility with a smooth aluminum heater, the critical heat flux (CHF) and heat transfer coefficient were measured for the pool boiling of FK-649 at various saturation conditions. The commonly used refrigerant tetrafluoroethane (R-134a) is tested in the same pressurized facility to act as a benchmark for the new fluid. While R-134a exhibited a higher heat transfer coefficient and CHF, this behavior is expected from the fluid properties. Two-phase heat transfer performance of FK-649 is expected to be similar to that of the fluorocarbon FC-72. Experimental data are compared to predictions using the Rohsenow, Borishanskii–Mostinski, Stephan and Abdelsalam, Cooper, and Leiner correlations. Where applicable, empirical constants are obtained by using a least-squares fit to experimental data. The Rohsenow correlation yielded the best result with a new surface–fluid constant C s,f of 0.0037 for FK-649.