Experimental study on pool boiling performance of various dielectric fluids on a smooth aluminum surface

The continuous increase in high heat flux densities in advanced electronic systems is challenging the operational limits of conventional cooling technologies. Two-phase immersion cooling with dielectric fluids is attracting interest as passive efficient cooling technique. However, its large-scale adoption is increasingly constrained by environmental concerns, including high Global Warming Potential (GWP) and the persistence of per- and polyfluoroalkyl substances (PFAS). These issues are motivating the development and adoption of coolant fluids with low GWP values and reduced environmental impact. In this work, the pool boiling performance of FC-72, Novec 649, HFE 7100, TMC 49, and SF 33 is experimentally investigated using the same operating conditions to enable direct comparison. Boiling curves, Critical Heat Flux (CHF), and Heat Transfer Coefficients (HTC) are systematically measured, providing a unified dataset across fluids spanning different chemical classes and environmental impact levels. The results highlight that low-GWP alternatives can effectively match or overcome the performance of traditional fluids. Novec 649 and TMC 49 show boiling behavior comparable to FC-72, while significantly reducing environmental impact. SF 33 and HFE 7100 exhibit enhanced CHF and HTC values, with SF 33 combining high thermal performance and low GWP, making it a promising candidate. Comparison with predictive models shows that classical CHF correlations provide acceptable agreement with the experimental data, whereas HTC predictions show a stronger dependence on the correlation. This study provides clear experimental evidence supporting the ongoing shift toward environmentally sustainable dielectric fluids, identifying candidates capable of competitive pool boiling performance, under increasingly stringent environmental regulations.