Aqbal Ahmad

The present investigation conducts a comparative analysis of the nucleate pool boiling heat transfer performance of two dielectric fluids, a low-GWP hydrofluoroolefin-based fluid (commercially known as Opteon™ SF33, referred to hereafter as SF33) and a perfluoropolyether-based fluid with a high GWP (commercially known as Galden^R HT55, referred to hereafter as HT55) under atmospheric pressure conditions. Pool boiling experiments and visual observations were performed to assess essential performance parameters, such as critical heat flux, heat transfer coefficient, and boiling dynamics. SF33 exhibits enhanced heat transfer performance, achieving markedly higher heat transfer coefficient values at all the heat flux levels and attaining superior critical heat flux relative to HT55. The results show that SF33 provides a consistently higher heat transfer coefficient, reaching approximately 12 W/m²·K at maximum heat flux, compared to only 6 W/m²·K for HT55, representing nearly a 100% improvement. The visual observations indicated that reduced surface tension and increased latent heat of vaporization of SF33 facilitate more frequent bubble nucleation and smaller bubble departure, thereby enhancing its boiling performance. Properties of SF33 render it a superior candidate for high-performance cooling systems in data centers and power electronics. The study concludes that SF33 is a more efficient and adaptable fluid for next-generation cooling systems, providing superior heat dissipation and energy efficiency relative to HT55.