Saturated pool boiling of FC-72 from enhanced surfaces produced by Selective Laser Melting

This paper presents the results of an experimental investigation on the saturated pool boiling heat transfer performances of microstructured surfaces fabricated by the Selective Laser Melting (SLM) technique. A plain surface and intrinsic micro-cavity and micro-fin surfaces of different configurations were produced from AlSi10Mg base powder using a Gaussian distributed Yb:YAG laser and the surfaces were tested in a water-cooled thermosyphon with FC-72 as the coolant fluid. In comparison with the commercially available plain Al-6061 surface, the SLM produced surfaces show significant enhancements in heat transfer coefficients and CHF. A maximum heat transfer coefficient of 1.27 W/cm2·K and up to 70% improvement in the average heat transfer coefficient as compared to a plain Al-6061 surface was achieved with the microstructured surfaces. In addition, the highest CHF value of 47.90 W/cm2, which corresponds to 76% enhancement in CHF as compared with plain Al-6061, was similarly obtained with the microstructured surfaces. Through experimental observations, it was determined that the enhanced heat transfer performances of the SLM fabricated surfaces were due to presence of inherent surface grooves and cavities created from the laser melting process. In addition, analyses of the possible thermal transport mechanisms due to the presence of surface micro-features were also elucidated. Finally, using the Rohsenow model, a general correlation was developed to characterize the pool boiling curves of the SLM fabricated surfaces by incorporating the effects of the surface micro-features, where the predicted heat fluxes were determined to be within ±20% of the heat fluxes obtained from the experiments. In summary, the present work demonstrates the promising use of SLM in fabricating intrinsic microstructured surfaces for enhancing pool boiling heat transfer.