Influence of System Pressure on Pool Boiling Regimes on A Microstructured Surface Compared to A Smooth Surface

This study focuses on the influence of the system pressure on pool boiling regimes on a microstructured surface compared to a smooth surface. The microstructured surface consists of copper wires with diameters and lengths of 1 and 20 mu m, respectively. The saturation pressure of FC-72 is varied between 0.5 and 1.8 bar. Boiling curves are determined and compared to those of a smooth copper surface. The results with the microstructured surface show no distinctive pressure dependency, contrary to those with a smooth surface being in good agreement with a state-of-the-art correlation. The microstructured surface exhibits higher heat transfer coefficients and lower critical heat fluxes than the smooth surface. The Nukiyama-curves of the microstructured and the smooth surface suggest the existence of distinctive sub-regimes of the isolated bubble regime: the partially activated isolated bubble regime and the fully activated isolated bubble regime.