Determination of bubble diameters during pool boiling on surfaces with minichannels partially filled with porous elements

This article presents experimental studies conducted on enhanced surfaces in the form of minichannels partially filled with porous structures. The experiments were carried out during pool boiling of water for five different surfaces. For the tested samples as well as for the reference surfaces: minichannels without additional porous fillings (MC) and a plain surface, the heat flux and heat transfer coefficient were determined. All samples with additional fillings achieved higher heat fluxes and heat transfer coefficients with lower superheating compared to the MC and flat surface samples. Visualization of the boiling process was performed, enabling the measurement of the bubble diameters at the moment of detachment. Based on modified correlations from the literature, the diameters of the departure bubbles were determined and compared with the experimental data.