A parametric study on pool boiling heat transfer and critical heat flux on structured surfaces with artificial cavities

Emerging applications in new generation electronic devices require effective heat removal and thermal man-agement. In this regard, boiling is a phase change phenomenon capable of dissipating a large amount of heat compared to the sensible heat. In this study, comprehensive series of pool boiling experiments were carried out on surfaces having microchannels with different spacings and holes by using deionized (DI) water as the working fluid to investigate the mutual effect of surface structure and artificial cavity on the heat transfer performance and critical heat flux (CHF). For this, surfaces with different microchannel spacings and number of circular artificial cavities were fabricated on silicon surfaces. A high-speed camera was used to visualize bubble dynamics for better understand heat transfer and CHF mechanisms. While microchannel configurations had no significant effect at low heat fluxes, further increase in heat flux revealed the effect of surface structure on BHT and bubble dynamics. For samples with artificial cavities, the largest spacing between microchannels exhibited the best performance at high heat fluxes. It was found that the interaction between generated bubbles from artificial cavities and microchannel spacing on structured surfaces with lowest spacing value (20 mu m) resulted in BHT and CHF deterioration. The visualization results revealed different CHF mechanisms for structured surfaces without artificial cavities (hydrodynamic instability) and those with artificial cavities (microlayer dryout).