Pool boiling occurs when a horizontal surface of a stationary fluid is heated, resulting in natural convection due to the difference in buoyancy near the surface and bubble growth and separation. So pool boiling refers to boiling processes without an imposed forced flow, where natural convective phenomena only cause fluid flow. There are four modes of boiling: natural convection boiling, nucleate boiling, transition boiling, and film boiling. The onset of boiling (ONB), boiling convective heat transfer coefficient (HTC), and critical heat flux (CHF) are essential factors.

Improvements in boiling heat transfer performance create thermal management solutions for data center or supercomputer cooling. Microporous coatings are one way to improve boiling heat transfer performance. The boiling enhancement method forms micro-scale cavities to promote boiling heat transfer, lower the superheat of the wall, and improve the boiling heat transfer coefficient. Typical fabrication methods, including sintering, electrodeposition, and micro fin shapes, are studied in the advanced thermal management laboratory at Ajou University.

In pool boiling studies using metallic foams, foam thickness is an essential design factor, and the effect of thickness is more dominant at higher pore densities. Nevertheless, studies on the boiling performance of metal foams with a micro-thick are still lacking. This study confirmed the effect of improving boiling heat transfer performance through micro-thick copper metallic foams in the saturated water pool.

Sandblasting is a type of surface modification method in which abrasive released under strong pressure collides with the surface to make the surface rough. In Pool boiling, rough surfaces typically produce boiling at a relatively low superheated surface temperature compared to smooth surfaces, indicating higher CHF points. We use various abrasive materials to determine the release pressure of the abrasive to meet the target surface roughness and conduct research to confirm the improvement of boiling performance due to surface roughness.

Flow boiling is considerably more complicated than pool boiling because of the coupling between hydrodynamics and boiling heat transfer processes. A sequence of two-phase and boiling heat transfer regimes takes place along the heated channels during flow boiling due to the increasing quality. The two-phase flow regimes in a boiling channel are therefore developing everywhere and are morphologically different than their namesakes in adiabatic two-phase flows.
The mini channel was uniformly heated from the bottom copper surface. A 10 mm thick Pyrex glass was used for the top plate of the channel to visualize two-phase flow during the experiment. The microporous coating was fabricated by sintering copper particles on the top surface of the copper block. The average particle size was 50 μm, the average coating thickness was 300 μm, and the porosity was 41%, respectively. The sintered microporous surface showed a smaller increase in wall superheats than the plain surface at higher wall superheats.