Effects of pore size distribution in a honeycomb porous plate on the onset of nucleate boiling in AE-3000

• Investigates the impact of pore size distribution (PSD) on boiling incipience (Δ T ONB ) in dielectric liquids. • Larger pores demonstrated a significant reduction in boiling incipience (Δ T ONB ), improving heat transfer efficiency. • The best-performing porous surface showed an HTC increase of up to 4.7 times compared to a plain surface. • HPPs with larger pore sizes maintained enhanced boiling performance after 48-hour immersion in dielectric liquid. This study investigates the relationship between pore size distribution (PSD) on porous surfaces and the onset of nucleate pool boiling (ONB) for dielectric liquids. Reducing the boiling incipience (Δ T ONB ) is critical for enhancing boiling heat transfer efficiency in immersion cooling, especially as data centers face increasing heat fluxes demands due to AI advancements. However, this relationship has not been thoroughly examined due to the complex dynamics of boiling initiation. To address this, three different honeycomb porous plates (HPPs) were fabricated and attached to an indium-tin oxide (ITO) heater for boiling experiments. Detailed assessments of the pores were conducted using scanning electron microscopy (SEM), CT scanning, and mercury penetration porosimetry. Additionally, a novel measurement technique that synchronized infrared with high-speed video cameras allowed for precise measurement of average Δ T ONB , local Δ T ONB , and hot spots. The results demonstrated that increasing pore size effectively lowers Δ T ONB , reducing the risk of temperature overshoot in electronics. Durability tests, including 48-hour immersion in AE-3000 liquid, revealed that HPPs with larger pore sizes maintained enhanced boiling performance over time. Re -entrant cavities, observed through CT scanning in the HPP with the largest pore size, contributed significantly to this stability. As a result, the heat transfer coefficient (HTC) was enhanced up to approximately 4.7 times compared to a plain surface. This increased HTC is especially beneficial for cooling schemes that demand efficient heat removal. These findings represent an initial step toward quantitatively understanding the principles of Δ T ONB control in the engineered porous surfaces, providing new guidelines for designing enhanced surfaces for future applications.