Boiling Heat Transfer on Bimetallic and Electron Beam Modified Surfaces: Experimental Investigation

This work presents an experimental study of saturated pool boiling heat transfer of the dielectric fluid Novec 7100 (HFE-7100) on bimetallic surfaces and surfaces modified by electron beam treatment, at pressures from 1 to 4 atm. The influence of surface structure and material composition on critical heat flux (CHF) was evaluated. For bimetallic samples made of copper with stainless steel inserts, the highest CHF enhancement (26%) was observed at 1 atm for the configuration with the smallest insert spacing. On average, CHF increased by 51% compared to unmodified stainless steel. These results are supported by previous thermal modeling, which showed non-uniform heating promoting more stable boiling. Electron beam-modified copper achieved a 37% CHF increase over smooth copper; modified molybdenum showed a 30% increase compared to calculated smooth molybdenum values. At 1 atm, CHF on modified molybdenum exceeded that of smooth copper by 13%. The performance of the modified copper surface is comparable to advanced surfaces like mesh or powder coatings. The results demonstrate the effectiveness of combining surface material design and modification techniques to enhance boiling heat transfer. These findings are relevant for the development of high-performance cooling systems in electronics, power engineering, and aerospace applications.