MSE Masters Thesis Presentation: Tingwei Lin

MSE Master’s Final Thesis Presentation: Tingwei Lin

TITLE: Coupling Electrolysis and Surface Patterning to Improve Onset of Nucleate boiling and Bubble Departure in Pool Boiling Heat transfer

ADVISOR: Chuanhua Duan (ME, MSE)

COMMITTEE: Uday Pal (ME, MSE)

ABSTRACT: This master’s thesis investigates the enhancement of pool boiling heat transfer through the combined effects of electrolytic activation of bubble nucleation ( via the hydrogen evolution reaction, HER) and engineered gold thin-strip microstructures fabricated on silicon substrates. The central hypothesis is that electrochemically generated hydrogen bubbles near the heating surface can significantly increase nucleation site density at low superheat, while patterned gold thin strips surfaces facilitate coalescence-induced bubble departure, further improving boiling performance. To verify this hypothesis, a pool boiling setup was designed and developed. The system employs an embedded cartridge heater inside of the copper block to supply power to the test chip, along with a series vertically arranged thermocouples to accurately determine the heat flux and surface temperature. Using this setup, pool boiling was first measured for plain silicon, plain gold and gold microstrips samples. The boiling curves for pure silicon and flat gold samples are consistent with those reported pool boiling literature. Plain gold surfaces exhibit higher heat transfer coefficients than silicon at low superheat. Attributed to their more hydrophobic characteristics. This patterned gold strip surface demonstrates superior performance compared to both flat plain silicon and flat plain gold at low superheat, likely due to a balance between increased nucleation site density, improved liquid replenishment, and coalescence-induced bubble departure. Finally, the plain gold and gold microstrips samples were tested with and without electrolysis-assisted bubble generation. Electrolysis substantially advances the onset of nucleate boiling ( by approximately 9°C for plain gold) and enhances heat transfer performance for both type of samples. However, for the patterned gold microstrip surfaces, the addition of electrolysis does not result in a further enhancement in heat transfer performance. This suggests that the patterned gold strips surface has already optimized nucleation site density and bubble departure behavior, thereby limiting the additional contribution from electrolysis-assisted bubble generation. Overall, this study introduces a novel method to actively control bubble nucleation and departure dynamics, leading to enhanced boiling heat transfer performance. The findings provide new insights into the coupled effects of surface fabrication and electrochemical activation, with potential applications in advanced thermal management systems, including high-power electronics cooling, energy systems, and phase-change heat transfer technologies.