Magnetically aligned metal-organic deposition (MOD) ink based nickel/copper heater surfaces for enhanced boiling heat transfer

We present high boiling heat transfer properties achieved by magnetically aligned nickel precursor inks on copper substrates measured atmospheric pressure. Alignment was performed in a single direction and grid orientation. Pool boiling studies were performed to obtain correlations between the heat flux, heat transfer coefficients, and wall superheat using water and ethanol. The effects of surface wettability and roughness on nucleate boiling heat transfer properties and bubble dynamics are reported. Our studies yielded a critical heat flux (CHF) of 185.9 W/cm² and a heat transfer coefficient (HTC) of 106.9 kW/m² °K for water on Ni grid patterned surface, representing an improvement of 49.9% in CHF and 105% in HTC compared to plain copper surface. The alignment of nickel followed by its sintering introduced nucleation characteristics that improved bubble dynamics. This is attributed to a) altered three-phase contact angle via chemically heterogeneity of Ni/Cu surface, and b) increased surface roughness due to nickel microstructures that induced wickability.