Enhancement of HFE-7200 pool boiling heat transfer on copper surfaces with nanoparticle coatings

Saturated pool boiling heat transfer of HFE-7200 is investigated experimentally on copper surfaces with nanoparticle coatings at atmospheric pressure. The coatings are generated by an electrophoretic deposition method. Two modified surfaces are prepared with Cu-Zinc nanoparticles of 0.3 mg and 0.6 mg, respectively. During the deposition, ethanol works as the solvent while the electrical potential and deposition time are controlled as 9.5 V and 30 min, respectively. The experimental results show heat transfer is considerably enhanced by the nanoparticle coatings. The surface with 0.6 mg nanoparticles (EDS-2) performs better than the surface with 0.3 mg nanoparticles (EDS-1), and a maximum 140% heat transfer enhancement is achieved on the surface EDS-2 compared with the SS. However, the critical heat flux is not enhanced by the coatings but even slightly decreased. A high speed visualization is employed to capture bubble behavior. It is found that bubbles on EDS-1 and EDS-2 have smaller sizes and higher departure frequency than those on the SS before reaching the critical heat flux. However, at critical heat fluxes, a vapor blanket appears on all surfaces.