POOL BOILING PERFORMANCE COMPARISON OF SMOOTH AND SINTERED COPPER SURFACES WITH AND WITHOUT CARBON NANOTUBES

Pool boiling heat transfer is measured with two individual working fluids on copper surfaces enhanced with sintered copper powder and carbon nanotubes. The working fluids are a segregated hydrofluoroether, HFE-7300 (3M Electronic Markets Materials Division, St. Paul, MN), and deionized water. The surfaces considered in the experiments include smooth copper, copper with sintered copper particles, smooth copper with copper-coated carbon nanotubes (CNT), and copper with sintered copper particles and copper-coated carbon nanotubes. Characteristics of the resulting boiling curves are discussed and analyzed. Lower wall superheats resulted from both the sintered particles and the CNT array for both working fluids. For water, there was no additional benefit from the addition of CNTs on the sintered particle substrate. For HFE-7300, however, the hybrid (sintered with CNTs) surface achieved the lowest wall superheat at high heat fluxes. Critical heat flux for HFE-7300 increased by more than 45% for the hybrid surface relative to the smooth copper surface.