Microscale Morphology Effects of Copper–Graphene Oxide Coatings on Pool Boiling Characteristics

Abstract

Enhanced pool boiling heat transfer, with simultaneous increase in critical heat flux (CHF) and heat transfer coefficient (HTC), is desired to improve overall system efficiency and reduce equipment size and cost. This paper focuses on combining graphene oxide (GO) and porous copper particles to generate microstructures based on their ability to enhance HTC, CHF, or both. Three pool boiling performance characteristics based on CHF improvements and wall superheat reductions are identified: Type I-reduction in wall superheat only, type II-increase in CHF only, and type III-increase in CHF with reduction in wall superheat at higher heat fluxes. Specific microscale morphologies were generated using (a) screen-printing and (b) electrodeposition techniques. In type-I, rapid bubble activity due to increased availability of nucleation cavities was seen to influence the reduction in the wall superheats, while no increase in CHF was noted. Roughnessaugmented wettability was found to be the driving mechanism in type-II enhancement, while wicking and increased nucleation site density were responsible for the enhancement in type-III. An HTC enhancement of $216% in type-I and a CHF improvement of $70% in type-II were achieved when compared to a plain copper surface with water. In type-III enhancement, a CHF of 2.2 MW/m 2 (1.8Â over a plain surface) with a HTC of 155 kW/m 2 C ($2.4Â over a plain surface) was obtained. Furthermore, close correlation between the boiling performance and the microscale surface morphology in these three categories has been identified.

Extended MARTINI water model for heat transfer studies

“…In mW model, one water molecule is mapped onto one coarse grain bead and water is modeled as an intermediate element between carbon and silicon. The functional form of SW potential is as shown in below equations (2,3,4).…”

Salt templated and graphene nanoplatelets draped copper (GNP-draped-Cu) composites for dramatic improvements in pool boiling heat transfer

“…The thermal conductivity of this section was 391 W/m K (± 9 W/m K). The copper rod was machined to achieve the desired dimensions using a computer based numerically controlled micro-milling process 19 . The surface roughness of the copper surfaces was then reduced to ~ 1.3 μm using a grinding operation.…”

“…Due to unique surface properties and higher thermal conductivity exhibited by graphene (~ 3,000–5,000 W/m K), there has been an ample interest in utilizing graphene-based coatings for heat transfer applications 14 , 15 . Additionally, various surface modification techniques such as chemical vapor deposition 16 , electrodeposition 17 , 18 , sintering 19 , 20 , and electroplating 21 can be adopted to form highly surface-active graphene-based coatings with unique surface features that can impart properties to further improve the heat dissipation rates and overall performance.…”

Micro-Nano Scale Surface Coating for Nucleate Boiling Heat Transfer: A Critical Review

“…They reported 47% and 42% of enhancement in HTC and CHF. In their follow up study, Jaikumar et al [119] presented combined effect of GO with porous copper particles and reported increase in CHF and HTC values. Rishi et al [196] compared GO and composite GO-Cu for boiling heat transfer performance.…”