Effect of GNPs Concentration on the Pool Boiling Performance of R-134a on Cu-GNPs Nanocomposite Coatings Prepared by a Two-Step Electrodeposition Method

Graphene nanoplatelets (GNPs) have been widely used as an effective reinforcing element in composite coatings owing to its intrinsic ultrahigh thermal and mechanical properties. This study aims to investigate the role of GNPs concentration on pool boiling performance of R-134a on Cu matrix nanocomposite coatings. Cu-GNPs nanocomposite coatings were synthesized on a plain Cu sample via a two-step electrodeposition method with different concentrations of GNPs (100 mg·L−1, 200 mg·L−1, 300 mg·L−1 and 400 mg·L−1) in the plating bath. The impacts of GNPs concentration on morphology, composition, thickness, roughness and porosity of the composite coatings were investigated. The Cu-GNP nanocomposite coating prepared at 400 mg·L−1 of GNPs concentration in the plating bath exhibited maximum BHT coefficient ratio (hER) of 2.73 than that of the plain Cu sample. It is revealed that the addition of GNPs increased the surface roughness, porosity and density of nucleation site of heating surface, which in turn improved the boiling performance.