Experimental Study on Cu–Cu–MWCNTs-Hybrid-Nanocomposite Coated Nanostructured Surfaces for Augmenting Pool Boiling Heat Transfer Performance

Abstract

Inadequate adhesion between the multi-walled carbon nanotube (MWCNT) and the substrate's surface, which will raise the intermediate obstruction, is reported to be a key issue for MWCNT coatings over metallic substrates in the published literature. By utilizing an intermediary layer, the adherence between the metallic substance and the CNT may be strengthened. Emphasis on boiling pools of micro-nano-porous (nanopores on micropores) coverings, particularly MWCNTs on micropores, is currently limited. Two nanocomposites (Cu–Cu) intermediate layers were deposited between the CNTs and a foundation polished metal surface in the current study to increase the bonding between the CNTs and the Cu foundation. Moreover, a three-stage sintering process is used to improve the adhesion between the Cu–Cu–MWCNTs layer and the metallic substrate. The pool boiling of DI water was experimentally investigated with respect to heat transport, bubble behavior, and critical heat flux. The Cu–Cu–MWCNTs-coated substrate achieved the highest heat transfer augmentation and critical heat flux of 374 % and 116 %, respectively, in comparison to a smooth bare surface. With the surface coated with Cu–Cu–MWCNTs, the early signs of nucleate boiling were seen. Highest critical heat flux for the Cu–Cu–MWCNTs-coated substrate was achieved by delayed dryout owing to better rewetting nature of the drier area beneath the created vapor bubble.