The Effect of CNT Coating on Convective Heat Transfer Coefficient, Heat Flux, Roughness, Pressure Drop of Porous Material with 3-Omega Technique: A Review

Abstract

The paper deals with the tentative survey on the heat transfer and pressure drop characteristics of CNT glaze on a stainless steel substrate in a rectangular comprehensive channel with water as the working fluid. The extremely high thermal conductivity of individual carbon nanotubes was predicted hypothetically and pragmatic experimentally. Under both, laminar and turbulent flow conditions, the experiments were conducted with Reynolds number unpredictable from 500–2600. A nanofluid, which depends on multi-walled carbon nano-tubes; due to which, its heat transfer uniqueness is experimentally examined for turbulent flow in a straight tube. The experimental results using an uncoated stainless steel plate were compared with that of the coated plate results. The augmentation in Nusselt number in the turbulent flow was less compared to the laminar section. The coating increased the roughness on the surface and also there was adverse effect on the pressure drop, particularly, in the turbulent flow area. Equivalent circuit simulations and antentative self-heating 3-omega method were used to establish the peculiarity of anisotropic heat flow and thermal conductivity of single MWNTs, bundled MWNTs and aligned, free-standing MWNT sheets. The thermal conductivity of individual MWNTs grown by chemical vapor deposition and normalized to the density of graphite is much lower (kMWNT=600±100 W m−1 K−1) than theoretically predicted. Coupling within MWNT bundles decreases this thermal conductivity to 150 W m−1 K−1.