Role of wall-fluid interaction and rough morphology in heat and momentum exchange in nanochannel. (15th September 2021)

• Record Type: Journal Article
• Authors: Yao, Shuting; Wang, Jiansheng; Liu, Xueling
• Is Part Of: Applied energy. Volume 298(2021)
• Publication Date: 2021-09-15
• Subjects: Wall-fluid interaction -- Rough morphology -- Heat transfer -- Molecular dynamics; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2021.117183
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Flow resistance of convective heat transfer in rough nanochannel is probed. Weak wall-fluid interaction is conducive to drag reduction but not to heat transfer. Smaller free shear ratio is beneficial for heat transfer and drag reduction jointly. Optimum heat transfer performance is achieved at shear free ratio of 0.1875. Abstract: As an efficient cooling method, the convective heat transfer in nanochannel has been widely utilized in thermal management of various energy systems. However, the effects of surface roughness on velocity slip and flow resistance in nanochannel are still unclear. The effects of rough morphology and wall-fluid interaction on the flow and thermal characteristics in rectangular nanochannel are probed with molecular dynamics method. The results show that nanostructure morphology and wall-fluid interaction induce distinct variations in temperature jump and velocity slip, which further determine the heat and momentum exchange between the channel wall and fluid. Specifically, rough morphology is responsible for the augments of heat transfer and flow resistance, which is derived from limitation on the motion of fluid atoms by the nanostructure grooves in channel. In comparison, the strong wall-fluid interaction brings about the improvement of heat transfer and the increase of flow resistance, which owes to the adsorption enhancement. As the nanostructure free shear ratio increases from 0.1875 to 0.75, the flow resistance increases and heat transfer performance weakens. Yet, the combination of rough morphology and wall-fluid interaction is significant for overall heat transfer performance. The overall heat transfer performance in rough channel with the weak wall-fluid interaction is superior. The Nusselt number in rough channel only decreases by 1.78% while the resistance coefficient reduces by 27.1%. The optimal overall performance is achieved in rough channel with the nanostructure free shear ratio of 0.1875.