Effect of surface coupling characteristics on the flow and heat transfer of nanochannel based on the orthogonal test.

Micro/nanochannels are considered as a promising method to enhance heat transfer due to the large ratio of surface area to the volume. To clarify the optimization direction of micro/nanochannel walls, the convective heat transfer of nanochannels under different surface coupling characteristics are explored with molecular dynamics. Specifically, the effects of solid-liquid interaction, wall atomic vibration property, rough morphology and their interactions on heat transfer and hydrodynamic characteristics of nanochannels are investigated based on orthogonal test method. The results show that the solid-liquid interaction and vibration frequency of wall atoms are the two most important factors affecting Nusselt number and comprehensive performance coefficient. Strengthening the vibrational coupling between wall atoms and liquid atoms is critical for promoting heat transfer. Unlike this, the two most significant factors influencing friction factor are solid-liquid interaction and rough morphology. The increase in static structure factor of liquid leads to an increase in its microstructural orderliness, which is the fundamental reason for the decrease of slip length and subsequently leads to an increase in the friction factor. Taking into account the heat transfer and flow resistance characteristics, the optimal combination of wall surface characteristics composed of the solid-liquid interaction, vibration frequency of wall atoms and roughness factor has been selected, which can achieve the best overall heat transfer performance of nanochannels. [Display omitted] • Some mechanisms that occur in nanochannel convective heat transfer are revealed. • Effect of surface characteristics coupling on flow and heat transfer is explored. • The priority order of influencing factors is determined by orthogonal test method. • Optimal combination of surface characteristics for nanochannel wall is proposed. • The optimal combination provides a reference for structural optimization design. [ABSTRACT FROM AUTHOR]