Effect of temperature difference between channel walls on the heat transfer characteristics of nanoscale-confined gas

We present molecular dynamics simulations of stationary argon gas in nanoscale confinement and under various temperature differences between walls. For a channel of 5.4nm height, we vary the gas density and find that in addition to the temperature difference between the walls, the absolute temperature of each wall plays an important role in the determination of the gas molecule distribution regardless of the level of rarefaction. The combined effect of the wall force field, the temperature difference between the walls and the wall temperature leads to the fact that the normalized temperature profile along the channel height does not coincide for various temperature differences between the walls. As the gas density is increased, it is observed that the wall force field effect on the density and temperature profiles reduces considerably due to the increment in the magnitude of the gas force field for all implemented temperature differences. Considering the temperature profiles and the distribution of the effective local thermal conductivity (ELTC) along the channel height, it is inferred that a diffusive transport mechanism is dominant throughout the dense gas medium. Besides, as the gas becomes rarefied, ballistic transport in the bulk region and diffusive transport in the regions close to the walls are observed. Furthermore, the effective thermal conductivity is a function of the implemented temperature differences between the walls and its value at 300K varies from 0.18 to 12mW/mK as the bulk gas density changes from 1.95 to 196kg/m3.