Mechanism of Heat Transfer in Confined Nanofluid via Coarse-Grained Molecular Dynamics

Abstract

We described the heat transfer mechanism in the pipe flow, especially in case of ethylene glycol solution. Pipe flow has been studied at macroscopic levels, but in this study we showed the validation of pipe flow at the nanoscale level. We implemented entry and fully developed region of pipe flow with Fe pipe, of which diameter was 40 nm, and showed the increase of temperature of fluid at the constant temperature (i.e. 325 K) of the pipe. The mechanism of heat transfer between pipe and fluid was revealed by the velocity, temperature and heat flux profile of fluid inside the pipe. The velocity of fluid was highest at the center of the cross-section of pipe and lowest near the pipe due to the interaction between pipe and fluid. In the entry region, the temperature of fluid was the highest at the center of the cross-section of pipe and lowered toward the pipe, but the temperature along the radial distance became similar as the pipe depth deepened. The heat flux and heat transfer coefficient of fluid increased toward the pipe outlet. Pipe flow was implemented using coarse-grained molecular dynamics (CGMD) and the density, diffusion coefficient and thermal conductivity of water and ethylene glycol were considered for developing the inter-particle potential.