Assessment the thermal performance of square twisted double tube heat exchanger with Al2O3 nanofluid

Abstract

Abstract The effect of a twisting parameter on heat transport in a square-sectioned twisted tube was studied. One definition of a twisting parameter is the ratio of the hydraulic diameter to the length of the tube at the point when it completed a full 360-degree twist. The twist parameters that were selected are 5, and they were compared to the Double Twisted Square Tube heat exchanger (DTSTHE). Transient flow was taken into account when evaluating the sets of Reynolds numbers. On the other hand, there are four different concentration volumes of nano fluid amounts of 0.005, 0.01, 0.025, and 0.04 for turbulent flow, and the Reynolds number ranges from 5,000 to 25,000. An examination was conducted into the effect of the twist parameter on the convective heat transfer coefficient through turbulent flow. The finite volume approach and the conventional − turbulence model were used to conduct numerical simulations of three-dimensional, steady-state incompressible flow in body-fitted coordinates. It was found that as the twist parameter is decreased, the heat transmission coefficient increases. What this means for the created span-wise swirling flow is unclear. With increasing distance from the tube center towards the walls, the whirling causes the cross-flow velocity vectors to increase. The boundary layer has good thermal properties because it thins out at the tube wall as the near-wall velocity increases. Internal thermal balance is further improved by spinning since it increases the mixing process. A higher Reynolds number, along with larger velocity components, results in a higher heat transfer coefficient.