Investigations on the effect of graphene coating on thermophysical properties of aluminium and mild steel for cross flow heat exchanger

Abstract

In a cross-flow heat exchanger, heat transfer and fluid dynamics studies were conducted to observe the performance of graphene coated pipes. The heat exchanger consists of a linear pipe made of Aluminum 6061-T6 and Mild Steel in separate studies carrying a heated fluid. The thermal interactions between the heated fluid having a laminar flow and the walls of the pipe have been studied under the influence of an external environment of water having a turbulent flow, in a direction normal to the pipe. A RANS model with a k-ε variant was used to model the behavior of different material pipes which were observed under the varying conditions of turbulence, velocity, pressure, and vorticity. When subjected to the same conditions, plots of the temperature gradient, isothermal contours, heat transfer coefficient against Reynolds number and thermal conductivity modelled against the various graphene coating thicknesses studied have shown that out of Aluminum 6061-T6 and Mild Steel, the former has shown a significant increase in thermal conductivity on the addition of a Graphene coating. Simulation results showed an increase in Aluminium 6061 T6′s conductivity by 6.8975% with a continuous decrease in the heat transfer coefficient, whereas Mild Steel showed an anomaly in the heat transfer coefficient value which peaked at 1.2 mm thickness of graphene coating with a value of 3858.862 W/m2K.