Numerical Simulation of a Brazed Plate Heat Exchanger using Al2O3- Water Nanofluid with Periodic Boundary Conditions

Abstract

Brazed plate heat exchangers are used as evaporators, condensers, and single-phase heat exchangers in the industry. This complex piece of engineering has the effectiveness and compactness to give it an edge over many conventional heat exchangers. Solar power plants and organic Rankine cycle systems do use these heat exchangers as a part of heat recovery systems. The complex channels formed by the angled sinusoidal plates allow the fluid to be in a turbulent zone at a low Reynolds number, thus promoting better heat transfer characteristics. The challenge of simulating these heat exchangers is the large computational requirements. This can be solved by using periodic boundary conditions where a single repeating element is simulated to analyze the heat transfer characteristics of the entire channel. Varying concentrations of Al2O3 Nanofluid were considered as the working fluid for this study. The variation in the concentration did not affect the Nusselt number showing that the heat transfer coefficient was completely dependent on the hydraulic diameter and the thermal conductivity of the fluid. The friction factor also did not change with varying concentrations but the pressure drop increased as the chevron angle, pitch, and concentration increased.