Thermo-hydrodynamic analysis of a nanofluid flow over diamond-shaped tubes array of a heat exchanger

Heat exchangers have been widely used as the main thermal part of many industries for years. They dominantly affect the performance of the whole system and therefore, any attempts to design efficient heat exchangers are so desirable. In recent years, it has been shown that the non-circular cross sections of the heat exchanger tubes can be more hydrodynamically or thermally useful. However, the related studies are limited to single cylinder. Although an array of heat exchanger tubes with non-circular cross section can be practically important, it is rarely investigated in the literature. The current work, thus, numerically aims to conduct a thermo-hydrodynamic evaluation for Al2O3-air nanofluid flow over two configuration of diamond-shaped array tubes. It is shown that the triangular replacing of the tubes can raise about 20% in heat transfer in comparison to that of quadrilateral replacing. This value for drag coefficient reduction by using triangular pattern is about 50%. Further, the tube cross section is assumed to be square or diamond and it is illustrated that the diamond-shaped cylinders make higher heat transfer and stronger drag force. Increasing nanoparticles concentration or Reynolds number cause higher heat transfer. Raising Reynolds number from 20,000 to 50,000 can intensify the heat transfer by a factor of 2. The thermal response with respect to Reynolds number variation depicts a linear trend.