Three-dimensional numerical simulation of external fluid flow and heat transfer of a heat exchanger in a wind tunnel using porous media model
© 2020, Akadémiai Kiadó, Budapest, Hungary. Notwithstanding the widespread use of wind tunnel to investigate the performance of radiators and heat exchangers, has never been considered a numerical analysis of radiator inside the wind tunnel with complete three-dimensional geometry of tunnel. In the present study, three-dimensional numerical simulation of thermal performance of a car radiator inside a wind tunnel is performed to predict and improve the air flow behavior in a wind tunnel. The effect of the Reynolds number of air and the mass flow rate of hot water supply into the heat exchanger to preheat the air is investigated on heat transfer and fluid flow. Radiator, heat exchanger, honeycomb and flow straighteners in the diffusers are defined as porous media due to their complex geometry. To solve this problem, the k- ε turbulence model with a high-resolution discretization was used along with the (RMS) convergence criterion. Moreover, the results of the present numerical analysis are compared with the performance results of a car radiator in a thermal wind tunnel and demonstrated that the results are in good agreement. It can be seen in the results that in formation of vortex and reverse flows, there are the test section and the corner of diffusers. But the maximum variety of pressure, velocity and temperature is observed in the test section. The agitation is enhanced by increasing the Reynolds number and the difference between the size of radiator and test chamber. That can lead to undesired errors during the measurement process in experimental tests. In addition, the air non-dimensional temperature decreases by 30.1% and the air total pressure drop increases by 230 times by increasing the Reynolds number of air from 1e5 to 1.5e6 at a constant water mass flow rate of 8 kg s−1. Also, at Reynolds number of 1.5e6, air non-dimensional temperature decreases by 54.03% as the water mass flow rate changes from 18 to 4 kg s−1.