Parametric Analysis of Air to Air Tubular Cross Flow Heat Exchanger Using Computational Fluid Dynamics

Abstract

Air to air tubular cross flow heat exchanger used for cooling of large electric motors has been taken for study. The computational fluid dynamics analysis was done by using ANSYS FLUENT 15.0 on heat exchanger and obtained results were compared with experimental results. Then, the actual model was simulated by varying the cold air inlet velocities from 14 to 20 m/s using CFD. A computer program was developed using MATLAB programming based on analytical formulation of heat exchanger using ε-NTU technique for actual design. The results obtained from the MATLAB program at different velocities has shown close agreement with the CFD simulation results. Two models were also modelled by changing the geometrical parameters such as baffle position and number of tubes. Simulation was performed and results were compared with the actual model. It has been seen that there is not much change in temperature distribution of hot and cold air on shifting of baffle locations. It is found that with increase in cold air inlet velocities, there is not significant change in outlet temperatures of both hot and cold air, whereas pressure drop has shown parabolic increasing trend. Also, on addition of three additional tubes the values of temperatures of hot and cold air has decreased, so an optimum model with three additional cold air tubes and 14 m/s cold air inlet velocity was proposed and it was seen that the thermal performance of heat exchanger has increased even with lower cold air flow rates and pressure drops.