Minimizing Entropy Generation in Heat Exchanger Tubes With Ball Inserts: Numerical Simulation

ABSTRACT This study analyzed entropy generation (EG) in a heat exchanger tube with ball inserts, with a constant heat flux boundary condition. The effects of ball diameter (4−6 mm) and ball pitch (15−25 mm) on EG were analyzed within the Reynolds number range Re = 6000−18,000. Furthermore, a mathematical model of EG was developed, and analyses were performed using a numerical simulation approach. The results indicate that EG decreases as the ball diameter increases, the ball pitch decreases, and the Reynolds number increases. Therefore, the smallest ball pitch and the largest ball diameter result in low EG. In this configuration, the Nusselt number and friction factor increase by 1.48−1.74 and 2.99−3.55 times, respectively, compared with a smooth tube, and the maximum thermohydraulic performance reaches 1.2 at the minimum Reynolds number. The maximum deviation between the predicted value of EG and the simulation data is 8%. Overall, the configuration with the largest ball diameter and smallest ball pitch yields the lowest EG, an enhanced heat transfer rate, and a potential solution to the group of solutions for enhancing heat transfer in heat exchanger tubes.