Numerical analysis of ball-type turbulators in tube heat exchangers with computational fluid dynamic simulations

In the tube heat exchangers, heat transfer enhancement by creation of turbulent flow has been investigated in a number of previous research using different turbulator forms and methods, whereas in the present work a novel ball-type turbulators is used as a new technique implementation to increase heat transfer rate by vortex generation in the flow. Numerical analysis is performed for proposed novel turbulator to probe heat and flow characteristics. Ball-type turbulators have been designed in three different ball diameters inside a tube exchanger. The effects of balls diameter, pitches and Reynolds number on the heat transfer, friction factors and also entropy generation are analyzed at four different Reynolds numbers between 5000 and 20,000. The Nusselt number and friction factor outcomes are compared with those of smooth tube under the same flow and thermal conditions to determine the heat transfer enhancement. From the numerical analysis, it is specified that the suggested turbulators generate a larger vortex flow at low Reynolds numbers, and consequently, more effective heat transfer can be obtained. Moreover, increasing the ball diameter will lead to more heat transfer rate due to the wider vortex region at behind of the ball.