Numerical Investigation to Enhance Heat Transfer in a Circular Tube with Nozzles Formed Sinusoidal Geometry

Abstract

This paper presents the effect of formed sinusoidal conical-nozzle turbulators which are embedded in a circular tube on heat transfer and friction characteristic on a uniform heat-flux applied tube. In this study, a numerical investigation was conducted to analyze heat transfer, friction characteristic and thermo-hydraulic performance by using two-dimensional axisymmetric geometry. An experimental study was used to validate numerical solution methodology and, was ensured a good agreement Nu (average Nusselt Number) and ƒ (average friction factor). k-ε RNG turbulence model was fixed on to simulate turbulent airflow throughout the tube fitted formed sinusoidal conical-nozzles for nine different Reynolds numbers ranges from 8000 to 24000. Grid independence was ensured with three different grid models by getting less than 1% variation on average Nusselt number and average friction factor value. Twelve different configurations between amplitudes and periods were employed to introduce the effect of different geometry on thermo-hydraulic performance. Results show that amplitude and period values are of rather effects on increasing turbulent near the nozzles, and that caused to increase both increasing of heat transfer and friction factor.  As a result, the highest thermo-hydraulic performance is obtained for type-11 model which is amplitude of 2 mm and period of 2.5.

Keywords: Heat transfer enhancement, friction factor, turbulent flow, sinusoidal nozzle.