3d computational study of fluid flow and heat transfer in a dimple enhancer channel

Abstract

Heat transfer behaviour in dimple enhancer channel swirl generator is investigated numerically. Vortex generator geometry is a widely used procedure for heat transfer improvement. This work presents the investigation of a dimple enhancer channel for turbulent heat transfer with air (Pr 0.707) as the working fluid. In the present paper, transition - SST model which can predict the change of flow regime from laminar through intermittent to turbulent has been used for numerical simulations. The simulation are performed using three dimple ratio (r = d/D = 0.1, 0.15 and 0.2) and three different space ratios (s = y/D = 2.0, 2.5, and 3.0). The computations were conducted with Reynolds number ranging from 100 to 50,000. The results indicate that the large dimple ratio and small space ratio yields a higher heat transfer value with relatively lower performance penalty. The transition from laminar to turbulent regime is observed between Reynolds numbers of 2000 to 3500 for all cases. For all investigated cases the performance factor (η) are almost greater than unity. This result is useful for the design of solar thermal heaters.