The experimental investigation concerning the heat transfer enhancement via a four-point star swirl generator in the presence of water–ethylene glycol mixtures

Abstract

In the present study, a new swirling flow generator is studied which aims to enhance the convective heat transfer rate in a heat exchanger tube. This device has a four-point star cross section. The study mainly investigates the effect of swirl generator on heat transfer rate and pressure drop along the test tube which is under a constant and uniform heat flux. The working fluid in the experiments is the water–ethylene glycol mixtures with Prandtl numbers ranging from 5 to 150 at different Reynolds numbers from 12,000 to 27,000. The results clarify the potential of the applied swirl generator to make a significant enhancement in the heat transfer rate with a satisfactory rise in the pressure drop. Based on studies of different cases, it is found that the swirl generator enhances the heat transfer and also the pressure drop up to 75% and 55%, respectively. The results show that the swirl generator is more efficient at lower Reynolds numbers. Moreover, the results lead to this finding that the swirl generator has a better performance for water and consequently for water–ethylene glycol mixtures with lower ethylene glycol percentage. In other words, the swirl generator has a better performance for the working fluids with a lower Prandtl number.