Enhancing the efficiency of a double tube heat exchanger via a novel vibrating woven wire turbulator combined with a helical coiled wire; an experimental study

Abstract

Vibrating turbulators have emerged as innovative methods for enhancing heat transfer in heat exchangers over the past two years. Previous studies have mainly employed string or strip configurations for turbulator construction. In this research, a novel vibrating turbulator, known as the vibrating woven wire turbulator, is introduced to enhance the thermal efficiency of heat exchangers. This study proposes the first-ever application of a turbulator with this unique geometry. This turbulator consists of intertwined metallic wires, providing a lightweight design with a substantial contact surface area for the fluid. Experiments are conducted for Reynolds numbers ranging from 1000 to 8500, covering both laminar and turbulent flow regimes. The findings demonstrate that this turbulator significantly enhances heat transfer by up to 236 %, while only resulting in a marginal increase in pressure drop. This remarkable improvement in heat transfer, while keeping the pressure drop within acceptable limits, gives rise to an impressive thermal enhancement factor (TEF) of 2.45. To achieve an even higher TEF, this study investigates the synergistic combination of the vibrating woven wire turbulator with a helical coiled wire turbulator. Experiments are conducted on coils with diameters ranging from 0.5 to 1.5 mm. The simultaneous utilization of both turbulators leads to a significant improvement in heat transfer coefficient and pressure drop, with an increase of 545 % and 320 %, respectively, resulting in a high TEF of up to 3.13.