ULTRASOUND-ASSISTED ENHANCEMENT OF HEAT TRANSFER IN STAGGERED PIPES

Development of renewable energy technology and improvement of energy efficiency have currently become necessary. In particular, active ultrasonic cavitation has attracted a great deal of attention in the enhancement of heat transfer efficiency, and this has been investigated in the current work using numerical methods. A physical model and associated simulation methods are first introduced. Next, the influence of various operational parameters on heat transfer enhancement are presented and analyzed. Finally, simulations with different configurations, with the inclusion of ultrasonic vibrations, are presented. The results show that the average outlet temperature and Chilton and Colburn factor j rise with increasing ultrasonic amplitudes and Reynolds numbers, but decrease with increasing ultrasonic frequencies. The friction factor f decreases with similar changes in parameters. The optimum values obtained for Reynolds number and ultrasonic frequency are 63.5 and 20 kHz, respectively. Additionally, the ultrasonic vibrations enhanced the heat transfer performance at the front and back pipe walls. It is recommended that ultrasonic vibrations be applied at pipe locations with fully developed flow.