Effect of ultrasonic on thermo-hydraulic characteristics of shell and tube heat exchangers with twisted tape

Abstract

Ultrasonic technology was combined with twisted tape insert technology to improve the performance of shell and tube heat exchangers. The effects of sound intensity, sound frequency, and ultrasonic transducer position on thermal transfer, resistance reduction, and overall performance of shell and tube heat exchangers with twisted tape (STHXTT) at different Reynolds numbers were investigated compared to the non-ultrasonic conditions. The experimental results show that applying ultrasonic can significantly enhance thermal transfer, reduce flow resistance, and improve the overall performance. The maximum increase of Nu is 36.53 %, the maximum decrease of f is 12.50 %, and the maximum value of PEC is 1.41. With the increase in Reynolds number, the performance is enhanced but the resistance reduction and overall performance are weak. When the ultrasonic intensity increases, the thermal transfer and resistance reduction performance is enhanced, but a critical ultrasonic intensity exists. When the ultrasonic intensity is large enough, the ability to reduce resistance is enhanced with the decrease of ultrasonic frequency. When the ultrasonic transducer is installed vertically, the thermal transfer performance is the best, however, the resistance reduction effect is the worst. When installed horizontally, the STHXTT has the best resistance reduction performance but the worst thermal transfer effect.