EXPERIMENTAL STUDY OF THE ULTRASONIC EFFECT ON HEAT TRNASFER INSIDE A MINI-TUBE by Chen I Ping Thesis Supervisor: Prof. Lap Mou Tam Master of Science in Electromechanical Engineering Ultrasound has been widely used in drying, welding, cleaning, chemical, and heat transfer processes. Moreover, in recent years there has been an increased interest in the application of ultrasound for heat transfer enhancement in the field of heat transfer. However, a few papers investigated the effect of ultrasound on heat transfer inside the horizontal tube. Therefore, the objective of this experimental study is to investigate the influence of ultrasound on the heat transfer inside the horizontal tube in the laminar region. In this study, the stainless steel test tube with the diameter of 4 mm was used as the test section under the uniform wall heat flux boundary condition. The entrance and fully developed regions heat transfer coefficients were analyzed. The Reynolds number ranged from 600 to 3000. A series of experiments with the different numbers of ultrasonic heads and the different locations of the heads placed on the tube were conducted. The results showed that a substantial heat transfer enhancement by ultrasound was observed in the laminar region. Based on the combinations of different number and position of ultrasonic heads, two ultrasonic heads were observed to give a better heat transfer enhancement in the entrance and fully developed regions.