Analysis And Simulation On Acoustic Characteristics Of Heat Exchanger For Ultrasonic Cleaning

Heat exchangers are widely used in energy, chemical industry, pharmacy, petroleum and other industries. Scaling of the heat exchangers' inner tubes has plagued the people.Scale not only affects the heat transfer efficiency of heat exchangers, which causes the waste of energy, but also the corrosion of heat exchange equipments, increases the cost of maintenance. For these reasons, the paper carries out research on heat exchanger descaling, which can not only increase productivity, but also has significant economic benefits. At present, descaling of the heat exchanger widespread use mechanical and chemical methods. Both of mechanical and chemical methods will result in equipment heat transfer surface damage, destruction of the ecological environment, increasing operating costs. Ultrasonic descaling as a new physical descaling method, with favorable overall benefits, has been applied more and more widely.The main mechanism of ultrasonic descaling is the ultrasonic mechanical effect and cavitation effect. Mechanical effect makes the particles have a huge acceleration and separate the dirt from the wall; The cavitation effect is the cause that alternating positive and negative pressure formed by longitudinal propagation of ultrasonic makes micro bubbles sustained tension and compression,and even collapse when the pressure reaches a certain value. When cavitation occurs, the micros bubbles release plenty of energy, which can impact the dirt and achieve the purpose of descaling.This paper makes the numerical analysis of ultrasonic from mechanical effect and cavitation effect. ANSYS Workbench transient analysis module is used to evaluate the mechanical effect of ultrasonic by different particle displacement at different periods,which can judge the intensity of mechanical effect; this paper also simulates cavitation by using fluid-structure coupling methods and the pressure contour in the flow field to judge the intensity of cavitation effect. Ultrasonic descaling effect is also affected by the actual working conditions, fluid parameters and the form of the ultrasonic transducer arrangement and other factors. This paper studies the influence of mechanical effect and cavitation effect by using different ultrasonic transducers and mounting positions under certain conditions and circumstances fluid. The analysis results show that it can obtain different descaling effect by changing the number of transducers and the installation positions. At last, combining with theoretical analysis and simulation results, it will get the best descaling effect by studyding and optimizing the methods of the ultrasonic descaling using in the fields of heat exchangers.