Research on the Growth Characteristics of Fouling on Heat Transfer Tube Surfaces and the Performance of Ultrasonic Fouling Removal and Prevention

Abstract In the context of the global energy transition towards carbon neutrality, improving energy conversion efficiency in thermal systems has become a critical challenge for nuclear power and renewable energy industries. Fouling growth on heat exchanger surfaces is a common and challenging issue in the nuclear power industry. To investigate the growth characteristics of mixed fouling on the surface of heat transfer tubes in shell-and-tube heat exchangers, as well as the ultrasonic descaling and scale inhibition performance on the outer walls of these tubes, this study presents an experimental design and construction of a simplified system to simulate fouling growth on heat transfer tube surfaces and assess the effects of ultrasonic descaling and scale inhibition. The system replicates changes in mixed fouling growth on the surface of heat transfer tubes. The researchers examined the impact of long-term exposure on the fouling growth rate and microscopic morphology, as well as evaluated the effectiveness of ultrasonic descaling and scale inhibition on the outer walls of the heat transfer tubes. The results indicate that, when comparing the thickness and weight of the fouling layer at 12, 24, and 36 hours of growth, the growth rate of the calcium carbonate scale initially increases before subsequently decreasing. Following this, ultrasonic waves with a power of 500 W and a frequency of 10 kHz were employed to assess the descaling and scale inhibition performance. It was found that the descaling efficiency of the ultrasonic waves was positively correlated with sound intensity, and both descaling and scale inhibition effects improved as the distance between the outer wall and the transducer decreased. Therefore, this study provides a theoretical foundation and technical guidance for applying ultrasonic descaling and scale inhibition in heat exchangers.