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Dissertation
A study of fouling in a heat exchanger with an application of an electronic anti-fouling technology
Doctor of Philosophy (Ph.D.), Drexel University
1999
DOI:
https://doi.org/10.17918/00009660
Abstract
The objective of the present study was to study the mechanism of fouling and investigate the effect of an electronic anti-fouling (EAF) technology on fouling control for the efficient operation of shell-and-tube heat exchangers. Three steps were taken in the present study. The first step was to identify the important factors that control the fouling process. Existing fouling models and data were examined. A step-by-step improvement on the fouling model was given. A new fouling model was proposed, combining precipitation and particulate fouling processes, and time dependent variables. The present fouling model showed the significance of particulate fouling. The second step was to study fouling control methods, focusing on the mechanism of the EAF technology. It was hypothesized that since the EAF treatment produced induced oscillating electric fields, large mineral salt particles were created in bulk solution, resulting in particulate fouling. It was also hypothesized that the EAF treatment produced weak scales due to the particulate fouling. The third step is the experimental validation of the two hypotheses. The present experiments showed that water hardness was reduced with the EAF treatment, especially when filtration and vortex-flow mixing methods were used together with the EAF treatment. The present experimental studies on scale removal were conducted to verify the second hypothesis. For this purpose, tube-side fouling in shell-and-tube heat exchangers was produced, and the overall heat transfer coefficient and tube diameter changes were measured. The chemical cleaning method was found to be the most effective, then the hydrolazing method, and the brush punching method was the least effective. The present study validated that the scale formed with the EAF treatment was not only less but also much easier to remove. In particular, when a spirally-finned water chiller tube was tested, brush punching removed almost all the scale above fins for the case with the EAF treatment, thus confirming that the EAF treatment produced weak scales. Based on the present test results, it is concluded that the EAF treatment is an effective tool to control mineral fouling.
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Details
- Title
- A study of fouling in a heat exchanger with an application of an electronic anti-fouling technology
- Creators
- Rong Liu
- Contributors
- Young I. Cho (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xiv, 284 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991021888968304721