{"title":"Heat Transfer in a Falling Liquid Film of Freon R21 on an Array of Horizontal Tubes with Modified MAO Coatings","authors":"N. I. Pecherkin, A. N. Pavlenko, O. A. Volodin","doi":"10.1134/S1810232823020029","DOIUrl":null,"url":null,"abstract":"<p>The paper presents the results of a study of heat transfer in a falling film of freon R21 on a single-row bundle of horizontal tubes made of aluminum alloys with outer diameters of 10 mm and modified oxide porous coatings. The oxide coatings were deposited by micro-arc oxidation (MAO) in phosphate, acid, and silicate-alkaline electrolytes. The surface modification of the MAO coatings consisted in the deposition of copper particles in a solution of copper sulphate. The heat transfer coefficients for the modified MAO coatings were compared with the results for the surface of tubes with base MAO coatings in electrolytes of similar compositions, as well as for a smooth metal tube without coating for Reynolds numbers of the falling film varying from 600 to 1500. Additional surface treatment of the porous ceramic coatings by the deposition of copper particles has led to a significant decrease in the heat transfer coefficients in the falling film compared with the base MAO coatings. The highest enhancement of the heat transfer relative to the case of the smooth tube (of up to 80%) was obtained on the modified MAO coating deposited in the phosphate electrolyte.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"32 2","pages":"196 - 207"},"PeriodicalIF":1.3000,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Engineering Thermophysics","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1134/S1810232823020029","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
Heat Transfer in a Falling Liquid Film of Freon R21 on an Array of Horizontal Tubes with Modified MAO Coatings
The paper presents the results of a study of heat transfer in a falling film of freon R21 on a single-row bundle of horizontal tubes made of aluminum alloys with outer diameters of 10 mm and modified oxide porous coatings. The oxide coatings were deposited by micro-arc oxidation (MAO) in phosphate, acid, and silicate-alkaline electrolytes. The surface modification of the MAO coatings consisted in the deposition of copper particles in a solution of copper sulphate. The heat transfer coefficients for the modified MAO coatings were compared with the results for the surface of tubes with base MAO coatings in electrolytes of similar compositions, as well as for a smooth metal tube without coating for Reynolds numbers of the falling film varying from 600 to 1500. Additional surface treatment of the porous ceramic coatings by the deposition of copper particles has led to a significant decrease in the heat transfer coefficients in the falling film compared with the base MAO coatings. The highest enhancement of the heat transfer relative to the case of the smooth tube (of up to 80%) was obtained on the modified MAO coating deposited in the phosphate electrolyte.
期刊介绍：
Journal of Engineering Thermophysics is an international peer reviewed journal that publishes original articles. The journal welcomes original articles on thermophysics from all countries in the English language. The journal focuses on experimental work, theory, analysis, and computational studies for better understanding of engineering and environmental aspects of thermophysics. The editorial board encourages the authors to submit papers with emphasis on new scientific aspects in experimental and visualization techniques, mathematical models of thermophysical process, energy, and environmental applications. Journal of Engineering Thermophysics covers all subject matter related to thermophysics, including heat and mass transfer, multiphase flow, conduction, radiation, combustion, thermo-gas dynamics, rarefied gas flow, environmental protection in power engineering, and many others.
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