Measurement of the thermal resistance of scale on the inner surfaces of boiler tubes

✍ Scribed by Osamu Makishi; Tetsu Fujii; Atsushi Kawabe; Tadashi Tamagawa

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 157 KB
• Volume: 31
• Category: Article
• ISSN: 1099-2871
• DOI: 10.1002/htj.10020

✦ Synopsis

Abstract

This paper proposes a method of measurement of the thermal resistance of scale on the inner surface of a boiler tube. The principle of the method is to measure the temperature rise due to the scale when the tube is radiantly heated from outside. An experiment was performed with a test piece composed of three tubes 300 mm in length, which had been cut out from a supercritical pressure boiler. A 120 mm × 140 mm area of the test piece was radiantly heated, boiling of water took place inside the tubes, and the temperature at the crest of the tube was measured with welded thermocouples 80 µm in diameter. Similar measurement was performed after cleaning the inside of the tubes with hydrochloric acid, and both measured data were compared. As an example of the results, the difference of the temperature rise was 8.24 K for a heat flux of 100 kW/m^2^, and the estimated thermal resistance of the scale was 0.082 m^2^K/kW. © 2002 Scripta Technica, Heat Trans Asian Res, 31(2): 117–127, 2002; DOI 10.1002/htj.10020