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Measurement of heat transfer coefficients in tubes by temperature oscillation analysis
Author(s) -
Roetzel Wilfried
Publication year - 1989
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.270120154
Subject(s) - heat transfer , mechanics , thermodynamics , tube (container) , turbulence , oscillation (cell signaling) , heat transfer coefficient , inlet , fluid dynamics , mixing (physics) , chemistry , flow (mathematics) , materials science , physics , mechanical engineering , composite material , biochemistry , quantum mechanics , engineering
An experimental technique and evaluation method is described for the determination of local heat transfer coefficients in tubes or other ducts. By means of a rotary mixing valve, cold and warm fluid flows are mixed in order to generate an arbitrarily shaped but periodically oscillating inlet temperature profile at the test tube. The propagation of the fundamental harmonic oscillation from the fluid to the outer surface of the tube wall is calculated analytically. Comparison of fluid and wall oscillations yields the heat transfer coefficient to be measured. The inaccurate measurement of fluid bulk temperature in the centre of the cross‐section is compensated by an additional correction. Experiments were carried out with turbulent water flow through a copper tube. Measured heat transfer coefficients were compared to values calculated using Hausen's equation and good agreement was obtained.