Estimation of local convective heat transfer coefficients using thermal wave analysis
- Univ. der Bundeswehr Hamburg (Germany)
An experimental temperature oscillation technique is described for the measurement of local convective heat transfer coefficients at the fluid side of heat transferring walls. By periodic heating with a sinusoidally modulated laser beam a temperature oscillation is generated at a spot of the wall. The temperature oscillation at the heated spot results in a wavelike propagation behavior of heat flow and temperature within the wall parallel to the surface. With increasing distance this thermal wave is strongly attenuated and phaseshifted. The characteristic of thermal wave propagation depends directly on local heat transfer conditions at the fluid side of the wall. So the heat transfer coefficient can be calculated from the attenuation of amplitude as well as from the phase lag of the thermal wave. For monitoring thermal waves an infrared line scanner is used, which allows a non contacting real time measurement of temperature distributions. Fluid temperatures are not measured in this method. The fluid bulk temperature has merely to be kept constant. To confirm the applicability of the method experiments were performed to measure the local heat transfer coefficient of water flowing turbulently through smooth copper and iron tubes. The measured results agree reasonably well with data obtained from literature.
- OSTI ID:
- 449522
- Report Number(s):
- CONF-950828-; ISBN 0-7918-1711-3; TRN: IM9714%%79
- Resource Relation:
- Conference: 1995 National heat transfer conference, Portland, OR (United States), 5-9 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of 1995 national heat transfer conference: Proceedings. Volume 10: Conjugate heat transfer, inverse problems, and optimization; Inverse problems in heat transfer; HTD-Volume 312; Bryan, W.J.; Beck, J.V. [eds.]; PB: 193 p.
- Country of Publication:
- United States
- Language:
- English
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