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Estimates of the Uncertainty of Radiative Heat Flux Calculated From Total Heat Flux Measurements.


pdf icon Estimates of the Uncertainty of Radiative Heat Flux Calculated From Total Heat Flux Measurements. (301 K)
Bryant, R. A.; Johnsson, E. L.; Ohlemiller, T. J.; Womeldorf, C. A.

NIST SP 971; August 2001.

NIST SP 971: "Collected Reports and Publications by the National Institute of Standards and Technology on Heat Flux Gage Calibration and Usage." AND Interscience Communications Ltd.; Building Research Establishment; National Fire Protection Association; National Institute of Standards and Technology; Society of Fire Protection Engineers; and Swedish National Testing and Research Institute. Interflam '2001. International Interflam Conference, 9th Proceedings. Volume 1. September 17-19, 2001, Edinburgh, Scotland, Interscience Communications Ltd., London, England, 605-616 pp, 2001.

Available from:

For More Information on NIST SP 971 visit: WEBSITE: http://www.bfrl.nist.gov/866/heatflux/index.htm

ON BOOK SHELF: TH9112.I57 2001

Keywords:

heat flux; uncertainty; room fires; corner tests; fire tests; radiative flux; thermal radiation; thermopiles

Abstract:

As part of an effort to characterize the uncertainties associated with heat flux measurements in a fire environment, an uncertainty analysis example was performed using measurement data from a room corner surface products test that followed the guidelines of ISO 9705. Equations to model the heat transfer at the surface of a Schmidt-Boelter (thermopile) type total heat flux gauge were selected for use to calculate the incident radiative flux from a total heat flux measurement. The effects of the possible heat flux measurement uncertainty sources were evaluated by employing an uncertainty propagation on the resulting equation for incident radiation. For the model equations and the example conditions selected, the free-stream temperature measurement and the heat flux gauge calibration constant were suggested as major uncertainty contributors. The study demonstrates how to systematically identify major sources of uncertainty for the purpose of reducing total uncertainty and therefore enhancing experiment design.