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Heat-Flux Measurement - Issues

Heat-Flux Measurement - Issues. Convection heat transfer effects (Schmidt-Boelter & Gardon) Non-uniform temperature distribution on sensor (Gardon) Different calibration methods by manufacturers Lack of suitable traceability to National Standards. Heat-Flux Measurement - Status.

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Heat-Flux Measurement - Issues

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  1. Heat-Flux Measurement - Issues • Convection heat transfer effects (Schmidt-Boelter & Gardon) • Non-uniform temperature distribution on sensor (Gardon) • Different calibration methods by manufacturers • Lack of suitable traceability to National Standards

  2. Heat-Flux Measurement - Status • No major break-through in sensor manufacture • Calibration issues still persist (Sarkos, Hill & • Johnson 1995)

  3. Calibration Approach - NIST Blackbody radiation Detector Based (Flux) Source Based (Temperature) Flux measured Absorbs incident flux Flux traceability to National Standards Flux derived Effective emissivity Configuration factor Source temperature Establish equivalence Factors: Calibration range, source temperature, view angle

  4. Resolving Calibration Issues National Level • Common Interest Group – Government/Users/ Manf. • Evaluation of different calibration techniques • Standard development efforts – ASTM/ASME • Provide traceability to Primary Standards

  5. Resolving Calibration Issues International Level • Fire Laboratories Round-robin [NIST-BFRL/PL] • International Standards Organization • ISO Flux Meter calibration standard Development • Ellipsoidal radiometer evaluation [SP, Sweden]

  6. Major Outcome of Collaboration • Flux-scale calibration suitable when • reflected component is large part of incident flux, • source characteristics difficult to establish • Temperature & flux scales equivalence demonstrated • Low/moderate heat flux - convection effects important • High heat flux – source effective emissivity important

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