A New Calibration Technique for Thin-Film Gauges and Coaxial Thermocouples Used to Measure the Transient Heat Flux

A new calibration technique, in which the thermal product and thermoelectric coefficient are treated as one integrated coefficient, is applied to calibrate thin-film gauges (TFGs) and coaxial thermocouples (CTs) for a reliable and accurate measurement of the heat flux, since the two-stage calibration approach generally used to separately determine the effective thermal product and thermoelectric coefficient inherently brings more error sources to the measured heat flux. Simultaneously the foregone input heat flux determined with the Gardon gauge and the absorption ratio can correct the error resulting from the perfect semiinfinite-body hypothesis. The principles of the calibration technique, including the upper and lower limits of time and the necessary absorption layer, are presented in detail. With the calibration technique, the calibration results of TFGs and CTs show a good linearity with a relative expanded uncertainty below 7%, which is lower than that reported in other researches.