UNCERTAINTY ASSESSMENT IN THE PLANE SOURCE - SENSOR CALIBRATION

Svetozár Malinarič

   The Extended Dynamic Plane Source (EDPS) method is one of transient methods for measuring thermal conductivity and diffusivity in solids. This technique uses a plane source-sensor (PS) which serves as a heat source and thermometer. Its calibration consists in measuring the temperature dependence of PS resistance and computing the temperature coefficient of resistance (TCR) using the least squares (LS) estimation. The apparatus is designed as a modification of the EDPS experimental equipment. The uncertainty analysis showed that the sources of uncertainty should be evaluated in two stages. First, the standard deviation of residuals and uncertainties of PS temperature and resistance measurement should be combined together. Then the result is used for calculation of the LS component to the uncertainty of TCR estimate. The LS estimate of TCR in nickel plane source-sensor becomes 4.81 x 10^-3 K^-1 at 20°C and 4.59 x 10^-3K^-1 at 40°C with a combined standard uncertainty of 0.033 x 10^-3 K, that is 0.7 %.

Keywords: transient method, thermophysical parameters, plane source-sensor, temperature coefficient of resistance, uncertainty

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