The calibration of heat flow meters

The heat flow meter electromotive force is first expressed as a function of the heat flow meter thermal conductivity and its correlation with temperature and density, as a function of the thermoelectric voltage of the couples of junctions of the thermopile in the heat flow meter, and as a function of the modulus of elasticity of the material used to build the heat flow meter. This relationship can define a heat flow meter model useful for predicting the range of operating conditions. The second step is to assume a model for the reference specimen used in the calibration, in order to set limits of thickness, thermal conductivity, temperature difference, and mean specimen test temperature, once the calibration accuracy is defined. The last step is to compare the calibration of the heat flow meters, using a double-specimen reference sample in a heat flow meter apparatus with a single meter and a single specimen, two meters and a single specimen, or a single meter between two specimens. The paper also gives an account of the speed and edge heat losses: moreover, the reader is cautioned against some possible errors in the use of the heat flow meters and in the interpretation of measured data.