AN APPARATUS AND METHOD OF DETERMINING A CHARACTERISTIC RELATED TO THE THERMAL POWER OF A SAMPLE

A calorimeter is disclosed comprising a sample chamber (12) adapted to enclose a sample, a thermally conductive reference surface (14) surrounding and insulated from the sample chamber (12) and a casing (16) surrounding and insulated from the reference surface. Temperature transducers, in communication with a micro-computer, record the temperatures of the sample chamber (VS) and reference surface (V1) at periodic intervals. The micro-computer is programmed to calculate the theoretical temperature (VT) of the sample chamber from the measured values of the temperature of the reference surface (V1) and estimated values of the thermal power of the sample (I), the thermal resistance from the sample to the sample chamber (RS) and the thermal capacity of the sample (CS), and to optimize the fit between the theoretical calculations (VT) and the corresponding measured values (VS) of the temperature of the sample chamber. A simplex form of optimization may be used to arrive at the optimum value of, inter alia, the thermal power (I) of the sample, the quantity which is to be indirectly measured.