Thermochimica Acta, Vol.271, 115-125, 1996
Heat-Capacity Determination by the Pulsating Current Method
The pulse calorimeter is normally used to measure unsteady heat capacities on electric conductors in the temperature range between 70 degrees C and 1200 degrees C, with a relative uncertainty of measurement of approx. 2%. The aim was to investigate under which conditions the pulse calorimeter will allow quasi-stationary heat capacity values to be obtained for the same sample. Measurements were carried out on platinum using the pulsating direct current method (heating of the sample by means of direct current superimposed with a low alternating current). The results show that the modulation frequency must not exceed a limiting frequency which depends on the temperature, and that agreement between the heat capacity values measured and the values determined by the pulse method is better the smaller the deviation from the stationary state.