Estimation of Reacting Samples Temperature Using Calorimetric Measurements in Thermoanalytical Study of Exothermic Reactions

Abstract

The article proposes a method for processing data obtained using differential scanning calorimetry in experimental studies of the kinetics of processes with high heat release under the conditions of thermogravimetric analysis. Due to the nonlinear dependence of the chemical reaction rate on temperature, the regulation of heat exchange conditions requires special measurement conditions, including the possibility of changing the temperature program during the process under study. A simpler approach is to estimate the temperature difference between the reacting sample and the gas environment. However, this approach has a significant drawback, as it does not directly relate the heat release intensity to the sample temperature. In this regard, the processing of measurements should include a greater number of free parameters, including heat transfer coefficients. Instead, the solution of an inverse problem is proposed to estimate the unknown parameters, including the deviation of the sample temperature from the furnace temperature. The main assumption is the selection of a simplified one-step chemical transformation scheme, which reduces the number of independent coefficients in the kinetic model. A grid of parameters is used to search for solutions, and statistical criteria are used to select the best-fitting parameters. The obtained parameter values allow for the estimation of the combustion temperature of the sample. According to the results of calculations, the temperature of carbon samples during oxidation with air-argon mixtures can significantly exceed the temperature of a furnace for small samples, so the kinetic analysis of the obtained curves without taking into account overheating can lead to errors in determining the parameters of reactivity. The choice of additional restrictions that allow for an unambiguous solution is discussed

The work was supported by the Russian Science Foundation (grant no. 23-29-00406, https://rscf.ru/project/23-29-00406/)

Please cite this article in English as:

Donskoy I.G., Kozlova M.A. Estimation of reacting samples temperature using calorimetric measurements in thermoanalytical study of exothermic reactions. Herald of the Bauman Moscow State Technical University, Series Instrument Engineering, 2026, no. 1 (154), pp. 17--33 (in Russ.). EDN: DVTLIV

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