THE DEVELOPMENT OF A CRYOGENIC CALORIMETRIC SYSTEM FOR STUDYING THE STATE OF LIQUIDS IN INHOMOGENEOUS MATERIALS

The analysis of methods and means of experimental determination of the ratio of free and bound moisture in materials is carried out, and it is shown that most of the available measuring instruments do not allow investigating the ratio of free and bound moisture on representative samples of heterogeneous materials, therefore there is a need to create a specialized device for these purposes. Thus, the concerned work is aimed to the development of the differential scanning calorimetry method for studying the state of liquids in inhomogeneous materials and the creation of a cryogenic calorimetric system for the implementation of this method. On the basis of the performed analysis, recommendations were formulated for the development of a measuring system that is capable of examining representative samples of heterogeneous materials of various structures without the need for their preliminary grinding. The method of differential scanning calorimetry has been improved for studying the state of water and organic liquids in inhomogeneous materials in a wide temperature range, which is based on the use of a three-cell differential measurement scheme, as well as the use of cells, the configuration of which allows taking into account the peculiarities of inhomogeneous raw materials. A prototype of a cryogenic calorimetric system has been created, and a method for studying the metrological characteristics of such a system has been developed. On the basis of experimental studies, it has been established that the limits of the permissible relative measurement error of using the developed cryogenic calorimetric system are ± 5%, which corresponds to world analogues.

THERMAL PROCESSES MODELING IN QUASI-DIFFERENTIAL CALORIMETER

The model of the quasi-differential calorimetric system based on the electrothermal analogy method is proposed. Using the model, the dynamics of average temperatures and heat flow changes in the system elements, the temperature perturbations and the technological parameters spread influences on the measurement error are researched.