Analysis of Thermal Hysteresis Phenomena During Melting and Crystallization Na2S2O3·5H2O
S. A. Frolova, O. V. Sobol, A. Yu. Sobolyev
Donbas National Academy of Civil Engineering and Architecture
Abstract: The processes of melting and crystallization underlie the creation of phase-transitive heat-accumulating materials (PTHAM). Since hysteresis phenomena are undesirable for PTHAM, it is quite an urgent task to clarify the mechanisms of direct and reverse phase transformations, their interrelation with each other, to identify the reasons for the difference between nonequilibrium crystallization and equilibrium, the study of thermal hysteresis is quite an urgent task. In this work, various thermal hysteresis processes were analyzed based on the analysis of heat and cooling thermograms Na2S2O3·5H2O. Three types of thermal hysteresis were identified: the first type (TG-I) – when comparing the equilibrium melting process with the non-equilibrium crystallization process; of the second type (TG-II) – when comparing equilibrium melting and crystallization processes with different melting and crystallization temperatures, as well as combined (KG), combining TG-I and TG-II. Schemes for changing enthalpy and Gibbs energies in various types of hysteresis phenomena have been developed. According to the above enthalpy change schemes, it is possible to predict values of the thermal hysteresis value, which is desirable for the creation of phase transition heat storage materials.
Keywords: melting, crystallization, sodium thiosulfate pentahydrate, heat storage material, thermal hysteresis.
Pages: 134-141.
Link for citation: Frolova, S. A.; Sobol, O. V.; Sobolyev, A. Yu. Analysis of Thermal Hysteresis Phenomena During Melting and Crystallization Na2S2O3·5H2O. – Text : electronic. – In: Proceeding of the Donbas National Academy of Civil Engineering and Architecture. – 2022. – Issue 2022-1(153) Modern building materials. – Р. 134-141. – URL: https://donnasa.ru/publish_house/journals/vestnik/2022/2022-1(153)/st_19_frolova_sobol_sobolev.pdf (date of access: 15.10.2024). (in Russian)
Issue 2022-1 (153)Journal: Proceeding of the Donbas National Academy of Civil Engineering and Architecture
Publish house: Donbas National Academy of Civil Engineering and Architecture