METHOD FOR CALCULATING THE DYNAMICS OF CHANGES IN THE AVERAGED TEMPERATURE AND CHARGE CARRIER CONCENTRATION IN ELEMENTS OF ENERGY DEVICES USING ELECTROLYTES

• Date: 2026
• Main Authors: Matiakh , S., Surzhyk , T., Tereshenko , A., Sheiko, I.
• Format: Article
• Language: Ukrainian
• Published: Institute of Renewable Energy National Academy of Sciences of Ukraine 2026
• Subjects: electrolyte; volume-averaged temperature; charge carrier concentration; heat and mass transfer; electro-mass transfer; ambipolar diffusion; electrochemical battery; fuel cell; electrolyzer.
• Online Access: https://ve.org.ua/index.php/journal/article/view/629
• Journal Title: Vidnovluvana energetika

The article proposes a method for calculating the dynamics of changes in the volume-averaged temperature and concentration of electric charges in elements of energy devices that use electrolytes. The relevance of the study is determined by the fact that, for electrochemical batteries, fuel cells, electrolyzers, and other related systems, the experimental determination of local values of temperature, electric field strength, and charge carrier concentrations is significantly complicated, whereas integral or volume-averaged parameters are accessible for measurement. The aim of this work is to develop a theoretically substantiated approach that enables the transition from local heat and mass transfer equations to equations describing spatially averaged characteristics. The method is based on reducing the initial equations to divergence form, integrating them over the volume, and applying Newton’s law to describe heat exchange with the external environment. As a result, an ordinary differential equation for the volume-averaged temperature and a system of equations for the averaged concentrations of charges of different signs were obtained. It is shown that, within the approximation of ambipolar diffusion, the concentration equation acquires a structure analogous to the equation of transient heat conduction for averaged parameters. The practical significance of the work lies in the possibility of interpreting experimentally determined integral parameters and using the obtained relationships to assess the thermal and concentration states of electrolyte-containing energy systems.