ABSTRACT
When solving various problems of heat transfer between multilayer structures separating physical media with different temperature characteristics, various heat exchangers or devices are used (Gorshkov et al., 2018; Korniyenko et al., 2016; Gorshkov et al., 2015). Examples of heat exchange devices may include a heater and various heat utilization appliances. In real operating conditions of multilayer structures separating media with different temperatures, the heat transfer behaviour through their boundaries is almost always unsteady (Gorshkov et al., 2014; Grinfeldi et al., 2014; Vatin et al., 2014). However, for the overwhelming majority of practical problems, as a rule, a quasi-stationary heat transfer mode is considered, characterized by the time constancy of the heat flux through the structure. The quasi-stationary heat transfer mode can only be established in very short time intervals. The convenience of such a mode of heat transfer is stipulated by the fact that when considering it, all thermotechnical calculations that are used in design practice are greatly simplified (Gorshkov et al., 2013a; Gorshkov et al., 2013b; Zimin et al., 2013). Unsteady heat transfer also occurs when solving problems of heating and cooling objects, damping temperature fluctuations in structures and some others. However, their practical use is often happens to be limited.
