Izvestiâ Akademii nauk SSSR. Ènergetika

The article proposes methods for developing integrated heating and cooling systems (IHCS) in the Far North to improve the efficiency of combined cooling, heat and power systems and to reduce harmful emissions. The IHCS technology may be relevant in the Far North regions with cold winters down to minus 65°C and hot summers up to plus 39°C. In such regions, combined heat and power plants based on gas turbine units are mainly built to provide winter heat loads, which leads to the emergence of a significant amount of waste heat in the summer due to the inefficient use of the heat of fuel combustion. Waste heat from thermal power plants can be used as cheap energy for the operation of absorption chillers for district cooling of consumers as part of the IHCS. The solution to the problem of developing such systems in the Far North requires the formation of a cooling load scenario taking into account local conditions. For the developed cooling load scenarios, a variant of the cold supply technology with the best technical and economic parameters is selected, taking into account the fulfillment of technical conditions and restrictions. The results of applying the methods to solve the problem of developing the IHCS of Yakutsk showed a reduction in the cooling price to 39% relative to electric air conditioners, an increase in the coefficient of use of fuel heat in the summer months to 55% and a reduction in CO2 emissions to 69 thousand tons per year.

The intelligent integration of electricity, heat, cold and gas supply systems is a promising technology for creating integrated energy systems. Within integrated energy systems, prosumers are widely developed, which have a significant impact on the operation of the system by regulating their load schedules and having energy sources independent of the centralized energy system. Management of integrated energy systems that include prosumers with their own energy sources is a complex task and requires the use of the latest methods and approaches that take into account the following features: complex behavior of objects of integrated energy systems, the presence of different interests among participants in the energy supply process. In connection with the listed features, this study proposes to use a multi-agent approach as a tool for research and optimal management of prosumers in integrated energy systems. To describe the interaction of the centralized system and prosumers in cooperation, a mathematical model has been developed that has a two-level hierarchical formulation. The structure of a multi-agent system is proposed, including three levels of interaction of agents, on the basis of which a number of experiments on the study of the interaction of prosumers in cooperation are carried out. The obtained results showed the effectiveness and efficiency of the proposed principles and mechanisms for organizing the interaction of a centralized system and prosumers during their cooperation in integrated energy systems.

This study presents a comprehensive review of fission gas release (FGR) mechanisms in oxide and nitride nuclear fuels, along with modern approaches to their modeling. A schematic representation of the current understanding of FGR processes has been developed, encompassing intragranular diffusion, bubble coalescence, growth at grain boundaries, and the formation of interconnected gas tunnels. Special attention is given to atomistic methods (DFT, MD), which enable the assessment of how fuel type, stoichiometry, and lattice defects influence the migration mechanisms of fission gases. A comparative analysis of activation energy values obtained through DFT and MD simulations has been performed against experimental data, leading to the identification of discrepancies and their underlying causes. Preferred vacancy sites for fission gases in nitride and oxide fuels have been determined. The study also examines the diffusion and kinetic models implemented in fuel performance codes: their features and role in predicting FGR behavior. Key unresolved questions requiring further investigation are highlighted, including the primary nucleation sites of fission gas bubbles (intragranular vs. intergranular), the role of grain boundaries in tunnel formation, and the conditions under which burst release occurs at high burnups. The study emphasizes the necessity of an integrated approach combining experimental investigations and advancements in fuel performance modeling through atomistic and CFD methodologies to improve the predictive capabilities of fuel behavior under various reactor operating conditions.