The study deals with the possibility of elimination of stagnation of thermal systems. The state of stagnation of thermal systems leads to overheating and evaporation of the heat transfer medium, which increases pressure and can lead to damage to the solar thermal system. Stagnation can occur due to a fault and stopping of the circulation pump, which causes the circulation of the heat transfer medium to stop. Another possibility is to achieve thermal saturation in the system, which can be affected by low heat consumption from the system. Elimination of stagnation is possible by various construction designs of collectors or by using other technical means. This study describes an experiment verifying the usability of a thermal collector’s tilting system to eliminate thermal stagnation of the system. The system is fully automatic, and when recording the limit values, ensures that the panel is rotated out of the ideal position, thus reducing the amount of received energy. In this way, the temperature of the medium in the system can be reduced by up to 10% in one hour. In the case of thermal saturation of the system, the solution is the automatic circulation of heat-transfer fluid through the system during the night and the release of thermal energy to the outside. These results suggest that the methods used actively eliminate stagnation of thermal systems.

The application of cooling systems is a relatively efficient way to ensure the required thermal comfort conditions. One option is the application of cooled ceilings, where the heat load is removed using a ceiling structure with integrated cooling panels. These systems allow for a suitable way remove the heat load, but at the same time, compared to conventional air conditioning systems, they are characterized by a certain time dependence. The presented article describes experimental measurements carried out on days with high exterior heat exposure. Measurements evaluating the effect of the phase shift of temperature oscillations on the operation of the system were carried out using two cooling operating modes. According to results, it can be concluded that cooling systems based on cooling ceilings can be used effectively even with high external heat gains.

To minimize the existing risks associated with the energy production, distribution, and development of urban areas, the concept of sustainable development of smart manufacturing is being introduced everywhere. However, most of existing digital transformation technologies do not sufficiently take into account environmental, economic, and social components. It requires the development of specialized solutions that, on the one hand, contribute to the development of the urban environment, and on the other, are focused on the use of innovative technologies that have a positive effect on the environment. However, in order to provide electric power to objects of a smart urban environment, we propose using autonomous power plants with renewable energy sources (wind and sun) instead of classical central power supply. The article describes the benefits of using combined wind-solar power plants to provide electricity to smart urban environments. The article considers advantages and disadvantages of this solution. We describe the design of the combined wind-solar installation with a vertical Darier rotor and photoelectric converters located on a common supporting structure. This solution allows getting a positive synergistic effect from the use of several renewable energy sources. The presented main advantages of this solution include increasing the energy efficiency of photovoltaic converters due to the intensification of heat removal from the surface of solar cells by the wind flow from the Darier rotor. In addition, this article considers the efficient use of the area and stability of electricity output. Digital aerodynamic modeling performed the parametric optimization of the Darier rotor having three blades with NACA 0021profile. The simulation demonstrated that the blades installed at an angle of 3.8° provide the maximum value of the wind utilization coefficient. This article also considers parametric optimization of a photovoltaic installation. In particular, the optimal installation angle of photovoltaic modules for Sevastopol is 34°.

Waste is a product of society and one of the biggest challenges for future generations is to understand how to sustainably dispose of large amounts of waste. The main objective of this study was to determine the possibility and conditions of the decentralized combustion of non-hazardous municipal waste. The analysis of the combustion properties of a mixture of wood chips and 20–30% of municipal solid waste showed an improvement in the operating parameters of the combustion process. Analysis also confirmed that the co-combustion of dirty fuels and biomass reduced the risk of releasing minerals and heavy metals from fuel into the natural environment. Approximately 55% of the heavy metals passed into the ash. The analysis of municipal solid waste and fuel mixtures containing municipal solid waste for polycyclic aromatic hydrocarbons showed the risk of increasing polycyclic aromatic hydrocarbon concentrations in flue gases.

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