In calculating children's thermal comfort, it is important to consider internal heat emissions, one of the main sources of which are the children themselves (heat exchange with the body surface, breathing, sweating). The accuracy of the calculation is influenced by their number, nature and intensity of activity, age, gender, and other parameters. Most regulatory documents base heat input calculations on a person with the following parameters: male, 20-30 years old, 70 kg, living in a temperate climate. This approach does not account for the physiological and age-specific characteristics of different age groups. The paper examines and refines the physiological parameters of children and uses models to numerically reflect the level of thermal comfort in a room. A calculation method is proposed that uses refined physiological parameters of children and evaluates thermal sensation of the indoor microclimate through the determination of Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD). Calculations of several microclimatic regimes were carried out, assessing the state of children of different ages and physical activity levels within the considered microclimate parameters. Analyzing the obtained data led to the conclusion that assessing human comfort using refined energy expenditures allows for a more flexible consideration of the thermal states of children in specific age groups. This enables higher quality regulation of the indoor microclimate of a specific room considering the examined factors.

The features of the development of technical diagnostic methods for remote control of the parameters of the operation of thermal power pipeline systems are considered, with a main focus on heat supply systems, including leak detection, as well as in the creation of software for automated control systems. Mathematical models for remote leak detection are proposed, implemented using software for regular monitoring and maintenance to ensure reliable operation of the systems under consideration. It is shown that the creation of algorithms and a system is required to detect leaks, including determining their location and scale. The created software can be used for automated control and monitoring of a thermal power system based on the results of the study. Based on the collected data related to the parameters of the heat supply system, such as pressure, gas flow and others, it is possible to build a statistical model that may include the probability distribution, expected values and variances of the parameters. The solution to the problem of specific leak detection may vary depending on the type of heat supply and the technologies used. It is shown that the study will contribute to improving the reliability and safety of heat supply systems by providing more effective detection and control of leaks and other anomalies in the operation of pipeline systems.

The paper considers environmental metrics that assess the man-made impact of energy-converting refrigeration systems on the environment. The results of a comparative analysis of TEWI and LCCP obtained for a medium-temperature vapor-compression heat pump unit (VCHP) operating on refrigerants R1234ze, R1336mzz (E), R600a and R744 are presented. R1336mzz (E) has the worst environmental indicators, because the total emission of equivalent CO2 for the entire period of the life cycle exceeds the same indicator for R600a by 4.2 times. The LCCP results show that system performance and equipment manufacturing emissions are the dominant drivers of CO2 emissions over the life of the SHP unit. The results of comparing refrigerants based on TEWI and LCCP are directly proportional and depend on the amount of energy consumed by the VCHP, which is also reflected in the energy efficiency indicators of the system. It is advisable to take into account the TEWI, LCCP and LCC criteria when comparing and selecting energy-converting refrigeration systems using the multi-criteria optimization method, which will help the user get a more informative understanding of the VCHP.

The problem of voltage unbalance and the need to power factor correction remain a relevant objective for electric power engineering. A variable load profile reduces the operating efficiency of electric power plants and leads to an overestimation of the power of transformer substations and the wire size of supply lines. Thus residential buildings power equipment remains underloaded for a significant part of the time. The decrease of power-frequency characteristic is becoming increasingly noticeable. This situation is not a problem yet, but in the future it may complicate the task of frequency stabilization. Finding solutions to existing and predicted problems is an important topic of research. To solve the problems posed, the work proposes the concept of a reversible energy converter, that is an electrotechnical complex with a flywheel energy storage and a two-section frequency converter based on two reversible voltage converters (active front end). The planning area of application of a reversible energy converter is transformer substations of residential and public buildings of urban power supply systems. The reversible energy converter is designed to solve such problems as load leveling, reactive power compensation (power factor correction), balancing voltages and power-frequency characteristic control. The work presents a connection scheme a reversible energy converter to the supply system and provides an expression for the phase load voltage.

Abstract Most recently, the European energy system has undergone a fundamental transformation to meet decarbonization targets without compromising the security of the energy supply. The transition involves several energy-generating and consuming sectors emphasizing sector coupling. The increase in the share of renewable energy sources has revealed the need for flexibility in supporting the electricity grid to cope with the resulting high degree of uncertainty. The new technologies accompanying the energy system transition and the recent political crisis in Europe threatening the security of the energy supply have invalidated the experience from the past by drastically changing the conventional scenarios. Hence, supporting strategic planning tools with detailed operational energy network models with appropriate mathematical precision has become more important than ever to understand the impacts of these disruptive changes. In this paper, we propose a workflow to investigate optimal energy transition pathways considering sector coupling. This workflow involves an integrated operational analysis of the electricity market, its transmission grid, and the gas grid in high spatio-temporal resolution. Thus, the workflow enables decision-makers to evaluate the reliability of high-level models even in case of disruptive events. We demonstrate the capabilities of the proposed workflow using results from a pan-European case study. The case study, spanning 2020–2050, illustrates that feasible potential pathways to carbon neutrality are heavily influenced by political and technological constraints. Through integrated operational analysis, we identify scenarios where strategic decisions become costly or infeasible given the existing electricity and gas networks.

Abstract The object of the present paper is to determine the minimum support requirements provided for the safe execution of trench excavation works for underground network receptacles. This term is used to define the open excavations, which are carried out for underground networks to be installed or constructed, and which are classified in terms of place of execution and soil categories. This paper focuses on the study of the free earth support method in excavations carried out in earthy soils and in places where the passage of the pipeline requires deep excavations of vertical front. In these cases, for reasons of safety of both the personnel and the equipment, it is necessary to support the vertical excavation fronts, even when the analyses indicate their stability. In this context, and to avoid the consequences, before the start of the excavation and at its limit, the formation of vertical support structures is required, which are commonly known as "retaining bulkheads". The basic criteria for selecting the type of the support system are soil characteristics, local conditions (surface load, groundwater table) and finally, the lifetime of the trench. Based on the above, the objective of the study is to investigate the temporary support of vertical fronts of depth trenches about 10 m, the excavation of which is carried out on earthy soil. The study is based on the implementation of the limit equilibrium method, which is applied according to the provisions—guidelines set out in Eurocode 7 (EN 1997). The study investigates the distribution of earth pressures in an anchored retaining structure of a deep excavation by extracting the main design parameters of similar systems. The goal of this work is to select the type of the support system depending on the soil properties (c, γ, φ and Ε) and local conditions, as a prerequisite for safe and rational design, while in the end of the project useful conclusions are drawn.