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Due to the dynamic development of energy generation in photovoltaic installations, a reliable assessment of their impact on the level of energy losses in distribution networks is needed. For energy companies managing network resources, this issue has a very tangible practical aspect. Therefore, ongoing analyses of the level of electricity losses based on actual measurement data of prosumers are needed. In the paper, the influence of energy introduced by prosumer photovoltaic installations on energy losses in a low-voltage radial line is investigated. The issue is examined from three perspectives: 1. Focused on energy supplied into the low-voltage grid from photovoltaic installations; 2. the installations' locations; and 3. the product of energy and distance from the power source. Comparative assessments are made of the examined aspects for 87 possible locations of prosumer installations in the tested low-voltage network. An analysis of energy losses is carried out both for the entire analysed network and separately for the line and the transformer. The changes in energy losses are influenced by both the power and the location of the photovoltaic installations. Based on the research findings, functions defining relative changes in energy losses in the low-voltage network are determined. [ABSTRACT FROM AUTHOR]

This paper presents an experimental analysis and performance evaluation of a grid-connected photovoltaic plant installed on the rooftop of the Electronics Research Institute in Cairo, Egypt. Cairo is classified as a hot-desert climate region according to the standard Koppen-Geiger climate classification system. Over a year, we monitored real-time data to assess key system performance metrics, such as energy yield, efficiencies, performance ratio, capacity factor, and losses. Based on the obtained experimental results, the highest final yield of 5.2498 hr/day was observed in the summer, whereas the lowest yield of 3.439 hr/day occurred in the winter months. The photovoltaic plant had an average annual system efficiency of 15.8%, while the photovoltaic and inverter had mean yearly efficiencies of 17.1% and 97.2%, respectively. The average annual performance ratio is 83.03%, and the capacity factor is 18.72%. The monthly total loss exhibited a linear rise alongside increasing ambient temperature and solar irradiance. The ambient temperature affected the system efficiency, photovoltaic efficiency, and performance ratio. The findings can help strengthen forecasts of future large-scale photovoltaic plants in hot desert climates. Moreover, they can guide the design, optimization, operation, and maintenance of new grid-connected photovoltaic systems. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the flow dynamics and energy losses of Tesla turbines using Computational Fluid Dynamics with OpenFOAM. Our goal is to identify the main sources of energy loss. Four main sources of energy loss were identified. The most significant loss occurred during the conversion of pressure energy to kinetic energy, estimated to range from 88 % to 64 % of the total energy. Energy losses due to leaks between the rotor and the casing were also quantified, ranging from 4.97 % to 7.95 % of the kinetic energy at peak efficiency points. Design modifications, such as incorporating a nozzle at the entrance of the turbine, can improve efficiency. These findings highlight specific areas for efficiency improvement, offering opportunities for improved turbine design and integration into energy‐generation systems.

This study investigates the flow dynamics and energy losses of Tesla turbines using Computational Fluid Dynamics with OpenFOAM. Our goal is to identify the main sources of energy loss. Four main sources of energy loss were identified. The most significant loss occurred during the conversion of pressure energy to kinetic energy, estimated to range from 88% to 64% of the total energy. Energy losses due to leaks between the rotor and the casing were also quantified, ranging from 4.97% to 7.95% of the kinetic energy at peak efficiency points. Design modifications, such as incorporating a nozzle at the entrance of the turbine, can improve efficiency. These findings highlight specific areas for efficiency improvement, offering opportunities for improved turbine design and integration into energy‐generation systems. [ABSTRACT FROM AUTHOR]

This study investigates the IEEE 69-bus distribution network with three wind turbines (WTs) connected at the same buses of three battery energy storage systems (BESSs), with three 20- or 30-outlet electric vehicle charging stations (EVCSs) for charging electric vehicles (EVs). The honey badger algorithm (HBA) is adopted to minimize daily energy loss. The HBA determines the best size and position for three WT-BESS buses and three EVCS buses. The HBA calculates BESS size and operation mode to minimize daily energy loss. The demand of EVCSs varies throughout the day depending on the random choice of the number and state of charge of EVs entering the station. This results in the active and reactive energy losses and utility input energy decreasing by 63.5%, 60.6% and 59.6%, respectively, and the minimum voltage increasing from 0.9256 to 0.9839 pu. The network voltage profile and stability are also improved. [ABSTRACT FROM AUTHOR]

This article presents an original methodology to determine the optimal level of reactive energy transmission to low-voltage consumers supplied from MV/LV substations that guarantees the lowest total costs of reactive energy transmission through the DSO network and its generation in receiving installations within the reactive power compensation process. The average value of the optimal factor tgφ to be maintained by customers depends on the efficiency of the network, the characteristics of the load, and the market costs of energy losses due to the transmission of reactive energy through the network that are covered by the DSO and the costs of reactive energy generation in receiving installations. The results presented for real MV/LV substations operating in the Polish distribution network demonstrate the application of annual measurements of active and reactive energy consumed and generated registered by AMI systems to calculate the optimal reactive power compensation level. They can be applied to verify the permissible levels of reactive energy compensation applied by the DSOs until now within the yearly tariffs for customers. [ABSTRACT FROM AUTHOR]

In connection with the growing requirements regarding the quality and continuity of energy supply and the dynamic development of renewable energy sources, the need for a thorough analysis of factors affecting power and energy losses and the effectiveness of the MV network increases. One of the biggest challenges in managing power networks is the problem of load asymmetry. Load asymmetry can lead to numerous adverse phenomena, such as increased power losses, deterioration of the quality of energy supplied, and an increased risk of network failure. Despite various research on this issue, there is still a need for a more accurate understanding of mechanisms leading to the development of methods of minimizing these phenomena. The relationships describing power losses in lines and power transformers are widely known. However, most published analyzes assume the same load on each phase. If the asymmetrical load of the line already appears, such analysis is not based on the data of actual lines and applies to a homogeneous line with equal load along its entire length. Therefore, the authors decided to modify the method of calculating power losses so that they can be determined in a branched line loaded in many points, with knowledge of the current flowing into the line, its length, and the number of acceptances. This method allows for the determination of power losses in an innovative way, taking into account line load asymmetry. The use of relationships commonly available in the literature to determine power losses leads to errors of 5.54% (compared to the actual, measured losses). Taking into account both the asymmetry and multi-point loading in the method proposed by the authors allows us to limit this error to 3.91%. To estimate the impact of asymmetry on power losses in lines and power transformers, the authors performed field tests in the selected medium voltage power network. The increase in power losses determined on their basis caused by the asymmetry of the load currents obtained values from 0.03% to 4.78%. Using generally known methods of reducing asymmetry, these losses can be avoided, and therefore the energy transmission costs may be reduced, and the greenhouse gas emissions might be lowered. [ABSTRACT FROM AUTHOR]

The effect of side-chain engineering of conjugated molecules on the morphology and device performance in binary organic solar cells has been widely investigated. However, this relationship has hardly been studied in the guest components of ternary organic solar cells. In this study, a family of non-fullerene guest acceptors, namely XY-3, XY-5 and XY-7, with hydrogen substituent, straight and branched alkyl chains on the bithiophene units, respectively, were designed and synthesized to understand their effects on aggregation properties and device performance. The straight and branched alkyl chains on the bithiophene units result in sightly blue-shifted absorption compared to the hydrogen substituent and the XY-7 demonstrates the most appropriate phase separation scale and the most balanced charge transport. Consequently, the OSCs based on D18:eC9:XY-7 achieve a high short-circuit current density (JSC) and fill factor (FF), while maintaining the enhancement of the open-circuit voltage (VOC) achieving an efficiency of 19.32%, exceeding those of D18:eC9, D18:eC9:XY-3, D18:eC9:XY-5 (PCE:18.28%, 19.04%, 18.75%, respectively). These results highlight that the side-chain engineering of Y series non-fullerene acceptors as the guest acceptors has great potential in optimizing morphology properties and promoting photovoltaic performance. [ABSTRACT FROM AUTHOR]

Crude oils are a complex mixture of hundreds of different volatile hydrocarbon molecules and organic materials in the liquid phase accompanied by elemental compounds and contaminants. In the present work, sulfur content influence variations on velocity flow (Reynolds number) of different Iraqi crude oil fields (Refinery of Diwaniya, East Baghdad, and Thi-Qar), and pressure gradient (dp) on the pump power, power loses and the crude oil flow rate have been evaluated. Further, energy losses and the total discharge are appraised to state the feasibility of using desulfurization unit's in the oil fields. All the experiments have used different API crude oil, with the studied at the oil field surface pipelines sections connecting operating at different sulfur content % and taking the pressure gradient of (2, 4, and 6 kg/cm2), at constant temperature of 28.9°C, and with a constant 4 in pipe diameter. When the sulfur content increases results show that the three types of crude oils (Refinery of Diwaniya, east Baghdad, and Thi-Qar oil fields) the total pumping energy rises when the flow rate becomes smaller through the pipeline, while small influence for energy losses. The increasing pressure gradient (this means that differential pressure was increased), there was more flow rate and with the same behavior vis sulfur content. There is a direct proportion between the flow rate and the pressure differential. Greater flow rates produced from higher pressure differences, as the high-pressure gradient in the line consumes energy must also be large. Also expected that when increasing the sulfur content in the field especially for high percentage (2.1%) in the crude oil will decrease the flow rate and increase the pump power, power losses therefore adding unit to treatment the sulfur very important economically to avoid this entire problem. [ABSTRACT FROM AUTHOR]

This paper focuses on determining the friction energy loss in the mechanism of a mechanical crank press. After defining the crank press mechanism and how it works, we describe the energy balance of a technological operation—forming. Four distinct methodologies for calculating friction loss in the mechanism are then presented, namely an empirical method, a spreadsheet calculation utilising force decomposition in a crank mechanism, an analytical calculation of the dynamic behaviour of a press, and a multibody simulation. Each additional approach expands the possibilities for approaching reality, but as the primary aim of the study is to compare the approaches, these possibilities are not exploited. Multibody simulation has proved itself to be accurate and suitable for simulating press mechanisms and investigating their dynamics. Multibody simulation is a much more powerful tool that can lead to a digital twin, which can help us to develop a less energy-demanding press. Confirmation of the multibody simulation results is the main outcome of the comparison and will be used in future work. [ABSTRACT FROM AUTHOR]

Non‐centrifugal sugars (NCS) are traditionally consumed sweeteners which are gaining momentum in the global market due to the presence of nutritional and mineral content. Traditionally NCS is produced by concentrating sugarcane juices in an open pan evaporation process using dried bagasse as a fuel. Field trials at the traditional production site of NCS showed the energy efficiency as low as 8%–10%. Moreover, the effective bagasse consumption as a fuel stands at 7–8 kg/kg NCS production, whereas, as per stoichiometry and theoretical calculations, the actual bagasse consumption required for the production of NCS is a mere 0.65 kg/kg NCS production. Hence, as an alternative to the existing process, the concentration of cane juices by steam‐controlled evaporation has been studied and it has been found that the steam‐controlled evaporation can enhance the energy efficiency to 78%–83% with an effective bagasse consumption of 1.05 ± 0.04 kg/kg NCS production. [ABSTRACT FROM AUTHOR]

In this study, a system was investigated where the pump line in a drinking water treatment plant is combined with the gravity flow line in a pipeline header. When the pumps are operated in combination in the existing system, flow rate is lower than the expected level. It is emphasized how to overcome the problems analyzing the issues that cause flow and energy losses in the pumps. Experimental studies were carried out on the pumps and pipelines at the treatment plant. A high-pressure gravity flow was diverted to the pump line while the pumps were running. Then the flow entering the pumped system was cut off. The results of both cases were compared. The electrical energy consumed by the pumps and their efficiency were calculated. In the experimental studies, it was observed that connecting the pump line with other lines caused high energy losses. In a scenario, it was estimated that operating different pumps in series yielded a similar flow rate, however right group of pumps provided the same flow rate reducing costs by 54.95%. The most economical combination of pumps were determined to operate depending on the desired flow rate. Numerical analyses were conducted through CFD method to understand the effects that caused flow and energy losses in the pipe. The analyses indicated that high-pressure flow entering low-pressure pump line disrupted pressure balance of the system, posed problems for the pumps and caused energy losses. [ABSTRACT FROM AUTHOR]

—This paper introduces an enhanced Satin bowerbird optimizer (SBO), specifically tailored for the integration of photovoltaic distributed generation (DG) units into radial distribution systems. The upgraded SBO version involves two pivotal adjustments. Firstly, the positional updating mechanism of the newly generated bower is modified to enable exploration around the iteration's elite bower. Secondly, an adaptive constriction factor is introduced, progressively decreasing during iterations to concentrate the search in promising areas. These modifications significantly amplify the exploration capacity of each new bower in the SBO algorithm. The proposed upgraded SBO aims at minimizing costs related to CO2 emissions from the grid and those linked with photovoltaic units, in addition to energy losses. The variability of photovoltaic DG units is represented using the Beta Probability Density Function (PDF) to portray distinct solar irradiation conditions experienced daily. The enhanced SBO version undergoes testing on a practical Nigerian distribution system, the Ajinde 62-bus network, and a standard IEEE 69 nodes system. Simulation results underscore the effectiveness of the upgraded SBO version, revealing substantial reductions in energy losses and emissions. Specifically, for the Ajinde 62-bus network, the proposed SBO version achieves a noteworthy 31 % reduction in the combined yearly costs of energy losses and emissions compared to the initial case. Additionally, for the IEEE 69-bus system, it attains a considerable reduction of 35 %. Furthermore, the simulation results illustrate the competitive performance of the suggested SBO version when compared to Differential Evolution (DE) and Particle Swarm Optimization (PSO) algorithms, as well as the standard SBO.

Due to the dynamic development of energy generation in photovoltaic installations, a reliable assessment of their impact on the level of energy losses in distribution networks is needed. For energy companies managing network resources, this issue has a very tangible practical aspect. Therefore, ongoing analyses of the level of electricity losses based on actual measurement data of prosumers are needed. In the paper, the influence of energy introduced by prosumer photovoltaic installations on energy losses in a low-voltage radial line is investigated. The issue is examined from three perspectives: 1. Focused on energy supplied into the low-voltage grid from photovoltaic installations; 2. the installations’ locations; and 3. the product of energy and distance from the power source. Comparative assessments are made of the examined aspects for 87 possible locations of prosumer installations in the tested low-voltage network. An analysis of energy losses is carried out both for the entire analysed network and separately for the line and the transformer. The changes in energy losses are influenced by both the power and the location of the photovoltaic installations. Based on the research findings, functions defining relative changes in energy losses in the low-voltage network are determined.

This article, published in Frontiers in Physics, discusses the energy losses of highly charged Arq+ ions during grazing incidence on tungsten surfaces. The study focuses on the impact of electron density distributions on ion energy loss and the correlation between surface azimuthal angles and energy loss. The researchers used simulations and calculations to investigate these phenomena and found that axial channeling of surfaces significantly influences ion energy loss. The findings are important for understanding the surface structure of crystals. The text also discusses the advantages of using the generalized gradient approximation (GGA) over the local density approximation (LDA) for exchange-correlation energy calculations, as well as the charge-exchange energy loss in the simulation and provides a theoretical model for the motion and electron energy loss of ions. The document further presents results and discussions on the stopping power above the W surface and the energy loss of Ar16+ ions grazing on graphite. Another document in the collection examines the energy loss of Ar17+ ions interacting with tungsten crystal surfaces, emphasizing the importance of considering surface structure and electron density distribution in understanding ion-surface interactions. The references provided cover a range of research areas within the field of ion-surface interactions. [Extracted from the article]

With the increase in the use of solar energy, the investigation of the failures that cause the decrease in efficiency and loss in production is increasing day by day. It is extremely beneficial to conduct on-site testing of solar systems in order to evaluate the plant's actual performance and identify potential problems. There are important methods for on-site and fast detection of failures. In this study, the failures in the panels were analyzed using the Electroluminescence test, which is one of the most reliable methods for the detection of micro-cracks, and 11 failures were detected as a result of the EL imaging. The EL test, which is the most reliable method for detecting micro-cracks, has been compared with infrared thermal images and its superiority has been proven. Energy losses were prevented by intervening in the field with rapid fault detection. [ABSTRACT FROM AUTHOR]

Organic photovoltaics (OPVs) have recently achieved efficiencies of over 19% and are well underway toward practical applications. However, issues concerning operational stability remain a major challenge ahead of OPV commercialization. Here, when replacing the conventional hole‐transporting layer PEDOT:PSS with a self‐assembled monolayer of [2‐(3,6‐dichloro‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (3,6‐Cl‐2PACz) or [2‐(4,5‐dichloro‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (4,5‐Cl‐2PACz) it is found that the T80 lifetime of PM6:BTP‐eC9‐based devices can be improved from ~100 to ~470 and over 800 h, respectively. The power conversion efficiency is also improved from 17.29% to 18.17% and 18.67%, respectively. The improved performance and prolonged photostability in 4,5‐Cl‐2PACz‐based devices stem from the stabilized vertical distribution of donor and acceptor components, reducing the energetic disorder and thus alleviating non‐radiative recombination losses. It is further found that the surface energy of 4,5‐Cl‐2PACz‐modified substrates stays constant under prolonged illumination due to the improved intrinsic photostability of 4,5‐Cl‐2PACz, supporting the robust active layer morphology. Applying 4,5‐Cl‐2PACz in a ternary device of PM6:BTP‐eC9:L8‐BO‐F delivered an efficiency of 19.05% and a T80 lifetime over 1140 h. [ABSTRACT FROM AUTHOR]

Introduction. Electric locomotive wheel–rail adhesion is determined by various parameters (kinematic and energetic) that affect the mass and speed of the train, energy consumption, etc. Goods trains of increased weight and length considerably increase the urgency of the problem of electric locomotive wheel–rail adhesion, especially when using powerful electric traction motors, including commutatorless ones. Making reasonable decisions to increase the mass and speed of trains, reduce energy consumption for traction and generally reduce operating costs requires a clear understanding of the basic regularities of the processes in electric locomotive wheel–rail adhesion zones and their parameters.Materials and methods. The paper uses a system approach, methods of mathematical analysis and energy balance to consider the main regularities of processes in the electric locomotive wheel–rail adhesion zone, their kinematic and energy parameters. Consideration of these processes takes some assumptions: diameters of electric locomotive wheels and pressure of all wheels on rails at any moment of time and at each point of the track is the same, oscillations of wheel pairs are absent, etc. These assumptions do not significantly affect the final results but greatly simplify the derivation of the necessary analytical expressions.Results. The researcher obtained numerical values of the electric locomotive wheel–rail adhesion parameters, which agree with the experimental data.Discussion and conclusion. The author proposed the principles of analysis and a system of logically justified and interrelated kinematic and energy parameters of electric locomotive wheel–rail adhesion, identified the main regularities of changes in these parameters. The research results can be used to make science based decisions on the practical application of the electric locomotive wheel–rail adhesion.

The growing demand for electric power and the need for an energy transition that contributes to the reduction of global greenhouse gas emissions have driven the development of various energy generation, storage, and offset technologies. These technologies are known as distributed energy resources. Their integration into distribution power systems not only contributes to improving operating aspects, but also allows supplying electricity to areas that do not have access to large-scale power systems. Therefore, the integration and management of these resources has become a topic of interest, and several studies seek to optimize their impact on technical, economic, and environmental aspects. However, this optimization poses specific challenges related to the type and number of variables related to the operation of a distribution power system. This review article aims to describe the main challenges posed by three-phase AC three-phase distribution power systems under scenarios involving the integration of distributed energy resources. In addition, it presents some approaches proposed by different authors to improve the technical, economic, and environmental aspects of power grids. It can be stated that the strategies presented in the literature fail to consider scenarios that simultaneously integrate different types of technologies and optimize them while following a multi-objective approach and considering three-phase systems in a context of variable generation and demand. Therefore, future work in this field should address these aspects in a holistic manner, taking into account the computation efforts and processing times required by intelligent algorithms.

The management of electricity distribution faces numerous challenges, including energy losses arising from technical and non-technical issues such as electricity theft. Energy losses due to theft have a significant global impact, including in South Africa (SA). SA rural areas are suffering from poor voltage, and technical and non-technical losses due to old power system systems. Hence, this research project is a proposal for the upgradation of an old and technically weak network of Nottingham Road, Kwa-Zulu Natal in South Africa. To reduce non-technical losses, this research examines the influence and potential solutions of using smart meters. The paper focuses on modeling real low voltage (LV) distribution systems and the energy meters that measure various parameters of the smart meters. This research also examines the effect of illegal links on the network. However, implementing the smart metering technology for lesser power consumers in developing countries such as South Africa can be challenging because of the greater initial costs. Therefore, this paper investigates the possibility of various technology choices and their return on investment in both urban and rural regions.

This article presents an original methodology to determine the optimal level of reactive energy transmission to low-voltage consumers supplied from MV/LV substations that guarantees the lowest total costs of reactive energy transmission through the DSO network and its generation in receiving installations within the reactive power compensation process. The average value of the optimal factor tgφ to be maintained by customers depends on the efficiency of the network, the characteristics of the load, and the market costs of energy losses due to the transmission of reactive energy through the network that are covered by the DSO and the costs of reactive energy generation in receiving installations. The results presented for real MV/LV substations operating in the Polish distribution network demonstrate the application of annual measurements of active and reactive energy consumed and generated registered by AMI systems to calculate the optimal reactive power compensation level. They can be applied to verify the permissible levels of reactive energy compensation applied by the DSOs until now within the yearly tariffs for customers.

Hidden losses in the technological system occur accidentally due to the appearance of defects in the equipment, errone-ous actions of personnel, changes in uncontrolled external conditions. The paper considers a method of detecting and estimating hidden energy losses, based on machine learning and analysis of energy consumption precedents, aimed at eliminating such energy losses. Ref. 10.

In this study, we investigate the energy loss of highly charged ions interacting with various tungsten surfaces. The analysis primarily focuses on elucidating the impact of electron density distributions on energy loss of ions. Furthermore, we explore the correlation between surface azimuthal angles and energy loss under both uniform and inhomogeneous electron density distributions. Utilizing the classical over-the-barrier model (COBM), simulations involving trajectory calculations, energy loss, charge-exchange processes, and surface electron distributions, etc., were performed. Remarkably, the significant influence of axial channeling of surfaces on ion energy loss is observed. For the comparison of ion energy loss under uniform and inhomogeneous electron density distributions, the results reveal a more pronounced effect of electron density inhomogeneity on ion energy loss at higher energy-loss values. Additionally, the calculated energy-loss spectra of Ar16+ ions grazing on graphite surfaces show reasonable agreement with experimental data. These findings are crucial for understanding the surface structure of crystals.

Theoretical research on hydraulic processes occurring in aircraft hydraulic drives is presented in the studies. Installation of angular fitting connections in aircraft pipeline systems influences hydrodynamic processes and fluid flow characteristics analysed in the research. The provided analysis is based on a validated numerical model utilizing Navier–Stokes equations and the k-epsilon turbulence model. Fluid flow inside the aircraft hydraulic drive pipeline system was investigated with flow rates up to 100 l/min. A mesh independence study was conducted for numerical simulation of the fluid flow. The obtained results include fluid pressure drops, energy losses, and operational delays associated with fluid flow vortex formations at 45° and 90° angular fitting connections. Additionally, compared results from standard methods of calculation for angular fitting connections, including the equivalent length and equivalent length same shape methods.

Pumps as turbine (PAT) for small-scale hydropower, pressure relief valves, and hydro-pumping applications have recently gained popularity. In contrast to conventional turbines, pumps do not have movable guiding vanes to accommodate changes in flow rate and head. This limits their use to the single best operating point. As a result, the precise estimation of reverse mode operating parameters is critical. One of the most successful techniques in this regard is the energy loss model. However, it necessitates extremely detailed pump geometry and experimental data. Although it is claimed to be more accurate, the lack of data makes it impractical. This calls for the devising of a pump geometrical parameter prediction model from limited manufacturer information. Using 137 sets of commercial pump operating data, geometry redesign was carried out by MATLAB code. Following that, multivariate linear regression analysis was carried out, and a one-dimensional geometrical prediction model was developed. Then the result was validated with computational analysis and measurement. The model results were 99 %, 100 %, and 95 % correlated for pump inlet, volute, and throat inlet diameters, respectively, with the experimental results. Similarly, the model results were also 99 %, 71 %, and 89 % correlated for pump inlet, outlet, and volute blade width, respectively, with experimental results. The model gave a more accurate geometrical result than the analytical and numerical methods.

The objective of the presented paper is to verify economically justified levels of reactive energy compensation in the distribution network in the new market conditions, including the extensive use of smart metering systems, new types of load, or distributed generation. The proposed methodology is based on the minimization of annual costs of losses caused by the flow of reactive energy to the supplied loads through the equivalent resistance of the distribution system determined on the basis of statistical energy losses in this network. The costs of losses are compared to the costs of using compensating devices expressed by the levelized costs of reactive energy generation. The results are the relations describing the optimal annual average value of the tgφ factor to be maintained by customers to optimize the cost of loss of the distribution network caused by reactive energy flows. The dependence of the optimal tgφ value on the analyzed load and network parameters is also discussed. The resulting optimal tgφ levels should be considered in the tariffication process of services offered by distribution system operators to improve capacity and limit the costs of power network operation due to reactive energy transmission. [ABSTRACT FROM AUTHOR]

Theoretical research on hydraulic processes occurring in aircraft hydraulic drives is presented in the studies. Installation of angular fitting connections in aircraft pipeline systems influences hydrodynamic processes and fluid flow characteristics analysed in the research. The provided analysis is based on a validated numerical model utilizing Navier–Stokes equations and the k-epsilon turbulence model. Fluid flow inside the aircraft hydraulic drive pipeline system was investigated with flow rates up to 100 l/min. A mesh independence study was conducted for numerical simulation of the fluid flow. The obtained results include fluid pressure drops, energy losses, and operational delays associated with fluid flow vortex formations at 45° and 90° angular fitting connections. Additionally, compared results from standard methods of calculation for angular fitting connections, including the equivalent length and equivalent length same shape methods. [ABSTRACT FROM AUTHOR]

A method for refining the transmission gear ratios of vehicles by coordinating the load driving conditions with the design parameters of the transmission ensuring optimal speed and the ability to overcome road resistance is proposed. Overcoming the forces of resistance to motion is considered from the conditions of energy consumption of the vehicle. Correlations of traction and dynamic properties are obtained based on refined transmission parameters to determine the basic patterns characterizing the movement of a vehicle. The parameters are close to the values of transmission parameters, thereby ensuring maximum speed and minimum fuel consumption of the vehicle. [ABSTRACT FROM AUTHOR]

The paper refers to a new method to quantify the energy losses due to frictional effects and imperfections in contacts in the case of real industrial tribomechanical systems. Whereby energy losses represent an integral indicator of quality of the real industrial tribomechanical system, in terms of the characteristics of the contact element materials, geometric accuracy, and manufacturing and assembly errors. This paper presents a complex theoretical model based on the differential equation of motion of a real tribomechanical system down a steep plane. The outputs of the theoretical model are exact mathematical expressions that define the current values of the coefficient of friction and the friction-caused energy losses. The measuring system enables the quantification of current values of the distance traveled per unit of time. Based on a series of experimentally determined values of distance traveled per unit of time, the values of energy losses of the real industrial tribomechanical system are determined using the developed theoretical model and the appropriate software support. The obtained results indicate a high reliability, a large potential, and a wide range of possible applications of the proposed method. [ABSTRACT FROM AUTHOR]

In connection with the growing requirements regarding the quality and continuity of energy supply and the dynamic development of renewable energy sources, the need for a thorough analysis of factors affecting power and energy losses and the effectiveness of the MV network increases. One of the biggest challenges in managing power networks is the problem of load asymmetry. Load asymmetry can lead to numerous adverse phenomena, such as increased power losses, deterioration of the quality of energy supplied, and an increased risk of network failure. Despite various research on this issue, there is still a need for a more accurate understanding of mechanisms leading to the development of methods of minimizing these phenomena. The relationships describing power losses in lines and power transformers are widely known. However, most published analyzes assume the same load on each phase. If the asymmetrical load of the line already appears, such analysis is not based on the data of actual lines and applies to a homogeneous line with equal load along its entire length. Therefore, the authors decided to modify the method of calculating power losses so that they can be determined in a branched line loaded in many points, with knowledge of the current flowing into the line, its length, and the number of acceptances. This method allows for the determination of power losses in an innovative way, taking into account line load asymmetry. The use of relationships commonly available in the literature to determine power losses leads to errors of 5.54% (compared to the actual, measured losses). Taking into account both the asymmetry and multi-point loading in the method proposed by the authors allows us to limit this error to 3.91%. To estimate the impact of asymmetry on power losses in lines and power transformers, the authors performed field tests in the selected medium voltage power network. The increase in power losses determined on their basis caused by the asymmetry of the load currents obtained values from 0.03% to 4.78%. Using generally known methods of reducing asymmetry, these losses can be avoided, and therefore the energy transmission costs may be reduced, and the greenhouse gas emissions might be lowered.

This paper focuses on determining the friction energy loss in the mechanism of a mechanical crank press. After defining the crank press mechanism and how it works, we describe the energy balance of a technological operation—forming. Four distinct methodologies for calculating friction loss in the mechanism are then presented, namely an empirical method, a spreadsheet calculation utilising force decomposition in a crank mechanism, an analytical calculation of the dynamic behaviour of a press, and a multibody simulation. Each additional approach expands the possibilities for approaching reality, but as the primary aim of the study is to compare the approaches, these possibilities are not exploited. Multibody simulation has proved itself to be accurate and suitable for simulating press mechanisms and investigating their dynamics. Multibody simulation is a much more powerful tool that can lead to a digital twin, which can help us to develop a less energy-demanding press. Confirmation of the multibody simulation results is the main outcome of the comparison and will be used in future work.

In arid regions, the behavior of solar panels changes significantly compared to the datasheets provided by the manufacturer. Therefore, the objective of this study is to determine the performance of both polycrystalline and monocrystalline solar modules in an arid region characterized by a large potential for solar irradiation and high temperatures. The influence of environmental parameters, such as temperature and dust, on the output power of solar modules with different technologies (monocrystalline and polycrystalline) has been investigated. The Artificial Hummingbirds Algorithm (AHA) has been used to extract parameters for PV modules. As a result, it has been demonstrated that for high solar irradiation, the polycrystalline PV module experiences a smaller decrease in output power than the monocrystalline PV module as the module temperature increases. The percentage drop in output power is approximately 14% for the polycrystalline PV module and nearly 16% for the monocrystalline PV module. However, for low solar irradiation, it is advisable to use monocrystalline modules, as a 21% decrease in power was observed for polycrystalline modules compared to a 9% decrease for monocrystalline modules. Additionally, the monocrystalline PV module was more affected by dust than the polycrystalline PV module under high solar irradiation conditions, while under low incident solar radiation, the polycrystalline PV module was more affected by dust than the monocrystalline PV module. The power drop of the monocrystalline PV module was greater than that of the polycrystalline PV module for high solar radiation (>500 W/m2). Therefore, the advantage of this proposed work is to recommend the use of polycrystalline solar panels in regions characterized by high solar irradiation and high temperatures instead of monocrystalline solar panels, which are more efficient in regions worldwide characterized by low solar irradiation and low temperatures. [ABSTRACT FROM AUTHOR]

Mixed lead and tin (Pb/Sn) hybrid perovskites exhibit a great potential in fabricating all‐perovskite tandem devices due to their easily tunable bandgaps. However, the energy deficit and instability in Pb/Sn perovskite solar cells (PSCs) constrain their practical applications, which renders defect passivation engineering indispensable to develop highly efficient and long‐term stable PSCs. Herein, the mechanisms of strain tailoring and defect passivation in Pb/Sn PSCs by 2D ligands are investigated. The 2D ligands include electroneutral cations with long alkyl chain (LAC), iodates with relatively short alkyl chain (SAC) and their mixtures. This study reveals that LAC ligands facilitate the relaxation of tensile strain in perovskite films while SAC ligands cause strain buildup. By mixing LAC/SAC ligands, tensile strain in perovskite films can be balanced which improves solar cell performance. PSCs with admixed β‐guanidinopropionic acid (GUA)/phenethylammonium iodide (PEAI) exhibit enhanced open circuit voltage and fill factor, which is attributed to reduced nonradiative recombination losses in the bulk and at the interfaces. Furthermore, the operational stability of PSCs is slightly improved by the mixed 2D ligands. This work reveals the mechanisms of 2D ligands in strain tailoring and defect passivation toward efficient and stable narrow‐bandgap PSCs. [ABSTRACT FROM AUTHOR]

The modelling of output power for the photovoltaic system is essential for system design and local resource prediction. Accurate photovoltaic power modelling the foremost vital issue is systems efficiency analysis. The temperature plays the main role in the energy degradation of the photovoltaic systems, especially in the host sites. In this paper, experimental and theoretical investigation into the photovoltaic module energy degradation due to temperature effects. This work objectives to investigate the photovoltaic power generated due to the ambient temperature effect. The presented results show that the ambient temperature has positive effects on the photovoltaic module energy production during the winter period and negative effects during the summer period. For the proposed photovoltaic system with a capacity of 2.97 kWp the expected theoretical annual energy production by about 554.01 kWh while the annual experiment production was l493.73 kWh. The novelty of the work is to estimate the energy losses due to the ambient temperature effect on the photovoltaic energy production. [ABSTRACT FROM AUTHOR]

Due to decrease of oil reserves, the international commitment for the reduction of pollutant emissions and environmental protection, renewable energy sources are intensively studied, including solar energy applications. However, solar energy is not constant and one possible alternative are solar hybrid thermosolar power plants. A hybrid solar gas turbine has three subsystems: a solar concentrator with heliostat field and central tower receiver, a combustion chamber, and a regenerative gas turbine. A previous thermodynamic analysis allowed shows an energy and exergy study of the plant, from a thermodynamic model of the system that has a method of solar resource estimation. However, this analysis did not allow evaluation of the energy losses in the system components, although the original model considered the typical irreversibilities of these cycles. This work aimed to develop a thermodynamic model that estimates the energy losses in the subsystems and the solar hybrid gas turbine components from a few parameters. The model estimated the energy losses for a Brayton cycle hybrid solar thermal plant throughout the day July 20 in Barranquilla, Colombia. A Dymola compiler in Modelica language was used to evaluate the model, which facilitates the estimation of the results at different times of the day. In this case, the computations were performed hourly throughout the day. In the results, energy losses were 16 % in the solar concentrator when the solar resource was the maximum at noon and close to 1 % in the combustion chamber. Therefore, the hybrid solar Brayton cycle system is technically feasible and reduces fuel consumption. Consequently, it is important to continue developing concentration systems and reduce their energy losses. [ABSTRACT FROM AUTHOR]

In this study, the determinants of fossil fuel demand are investigated with the current period data in which the globalization process deepens. In the study using panel data methods, Argentina, Bangladesh, Bulgaria, Chile, China, Hungary, India, Mexico, Pakistan, Peru, Philippines, Poland, Romania, Thailand, Turkey and Ukraine economies were selected as cross-sectional units. While the share of fossil fuels in the total energy resources in the aforementioned 16 countries was 75.47% in 1990, it was 84.23% in 2018. Compared to 1990, total energy imports increased by 388.96% in the economies of the relevant countries in 2018, and a significant part of this increase is due to fossil fuel consumption. This situation can cause significant problems in terms of both current account deficit and environmental quality. In this study, the short- and long-term relationship between fossil fuel demand and economic growth, foreign direct investments, real energy prices, carbon dioxide emissions, urbanization and energy losses for the sample period of 1990-2018 is empirically examined. In the study where Pooled Mean Group (PMG), Mean Group (MG) and Dynamic Fixed Effects (DFE) estimators from panel data analysis methods are used, Hausman test is used for model choice. Empirical findings indicate that economic growth, real energy prices, foreign direct investment and urbanization reduce fossil fuel demand; On the other hand, it has been shown that carbon dioxide emissions and energy losses play an increasing role in fossil fuel demand.

Molecular engineering of organic semiconductors provides a virtually unlimited number of possible structures, yet only a handful of combinations lead to state‐of‐the‐art efficiencies in photovoltaic applications. Thus, design rules that guide material development are needed. One such design principle is that in a bulk heterojunction consisting of an electron donor and lower bandgap acceptor an offset (ΔIE) of at least 0.45 eV is required between both materials ionization energies to overcome energy level bending at the donor–acceptor interface, in turn maximizing the charge separation yield and the cell's internal quantum efficiency. The present work studies energy losses associated with ΔIE and, based on 24 blends, finds that losses are minimal up to a ΔIE of 0.6 eV. Electroluminescence spectroscopy shows that low energy losses are achieved when the charge transfer state energy (ECT) is similar to the acceptor's optical bandgap (EgA). Further ΔIE increase lowers ECT with respect to EgA, thus decreasing VOC. Within that 0.45–0.6 eV ΔIE sweet range, the fill factor FF, hence the power conversion efficiency, increases only marginally as the FF is often already close to maximal for ΔIE = 0.45 eV. The results are extended to 76 binary and ternary blends. [ABSTRACT FROM AUTHOR]

The results of experimental studies of the impact of mode parameters on power characteristics of the generator of plasma of N–O–C–H system and medium enthalpy of plasma, generated by the latter were presented. The studies were conducted in a two-electrode plasmatron with two schematic diagrams – with an automatic gas dynamic arc length stabilization and with a selfsetting arc. It is shown that all the benefi ts of using mixtures of air with a hydrocarbon gas are realized in the case of fi xing the arc length in the arc channel. The use of automatic gas dynamic arc length fi xation practically allows stabilizing the values of effi ciency throughout the whole range of changing generation mode parameters and, at the same time, eliminating the impact of effi ciency on the medium enthalpy of plasma fl ow. The transition to the system N - O (air) reduces the average level of effi ciency by 7…10 % and almost twice the value of medium enthalpy. The arsenal of means of infl uencing the mentioned parameters due to a constant composition of plasma gas reduces. The plasmotron with a self-setting arc on plasma-forming mixtures of the system N-O-C-H has by 15…20 % lower level of effi ciency values than in the case of fi xing the arc length. The medium enthalpy of plasma depends signifi cantly on the fl ow-rate and composition of plasma-forming gas. An increase in the values of medium enthalpy by an increase in the arc current leads to deterioration of power characteristics of the plasma generator. Coordination of own power characteristics of the device and parameters of plasma being generated can only be carried out only on the basis of a compromise. [ABSTRACT FROM AUTHOR]

This paper presents an optimal operation framework for electrical, gas, and thermal networks in the presence of energy hubs (EHs), so that EHs can benefit from day-ahead ancillary and energy markets. Therefore, to consider the goals of network operators (optimal operation of networks) and EHs (optimal operation in markets), the proposed model is developed in the form of a bi-level optimization. Its upper-level formulation minimizes the expected energy loss in the proposed networks based on the optimal power flow constraints and technical limits. At the lower-level problem, maximizing the expected profit of EHs in day-ahead energy and ancillary markets (including reactive and reserve regulation) is formulated based on the operational model of resources, storage devices, and responsive load in the EH framework, and the flexible constraints of EHs. This scheme includes the uncertainties of load, market price, renewable energy resources, and mobile storage energy demand, which uses the point estimation method to model them. Karush–Kuhn–Tucker is then used to extract the single-level model. Finally, by implementing the proposed scheme on a standard system, the obtained numerical results confirm the capability of the proposed model in improving the network's operation and economic status of EHs. As a result, the proposed scheme is able to decrease operation indices such as energy losses, voltage drop, and temperature drop by approximately 28.5%, 39%, and 27.8%, respectively, compared to load flow analysis. This scheme can improve the flexibility of EHs, including non-controllable sources such as renewable resources, by nearly 100% and it obtains considerable profits for hubs. [ABSTRACT FROM AUTHOR]

The relatively large non‐radiative recombination energy loss (ΔE3) is the main source of energy losses in organic solar cells (OSCs). The energetic disorder plays a crucial role in non‐radiative energy losses; however, reducing the energetic disorder by modifying terminal groups has rarely been investigated. Herein, four acceptors, BTP‐ICB1F, BTP‐ICB2F, BTP‐ICB3F, and BTP‐ICBCF3, with fluorinated phenyl terminal groups are reported at identified substitution sites. The theoretical and experimental results show that this system possesses smaller energetic disorder than the generally‐used Y6 acceptor due to the strong electron polarization effect arising from tight, 3D molecular packing. Therefore, the PM6:BTP‐ICBCF3 combination achieves high efficiency of 17.8% with high open circuit voltage (VOC) of 0.93 V and ultralow ΔE3 of 0.18 eV, which is the smallest ΔE3 for the binary OSCs with power conversion efficiency (PCEs) over 17% reported to date. Lastly, using the ternary strategy by incorporating the BTP‐ICBCF3 acceptor into PM6:BTP‐eC9, a higher PCE of 18.2% is achieved with enhanced VOC. The results imply that introducing new terminal groups in acceptors is promising for reducing energetic disorder and energy losses. [ABSTRACT FROM AUTHOR]

This investigation presents a comprehensive evaluation of an actual combined power plant in Barranquilla, Colombia, to quantify the energy losses. Data from two test campaigns were analysed to assess operational conditions and identify turbines inefficiencies. The original design of the combined power plant aimed to generate over 450000 kWh, but measurements showed a significant decrease of 3098 kWh, impacting the reliability charge of the plant. Results indicated that the plant performance varied between official tests, from 49.11% to 48.5%. The vapour turbine block was found to experience a power capacity reduction of 5240 kWh, while the gas turbine block saw an increase of approximately 2142 kWh. The evaluation showed that the relative electrical efficiency of the vapour turbine block decreased from 90.25% to 88.39%. In consequence, inefficiencies in the medium-pressure and low-pressure turbines accounted for 65.9% of the energy drop, while operational changes contributed 34.1%. The operational changes were identified between the inlet an outlet vapour turbine stage. Furthermore, it is crucial to inspect potential losses in moving crowns and losses resulting from clearance between the rotor and stage guides, as these factors may elucidate the decrease in the efficiency of the vapour turbines.