The harmless disposal of spent cathode carbon blocks (SCCBs) has become an urgent issue in the primary aluminum industry, and the disposal of SCCBs by co-combustion in pulverized coal boilers is expected to be the most effective treatment method. A muffle furnace at 815 °C was used in this study to perform a co-combustion experiment of meager coal and SCCBs. The ash fusion characteristics (AFTs), microscopic morphology, and minerals composition of co-combustion ash were characterized. The interaction mechanism of different mineral components and the change in AFTs and viscosity-temperature characteristics were investigated using FactSage software. Results show that the change in the ash deformation temperature (DT) is correlated linearly with the SCCB addition ratio, whereas other characteristic temperatures exhibit a nonlinear relationship. The contents of SiO2, Al2O3, and Na2O collectively determine the DT in the ash, and the influence degree from high to low is in the order of SiO2,... [more]

In Poland’s largest mining district, the Upper Silesian Coal Basin, there is a growing interest in resource development by small operators. Some concession areas are not yet directly affected by the mining industry. The objects of this research are two such areas and the goal is to determine a load of heavy metals (HM) in soils prior to mining projects and to assess the extent of their contamination at this stage. The metals studied were Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn, while HM contamination was assessed using the Contamination Factor (CF), Contamination Degree (CD), Pollution Load Index (PLI), and Geoaccumulation Index (Igeo). The Ecological Risk Potential Index (ER) and Comprehensive Potential Ecological Risk Index (PERI) were also employed. The pre-mining areas are close to an area where mining was terminated before 2000. For this area, we performed the same set of analyses as for the pre-mining areas studied. HM concentration levels and pollution indices in post-mining areas ar... [more]

The effect of intrinsic metal mineral elements in the combustion process of pulverized coal on the formation and transformation mechanism of PM was investigated in a drop-tube furnace in air atmospheres at 1200 °C, which laid a solid foundation for the control of particulate pollutants. The results show that reducing the evaporation of mineral elements or the generated PM1 aggregating to form PM1−10 or particles bigger than 10µm can reduce the emission of PM1 in the coal combustion process. The amount of PM0.2, PM0.2−1, PM1−2.5 and PM2.5 produced by the raw coal-carrying Mg are reduced by 36.7%, 17.4%, 24.6% and 21.6%, respectively. The amount of PM10 is almost unchanged. The addition of Mg increases the viscosity of submicron particles effectively, making it easier to aggregate and bond together to form ultra-micron particles. The amount of PM0.2, PM0.2−1, PM1−2.5, PM2.5 and PM10 produced by the raw coal-carrying Ca are reduced by 36.3%, 33.0%, 42.8%, 38% and 17.7%, respectively. The... [more]

The article reviews the existing methods of increasing the energy efficiency of electric transport by analyzing and studying the methods of increasing the energy storage resource. It is grouped according to methods, approaches, and solutions. The most effective methods and ways of their implementation are identified. General methods of increasing energy efficiency, methods of increasing recuperation during braking, methods of energy-efficient energy consumption, the use of energy-saving technologies, and improving the energy efficiency of the traction drive are considered. The purpose of this work is to identify the main operating factors on the basis of a critical review of existing methods for assessing the technical condition of batteries and experimental results on the degradation of lithium-ion batteries. Using the great experience of the research group in the field of modeling, diagnostics, and forecasting of life of electric cars, as well as their intellectual management, the ne... [more]

The application of rapeseed oil (RO) blends with diesel fuel and/or alcohols and/or ethers is known to significantly affect the combustion process. Aiming to further investigate the effects of rapeseed oil in a blend with diethyl ether (DEE) on this process, the coefficient of variation of the mean indicated pressure (COVMIP) of a 2.5l direct injection diesel engine was calculated. The analysis of the experimental results revealed the repeatability of the combustion process variability of diesel fuel (DF), rapeseed oil (RO), and DEE/RO blends containing up to 20% DEE. In these cases, the COVMIP does not exceed 4%. Additionally, it became obvious that for a higher content of DEE in blend with RO, the cyclic repeatability of the mean indicated pressure (MIP) was reduced. Thus, the values of COVMIP for fuels containing 30 and 40% of DEE by vol. in blend with RO were even three times higher than the values obtained for the reference fuel i.e., DF. The results indicate that the increased co... [more]

Power generation using small wind turbines connected to AC grids has been gaining attention and contributions in recent years. As small wind turbines are connected to remote areas as support energy systems, there are not extensive contributions connecting those small turbines to AC grids. This paper presents the integration of a small wind generation system which is AC-grid-connected. The system is composed of a 160 W commercial small wind turbine with a permanent magnet synchronous generator and a 140 W Texas Instruments (Dallas, TX, USA) development kit devoted to connecting photovoltaic panels to AC grids. Several experimental tests were developed to characterize the devices, e.g., to obtain the power−current curves of the synchronous generator. Moreover, a mathematical model of the flyback converter is developed in detail in order to design a new converter controller. All the control capacity of the development kit is used to extract the maximum power of the synchronous generator,... [more]

An experimental study was conducted to investigate the effect of high-ratio biodiesel and pure biodiesel on the emissions and performance of Euro4-compliant vehicles. The tested fuels were diesel fuel, biodiesel with a ratio of 30% by volume (B30), biodiesel with a ratio of 50% (B50) and pure biodiesel FAME (B100), while the tested vehicle is of the Euro4-compliant standard currently available in the Indonesian market. In this study, tests on emissions, performance and fuel economy were conducted based on the international standard of the UN ECE R83-05, adopted as UN ECE R-85 and UN ECE R-101 respectively. This study also investigated the effect of the carbon-to-hydrogen ratio on the carbon balance formula. Here, the paper proposed a modified R101 carbon balance formula to calculate the fuel economy for high-ratio and pure biodiesel fuels. The results showed that biodiesel had lower CO, HC and particulate emissions, while NOx emissions were higher compared to diesel fuel. However, pure... [more]

The influence of the outer reinforcement layers on the repair structure and aerodynamic performance was studied. Firstly, a continuous damage mechanics model was established, and the 3D Hashin criterion and cohesive zone material model were used to analyze the damage repair model. The failure load deviation was 5.5%. Secondly, on the basis of the γ−Reθ transition model and SST−ω turbulence model, the aerodynamic analysis model of DU300 airfoil was established. The numerical simulation results showed that the lift coefficient and pressure distribution at the angle of attack of 10° and 15° were deviated from the experimental values by 2%. Furthermore, 27 structural repair models, nine 2D aerodynamic repair models, and a 3D full-scale blade model were designed. It was found that, when the repair length accounted for 60% of the total model length, the failure load increased by 22%, but the aerodynamic power with the repair length of 10 m was decreased by 0.137%. When the repair area was la... [more]

Contact selectivity is a key parameter for enhancing and improving the power conversion efficiency (PCE) of crystalline silicon (c-Si)-based solar cells. Carrier selective contacts (CSC) are the key technology which has the potential to achieve a higher PCE for c-Si-based solar cells closer to their theoretical efficiency limit. A recent and state-of-the-art approach in this domain is the tunnel oxide passivated contact (TOPCon) approach, which is completely different from the existing classical heterojunction solar cells. The main and core element of this contact is the tunnel oxide, and its main role is to cut back the minority carrier recombination at the interface. A state-of-the-art n-type c-Si-based TOPCon solar cell featuring a passivated rear contact was experimentally analyzed, and the highest PCE record of ~25.7% was achieved. It has a high fill factor (FF) of ~83.3%. These reported results prove that the highest efficiency potential is that of the passivated full area rear c... [more]

The household as the primary decision-making unit is founded on classical and neoclassical economics. However, household behaviour changes have been noticeable in the last decade, moving towards more green and sustainable patterns, which have been pronounced in EU countries striving for a more significant share of renewable energy sources (RES) in energy consumption. These behaviours can be attributed to sustainable economics and are an essential part of energy transformation, as they are focused on pro-ecological attitudes, considering both financial activities and those related to caring for the environment and future generations. This article aims to segment energy consumers and to determine what attitudes prevailed in the selected segments and to what extent consumers were pro-ecologically oriented when making decisions regarding RES management before the pandemic and the energy crisis outbreak in Europe. We propose a three-segment model for archetyping household energy consumers i... [more]

To become sustainable, the production of electricity has been oriented towards the adoption of local and renewable sources. Distributed electric and thermal energy generation is more suitable to avoid any possible waste, and the Micro Gas Turbine (MGT) can play a key role in this scenario. Due to the intrinsic properties and the high flexibility of operation of this energy conversion system, the exploitation of alternative fuels and the integration of the MGT itself with other energy conversion systems (solar field, ORC, fuel cells) represent one of the most effective strategies to achieve higher conversion efficiencies and to reduce emissions from power systems. The present work aims to review the results obtained by the researchers in the last years. The different technologies are analyzed in detail, both separately and under a more complete view, considering two or more solutions embedded in micro-grid configurations.

Exergy-based methods provide engineers with the best information with respect to options for improving the overall thermodynamic efficiency of an energy conversion system. This paper presents the results of an advanced exergy analysis of an air-to-water reversible heat pump whose performance was analyzed with respect to different working fluids. Environmentally deleterious refrigerants, i.e., R410A and R134a (baselines), and their eco-friendly replacements (R290, R152a, R1234ze(E), and R1234yf) were selected. The evaluations were conducted under the same operating conditions (i.e., with the same cooling and heating demands and outdoor temperatures). Based on conventional exergy analysis, it was determined that different priorities should be given for the thermodynamic improvement of the components according to which heating and cooling modes of the system are in use. Therefore, integrated parameters, i.e., the annual values of exergy destruction, were applied for further analysis. The... [more]

In a proton exchange membrane fuel cell (PEMFC) system, proper management of water and heat transport is essential to improve its overall performance and durability. To comprehensively investigate the internal processes of PEMFCs, an improved two-phase non-isothermal model based on heat and water transfer mechanisms inside the fuel cell is developed. The results show that the model proposed in this work can predict the fuel cell’s performance accurately and is capable of exploring water and heat transfer phenomena inside fuel cells. Additionally, the water and heat transfer of cathodes and anodes under different relative humidity and temperatures are studied. It can be concluded that when the PEMFC operates under a constant voltage, the anode water content gradually increases, while the cathode water content gradually decreases. The maximum water content occurs at the interface between cathode catalyst layer and cathode gas diffusion layer, while the minimum value is attained at the in... [more]

Renewable energy sources are an attractive alternative to fossil fuels for several reasons. Firstly, these are ecological arguments, mainly reducing greenhouse gas emissions. Secondly, there are legal issues, particularly the obligations of the European Community countries in the field of climate as part of the implementation of the European Green Deal and the joint achievement of 40% of energy from renewable sources by 2030. Thirdly, these are international issues, primarily regarding reducing dependence on uncertain oil or gas markets. And finally, they may be economic reasons, such as diversification of energy supplies and associated costs, as well as opportunities for profits on the capital market. In Poland, over the last decade, a certain kind of boom in photovoltaics has been visible, both in terms of the number of companies dealing with solar collectors, as well as the annual increase in new capacity, or the level of installed capacity. Also, on the Warsaw Stock Exchange, photo... [more]

The global climate protection policy aimed at achieving a zero greenhouse gas emissions target has led to the fast incorporation of large-scale photovoltaics into the power network. The conventional AC grid was not modeled to be incorporated with large-scale non-synchronous inverter-based energy resources (IBR). Incorporating inertia-free IBR into the grid leads to technical issues such as the degradation of system strength and inertia, therefore affecting the safety and reliability of the electrical power system. This research introduced a new solution to incorporate a flywheel in the rotor of a synchronous machine to improve the dynamic inertia control during a system disruption and to maintain the constancy of the system. The objective of this work is to enhance large-scale photovoltaic systems in such a way that they can avoid failures during a fault. A model of transient constancy with two synchronous generators and a LSPV is established in PowerWorld modeling software. A line-to-... [more]

In this investigation, the motion of TiO2/H2O nano-structures towards heated and porous sheets by considering the MHD effect and partial slip at the boundary is inspected. The non-linear PDEs that correspond to the basic conservation laws are converted into ODEs with the help of suitable similarity transformation. Furthermore, the shooting method is used to solve these transformed ODEs and boundary conditions. The impact of thermophoresis properties has been shown graphically and the effect of these properties on the skin friction coefficient (Cf) and Nussetl number (Nu) are given in table form. The comparison between the present exploration and published work is carried out and validation among results is prepared. The enhancement in thermophysical parameters showed contrary results to the velocity profile of the TiO2/H2O nanofluid as compared with temperature profile. Moreover, it is observed that the higher estimation in the velocity slip parameter retards the flow and an enhancemen... [more]

Fuel contamination of engine lubricating oil has been previously determined to arise from two independent phenomena: the effect on oil flash point, and the effect of changing lubrication conditions on tribological pairs. This paper combines these effects and holistically analyzes the consequences of fuel in the lubricating oil of a trunk piston engine on the risk of crankcase explosion. The author hypothesized that diesel fuel as an oil contaminant increases the risk of an explosion in the crankcase of an engine due to the independent interaction of two factors: (1) changes in the oil’s combustible properties, and (2) deterioration of the lubrication conditions of the engine’s tribological nodes, such as main bearings, piston pins, or crank bearings. An experiment was performed to evaluate the rheological, ignition, and lubrication properties of two oils (SAE 30 and SAE 40) commonly used for the recirculation lubrication of marine trunk piston engines for different levels of diesel con... [more]

The battery management system (BMS) is a core component to ensure the efficient and safe operation of electric vehicles, and the practical evaluation of key BMS functions is thus of great importance. However, the testing of a BMS with actual battery packs suffers from a poor testing repeatability and a long status transition time due to the uncontrollable degradation of battery systems and testing environment variations. In this paper, to overcome this challenge, we propose an efficient BMS testing framework that uses virtual battery packs rather than actual ones, thus enabling a rapid and accurate evaluation of a BMSs key functions. A series-connected virtual battery pack model through leveraging Copula’s method is formulated to capture the dynamics and inconsistency of individual batteries in the pack. The developed lithium iron phosphate model features low computational efforts and is experimentally validated with different dynamical profiles, implying a high-precision virtual batte... [more]

Aeroengines and heavy-duty gas turbines are the core power equipment in the field of national defense and energy. Their research and development (R&D) level and manufacturing level represent the status of a country’s heavy industry in the world. The common cooling technologies of turbine blades including impingement cooling, film cooling, effusion cooling, layer cooling, pin fin cooling, and rough ribs were introduced in this paper. With the continuous improvement of the efficiency and performance of aeroengines and gas turbines, the turbine inlet temperature increases gradually every year; turbine blades will be exposed to higher gas temperatures in the future as gas temperatures break 2000 K. In order to ensure the safe operation of turbine blades under severe super-high temperature working conditions, cooling technology must be developed emphatically. This paper first reviews the research status of turbine blade cooling technology and points out future research focuses. The developm... [more]

In this study, we produced biodiesel fuel from two vegetal sources, rapeseed oil and sunflower oil, by transesterification reaction. The study aims to evaluate the impact of type of alcohol, its concentration and the reaction time, while keeping constant the temperature and the catalyst on the yield and quality of the biodiesel. For alcohol, methanol and ethanol were used at a molar ratio with the oil from 3 to 24. Transesterification was performed at various reaction times; 20, 40, 60 and 90 min for each oil and defined alcohol:oil molar ratio. The influence of these parameters on the biodiesel yield and properties were investigated in terms of density, viscosity, heating value, flash point, elemental content, density and oxidative stability of the final product. The benefit of oxidation stabilizers, catechol and 4-allyl-2,6-dimethoxyphenol was investigated. Results demonstrate that for rapeseed oil, the optimum reaction conditions to obtain a higher yield and quality of biodiesel wer... [more]

It is of practical significance to study the multi-physical processes of solid state nuclear systems for device design, safety analysis, and operation guidance. This system generally includes three multi-physical processes: neutronics, heat transfer, and thermoelasticity. In order to analyze the multi-physical field behavior of solid state nuclear system, it is necessary to analyze the laws of neutron flux, temperature, stress, and other physical fields in the system. Aiming at this scientific goal, this paper has carried out three aspects of work: (1) Based on Galerkin’s finite element theory, the governing equations of neutronics, heat transfer, and thermoelasticity have been established; (2) a neutronics-thermal-mechanical multi-physical finite element analysis code was developed and verified based on benchmark examples and third-party software for multi-physical processes; (3) for a solid state nuclear system with a typical heat pipe cooled reactor configuration, based on the analy... [more]

Focusing on the three technical features related to the offshore wind turbine and the offshore transmission channel, eight schemes of offshore wind power transmission and their corresponding key technologies are discussed. The first technical feature describes the grid-forming capability of the offshore wind turbine; two types of wind turbines are discussed, namely, the grid-following wind turbine and the grid-forming wind turbine. The second technical feature describes the frequency characteristics of the output voltage and current of the offshore wind turbine, including DC, low-frequency AC, power-frequency AC and medium-frequency AC. The third technical feature describes the power transmission modes adopted by the offshore high-voltage main transmission channel, which are HVDC, high-voltage low-frequency AC and high-voltage power-frequency AC. Finally, the technical characteristics and maturity of the eight offshore wind power transmission schemes are reviewed, and a technical devel... [more]

Waste engine oil (WEO), as a waste resource, has not been fully exploited. Using WEO as a reductant for copper slag cleaning is quite meaningful. Fe3O4 is an important element in copper slag cleaning. So the laws of thermal cracking of WEO at different temperatures and the effect on thermal cracking of WEO in the presence of Fe3O4 were investigated. The results show that the high-temperature cracking of WEO mainly produces H2, CO, CH4, CO2, and small molecules such as C. Raising the temperature is good for the cracking of WEO. When the temperature rises from 700 °C to 1300 °C, the total amount of gases produced by cracking 700 μL of WEO increases from 177.08 mL to 1010.2 mL. At 1300 °C, the total amount of gases produced by the cracking of WEO in the presence of Fe3O4 was 1408.11 mL. The result indicates that Fe3O4 can promote the pyrolysis of waste oil. This research provides a novel approach to the clean utilization of WEO.

This study mainly discusses the implications of solar radiation profiles and changes in load with respect to base load conditions on the PV placement, size, voltage violations, and curtailment cost of PV generation in the network. The PV installation is optimized using yearly solar radiation profiles, low, medium, and high, corresponding to three different locations. The network in the study is represented as a multiphase, with provision for the installation of both single- and three-phase PV systems. For the different load changes in either one of the phases or all three phases, the optimal placement and size of PV inverters are discussed. It is indicated that with load increase in all three phases, for low solar radiation profiles, the placement and size of PVs remain non-uniform, while for medium and high solar radiation, the distribution becomes comparatively uniform throughout the network. However, with a load increase in one of the phases, for low solar radiation, optimal placeme... [more]

The application of newly available technologies in the green maritime sector is difficult due to conflicting requirements and the inter-relation of different ecological, technological and economical parameters. The governments incentivize radical reductions in harmful emissions as an overall priority. If the politics do not change, the continuous implementation of stricter government regulations for reducing emissions will eventually result in the mandatory use of, what we currently consider, alternative fuels. Immediate application of radically different strategies would significantly increase the economic costs of maritime transport, thus jeopardizing its greatest benefit: the transport of massive quantities of freight at the lowest cost. Increased maritime transport costs would immediately disrupt the global economy, as seen recently during the COVID-19 pandemic. For this reason, the industry has shifted towards a gradual decrease in emissions through the implementation of “better”... [more]