The frequent appearance of sandy and dusty weather in Northwest China impacts the wind turbine. Meanwhile, the non-constant phenomena, dynamic stall speed during the wind turbine operation, will lead to large load fluctuations and unsafe operation. However, few studies have been conducted at home and abroad on the effect of particle parameters on the dynamic stall of airfoils. This paper investigates the impact of particle parameters on the airfoil dynamic stall through numerical simulation of the coupling between the continuous phase and discrete phase by using the SST k-ω turbulence model for a two-dimensional NACA 0012 airfoil. The effect of particle parameters on the airfoil dynamic stall aerodynamic performance, the impact of the flow field around the airfoil, and the particles motion were studied, respectively. The investigation shows a reduction in the aerodynamic performance of the airfoil, due to the addition of particles. The effect is more prominent under a large angle of at... [more]

The cryogenic carbon capture (CCC) process is a promising post-combustion CO2 removal method. This method is very novel compared with conventional and well-developed methods. However, cryogenic carbon capture is not yet commercially available despite its techno-economic benefits. Thus, a model-based design approach for this process can provide valuable information. This paper will first introduce the cryogenic carbon capture process. Then, a comprehensive literature overview that focuses on different methods for modeling the process at the component level will be given. The modelling methods which are deemed most effective are presented more in depth for each of the key system components. These methods are compared with each other in terms of complexity and accuracy and the simplest methods with an acceptable level of precision for modelling a specific component in the CCC process are recommended. Furthermore, potential research areas in modeling and simulation of the CCC process are a... [more]

The need for healthy indoor conditions, the energy crisis, and environmental concerns make building ventilation systems very important today. The elements of ventilation systems to reduce energy intensity are constantly the subject of much scientific research. The most recent articles published in the last three years are analyzed in this paper. Publications focused on the topic of reducing energy consumption in ventilation systems were selected and divided into five key research areas: (1) the aspect of the airtightness of buildings and its importance for the energy consumption, (2) the methods and effects of implementing the concept of demand-controlled ventilation in buildings with different functions, (3) the possibilities of the technical application of decentralized ventilation systems, (4) the use of earth-to-air heat exchangers, (5) the efficiency of exchangers in exhaust air heat-recovery systems. The multitude of innovative technologies and rapid technological advances are re... [more]

The large-amplitude sloshing behavior of liquid hydrogen in a tank for heavy-duty trucks may have adverse effects on the safety and stability of driving. With successful application of liquid hydrogen in the field of new energy vehicles, the coupled thermodynamic performance during liquid hydrogen large-amplitude sloshing becomes more attractive. In this paper, a three-dimensional numerical model is established to simulate the thermodynamic coupling characteristics during liquid hydrogen sloshing in a horizontal tank for heavy-duty trucks. The calculation results obtained by the developed model are in good agreement with experimental data for liquid hydrogen. Based on the established 3D model, the large-amplitude sloshing behavior of liquid hydrogen under extreme acceleration, as well as the effects of acceleration magnitude and duration on liquid hydrogen sloshing, is numerically determined. The simulation results show that under the influence of liquid hydrogen large-amplitude sloshi... [more]

Plate Heat Exchanger (PHE) and Shell and Tube Heat Exchanger (STHE) with identical heat transfer areas and material characteristics are proposed and a comparative thermal and economic comparative analysis is carried out on both exchangers. Ag-water nanofluid is used at low concentrations (0, 2.5, 5, 10 mg/L), flow rates (2, 5, and 8 L/min), and inlet temperatures (36, 46, and 56 °C) as hot flow and the heat transfer coefficient (U), electrical power consumption of the pump, and costs per unit of average U value are considered as the calculated parameters for each heat exchanger in co-current and counter-current flows. The results revealed that PHE generates a higher U value compared to the STHE under different Ag-water nanofluid concentrations. This is due to the existence of grooves on the plates of PHE which generates turbulent flow. The impact of nanofluid concentration on U is negligible for lower concentrations in both PHE and STHE. It is also found that the nanofluid flow rate ha... [more]

The use of a suitable modeling technique for the optimized design of a magnetic gear is essential to simulate its electromagnetic behavior and to predict its satisfactory performance. This paper presents the design optimization of an axial flux magnetic gear (AFMG) using a two-dimensional (2D) magnetic equivalent circuit model (MEC) and a Multi-objective Genetic Algorithm (MOGA). The proposed MEC model is configured as a meshed reluctance network (RN) with permanent magnet magnetomotive force sources. The non-linearity in the ferromagnetic materials is accounted for by the MEC. The MEC model based on reluctance networks (RN) is considered to be a good compromise between accuracy and computational effort. This new model will allow a faster analysis and design for the AFMG. A multi-objective optimization is carried out to achieve an optimal volume-focused design of the AFMG for future practical applications. The performance of the optimized model is then verified by establishing flux den... [more]

This paper investigates the design problem of an electric bus (E-bus) route with charging stations to smooth the operations between E-bus service and charging. The design variables include the locations of E-bus stops, number of charging piles at charging stations, fare, and headway. A mathematical programming model is proposed to maximize social welfare in consideration of the uncertain charging demand at charging stations. The model solution algorithm is also designed. The model and algorithm are demonstrated on the E-bus route 931 in the city of Suzhou, China. The results of the case studies show that (i) the right number of stops on a bus route can contribute to the highest social welfare; (ii) the pile−bus ratio decreases with the increase of E-bus fleet size, thereby improving the E-bus charging efficiency at charging stations; and (iii) deploying charging stations at one end of a bus route can achieve a shorter waiting time for E-bus compared with deployment at two ends.

Chemical looping gasification (CLG) technology is an effective approach to converting wood waste into high-quality syngas. In the present work, the reactivity of natural hematite is enhanced by doping with nickel oxide (NiO), and the effects of various operating parameters upon the CLG of wood waste are investigated using the NiO-modified hematite as an oxygen carrier. The NiO-modified hematite gives a significantly increased carbon conversion of 79.74%, and a valid gas yield of 0.69 m3/kg, compared to 68.13% and 0.59 m3/kg, respectively, for the pristine (natural) hematite, and 54.62% and 0.55 m3/kg, respectively, for the Al2O3, thereby indicating that the modification with NiO improves reactivity of natural hematite towards the CLG of wood waste. In addition, a suitable mass ratio of oxygen carrier to wood waste (O/W) is shown to be beneficial for the production of high-quality syngas, with a maximum valid gas yield of 0.69 m3/kg at an O/W ratio of 1. Further, an increase in reaction... [more]

The growing attention to sustainability and life cycle issues by European and international policies has recently encouraged the adoption, in the construction sector, of environmental labels able to quantify the impacts on environment associated with the fabrication of several building materials, e.g., their embodied energy and carbon. Within this framework, since walls represent a large percentage of building mass and therefore of embodied impacts, this article collects and analyzes nearly 180 Environmental Products Declarations (EPDs) of wall construction products such as masonry blocks and concrete panels. The data related to the primary energy (renewable and non-renewable) and the global warming potential extracted from the EPDs were compared firstly at the block level (choosing 1 kg as functional unit), enabling designers and manufacturers to understand and reduce the impacts from wall products at the early design stage. As the design progresses, it is therefore necessary to evalu... [more]

This study was carried out to estimate the relevance of biological supplementation in improving the economic efficiency of anaerobic digestion (AD). Three kinds of silages—maize, grass, and igniscum—were initially inoculated with digestate and then supplemented with one of four vaccines containing different bacteria species (APD®, PPT®, JENOR®) or a yeast and mold mixture (HAP®). In addition, each plant silage was fermented without any additives (control A—maize silage, B—grass silage, and C—igniscum silage). The biodegradability process was performed in batch tests at a mesophilic temperature (38 °C). To compare the energetic efficiency of AD, the process kinetics, biogas, and methane production were analyzed. We found that the applied supplementation measures improved biogas production in the case of maize and igniscum (7−62% higher than controls), but decreased the yield of AD when grass silage was fermented (2−34% lower than controls). The greatest increase in methane production (b... [more]

In recent years, boundary layer flame flashback (BLF) has re-emerged as a technological and operational issue due to the more widespread use of alternative fuels as a part of a global effort to promote carbon neutrality. While much understanding has been achieved in experiments and simulations of BLF in the past decades, the theoretical modeling of BLF still largely relies on the progress made as early as the 1940s, when the critical gradient model (CGM) for the laminar flame flashback was proposed by Lewis and von Elbe. The CGM does not account for the modification of the upstream flow by the flame, which has been recently shown to play a role in BLF. The aim of the present work is to gain additional insight into the effects of thermal gas expansion and confinement on the flame-flow interaction in laminar BLF. Two-dimensional simulations of the confined laminar BLF in a channel are performed in this work. The parametric study focuses on the channel width, the thermal gas expansion coe... [more]

The aim of this study was to assess the energy consumption of production in selected branches of the food industry in Poland and to identify its changes after Poland’s accession to the EU. This issue is particularly important in the period of energy transformation and soaring energy prices. The novelty of this article is the determination of changes in the energy efficiency of various branches of the food industry. The main source of data was mass statistics data and unpublished data from the Central Statistical Office for 2004−2020. Descriptive statistics, comparative analysis, and strategic group mapping were used in the data analysis. The research shows that the production of foodstuffs is one of the most energy-intensive processing sectors. This results, among others, from many active enterprises in this sector and a large variety of industries. Individual food-processing industries are characterized by large differences in the energy consumption of production, which determines the... [more]

This work addresses the internalization of externalities in energy decision making and in generation expansion planning (GEP). Although the linkage between externalities and energy is well recognized, the issue of the internalization in GEP models and from a sustainability perspective is still far from being fully explored. A critical literature review is presented, including scientific articles published in the period from 2011 to 2021 and selected from scientific databases according to a set of pre-defined keywords. The literature is vast and quite heterogeneous in the models and methods used to deal with these externalities, and therefore a categorization of these studies was attempted. This categorization was based on the methods used, the geographical scope, the externalities included in the planning model and the strategies for their inclusion. As a result, it was possible to perceive that most studies tend to focus on the internalization of externalities related to CO2 and equiv... [more]

This paper studies the definition and calculation method of power grid strength in the environment of high-proportion nonsynchronous-machine sources, focusing on the effect of nonsynchronous-machine sources on voltage support strength and frequency support strength. By dividing the nonsynchronous-machine sources into four types, the equivalent circuits of each type under normal state and fault state are derived, respectively. Based on the Thevenin equivalent impedance of the power grid and the equivalent impedance of the connected device, the definition and calculation method of voltage support strength is given, and the new meaning of single-infeed short-circuit ratio and multi-infeed short-circuit ratio in the context of high proportion nonsynchronous-machine sources is presented. Based on the initial frequency change rate and the steady-state frequency deviation of any node in the power grid under the maximum expected active power disturbance, the equivalent inertia lifting factor a... [more]

This study proposes an effective wind speed forecasting model combining a data processing strategy, neural network predictor, and parameter optimization method. (a) Variational mode decomposition (VMD) is adopted to decompose the wind speed data into multiple subseries where each subseries contains unique local characteristics, and all the subseries are converted into two-dimensional samples. (b) A gated recurrent unit (GRU) is sequentially modeled based on the obtained samples and makes the predictions for future wind speed. (c) The grid search with rolling cross-validation (GSRCV) is designed to simultaneously optimize the key parameters of VMD and GRU. To evaluate the effectiveness of the proposed VMD-GRU-GSRCV model, comparative experiments based on hourly wind speed data collected from the National Renewable Energy Laboratory are implemented. Numerical results show that the root mean square error, mean absolute error, mean absolute percentage error, and symmetric mean absolute per... [more]

This article investigates the impact of fiscal and financial incentives for energy efficiency labels on eco-friendly houses (houses with high energy efficiency certificates, such as A+, A, B, and B−) in 18 municipalities in the Lisbon metropolitan region during the period 2014−2020. The empirical results indicate that the variables of fiscal incentive policies for energy efficiency labels, income per capita, credit agreements for the purchase or construction of a house, and the number of completed dwellings in new constructions for family housing encourage eco-friendly houses. In contrast, the variable number of completed reconstructions per 100 completed new constructions has a negative impact. Although this study is constrained by data limitations resulting from the short period under analysis and the moderate number of municipalities available, it advances the discussions around energy efficiency in residential properties in Portugal. Furthermore, it investigates the effectiveness o... [more]

There has been so far no energo-environmental system, whose design is considered energy-wise as well as cleanliness-wise, put in practical use despite the fact that those systems would be of huge potential importance as disaster shelters for casualties and/or infectious disease patients, in particular, those of COVID-19. We have designed the energo-environmental system based on the 2-Dimensional PhotoRecepto-Conversion Scheme (2DPRCS) and Clean Unit System Platform (CUSP) technologies. We have demonstrated the energo-environmental system can be as clean as US 209D class 1000 or better, quite handily, in a couple of minutes. As for the solar-cell-based energy generation part, we have shown that the needed electric power could be generated using our original technology of the 2DPRCS by simulations, as the possible first application of casualties’ and patients’ highly clean rest-space that has monitoring ability of the status of those people including sleep assessment. This energo-environ... [more]

High-quality lighting of premises in the cultivation of farm animals is an important condition for the successful development of the agro-industrial complex. Sufficient lighting with the simulation of sunrise and sunset which increases daylight hours to 15−16 h can raise the level of production by 8−15%. The most innovative, economical and efficient light source for livestock, poultry and greenhouse buildings are LED lamps allowing for a short payback period. The difference between the models developed by the authors and the traditional point method is taking into account lamp length o, lamp suspension height, location of the illuminated area under the lamp at displacement and observation angles, and luminous flux of light source, and the most important thing is body angle of the light source. This paper presents the method for calculating illumination under the LED lamp due to the large error in the values obtained by theoretical methods due to the lack of a correction factor for chan... [more]

This paper investigates a novel controlled-temperature double-skin façade (DSF) building element. A three-dimensional time-dependent numerical model was developed for six different geometries for the investigation of thermal performance under different orientations (azimuth 0°, 90°, 180° and 270°). The boundary conditions of the numerical model were determined with the PVGIS tool and adjusted with the sol-air temperature equation. The results of the numerical simulation were validated with the use of measurements from an experimental test cell. The numerical results indicated an improved thermal performance when temperature-controlled air and flow were supplied through the building envelope with annual total energy savings in kWh/m2 of 1.99, 1.38, 2.13 and 2.06 for azimuth 0°, 90°, 180° and 270°, respectively. In regard to the total energy savings in %, the maximum benefit was considered to be in the winter season, with values of 65, 29, 80 and 28 for azimuth 0°, 90°, 180° and 270°, re... [more]

This paper presents work on a wave energy device with an on-board power take-off based on a magnetostrictively actuated deformable structure. Such devices potentially could be used in low-cost, short-term expeditionary operations. The paper discusses an analytical model that describes the heave oscillations of a buoy with two inclined, overhanging beams with magnetostrictive strips affixed to them. This work comprises the first steps toward an analytical model that would enable potential users to obtain quick power estimates at the planning stage. Here, the fully nonlinear magneto-mechanical-electrical constitutive relations are linearized about a desirable operating point, and a coupled dynamic model is derived using a variational formulation that includes buoy heave, flexural oscillations of the two beams, and the voltage response of the magnetostrictive strips. Energy conversion performance in wind-sea-dominated Pierson−Moskowitz spectra is found to be modest. However, present resul... [more]

A key focus of the Sustainable Development Goals (SDGs) is to harvest electricity from renewables. The fields of renewable energy sources (RES) and harvesting methods have seen tremendous growth. Multiport power electronic converter circuits integrate multiple energy sources. This integration aids in powering the load with different required voltage ratings. A simple and reliable control scheme for this system can maintain high power transfer efficiency and reliability. To integrate RES, non-isolated (NI) DC-DC multiport converters (MPC) are introduced; however, the main objective is to concentrate on NI MPC which provide a reliable output. In this paper non-isolated MPC topologies are reviewed and analyzed based on difference parameters considering circuit configuration; operating principal; number of components; complexity; and efficiency. This comprehensive review can be used as a guide for the suitable selection of converter topology to RES integration.

Decarbonization of urban mobility requires complex, interconnected actions. The instruments for decarbonizing urban mobility include urban collective transport, bicycles and means of personal transport, cybermobility and electromobility. The article presents the results of research on the transport behavior of the creative class, the effects of the COVID-19 pandemic on the functioning of urban mobility, and the results of research on the efficiency of electromobility in the field of the implementation of battery-powered buses. The research was aimed at a critical assessment of the current mobility model and creation of the basis for change in this area. In particular, these studies focused on changes in transport needs and greater use of cyberspace for various activities, which should reduce the volume of physical flows of people in urban transport networks. The aim of the article is to present the conclusions of these studies in terms of their use to change mobility models in cities.... [more]

The cooling with the traditional condensation method leads to huge energy consumption, while increasing attention has been paid to radiant cooling because of its characteristics of no additional energy consumption and no pollution. In order to obtain materials with higher infrared emissivity and better performance for daytime passive radiation cooling materials, the infrared emissivity of different materials was studied based on the finite-difference time-domain method. A new composite material with high emissivity has been found. The results show that the highest emissivity can reach 99.1% by adding Si3N4, Al2O3 and Fe2O3 particles with volume fractions of 6% and diameters of 50 nm into polydimethylsiloxane. This is the most excellent emissivity ever found. By combining the emitting layer made of polydimethylsiloxane mixed with nanoparticles with the reflecting layer made of Ag foil, the new film material can reach a solar transmissivity of 96.4% and a “sky window” mean emissivity of... [more]

This study proposed an isolated three-port bidirectional resonant converter that combines 2C3L and 2C2L resonant circuits for application in power dispatching. The proposed converter improves the bidirectional power dispatch capabilities of conventional three-port converters and utilizes different resonant converters to complete the energy charge−discharge through ports of different voltage levels. By modulating the frequency alone, bidirectional power regulation and electrical isolation were achieved among the three ports with different voltage levels. The converter involves the use of resonance techniques to enable the power switch to perform soft switching during bidirectional power transmissions, reducing switching loss and electromagnetic interference. The system control of the circuit was a Texas Instruments TMS320F28335 microcontroller. By simulating a DC grid port with a fixed voltage of 400 V, a vehicle battery port with a variable voltage of 280−403 V, and a battery charging... [more]

Pyrolysis has been applied in the human economy for many years, and it has become a significant alternative to the production of chemical compounds, including biofuels. The article focuses mostly on recent achievements in the technical and processing aspects of pyrolysis. The aim of the review is to present the latest research on the process of waste biomass pyrolysis to fuel production. The paper describes the mechanisms of the pyrolysis process, composition, and properties of the obtained fractions, namely pyrolysis gas, bio-oil, and biochar. Additionally, the technical aspects of the pyrolysis process are mentioned, with particular attention to the construction of the reactors. The process of waste biomass pyrolysis allows for obtaining many chemical compounds (second-generation biofuels). Optimization of the pyrolysis process allows obtaining the desired products that are applied in the chemical industry, energy, and transport. The application of pyrolysis gas, oil, and biochar as... [more]