The natatorium’s ventilation problem receives much concern because of its large wet load. The outdoor humidity ratio in transition season is the basic design parameter of the ventilation calculation, directly affecting the rationality of architectural design. At present, the ventilation-curve (V-C) method is the most widely used method to determine the outdoor humidity ratio in the transition season in China. However, due to failing to reflect non-guaranteed hours, the rationality of this value is difficult to assess by employing this approach. This paper presents a new method, the typical transition season method (TTS), for determining the outdoor humidity ratio in the transition season of a natatorium. The TTS method selects the transition season based on the typical meteorological year (TMY) data and calculates the outdoor humidity ratio with multiple non-guaranteed hours. This can well-represent the local perennial climate characteristics and clearly reflect the non-guaranteed hour... [more]

Renewable energy sources have been characterized by a persistent and rapid proliferation, which has resulted in a notable reduction in grid inertia over an extended period. There is a widely held belief that the primary source of inertia within the grid stems from generation-side conventional units. However, in power consumption, a significant number of induction motors are present, which can inherently offer rotational inertia by virtue of their kinetic energy. To investigate the influence of induction motors on grid inertia, in this paper, we propose two types of models, i.e., a detailed grid model and a dynamic equivalent model that considers multiple induction motors. Specifically, the detailed grid model with multiple induction motors is first established. However, the detailed model requires the specific parameters of induction motors, which are hard to acquire in large systems. Moreover, the accuracy of the model is unsatisfactory. To fill these gaps, the dynamic equivalent mode... [more]

Solar energy technology is now a mature and environmentally friendly solution. Long-term and credible solar radiation data are required for energy assessments of solar applications. Due to the lack of a typical year and accurate, long-term global solar radiation data for Taiwan, data for the typical meteorological year (TMY) of global solar radiation from 30 weather stations across Taiwan of the Central Weather Bureau were gathered for this study. The database for solar radiation contains data for the 15 years between 2004 and 2018, except for one (Chigu) weather station which provides data for the 12 years between 2004 and 2015, which possesses credible data quality and meets the requirements of the TMY method. The minimum and maximum TMY global radiation observed from the 30 weather stations are 3421.8 and 5479.9 MJ/m2 at the Zhuzihu (Station 2) and Tainan (Station 16) weather stations, respectively. The effects of topography, geography, and latitude on the global radiation distribut... [more]

With the development of ecological economics, energy-saving green energy chain management has been a wide concern of academia and industries. However, the relatively high cost of green investment makes manufacturers face the problem of financial constraints. On this basis, because the green level information of products is proprietary to manufacturers, manufacturers will lie about the green level of products in order to improve their profits out of the principle of profit maximization. As a result, banks cannot obtain the true green level of products, reducing the benefits of the green energy-efficient supply chain system and making the market of green products volatile. In view of this, blockchain technology is introduced in this paper to improve customer’s product green level sensitivity and obtain lower green credit interest rates from banks. In this paper, a green supply chain financing model based on blockchain technology was constructed under the condition of green information mi... [more]

The focus of this paper is to provide a comparative analysis of various common-ground converters that serve as dual-purpose power electronic interfaces. These interfaces are designed to be used in both DC and single-phase AC grids, utilizing the same terminals for both modes of operation. The idea lies in the utilization of the same semiconductors in the DC-DC and DC-AC configurations, resulting in minimal redundancy. Particular attention is focused on the comparative evaluation approach. A novel Flying Inductor (FI)-based converter was selected for experimental verification. The design example and experimental prototype of a dual-purpose DC-DC/AC power electronic converter is capable of providing 2 kVA of power in AC mode and 4 kW in DC mode. The experimental results indicate that the converter can operate in both AC and DC grids according to their respective modes. The conclusion of the study highlights the potential applications and main benefits of this technology.

Virtual synchronous generators (VSG) are considered a new generation of grid-friendly inverters with the same inertial support characteristics as synchronous generators (SG). However, the inertia support comes with the side effects of power and frequency response deterioration. The existing VSG power oscillation suppression methods have limitations such as complex controller parameter tuning, altering the frequency support characteristics, and power quality degradation. To address these issues, this paper proposes a universal VSG control strategy based on extended virtual inertia (VSG-EVI). Herein, the virtual inertia is no longer a constant or varying number; it is endowed with frequency domain characteristics to improve the VSG transient responses. Moreover, a detailed parameter design process is given in detail. Compared with the conventional VSG (CVSG), VSG-EVI significantly suppress the power and frequency oscillations. Compared with the existing VSG oscillation suppression method... [more]

Future wireless communication systems require higher performance requirements. Based on this, we study the combinatorial optimization problem of power allocation and dynamic user pairing in a downlink multicarrier non-orthogonal multiple-access (NOMA) system scenario, aiming at maximizing the user sum rate of the overall system. Due to the complex coupling of variables, it is difficult and time-consuming to obtain an optimal solution, making engineering impractical. To circumvent the difficulties and obtain a sub-optimal solution, we decompose this optimization problem into two sub-problems. First, a closed-form expression for the optimal power allocation scheme is obtained for a given subchannel allocation. Then, we provide the optimal user-pairing scheme using the actor−critic (AC) algorithm. As a promising approach to solving the exhaustive problem, deep-reinforcement learning (DRL) possesses higher learning ability and better self-adaptive capability than traditional optimization m... [more]

With the increasing attention to environmental protection and strict national standards, the production of high-quality clean gasoline is more and more required in modern refineries. At present, the molecular-level online modeling of the gasoline blending process is rarely reported due to the lack of a proper characterization method. In this study, we have developed a molecular reconstruction method based on near-infrared (NIR) spectroscopy. We established a library that comprises an NIR spectrum and molecular composition of known reformates. We developed the sample selection algorithm that finds the sample with an NIR spectrum close to the target sample. The method-solving algorithm based on multiple linear regression was used to obtain the molecular composition of gasoline quickly. The method combines online measurement methods and molecular management technology to achieve online composition reconstruction. Seventy-five groups of reformates were collected to verify the feasibility o... [more]

Chemical compatibility and cation interdiffusion between the double perovskite cobaltites RBaCo2O6−δ (R = Gd, Pr) and proton-conducting electrolyte BaZr0.8Y0.2O3−δ were studied. Chemical interaction was found to occur already at 1100 °C as a result of the partial dissolution of RBaCo2O6−δ (R = Gd, Pr) in BaZr0.8Y0.2O3−δ. Analysis of the element distribution along the cross sections of diffusion couples RBaCo2O6−δ(R = Gd, Pr)|BaZr0.8Y0.2O3−δ showed strong interdiffusion of cations, with cobalt being the most mobile one. Its diffusion depth in the electrolyte reaches up to several hundreds of micrometers. The addition of NiO as a sintering aid to BaZr0.8Y0.2O3−δ promotes cation diffusion especially through the grain boundary mechanism, increasing the diffusion depth of Co. The possible implications of cation interdiffusion on the performance of proton-conducting SOFCs are discussed based on the results obtained.

This article deals with the degrees of freedom and possible optimums, specifically with the energy optimums of the heat pump heating system. The authors developed an multi objective optimization procedure that allows for the determination of the optimal motor power for the circulation and well pumps in order to achieve the maximum COP. Upon selecting the type and size of the water-to-water heat pump, based on the heating demand of the buildings, the proper power of the circulation and well pumps must be determined. There are several procedures used for determining the pump’s power. However, none of those methods ensures the optimum power, i.e., the maximum coefficient of performance, COP of the heating system. In this study, a multi objective analytical-numerical dimensioning procedure was developed for the determination of the optimal mass flow rate of warm and well water. Based on the flow rate values, the optimum power of the circulation and well pumps can be calculated. Due to the... [more]

Calibration of the existing building simulation model is key to correctly evaluating the energy savings that are achievable through retrofit. However, calibration is a non-standard phase where different approaches can possibly lead to different models. In this study, an existing residential building is simulated in parallel by four research groups with different dynamic simulation tools. Manual/automatic methodologies and basic/detailed measurement data sets are used. The calibration is followed by a validation on two evaluation periods. Monitoring data concerning the windows opening by the occupants are used to analyze the calibration outcomes. It is found that for a good calibration of a model of a well-insulated building, the absence of data regarding the users’ behavior is more critical than uncertainty on the envelope properties. The automatic approach is more effective in managing the model complexity and reaching a better performing calibration, as the RMSE relative to indoor te... [more]

The deposition of sulfur particles in gathering and transportation pipeline system can cause serious safety problems and economic losses. When the high sulfur content natural gas (HSCNG) flows through the throttle valve of the gathering and transportation system, it will cause the supersaturation of elemental sulfur in the gas phase, and then the sulfur crystal nuclei and sulfur particles will appear in the pipeline system. Studying the initial growth behavior of sulfur crystal nuclei and sulfur particles can lay a necessary prerequisite for the accurate prediction of sulfur particle deposition in high sulfur content natural gas gathering and transportation (HSCNGGT) pipelines. Based on the homogeneous nucleation theory in crystallization kinetics, a mathematical model of elemental sulfur nucleation was established. Taking the throttling condition in the process of HSCNGGT as an example, the effects of temperature, pressure and H2S concentration in HSCNG on the critical nucleation radi... [more]

This paper aims to present the real improvement opportunities of a simple organic Rankine cycle (ORC) as waste heat recovery system (WHRS) from the exhaust gases of a natural gas engine using toluene as the working fluid, based on the exergy and environmental point of view. From the energy and exergy balances, the advanced exergetic analysis was developed to determine the irreversibilities and opportunities for improvement. Since the traditional exergo-environmental analysis, it was found that the component with the greatest potential environmental impact associated with exergy (bF = 0.067 mPts/MJ) and per unit of exergy (ḂD = 8.729 mPts/h) was the condenser, while the exergy-environmental fraction was presented in the turbine (52.51%) and pump-2 (21.12%). The advanced exergo-environmental analysis showed that the environmental impact is more associated with the operational behavior of the components, with 75.33% of the environmental impacts being of endogenous nature, showing that the... [more]

The vehicle market at the European level (and also elsewhere) has registered a high dynamic for the adoption of electric vehicles as the future means of transport. Government policies and decisions fully support this move, but there are still massive barriers to entry into the EV market due to consumer attitudes and perceptions. Consumer attitudes and perceptions will be decisive in the market success of future electric vehicle models, given that consumers are particularly interested in the vehicles’ technical and dynamic performance. The pressure from customers’ demands for performance leaves its mark not only on the increase of performance and technical parameters, but directly contributes to the generation of interdependence between these parameters. This article presents a comparative statistical analysis of 203 electric vehicle models (from various construction categories), present in the European vehicle market (between the years 2019 and 2022), to highlight the direct and indire... [more]

Methane and methanol are promising products for CO2 hydrogenation for carbon capture and utilization concepts. In the search for effective, robust, easy-to-manufacture and stable catalysts, supported metal-based catalysts have proven advantageous. Whereas nickel for methane synthesis and copper for methanol synthesis stand out as efficient and cost-effective catalytically active metals, the best choice of support material is still a matter of ongoing debate. This review discusses the potential of the alkaline earth metal oxide MgO as support material for CO2 hydrogenation catalysts. Due to its basicity, it gives access to bifunctional catalysts as it shows pronounced CO2 adsorption capacity. Whereas carbonate formation seems to be beneficial in CO2 methanation, it may even have an adverse effect in methanol synthesis from CO2.

In view of the key geological factors restricting reservoir development, the reservoir heterogeneity of an alluvial fan sandy conglomerate reservoir in the Qie12 block of Qaidam Basin, Northwest China, and its influence on remaining oil distribution, were studied according to geology, wireline logging data, and dynamic production data. This study illustrates that the difference in pore structures, which are controlled by different sedimentary fabrics, is the main cause of reservoir microscopic heterogeneity. Besides, the temporal and spatial distribution of architectural units in the alluvial fan controls reservoir macroheterogeneity. Our results show that the thick sandy conglomerate develops two types of pores, two types of permeability rhythms, two types of interlayers, two types of interlayer distribution, two types of effective sand body architecture, and four types of sand body connecting schemes. The strongest plane heterogeneity is found in the composite channel unit formed by... [more]

Theoretical line loss rate is the basic reference value of the line loss management of low-voltage grids, but it is difficult to calculate accurately because of the incomplete or abnormal line impedance and measurement parameters. The traditional algorithm will greatly reduce the number of samples that can be used for model training by discarding problematic samples, which will restrict the accuracy of model training. Therefore, an improved random forest method is proposed to calculate and analyze the theoretical line loss of low-voltage grids. According to the Influence mechanism and data samples analysis, the electrical characteristic indicator system of the theoretical line loss can be constructed, and the concept of power supply torque was proposed for the first time. Based on this, the attribute division process of decision tree model is optimized, which can improve the limitation of the high requirement of random forest on the integrity of feature data. Finally, the improved effe... [more]

This paper is the second part of the study of a planar manipulator and this section presents the construction of a prototype manipulator. A fuzzy control system for the manipulator is described in detail. An experimental study was carried out on the positioning of the end effector of the manipulator and a program written in the Delphi 6 environment was proposed to calculate the position. Prototype tests were performed for transpose and follow-up control. Based on the experimental results, a control quality analysis was carried out.

Energy systems need a complete decarbonization within the next 20−30 years, calling for the introduction of CO2-free renewable energy sources (RES). All final uses must face this challenge, now finally including the transportation sector which should mostly be electrified. This option could constitute both a challenge and an opportunity for the electric grid. In fact, connection to the grid of all electric vehicles (EVs) together with their electricity storage systems (ESSs) could reduce issues due to the nonprogrammable use of RES in electricity production; to this aim, sufficiently smart bi-directional vehicle-to-grid technologies (V2G) have to be designed and widely installed. Parallelly, electric grid capabilities must become fully bidirectional in all nodes, both physically and in terms of ICT capabilities (so-called smart grid paradigm). In the meanwhile, some of those V2G technologies may already be locally implemented in individual home contexts. Following previous research act... [more]

A new method including suspension and wheel vibration energy regeneration is proposed in this study to coordinate the contradiction between vibration energy regeneration and dynamic performance of in-wheel motor electric vehicles (IWM-EVs). The influence mechanism of unsprung mass on the dynamic characteristics of IWM-EVs is investigated from the perspective of energy flow, and potential of energy regeneration of IWM-EVs is explored on this basis. A parameter sensitivity analysis of the proposed new method is conducted, and the optimal parameters are determined for a comparative simulation analysis among focus-driven electric vehicles, IWM-EVs, and IWM-EVs with linear electromagnetic dynamic vibration absorber (LEM-DVA). Results show that the proposed new method effectively improves the dynamic performance and achieves coordination between energy regeneration and dynamic performance despite its reduction of the vibration energy regeneration potential of IWM-EVs. A new structure, which... [more]

Cutting-edge building energy management systems (BEMS) interact with heating, ventilation, air conditioning (HVAC) systems, which generally account for much of the energy consumption. Major attention is focused on the BEMS themselves, barring on-field equipment. In HVAC equipment, sub-optimal controller settings may lead to energy losses and user discomfort, for instance, due to oscillations of air temperature and fan speeds. The way to solve this problem could be to replace classical PID controllers with an alternative concept that does not require tuning and works optimally for a wide range of parameters. This paper compares a fuzzy logic controller (FLC) with a standard PID for a model-based simulation of an HVAC system in Simulink for different conditions using real building measurement data. The end result is the implementation of the developed methods in a newly designed universal control board for air handling units (AHU). The proposed FLC achieves better integral control qualit... [more]

The last Intergovernmental Panel on Climate Change (IPPC) assessment report highlighted how actions to reduce CO2 emissions have not been effective so far to achieve the 1.5 C limit and that radical measures are required. Solutions such as the upgrading of waste biomass, the power-to-X paradigm, and an innovative energy carrier such as hydrogen can make an effective contribution to the transition toward a low-carbon energy system. In this context, the aim of this study is to improve the hydrogen production process from wet residual biomass by examining the advantages of an innovative integration of anaerobic digestion with thermochemical transformation processes. Furthermore, this solution is integrated into a hybrid power supply composed of an electric grid and a photovoltaic plant (PV), supported by a thermal energy storage (TES) system. Both the performance of the plant and its input energy demand—splitting the power request between the photovoltaic system and the national grid—are... [more]

The global energy sector is in a period of transition, during which time it is expected that renewable and low-carbon energy sources, such as wind and solar, will replace traditional fossil fuels, including oil, gas, and coal. The energy transition is happening not only to limit the environmental impact of fossil fuel production and consumption but also to ensure energy security, reliability, access, affordability, and sustainability. The importance of the energy transition has been amplified by recent events, notably the Russian-Ukraine conflict. Economic, financial, and trade sanctions against Russia, and in particular its oil and gas industry, have forced countries to find new suppliers in the short term, but also to investigate new and more sustainable sources to guarantee long-term energy security. Given the importance of energy, it is perhaps not unexpected that there is a considerable body of recent academic literature, particularly over the last 4−5 years, studying what industr... [more]

Protection of the natural environment is one of the most significant global challenges for the international community. World problems arising as a result of the incineration of fossil fuels, excessive CO2 emissions, erosion and soil degradation, as well as air pollution with the accelerating greenhouse effect and changes to the climate condition, make it necessary to take action at many levels. Environmental protection and the protection of natural resources need to follow the principles of sustainable development. Looking for alternative energy sources is appropriate but not sufficient and should be conducted in various areas since natural environmental changes are accelerating with many consequences. Therefore, there is demand for implementation of applications aimed at protecting air, and soil, preventing waste formation and combating the greenhouse effect. Therefore, the multi-directional use of various biocarbon substances for activities related to renewable energy, land reclamat... [more]

In electric vehicles, currents with high-frequency ripples flow in the power cabling system due to the switching operation of power converters. Inside the cables, a strong coupling between the thermal and electromagnetic phenomena exists, since the temperature and Alternating Current (AC) density distributions in the strands affect each other. Due to the different time scales of magnetic and heat flow problems, the computational cost of Finite Element Method (FEM) numeric solvers can be excessive. This paper derives a simple analytical model to calculate the total losses of a multi-stranded cable carrying a Direct Current (DC) affected by a high-frequency ripple. The expression of the equivalent AC cable resistance at a generic frequency and temperature is derived from the general treatment of multi-stranded multi-layer windings. When employed to predict the temperature evolution in the cable, the analytical model prevents the use of complex FEM models in which multiple heat flow and m... [more]