Records with Subject: Energy Systems
Showing records 1 to 25 of 9060. [First] Page: 1 2 3 4 5 Last
A Review on Flame Stabilization Technologies for UAV Engine Micro-Meso Scale Combustors: Progress and Challenges
Gurunadh Velidi, Chun Sang Yoo
May 26, 2023 (v1)
Keywords: bluff body, combustion efficiency, flame stabilization, micro channel combustion, micro combustors, premixed combustion, UAV combustor
Unmanned aerial vehicles (UAV)s have unique requirements that demand engines with high power-to-weight ratios, fuel efficiency, and reliability. As such, combustion engines used in UAVs are specialized to meet these requirements. There are several types of combustion engines used in UAVs, including reciprocating engines, turbine engines, and Wankel engines. Recent advancements in engine design, such as the use of ceramic materials and microscale combustion, have the potential to enhance engine performance and durability. This article explores the potential use of combustion-based engines, particularly microjet engines, as an alternative to electrically powered unmanned aerial vehicle (UAV) systems. It provides a review of recent developments in UAV engines and micro combustors, as well as studies on flame stabilization techniques aimed at enhancing engine performance. Heat recirculation methods have been proposed to minimize heat loss to the combustor walls. It has been demonstrated th... [more]
The Fuel Flexibility of Gas Turbines: A Review and Retrospective Outlook
Michel Molière
May 26, 2023 (v1)
Keywords: Alternative Fuels, Biofuels, combustion, fossil fuels, fuel flexibility, gas turbine, Hydrogen, low emissions
Land-based gas turbines (GTs) are continuous-flow engines that run with permanent flames once started and at stationary pressure, temperature, and flows at stabilized load. Combustors operate without any moving parts and their substantial air excess enables complete combustion. These features provide significant space for designing efficient and versatile combustion systems. In particular, as heavy-duty gas turbines have moderate compression ratios and ample stall margins, they can burn not only high- and medium-BTU fuels but also low-BTU ones. As a result, these machines have gained remarkable fuel flexibility. Dry Low Emissions combustors, which were initially confined to burning standard natural gas, have been gradually adapted to an increasing number of alternative gaseous fuels. The paper first delivers essential technical considerations that underlie this important fuel portfolio. It then reviews the spectrum of alternative GT fuels which currently extends from lean gases (coal b... [more]
State-of-the-Art Grid Stability Improvement Techniques for Electric Vehicle Fast-Charging Stations for Future Outlooks
Kabir Momoh, Shamsul Aizam Zulkifli, Petr Korba, Felix Rafael Segundo Sevilla, Arif Nur Afandi, Alfredo Velazquez-Ibañez
May 26, 2023 (v1)
Keywords: battery state of charge, electric vehicle, fast charging station, grid stability, virtual synchronous machine
The growing trend for electric vehicles (EVs) and fast-charging stations (FCSs) will cause the overloading of grids due to the high current injection from FCSs’ converters. The insensitive nature of the state of charge (SOC) of EV batteries during FCS operation often results in grid instability problems, such as voltage and frequency deviation at the point of common coupling (PCC). Therefore, many researchers have focused on two-stage converter control (TSCC) and single-stage converter (SSC) control for FCS stability enhancement, and suggested that SSC architectures are superior in performance, unlike the TSCC methods. However, only a few research works have focused on SSC techniques, despite the techniques’ ability to provide inertia and damping support through the virtual synchronous machine (VSM) strategy due to power decoupling and dynamic response problems. TSCC methods deploy current or voltage control for controlling EVs’ SOC battery charging through proportional-integral (PI),... [more]
Analysis and Design of a New High Voltage Gain Interleaved DC−DC Converter with Three-Winding Coupled Inductors for Renewable Energy Systems
Shin-Ju Chen, Sung-Pei Yang, Chao-Ming Huang, Ping-Sheng Huang
May 24, 2023 (v1)
Keywords: closed-loop controller design, high voltage gain DC–DC converter, three-winding coupled inductor, zero-current switching
In this article, a new non-isolated interleaved DC−DC converter is proposed to provide a high voltage conversion ratio in renewable energy systems. The converter configuration is composed of a two-phase interleaved boost converter integrating a voltage-lift capacitor and three-winding coupled inductor-based voltage multiplier modules to achieve high step-up voltage conversion and reduce voltage stresses on the semiconductors (switches and diodes). The converter can achieve a high voltage conversion ratio when working at a proper duty ratio. The voltage stresses on the switches are significantly lower than the output voltage, which enables engineers to adopt low-voltage-rating MOSFETs with low on-state resistance. The switches can turn on under zero-current switching (ZCS) conditions because of the leakage inductor series reducing switching losses. Some diodes can naturally turn off under ZCS conditions to alleviate the reverse−recovery issue and to reduce reverse−recovery losses. The i... [more]
Renewable Energy Potential and CO2 Performance of Main Biomasses Used in Brazil
Elem Patricia Rocha Alves, Orlando Salcedo-Puerto, Jesús Nuncira, Samuel Emebu, Clara Mendoza-Martinez
May 24, 2023 (v1)
Keywords: Biofuels, Biomass, Carbon Dioxide, Renewable and Sustainable Energy, thermochemical conversion
This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize source-related emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of for... [more]
Evaluation of an Energy Separation Device for the Efficiency Improvement of a Planar Solid Oxide Fuel Cell System with an External Reformer
Jinwon Yun, Eun-Jung Choi, Sangmin Lee, Younghyeon Kim, Sangseok Yu
May 24, 2023 (v1)
Keywords: CHP efficiency, electric efficiency, energy separation device, solid oxide fuel cell
Due to the high operating temperature of solid oxide fuel cells (SOFC), the system efficiency depends on efficient thermal integration and the effective construction of system configuration. In this study, nine configurations of system integration design were investigated to evaluate the possible improvement of system efficiency with energy separation devices. The models were developed under the Matlab/Simulink® platform with Thermolib® module. The reference layout of the simulation included an SOFC stack, a compressor, an external reformer with a burner, a three-way valve, a heat exchanger, and a water pump. From the reference case, eight cases extended layouts for the capability of thermal energy utilization with a catalytic converter, SOFC hybridization, and an energy separation device. Since the energy separation device was beneficial to thermal energy utilization via a boost to the gas temperature, electric efficiency, and combined heat and power (CHP) efficiency was improved with... [more]
Sand and Dust Storms’ Impact on the Efficiency of the Photovoltaic Modules Installed in Baghdad: A Review Study with an Empirical Investigation
Miqdam T. Chaichan, Hussein A. Kazem, Ali H. A. Al-Waeli, Kamaruzzaman Sopian, Mohammed A. Fayad, Wissam H. Alawee, Hayder A. Dhahad, Wan Nor Roslam Wan Isahak, Ahmed A. Al-Amiery
May 24, 2023 (v1)
Keywords: photovoltaic modules performance, PM1.0, PM2.5, sand and dust storms, total suspended particles
Airborne dust and dust storms are natural disasters that transport dust over long distances from the source basin, sometimes reaching hundreds of kilometers. Today, Iraq is a basin that produces dust storms that strike all neighboring countries such as Iran, Kuwait and Saudi Arabia. These storms affect the productivity and capacity of the photovoltaic modules and reduce the amount of electricity that is generated clearly. Airborne dust reduces the intensity of solar radiation by scattering and absorbing it. In addition, the dust accumulated on the photovoltaic modules causes a deterioration in their productivity. In this study, an extensive review of wind movement and its sources, especially those that hit the city of Baghdad, the capital of Iraq, was conducted. Practical experiments were also carried out during a storm to measure important variables that had not been measured practically before at this site. The experimental tests were carried out starting from 1 April 2022 and contin... [more]
Seismic Monitoring at the Farnsworth CO2-EOR Field Using Time-Lapse Elastic-Waveform Inversion of 3D-3C VSP Data
Xuejian Liu, Lianjie Huang, Kai Gao, Tom Bratton, George El-Kaseeh, William Ampomah, Robert Will, Paige Czoski, Martha Cather, Robert Balch, Brian McPherson
May 24, 2023 (v1)
Keywords: CO2 monitoring, elastic-waveform inversion, enhanced oil recovery, Farnsworth, geologic carbon storage, time-lapse seismic monitoring, vertical seismic profiling (VSP)
During the Development Phase of the U.S. Southwest Regional Partnership on Carbon Sequestration, supercritical CO2 was continuously injected into the deep oil-bearing Morrow B formation of the Farnsworth Unit in Texas for Enhanced Oil Recovery (EOR). The project injected approximately 94 kilotons of CO2 to study geologic carbon storage during CO2-EOR. A three-dimensional (3D) surface seismic dataset was acquired in 2013 to characterize the subsurface structures of the Farnsworth site. Following this data acquisition, the baseline and three time-lapse three-dimensional three-component (3D-3C) vertical seismic profiling (VSP) data were acquired at a narrower surface area surrounding the CO2 injection and oil/gas production wells between 2014 and 2017 for monitoring CO2 injection and migration. With these VSP datasets, we inverted for subsurface velocity models to quantitatively monitor the CO2 plume within the Morrow B formation. We first built 1D initial P-wave (Vp) and S-wave (Vs) velo... [more]
Hosting Capacity Estimate Based on Photovoltaic Distributed Generation Deployment: A Case Study in a Campus of the University of São Paulo
Igor Cordeiro, Welson Bassi, Ildo Luís Sauer
May 24, 2023 (v1)
Keywords: distributed generation, hosting capacity, photovoltaic, power flow, utility
Distributed generation, which is mainly deployed with PV systems that benefit economically prosumers, has soared in use in Brazil. Despite this, PV capacity in excess may cause technical issues which concern planning engineers who have adopted rules of thumb to screen interconnection requests without any detailed study. Recently, the hosting capacity concept has been employed to assess how much PV capacity a distribution grid can host without deteriorating grid parameters, reliability, or power quality. A steady-state and worst-case-based scenario was used to run deterministic power flow simulations to estimate the hosting capacity of a specific radial circuit at a campus of the University of São Paulo, referred to as “USP-105”. Although the result may be not completely accurate, it was found that USP-105 can accommodate 103% of its peak load or 4970.6 kW of PV power, which reduced the circuit’s annual peak load by 9%. Another finding was that hosting capacity increased when PV-DG depl... [more]
Clean Energy Action Index Efficiency: An Analysis in Global Uncertainty Contexts
Rui Dias, Nicole Horta, Mariana Chambino
May 24, 2023 (v1)
Keywords: clean energy, correlation, dirty energy, financial arbitrage, financial turmoil, market efficiency
Climate change, the scarcity of fossil fuels, advances in clean energy, and volatility of crude oil prices have led to the recognition of clean energy as a viable alternative to dirty energy. This paper investigates the multifractal scaling behavior and efficiency of green finance markets, as well as traditional markets such as gold, crude oil, and natural gas between 1 January 2018, and 9 March 2023. To test the serial dependency (autocorrelation) and the efficient market hypothesis, in its weak form, we employed the Lo and Mackinlay test and the DFA method. The empirical findings showed that returns data series exhibit signs of (in)efficiency. Additionally, there is a negative autocorrelation among the crude oil market, the Clean Energy Fuels Index, the Global Clean Energy Index, the gold market, and the natural gas market. Arbitration strategies can be used to obtain abnormal returns, but caution should be exercised as prices may increase above their actual market value and reduce t... [more]
Graded-Index Active Layer for Efficiency Enhancement in Polymer Solar Cell
M. A. Morsy, Khalid Saleh
May 24, 2023 (v1)
Keywords: 2D-PhC, FDTD, FF, GI-Active layer, PCE, PSC
In this paper, narrow-bandgap polymer acceptors combining a benzotriazole (BTz)-core fused-ring segment, named the PZT series, were used with a high-absorption-efficiency polymer (PBDB) compound with branched 2-butyl octyl, linear n-octyl, and methyl to be utilized as a graded-index (GI) active layer of the polymer solar cells (PSCs) to increase the photocurrent and enhance solar efficiency compared to the existing PBDB-T:PZT and PBDB-T:PZT-γ. In addition, a two-dimensional photonic crystal (2D-PhC) structure was utilized as a light-trapping anti-reflection coating (ARC) thin film based on indium tin oxide (ITO) to reduce incident light reflection and enhance its absorption. The dimensions of the cell layers were optimized to achieve the maximum power-conversion efficiency (PCE). Furthermore, the design and simulations were conducted from a 300 nm to 1200 nm wavelength range using a finite difference time-domain (FDTD) analysis. One of the most important results expected from the study... [more]
Yaw Optimisation for Wind Farm Production Maximisation Based on a Dynamic Wake Model
Zhiwen Deng, Chang Xu, Zhihong Huo, Xingxing Han, Feifei Xue
May 24, 2023 (v1)
Keywords: dynamic wake model, production maximisation, wind farm, yaw meandering
In recent years, a major focus on wind farm wake control is to maximise the production of wind farms. To improve the power generation efficiency of wind farms through wake regulation, this study investigates yaw optimisation for wind farm production maximisation from the perspective of time-varying wakes. To this end, we first deduce a simplified dynamic wake model according to the momentum conservation theory and backward difference method. The accuracy of the proposed model is verified by simulation comparisons. Then, the time lag of wake propagation and its impact on wind farm production maximisation through wake meandering is analysed. On this basis, a yaw optimisation method for increasing wind farm energy capture is presented. This optimisation method uses the proposed dynamic wake model for wind farm prediction. The results indicate that the optimisation period is critical to the effect of the optimisation method on wind farm energy capture.
The Impact of ICT Capital Services on Economic Growth and Energy Efficiency in China
Huifang E, Shuangjie Li, Liming Wang, Huidan Xue
May 24, 2023 (v1)
Keywords: economic growth decomposition framework, Energy Efficiency, ICT capital services, panel regression
This study aims to investigate the impact of ICT capital services on economic growth and energy efficiency in China at both national and industrial levels during the period 2000−2020. To achieve this aim, this study introduces a measurement method for capital services, explores ICT’s contributions to economic growth, and analyzes the impact of ICT on energy efficiency. The empirical results of this study indicate that although the ICT capital services scale is relatively small, accounting for only 8.87% of the total in 2020, its growth rate is faster than that of non-ICT capital services, and the distribution of ICT capital services varies widely among different industries. Additionally, based on the economic growth decomposition framework, this study finds that the contribution of ICT capital services to economic growth is 6.95% on average. It is significantly higher in certain industries, such as Financial industry; Information transmission, software and information technology servic... [more]
Impact on Energy Yield of Varying Turbine Designs under Conditions of Misalignment to the Current Flow
Luke Evans, Ian Ashton, Brian G. Sellar
May 24, 2023 (v1)
Keywords: acoustic doppler profiler, IEC TS 62600-200, marine renewable energy, power curve, power performance, tidal energy, tidal flow asymmetry, turbine yaw misalignment, uncertainty
Tidal energy resource characterisation using acoustic velocimetry sensors mounted on the seabed informs developers of the location and performance of a tidal energy converter (TEC). This work studies the consequences of miscalculating the established flow direction, i.e., the direction of assumed maximum energy yield. Considering data only above the proposed TEC cut-in velocities showed a difference in the estimated flow direction of up to 4°. Using a power weighted rotor average (PWRA) method to obtain the established flow direction resulted in a difference of less than 1° compared with the hub-height estimate. This study then analysed the impact of turbine alignment on annual energy production (AEP) estimates for a non-yawing tidal turbine. Three variants of horizontal axis tidal turbines, which operate in different locations of the water column, were examined; one using measured data, and the other two via modelled through power curves. During perfect alignment to the established fl... [more]
Characteristics of Fracturing Fluid Invasion Layer and Its Influence on Gas Production of Shale Gas Reservoirs
Shijun Huang, Jiaojiao Zhang, Jin Shi, Fenglan Zhao, Xianggang Duan
May 24, 2023 (v1)
Keywords: CT scan, fracturing fluid invasion layer, fracturing fluid retention, numerical simulation, shale gas reservoir
With the increase of shale gas resource exploitation in our country during recent decades, the situations of low gas production, fast production decline rate, and low flowback rate have been appearing in field production. It is an urgent problem to be solved in shale gas production and it is therefore necessary to study the interaction of the shale gas reservoir and the detained fracturing fluid. In this paper, the Longmaxi Formation shale samples of Sichuan Basin were selected for a water invasion experiment. The fracture propagation law, the water invasion front location, and the water invasion thickness of deep and shallow shale reservoirs after water invasion were compared and analyzed by CT scanning technology. Based on the analysis of the experimental mechanism, a numerical simulation model was established. The dimensionless permeability and thickness of the fracturing fluid invasion layer were introduced to analyze the positive and negative effects of fracturing fluid retention... [more]
The Influence of Pressure on Local Heat Transfer Rate under the Vapor Bubbles during Pool Boiling
Vladimir Serdyukov, Ivan Malakhov, Anton Surtaev
May 24, 2023 (v1)
Keywords: boiling, heat transfer, infrared thermography, microlayer, subatmospheric pressures
This paper presents the results of an experimental study on the evolution of a nonstationary temperature field during ethanol pool boiling in a pressure range of 12−101.2 kPa. Experimental data were obtained using infrared thermography with high temporal and spatial resolutions, which made it possible to reconstruct the distribution of the heat flux density and to study the influence of pressure reduction on the local heat transfer rate in the vicinity of the triple contact line under vapor bubbles for the first time. It is shown that, for all studied pressures, a significant heat flux density is removed from the heating surface due to microlayer evaporation, which exceeds the input heat power by a factor of 3.3−27.7, depending on the pressure. Meanwhile, the heat transfer rate in the area of the microlayer evaporation significantly decreases with the pressure reduction. In particular, the local heat flux density averaged over the microlayer area decreases by four times as the pressure... [more]
Particles Morphology of Mechanically Generated Oil Mist Mixtures of SAE 40 Grade Lubricating Oil with Diesel Oil in the Context of Explosion Risk in the Crankcase of a Marine Engine
Leszek Chybowski, Marcin Szczepanek, Katarzyna Gawdzińska, Oleh Klyus
May 24, 2023 (v1)
Keywords: crankcase explosion, laser diffraction, lubricating oil properties, mechanical spray generation, oil dilution with distillation fuel, oil mist particle distribution
This article presents research results on mechanically generated oil mists. The research was carried out for oil mixtures for the Agip/Eni Cladium 120 SAE 40 API CF oil for industrial and marine engines diluted with diesel oil Orlen Efecta Diesel Bio at diesel oil concentrations of 2%, 5%, 10%, 20%, and 50% m/m. Pure lubricating oil and pure diesel oil were also tested. Droplet size distributions were determined for the reference moment at which residual discrepancies R between the measurement data and the sprayed pure diesel oil calculation model obtained the lowest value. For mechanically generated oil mists, the light transmission coefficient through the oil mist T, the specific surface area of the oil mist SSA, and the volumetric share of drops DV(V%) for 10%, 50%, and 90% of the total volume of the generated oil mist were determined. The span of the volumetric distributions of droplet sizes SPAN, Sauter mean diameter D[3,2], De Brouckere mean diameter D[4,3], the volumetric and ma... [more]
Investigation into Pressure Appearances and Hydraulic Fracturing Roof-Cutting Technology in Mining Working Face under Residual Pillars: A Case Study
Wenda Wu, Guorui Feng, Xiuxiu Yu, Jianbiao Bai, Xiangyu Wang, Xiangzhuo Zhao
May 24, 2023 (v1)
Keywords: hydraulic fracturing, mining pressure, numerical modelling, physical model, residual pillars
Strong mining pressure disasters are prone to happen when the mining working face is under residual pillars (MWFRPs). The purpose of this study was to experimentally investigate and evaluate pressure manifestations and hydraulic fracture roof-cutting technology in the development of a working face under residual pillars using a physical model and numerical modelling tools. A scheme for hydraulic fracturing cutting technology was proposed and carried out on-site at the 31106 working face. The results show that the instability of the overlying residual pillar causes the upper thick, hard strata (THS II) to rupture and form a “T-shaped structure”. The rotation and sinking movement of the structure leads to the transmission of the dynamic load downwards, causing shear failure in the lower thick, hard strata (THS I) along the boundary of the residual pillar. The smaller the length of the THS II fracture block, the smaller the shear damage of THS I, and the lesser the mining pressure in the... [more]
Study of Supercapacitors Built in the Start-Up System of the Main Diesel Locomotive
Boris V. Malozyomov, Nikita V. Martyushev, Viktor Alekseevich Kukartsev, Vladislav Viktorovich Kukartsev, Sergei Vasilievich Tynchenko, Roman V. Klyuev, Nikolay A. Zagorodnii, Yadviga Aleksandrovna Tynchenko
May 24, 2023 (v1)
Keywords: booster converter circuit, diesel locomotive, mainline diesel locomotive start-up, Simulation, storage battery, supercapacitor
A successful guaranteed launch of a mainline diesel locomotive is one of the most important and urgent problems of the rolling stock operation. Improvement of the start-up system of the main diesel locomotive when using a supercapacitor allows multiple restarts of diesel locomotives, meaning that the operation of the diesel locomotive can be stopped several times without wasting fuel in idle operations. In this study, we simulated the electric starting circuit of a diesel locomotive with a block of supercapacitors using the Matlab Simulink program. The simulation results show that using only a supercapacitor in the start-up system is impossible. Even though the supercapacitor produces the required current and voltage, its operating time is extremely insufficient. Using a storage battery along with a supercapacitor in the diesel locomotive start-up system is most effective. This reduces the peak current load on the standard battery. The article suggests an effective principle for starti... [more]
From Hydrometeor Size Distribution Measurements to Projections of Wind Turbine Blade Leading-Edge Erosion
Fred Letson, Sara C. Pryor
May 24, 2023 (v1)
Keywords: blade reliability, droplet size distributions, erosion, hail, hydrometeors, leading-edge erosion, metrology, wind energy, wind turbines
Wind turbine blade leading-edge erosion (LEE) is a cause of increased operation and maintenance costs and decreased annual energy production. Thus, detailed, site-specific quantification of likely erosion conditions are critically needed to inform wind plant owner/operator decisions regarding mitigation strategies. Estimating the damage potential at a wind plant site requires accurate measurement of precipitation intensity, phase, droplet size distributions, wind speeds and their joint statistics. The current work quantifies the effect of disdrometer type on the characterization of LEE potential at a site in the US Southern Great Plains. using observations from three co-located disdrometers (an optical, an impact and a video disdrometer), along with hub-height wind-speed observations from a Doppler lidar and two LEE models: a kinetic energy model and the Springer model. Estimates of total kinetic energy of hydrometeor impacts over the four-year study period vary by as much as 38%, and... [more]
Advanced Active and Passive Methods in Residential Energy Efficiency
Hessam Taherian, Robert W. Peters
May 24, 2023 (v1)
Keywords: active building energy systems, ground-source heat pumps, new refrigerants, passive building energy systems, Trombe wall, vegetated roofs, white roofs
Energy efficiency in buildings is very important since it contributes significantly to fossil fuel consumption and consequently climate change. Several approaches have been taken by researchers and the industry to address the issue. These approaches are classified as either passive or active approaches. The purpose of this review article is to summarize a number of the technologies that have been investigated and/or developed. In this technical review paper, the more commonly used active and passive building energy conservation techniques are described and discussed. The pros and cons of both the active and passive energy techniques are described with appropriate reference citations provided. This review article provides a description to give an understanding of building conservation approaches. In the active classification, several methods have been reviewed that include earth-to-air heat exchangers, ground-source and hybrid heat pumps, and the use of new refrigerants, among other met... [more]
Power Transmission and Control in Microturbines’ Electronics: A Review
Ahmad Abuhaiba, Mohsen Assadi, Dimitra Apostolopoulou, Jafar Al-Zaili, Abdulnaser I. Sayma
May 24, 2023 (v1)
Keywords: control strategies, micro gas turbine, PMSM, power electronics, silicon carbide, switching frequency
When the shaft rotates in microturbines, the rotational movement is converted to electrical power. This is achieved through a permanent magnet synchronous machine (PMSM) housed on the shaft and the power electronics components. To the best of the authors’ knowledge, articles that comprehensively describe the power transmission and control in the electrical part of microturbines have yet to be introduced, namely, the PMSM and power electronics. This review paper presents a detailed review of power conversion in each component of the electrical part of microturbines. The paper also reviews the existing literature on microturbines’ electrical performance, noting areas where progress has already been made as well as those where more research is still needed. Furthermore, the paper explains the control system in the electrical part of microturbines, outlining the grid synchronisation control approach for grid-connected microturbines and reviews the possibility of employing control strategie... [more]
Energy Storage Systems for Photovoltaic and Wind Systems: A Review
Djamila Rekioua
May 24, 2023 (v1)
Keywords: Energy Storage, multi-energy storage, photovoltaic, storage, wind turbine
The study provides a study on energy storage technologies for photovoltaic and wind systems in response to the growing demand for low-carbon transportation. Energy storage systems (ESSs) have become an emerging area of renewed interest as a critical factor in renewable energy systems. The technology choice depends essentially on system requirements, cost, and performance characteristics. Common types of ESSs for renewable energy sources include electrochemical energy storage (batteries, fuel cells for hydrogen storage, and flow batteries), mechanical energy storage (including pumped hydroelectric energy storage (PHES), gravity energy storage (GES), compressed air energy storage (CAES), and flywheel energy storage), electrical energy storage (such as supercapacitor energy storage (SES), superconducting magnetic energy storage (SMES), and thermal energy storage (TES)), and hybrid or multi-storage systems that combine two or more technologies, such as integrating batteries with pumped hyd... [more]
Latest Updates of Single-Junction Organic Solar Cells up to 20% Efficiency
Boudia Mohamed El Amine, Yi Zhou, Hongying Li, Qiuwang Wang, Jun Xi, Cunlu Zhao
May 24, 2023 (v1)
Keywords: bulk-heterojunction, organic solar cells, power conversion efficiency, ternary configuration
Single-junction organic solar cells have reached a power conversion efficiency of 20% with narrow bandgap non-fullerene electron acceptor materials such as Y6, as well as with large band gap electron donor materials and their derivatives. The power conversion efficiency improvement of single-junction organic solar cells is a result of highly efficient light harvesting in the near-infrared light range and reduced energy losses with the most promising active layer layout currently available, Bulk-Heterojunction. Ternary blending is known to be the most advanced strategy to construct Bulk-Heterojunction structures in organic solar cells at present. In this review, we examine different devices based on Bulk-Heterojunction structures with efficient electron donors and acceptors. Then, we review the performance of binary and ternary organic solar cells with high power conversion efficiency, in conjunction with different anode and cathode interfaces used in recent studies of high-power conver... [more]
Prospects of Controlled Auto-Ignition Based Thermal Propulsion Units for Modern Gasoline Vehicles
Abdullah U. Bajwa, Felix C. P. Leach, Martin H. Davy
May 24, 2023 (v1)
Keywords: advanced compression ignition, dedicated hybrid engines, gasoline compression ignition, HCCI, low temperature combustion
Gasoline engines employing the spatially distributed auto-ignition combustion mode, known as controlled auto-ignition (CAI), are a prospective technology for significantly improving engine efficiency and reducing emissions. This review paper provides an overview of developments in various gasoline CAI technologies and discusses their attendant strengths and weaknesses. Hybrid propulsion systems powered by high-efficiency gasoline CAI engines can provide a low-carbon pathway for mobility sector decarbonisation. Therefore, this paper focuses on the challenges and opportunities of CAI implementation, especially for electrified powertrains. Different control actuators that can extend the CAI operating range are discussed, and opportunities for synergistic operation between thermal and electric components of hybridised powertrains are identified. Such synergies can remove impediments in the way of CAI system adoption and can, thus, support CAI adoption and maximise efficiency gains from its... [more]
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