Records Added in March 2023
Records added in March 2023
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Showing records 1 to 25 of 12968. [First] Page: 1 2 3 4 5 Last
Performance Improvement of PWM Control Methods for Voltage Step-Down in Series Resonant DC−DC Converters
Vadim Sidorov, Andrii Chub, Dmitri Vinnikov
March 31, 2023 (v1)
Keywords: DC microgrid, DC–DC, PWM, series resonant converter, soft switching
The paper is focused on galvanically isolated series resonant DC−DC converters (SRCs) with a low quality factor of the resonant tank. These converters provide input voltage regulation at fixed switching frequency and good power density. Different modulation methods at the fixed switching frequency enable the implementation of the voltage buck functionality in these converters. The SRC under study is considered as a step-up front-end DC−DC converter for the integration of renewable energy sources in DC microgrids. The paper evaluates the voltage buck performance of the SRC achieved by using different pulse-width modulation (PWM) methods including conventional PWM and shifted PWM. Moreover, the new PWM methods, i.e., the hybrid shifted PWM (HSPWM), improved shifted PWM (ISPWM), and hybrid PWM (HPWM), are proposed to overcome the disadvantages of the existing methods. They improve the power conversion efficiency in the buck mode by reducing the power losses in the semiconductor switches a... [more]
Schedule Optimization in a Smart Microgrid Considering Demand Response Constraints
Julian Garcia-Guarin, David Alvarez, Arturo Bretas, Sergio Rivera
March 31, 2023 (v1)
Keywords: 0-1 knapsack problem, load shedding, optimization of energy demand supply, smart microgrid scheduling
Smart microgrids (SMGs) may face energy rationing due to unavailability of energy resources. Demand response (DR) in SMGs is useful not only in emergencies, since load cuts might be planned with a reduction in consumption but also in normal operation. SMG energy resources include storage systems, dispatchable units, and resources with uncertainty, such as residential demand, renewable generation, electric vehicle traffic, and electricity markets. An aggregator can optimize the scheduling of these resources, however, load demand can completely curtail until being neglected to increase the profits. The DR function (DRF) is developed as a constraint of minimum size to supply the demand and contributes solving of the 0-1 knapsack problem (KP), which involves a combinatorial optimization. The 0-1 KP stores limited energy capacity and is successful in disconnecting loads. Both constraints, the 0-1 KP and DRF, are compared in the ranking index, load reduction percentage, and execution time. B... [more]
Multi-Rate Real-Time Simulation Method Based on the Norton Equivalent
Junjie Zhu, Bingda Zhang
March 31, 2023 (v1)
Keywords: extrapolation method, ideal source equivalent, increment, multi-rate real-time simulation, Norton equivalent
For the problem of poor accuracy of the existing multi-rate simulation methods, this paper proposes a multi-rate real-time simulation method based on the Norton equivalent, compared with multi-rate simulation method based on the ideal source equivalent. After the Norton equivalence of the fast subsystem and the slow subsystem are established, they are solved simultaneously at the junction nodes. In order to reduce the amount of the simulation calculation, the Norton equivalent circuit is obtained by incremental calculation. The data interaction between the fast subsystem and the slow subsystem is realized by extrapolation method. For ensuring the real-time performance of the simulation, the method of the slow subsystem calculates ahead of the fast subsystem is given for the slow subsystem with a large amount of calculation. Finally, the AC/DC hybrid power system was simulated on the real-time simulation platform (FPGA-based Real-Time Digital Solver, FRTDS), and the simulation results w... [more]
Pattern Recognition of DC Partial Discharge on XLPE Cable Based on ADAM-DBN
Zhe Li, Yongpeng Xu, Xiuchen Jiang
March 31, 2023 (v1)
Keywords: adaptive moment estimation (ADAM), DC cross linked polyethylene (XLPE) cable, deep belief network (DBN), partial discharge (PD), restricted Boltzmann machines (RBM)
Pattern recognition of DC partial discharge (PD) receives plenty of attention and recent researches mainly focus on the static characteristics of PD signals. In order to improve the recognition accuracy of DC cable and extract information from PD waveforms, a modified deep belief network (DBN) supervised fine-tuned by the adaptive moment estimation (ADAM) algorithm is proposed to recognize the four typical insulation defects of DC cable according to the PD pulse waveforms. Moreover, the effect of the training sample set size on recognition accuracy is analyzed. Compared with naive Bayes (NB), K-nearest neighbor (KNN), support vector machine (SVM), and back propagation neural networks (BPNN), the ADAM-DBN method has higher accuracy on four different defect types due to the excellent ability in terms of the feature extraction of PD pulse waveforms. Moreover, the increase of training sample set size would lead to the increase of recognition accuracy within a certain range.
Design Space Exploration of Turbulent Multiphase Flows Using Machine Learning-Based Surrogate Model
Himakar Ganti, Manu Kamin, Prashant Khare
March 31, 2023 (v1)
Keywords: gaussian processes, large eddy simulation (LES), Machine Learning, turbulent multiphase flows
This study focuses on establishing a surrogate model based on machine learning techniques to predict the time-averaged spatially distributed behaviors of vaporizing liquid jets in turbulent air crossflow for momentum flux ratios between 5 and 120. This surrogate model extends a previously developed Gaussian-process-based framework applicable to laminar flows to accommodate turbulent flows and demonstrates that in addition to detailed fields of primitive variables, second-order turbulence statistics can also be predicted using machine learning techniques. The framework proceeds in 3 steps—(1) design of experiment studies to identify training points and conducting high-fidelity calculations to build the training dataset; (2) Gaussian process regression (supervised training) for the range of operating conditions under consideration for gaseous and dispersed phase quantities; and (3) error quantification of the surrogate model by comparing the machine learning predictions with the truth mo... [more]
Power-Optimized Sinusoidal Piston Motion and Its Performance Gain for an Alpha-Type Stirling Engine with Limited Regeneration
Mathias Scheunert, Robin Masser, Abdellah Khodja, Raphael Paul, Karsten Schwalbe, Andreas Fischer, Karl Heinz Hoffmann
March 31, 2023 (v1)
Keywords: efficiency, endoreversible thermodynamics, irreversibility, Optimization, piston motion optimization, power, stirling engine
The recuperation of otherwise lost waste heat provides a formidable way to decrease the primary energy consumption of many technical systems. A possible route to achieve that goal is through the use of Stirling engines, which have shown to be reliable and efficient devices. One can increase their performance by optimizing the piston motion. Here, it is investigated to which extent the cycle averaged power output can be increased by using a special class of adjustable sinusoidal motions (the AS class). In particular the influence of the regeneration effectiveness on the piston motion is examined. It turns out that with the optimized piston motion one can achieve performance gains for the power output of up to 50% depending on the loss mechanisms involved. A remarkable result is that the power output does not depend strongly on the limitations of the regenerator, in fact—depending on the loss terms—the influence of the regenerator practically vanishes.
Circuit-Based Electrothermal Simulation of Multicellular SiC Power MOSFETs Using FANTASTIC
Vincenzo d’Alessandro, Lorenzo Codecasa, Antonio Pio Catalano, Ciro Scognamillo
March 31, 2023 (v1)
Keywords: electrothermal (ET) simulation, finite-element method (FEM), model-order reduction (MOR), multicellular power MOSFET, silicon carbide (SiC)
This paper discusses the benefits of an advanced highly-efficient approach to static and dynamic electrothermal simulations of multicellular silicon carbide (SiC) power MOSFETs. The strategy is based on a fully circuital representation of the device, which is discretized into an assigned number of individual cells, high enough to analyze temperature and current nonuniformities over the active area. The cells are described with subcircuits implementing a simple transistor model that accounts for the utmost influence of the traps at the SiC/SiO2 interface. The power-temperature feedback is emulated with an equivalent network corresponding to a compact thermal model automatically generated by the FANTASTIC tool from an accurate 3D mesh of the component under test. The resulting macrocircuit can be solved by any SPICE-like simulation program with low computational burden and rare occurrence of convergence issues.
Development of a Variable Valve Actuation Control to Improve Diesel Oxidation Catalyst Efficiency and Emissions in a Light Duty Diesel Engine
José R. Serrano, Francisco J. Arnau, Jaime Martín, Ángel Auñón
March 31, 2023 (v1)
Keywords: aftertreatment thermal management, diesel engine emissions, light-duty diesel engine, light-off temperature, one- dimensional model, variable valve actuation, variable valve timing, world harmonized light-duty vehicle test procedure
Growing interest has arisen to adopt Variable Valve Timing (VVT) technology for automotive engines due to the need to fulfill the pollutant emission regulations. Several VVT strategies, such as the exhaust re-opening and the late exhaust closing, can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount. In this study, a one-dimensional gas dynamics engine model has been used to simulate several VVT strategies and develop a control system to actuate over the valves timing in order to increase diesel oxidation catalyst efficiency and reduce the exhaust pollutant emissions. A transient operating conditions comparison, taking the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC) as a reference, has been done by analyzing fuel economy, HC and CO pollutant emissions levels. The results conclude that the combination of an early exhaust and a late intake valve events leads to a 20% reduction in CO emissions with a fuel penal... [more]
Investigation of the Possibilities to Improve Hydrodynamic Performances of Micro-Hydrokinetic Turbines
Marina Barbarić, Zvonimir Guzović
March 31, 2023 (v1)
Keywords: diffuser augmented turbine, hydrokinetic turbine, hydropower, optimization based design, power augmentation, shrouded turbine
Horizontal axis turbines are commonly used for harnessing renewable hydrokinetic energy, contained in marine and river currents. In order to encourage the expansion of electricity generation using micro-hydrokinetic turbines, several design improvements are investigated. Firstly, optimization-based design of rotor blade is used to get as close as possible to the efficiency limit of 59.3% (known as Betz limit), that counts for bare turbine rotors, placed in the free flow. Additional diffuser elements are further added to examine the potential to overcome the theoretical efficiency limit by accelerating water at the axial direction. Various diffuser geometrical configurations are investigated using the computational fluid dynamics (CFD) to obtain insight into hydrodynamics of augmented micro-hydrokinetic turbines. Moreover, the turbines are compared from the energy conversion efficiency point of view. The highest maximum power coefficient increase of 81% is obtained with brimmed (flanged... [more]
Classification of Coal Structure Combinations and Their Influence on Hydraulic Fracturing: A Case Study from the Qinshui Basin, China
Du Liu, Yanbin Wang, Xiaoming Ni, Chuanqi Tao, Jingjing Fan, Xiang Wu, Shihu Zhao
March 31, 2023 (v1)
Keywords: coal structure combinations, fracturing curves, fracturing effect, Shizhuangnan Block
Coal structure directly correlates to permeability and hydraulic fracturing effects. Underground coal mining indicates that a single coal section generally contains multiple coal structures in superposition, making how to recognise the coal structure combination and predict its influence on coal permeability a challenging problem. Based on well-drilling sampled cores, the geological strength index (GSI), and well-logging data, the DEN, GR, CALX, and CALY were selected to establish a model to predict GSI by multiple regression to identify coal structure from 100 coalbed methane wells. Based on fitting GSI and corresponding permeability test values, injection fall-off (IFO) testing, and hydraulic fracturing results, permeability prediction models for pre- and post-fracturing behaviour were established, respectively. The fracturing effect was evaluated by the difference in permeability. The results show that a reservoir can be classified into one of nine types by different coal structure... [more]
Reduction in the Fluctuating Load on Wind Turbines by Using a Combined Nacelle Acceleration Feedback and Lidar-Based Feedforward Control
Atsushi Yamaguchi, Iman Yousefi, Takeshi Ishihara
March 31, 2023 (v1)
Keywords: combination of feedback and feedforward control, fluctuating load reduction, lidar-based feedforward control, nacelle acceleration feedback control, wind turbine control
An advanced pitch controller is proposed for the load mitigation of wind turbines. This study focuses on the nacelle acceleration feedback control and lidar-based feedforward control, and discusses how these controllers contribute to reduce the load on wind turbines. The nacelle acceleration feedback control increases the damping ratio of the first mode of wind turbines, but it also increases the fluctuation in the rotor speed and thrust force, which results in the optimum gain value. The lidar-based feedforward control reduces the fluctuation in the rotor speed and the thrust force by decreasing the fluctuating wind load on the rotor, which reduces the fluctuating load on the tower. The combination of the nacelle acceleration feedback control and the lidar-based feedforward control successfully reduces both the response of the tower first mode and the fluctuation in the rotor speed at the same time.
Experimental Investigation of the Hydrate-Based Gas Separation of Synthetic Flue Gas with 5A Zeolite
Xiaoya Zang, Na Zhang, Xuebing Zhou, Lihua Wan, Deqing Liang
March 31, 2023 (v1)
Subject: Environment
Keywords: 5A zeolite, CO2 separation, flue gas, hydrate
Coal combustion flue gas contains CO2, a greenhouse gas and driver of climate change. Therefore, CO2 separation and removal is necessary. Fortunately, 5A zeolites are highly porous and can be used as a CO2 adsorbent. In addition, they act as nuclei for hydrate formation. In this work, a composite technology, based on the physical adsorption of CO2 by 5A zeolite and hydrate-based gas separation, was used to separate CO2/N2 gas mixtures. The influence of water content, temperature, pressure, and particle size on gas adsorption and CO2 separation was studied, revealing that the CO2 separation ability of zeolite particles sized 150−180 μm was better than that of those sized 380−830 μm at 271.2 K and 273.2 K. When the zeolite particles were 150−180 μm (type-B zeolite) with a water content of 35.3%, the gas consumption per mole of water (ngas/nH2O ) reached the maximum, 0.048, and the CO2 separation ratio reached 14.30%. The CO2 molar concentration in the remaining gas phase (xCO2gas) was lo... [more]
Mitigation of Over-Frequency through Optimal Allocation of BESS in a Low-Inertia Power System
Nahid-Al Masood, Md. Nahid Haque Shazon, Hasin Mussayab Ahmed, Shohana Rahman Deeba
March 31, 2023 (v1)
Keywords: battery energy storage system, frequency response, low-inertia power system, over-frequency, voltage stability
The primary objective of this paper is to alleviate the over-frequency problem in low-inertia power systems through optimal allocation of a Battery Energy Storage System (BESS). With prolific integration of wind power, conventional fossil-fuel driven synchronous generators are being replaced in the generation fleet. Variable speed wind machines are connected to the grid via power electronics converters. As such, these machines usually do not participate in frequency regulation. During high wind penetration, a generation-rich zone of an interconnected power system may face significant over-frequency following the loss of interconnection. If the frequency goes above a certain threshold, an Over-Frequency Generator Shedding (OFGS) scheme is activated. This may cause considerable amount of generation cut in a low-inertia power system. To address this challenge, this paper develops a siting and sizing methodology of frequency-responsive BESS to simultaneously maintain frequency and voltage... [more]
Effect of Conical Strip Inserts and ZrO2/DI-Water Nanofluid on Heat Transfer Augmentation: An Experimental Study
Mohamed Iqbal Shajahan, Jee Joe Michael, M. Arulprakasajothi, Sivan Suresh, Emad Abouel Nasr, H. M. A. Hussein
March 31, 2023 (v1)
Subject: Materials
Keywords: friction factor, laminar flow regime, nanofluid, Nusselt number, staggered conical strip insert, swirl flow, thermal hydraulic performance, thermal performance factor, twist ratio
There is a significant enhancement of the heat transfer rate with the usage of nanofluid. This article describes a study of the combination of using nanofluid with inserts, which has proved itself in attaining higher benefits in a heat exchanger, such as the radiator in automobiles, industries, etc. Nanofluids are emerging as alternative fluids for heat transfer applications due to enhanced thermal properties. In this paper, the thermal hydraulic performance of ZrO2, awater-based nanofluid with various volume concentrations of 0.1%, 0.25%, and 0.5%, and staggered conical strip inserts with three different twist ratios of 2.5, 3.5, and 4.5 in forward and backward flow patterns were experimentally tested under a fully developed laminar flow regime of 0−50 lphthrough a horizontal test pipe section with a length of 1 m with a constant wall heat flux of 280 W as the input boundary condition. The temperatures at equidistant position and across the test section were measured using K-type ther... [more]
Catalytic Properties and Recycling of NiFe2O4 Catalyst for Hydrogen Production by Supercritical Water Gasification of Eucalyptus Wood Chips
Ane Caroline Pereira Borges, Jude Azubuike Onwudili, Heloysa Andrade, Carine Alves, Andrew Ingram, Silvio Vieira de Melo, Ednildo Torres
March 31, 2023 (v1)
Keywords: catalytic gasification, hydrogen production, nickel iron oxide, recycling tests, supercritical water
Nickel iron oxide (NiFe2O4) catalyst was prepared by the combustion reaction method and characterized by XRD, N2 adsorption/desorption, thermogravimetric analysis (TG), and temperature programmed reduction (TPR). The catalyst presented a mixture of oxides, including the NiFe2O4 spinel and specific surface area of 32.4 m2 g−1. The effect of NiFe2O4 catalyst on the supercritical water gasification (SCWG) of eucalyptus wood chips was studied in a batch reactor at 450 and 500 °C without catalyst and with 1.0 g and 2.0 g of catalyst and 2.0 g of biomass for 60 min. In addition, the recyclability of the catalyst under the operating conditions was also tested using recovered and recalcined catalysts over three reaction cycles. The highest amount of H2 was 25 mol% obtained at 450 °C, using 2 g of NiFe2O4 catalyst. The H2 mol% was enhanced by 45% when compared to the non-catalytic test, showing the catalytic activity of NiFe2O4 catalyst in the WGS and the steam reforming reactions. After the th... [more]
Saccharification Yield through Enzymatic Hydrolysis of the Steam-Exploded Pinewood
Merve Nazli Borand, Asli Isler Kaya, Filiz Karaosmanoglu
March 31, 2023 (v1)
Subject: Materials
Keywords: enzymatic hydrolysis, high-performance liquid chromatography (HPLC) analysis, hydrothermal pretreatment, lignocellulosic biomass, sugar yield
Pressure, temperature, and retention time are the most studied parameters in steam explosion pretreatment. However, this work aimed to fix these parameters and to evaluate the influences of several less investigated steam explosion parameters on the saccharification yield in hydrolysis. In this study, firstly, pinewood samples smaller than 200 µm were treated with steam explosion at 190 °C for 10 min. The variable parameters were biomass loading, N2 pressure, and release time. Steam-exploded samples were hydrolyzed with the Trichoderma reesei enzyme for saccharification for 72 h. The sugar content of the resultant products was analyzed to estimate the yield of sugars (such as glucose, xylose, galactose, mannose, and arabinose). The best glucose yield in the pulp was achieved with 4 g of sample, N2 pressure of 0.44 MPa, and short release time (22 s). These conditions gave a glucose yield of 97.72% in the pulp, and the xylose, mannose, galactose, and arabinose yields in the liquid fracti... [more]
A New Cross-Correlation Algorithm Based on Distance for Improving Localization Accuracy of Partial Discharge in Cables Lines
Xianjie Rao, Kai Zhou, Yuan Li, Guangya Zhu, Pengfei Meng
March 31, 2023 (v1)
Keywords: cross-correlation function, localization accuracy, partial discharge location, power cable
Locating the partial discharge (PD) source is one of the most effective means to locate local defects in power cable lines. The sampling rate and the frequency-dependent characteristic of phase velocity have an obvious influence on localization accuracy based on the times of arrival (TOA) evaluation algorithm. In this paper, we present a cross-correlation algorithm based on propagation distance to locate the PD source in cable lines. First, we introduce the basic principle of the cross-correlation function of propagation distance. Then we verify the proposed method through a computer simulation model and investigate the influences of propagation distance, sampling rate, and noise on localization accuracy. Finally, we perform PD location experiments on two 250 m 10 kV XLPE power cables using the oscillation wave test system. The simulation and experiment results indicate that compared with traditional TOA evaluation methods, the proposed method has superior locating precision.
Demonstration Study of Voltage Control of DC Grid Using Energy Management System Based DC Applications
Juyong Kim, Hongjoo Kim, Jintae Cho, Youngpyo Cho, Yoonsung Cho, Sukcheol Kim
March 31, 2023 (v1)
Keywords: DC applications, DC network, energy management system, network analysis, voltage control
This paper is about the development of the real-time direct current (DC) network analysis applications for the operation of DC power systems. The applications are located in the central energy management system (EMS) and provide the operator with the optimal solution for operation in real time. Developed DC applications are not limited by voltage level. Applications can be used at all DC voltage levels such as low voltage, medium voltage and high voltage. A program configuration and sequence for analyzing the DC distribution system are suggested. Algorithms of each program are presented and the differences when compared with the processes of the applications of the existing alternating current (AC) systems are analyzed. The DC grid demonstration site at the Korea Electric Power Corporation (KEPCO) power testing center is introduced. The details of EMS and applications installation are described. The developed DC applications were installed in the EMS of the demonstration site and verif... [more]
Text Analysis Reveals Major Trends in Exploration Geophysics
Timofey Eltsov, Maxim Yutkin, Tadeusz W. Patzek
March 31, 2023 (v1)
Subject: Other
Keywords: data analysis, data mining, SEG proceedings, text mining, web data analysis, word analysis
Evolution of professional language reveals advances in geophysics: researchers enthusiastically describe new methods of surveying, data processing techniques, and objects of their study. Geophysicists publish their cutting-edge research in the proceedings of international conferences to share their achievements with the world. Tracking changes in the professional language allows one to identify trends and current state of science. Here, we explain our text analysis of the last 30 annual conferences organized by the Society of Exploration Geophysicists (SEG). These conferences are among the largest geophysical gatherings worldwide. We split the 21,864 SEG articles into 52 million words and phrases, and analyze changes in their usage frequency over time. For example, we find that in 2019, the phrase “neural network” was used more often than “field data.” The word “shale” became less commonly used, but the term “unconventional” grew in frequency. An analysis of conference materials and me... [more]
Inelastic Material Models of Type 316H for Elevated Temperature Design of Advanced High Temperature Reactors
Gyeong-Hoi Koo, Ji-Hyun Yoon
March 31, 2023 (v1)
Subject: Materials
Keywords: elasto-plastic, elevated temperature, inelastic material model, isotropic hardening, kinematic hardening, material parameter, nuclear power, Type 316H, viscoplastic
In this paper, the inelastic material models for Type 316H stainless steel, which is one of the principal candidate materials for elevated temperature design of the advanced high temperature reactors (HTRs) pressure retained components, are investigated and the required material parameters are identified to be used for both elasto-plastic models and unified viscoplastic models. In the constitutive equations of the inelastic material models, the kinematic hardening behavior is expressed with the Chaboche model with three backstresses, and the isotropic hardening behavior is expressed by the Voce model. The required number of material parameters is minimized to be ten in total. For the unified viscoplastic model, which can express both the time-independent plastic behavior and the time-dependent viscous behavior, the constitutive equations have the same kinematic and isotropic hardening parameters of the elasto-plastic material model with two additional viscous parameters. To identify th... [more]
Degradation Mechanism Due to Water Ingress Effect on the Top Contact of Cu(In,Ga)Se2 Solar Cells
Deewakar Poudel, Shankar Karki, Benjamin Belfore, Grace Rajan, Sushma Swaraj Atluri, Sina Soltanmohammad, Angus Rockett, Sylvain Marsillac
March 31, 2023 (v1)
Keywords: alkali, CIGS, corrosion, ITO
The impact of moisture ingress on the surface of copper indium gallium diselenide (CIGS) solar cells was studied. While industry-scale modules are encapsulated in specialized polymers and glass, over time, the glass can break and the encapsulant can degrade. During such conditions, water can potentially degrade the interior layers and decrease performance. The first layer the water will come in contact with is the transparent conductive oxide (TCO) layer. To simulate the impact of this moisture ingress, complete devices were immersed in deionized water. To identify the potential sources of degradation, a common window layer for CIGS devices—a bilayer of intrinsic zinc oxide (i-ZnO) and conductive indium tin oxide (ITO)—was deposited. The thin films were then analyzed both pre and post water soaking. To determine the extent of ingress, dynamic secondary ion mass spectroscopy (SIMS) was performed on completed devices to analyze impurity diffusion (predominantly sodium and potassium) in t... [more]
The Spectrum of Proactive, Resilient Multi-Microgrid Scheduling: A Systematic Literature Review
Michael H. Spiegel, Eric M. S. P. Veith, Thomas I. Strasser
March 31, 2023 (v1)
Keywords: asset scheduling, fault mitigation, microgrid, multi-microgrid, networked microgrid, proactive scheduling, resilience, systematic review
Multi-microgrids address the need for a resilient, sustainable, and cost-effective electricity supply by providing a coordinated operation of individual networks. Due to local generation, dynamic network topologies, and islanding capabilities of hosted microgrids or groups thereof, various new fault mitigation and optimization options emerge. However, with the great flexibility, new challenges such as complex failure modes that need to be considered for a resilient operation, appear. This work systematically reviews scheduling approaches which significantly influence the feasibility of mitigation options before a failure is encountered. An in-depth analysis of identified key contributions covers aspects such as the mathematical apparatus, failure models and validation to highlight the current methodical spectrum and to identify future perspectives. Despite the common optimization-based framework, a broad variety of scheduling approaches is revealed. However, none of the key contributio... [more]
Synergistic Co-Digestion of Microalgae and Primary Sludge to Enhance Methane Yield from Temperature-Phased Anaerobic Digestion
Mekdimu Mezemir Damtie, Jingyeong Shin, Hyun Min Jang, Young Mo Kim
March 31, 2023 (v1)
Keywords: anaerobic digestion, biological pretreatment, co-digestion, methane yield, microalgae, primary sludge
A two-stage temperature-phased mesophilic anaerobic digestion assay was carried out to study the interaction between various biological pretreatment conditions and the possible synergistic co-digestion of microalgae and primary sludge. The study of growth kinetics of the biochemical methane potential test revealed that a maximum of 36% increase in methane yield was observed from co-digestion of a substrate pretreated by thermophilic aerobic conditions (55 °C and HRT = 2 days) and an 8.3% increase was obtained from the anaerobic pretreated substrate (55 °C and HRT = 3 days). Moreover, no synergistic effects on methane yields were observed in co-digesting the substrate pretreated with high temperature (85 °C). The study also identified specific conditions in which interaction between biological pretreatment and co-digestion might substantially reduce methane yield. Careful optimization of operating conditions, both aerobic and anaerobic pretreatment at moderate thermophilic conditions, c... [more]
Process Simulation for Li-MnO2 Primary Battery Recycling: Cryo-Mechanical and Hydrometallurgical Treatments at Pilot Scale
Pier Giorgio Schiavi, Ludovica Baldassari, Pietro Altimari, Emanuela Moscardini, Luigi Toro, Francesca Pagnanelli
March 31, 2023 (v1)
Keywords: Li primary batteries, pilot scale demonstration, process simulation, recycling
Li primary batteries are currently treated along with other Li batteries in several big pyro- metallurgical plants in Northern EU countries. Nevertheless, pyro-metallurgical processes do not allow for Mn and Li recycling and present negative environmental impacts, on the other hand hydrometallurgical processing can potentially ensure the integral recovery of all materials in Li primary batteries. In this work, preliminary experimental findings obtained in the LIFE-LIBAT project (LIFE16 ENV/IT/000389) are reported. In this project, end of life Li(0)-MnO2 batteries were cryo-mechanically treated and then the metals were recovered by a hydrometallurgical process. Representative samples of end of life Li(0) batteries were characterized by type and composition. Batteries were stabilized in an N2 bath and then crushed, sieved, and magnetically separated in the SEVal pilot units. Separated fractions (fine fraction, magnetic coarse fraction, and non-magnetic coarse fraction) were chemically ch... [more]
Simulation of the Energy Efficiency Auction Prices via the Markov Chain Monte Carlo Method
Javier Linkolk López-Gonzales, Reinaldo Castro Souza, Felipe Leite Coelho da Silva, Natalí Carbo-Bustinza, Germán Ibacache-Pulgar, Rodrigo Flora Calili
March 31, 2023 (v1)
Keywords: demand side bidding, Energy, Energy Efficiency, Gaussian mixture model, MCMC
Over the years, electricity consumption behavior in Brazil has been analyzed due to financial and social problems. In this context, it is important to simulate energy prices of the energy efficiency auctions in the Brazilian electricity market. The Markov Chain Monte Carlo (MCMC) method generated simulations; thus, several samples were generated with different sizes. It is possible to say that the larger the sample, the better the approximation to the original data. Then, the Kernel method and the Gaussian mixture model used to estimate the density distribution of energy price, and the MCMC method were crucial in providing approximations of the original data and clearly analyzing its impact. Next, the behavior of the data in each histogram was observed with 500, 1000, 5000 and 10,000 samples, considering only one scenario. The sample which best approximates the original data in accordance with the generated histograms is the 10,000th sample, which consistently follows the behavior of t... [more]
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