Records Added in October 2018
Records added in October 2018
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Showing records 1 to 25 of 99. [First] Page: 1 2 3 4 Last
Measurement of penetration and cycle time of jets from an industrial fluid coking spray nozzle
Francisco Sanchez Careaga, Cedric Briens, Franco Berruti
October 30, 2018 (v1)
Keywords: Fluidization, Liquid Injection in Fluidized Beds
Fluid CokingTM is a process to upgrade heavy oils through thermal cracking. Oil is injected in a downward-flowing bed of hot coke particles, where it heats up and cracks into smaller vapour molecules. The down-flowing coke particles are sent to a burner where they are reheated and send back to the reactor to provide heat for cracking reactions. Liquid sprayed with atomization gas into a fluidized bed forms a jet cavity that absorbs bubbles from the bubbling bed and periodically releases a large bubble from its tip. The jet penetration length, thus, cycles. With a faster jet cycle, the liquid is distributed more uniformly inside the bed, which is highly desirable. Poor liquid distribution increases the formation of wet agglomerates that slow down the coking reactions and lead to operating problems in commercial Fluid CokersTM. A novel method is proposed to measure the jet penetration and cycle time in large, room-temperature fluidized beds. It is applied to the study of jet cavities fro... [more]
Hydrodynamics in Recirculating Fluidized Bed Mimicking the Stripper Section of the Fluid Coker
Francisco Sanchez Careaga
October 30, 2018 (v1)
Keywords: Agglomerates Drying Model, Baffles, Fluid Cokers, Fouling, Radioactive Particle Tracking, Recirculating Fluidized Beds, Sheds
The stripper section of a Fluid CokerTM consists of a system of baffles (sheds) that enhances the removal of interstitial and adsorbed hydrocarbon vapors from the fluidized coke-particles. Most of the hydrocarbon-vapors released below a stripper shed flow up to the stripper shed, where they may crack and form coke deposits that foul the shed. Extensive fouling changes the shapes of the sheds, makes them thicker and reduces the free-space between the adjacent sheds until downward solids flow is so impaired that the Coker has to be shut down. The Radioactive Particle Tracking (RPT) technique allows the determination of a radioactive tracer-particle location within a certain space inside a fluidized bed and has been the main tool used to study the motion of agglomerates and their interactions with internals. The research presents an innovative use of the RPT system, as a tool to measure the growth of internals fouling in time without the need of stopping the process. Moreover, the techniq... [more]
Un Nuevo Método de Identificación de Procesos Continuos no Oscilatorios de Alto Orden
Francisco Sanchez Careaga
October 30, 2018 (v1)
Keywords: Dynamic System Analysis, Process Control, Process Intensification, Process Modelling
Continuous processes with time delay, in general, have been represented by using first order models with time delay (FOMTD). For this models, the parameter can be graphically estimated by plotting the process response when a step is applied to the manipulated variable. For higher order process, the FOMTD have poor results and the second order models with time delay (SOMTD) are more suitable for identifying the process. Nevertheless there is no simple graphic method for estimating the parameters of the SOMTD.

This research presents a simple graphic method for estimating the second order model with time delay parameter. The method requires to read four point of the process response when a step change in the manipulated variable is applied. From these readings the values of the time delay, gain and time constants of the SOMTD model are estimated.

Moreover, in this research, and alternative approximation of the time delay is proposed, this to avoid unstable zeros on the controller e... [more]
Los procesos continuos con tiempo muerto, generalmente han sido representados utilizando modelos de primer orden con tiempo muerto (FOPDT). Para este modelo, los parámetros pueden ser estimados gráficamente utilizando la gráfica de la respuesta del proceso, al aplicársele un escalón en la manipulación del mismo. Para procesos de alto orden, los modelos FOPDT dan pobres resultados y los modelos de segundo orden con tiempo muerto (SOPDT) son los más indicados para responder a las necesidades de identificación. Sin embargo no existe un método gráfico sencillo para estimar los parámetros del modelo SOPDT.

En esta investigación se presenta un método gráfico sencillo para estimar los parámetros del modelo de segundo orden con tiempo muerto. El método consiste en la lectura de cuatro puntos de la gráfica de respuesta del proceso real al aplicársele un cambio tipo escalón en la manipulación. De esas lecturas se estiman los valores del tiempo muerto, de la ganancia, y de las constantes de t... [more]
A novel sustainable design for production of liquid fuels
Leila Hoseinzade, Thomas A Adams II
October 30, 2018 (v1)
In this study, a novel biomass-gas-and-nuclear-to-liquids (BGNTL) process is proposed. In this process, nuclear heat is used as the heat source of a steam methane reforming (SMR) process. In a prior work, a rigorous model was developed for the integrated nuclear heat and steam methane reforming process in the gPROMS software package. This model was applied to simulate the integrated nuclear heat and SMR section of BGNTL in Aspen Plus within the other process sections. The BGNTL process was considered for producing different fuels including gasoline & diesel or dimethyl ether (DME). Carbon capture and sequestration (CCS) is considered as an optional section. The performance of the BGNTL process was compared against a non-nuclear process called biomass-and-gas-to-liquids (BGTL). The efficiency, economics, and environmental impact analyses show that the BGNTL process to produce DME is the most efficient, economic and environmentally friendly process among the considered designs. As a resu... [more]
Techno-Economic Analysis of Combining Petroleum Coke and Natural Gas for Efficient Liquid Fuels Production
Ikenna Joseph Okeke, Thomas A Adams II
October 30, 2018 (v1)
Subject: Uncategorized
Waste petcoke can be converted to liquid fuels instead of stockpiling which reduces the net CO2 emission by displacing additional petroleum usage. In this study, three petcoke to liquid fuels designs were compared based on the following performance criteria: conversion efficiency, economics, and environmental impacts. The designs considered were petcoke gasification only, a combination of natural gas reforming and petcoke gasification, and natural gas reforming integrated in the petcoke gasification step. The processes were modeled and simulated using a combination of Aspen Plus v10, ProMax, and gProms software. Each of the configurations were designed to operate with and without carbon capture and sequestration (CCS) technology along with a corresponding carbon emission penalty. Performance metrics analyzed were the net present value, minimum diesel selling price, cost of CO2 avoided, and cradle to plant exit gate life cycle greenhouse gas emissions. From the analysis, the integration... [more]
Techno-economic System Analysis for SOFC/GT Hybrid System Accounting for Degradation Effects
Haoxiang Lai, Thomas Adams II
October 30, 2018 (v1)
Keywords: Modeling and simulation, Process design, SOFC/GT Hybrid, Technoeconomic Analysis
Solid oxide fuel cells (SOFCs) produce power with higher efficiency and lower greenhouse gas emission than conventional power production systems such as coal/natural gas power plants. However, a major challenge with SOFCs is that they degrade over time, leading to a short lifetime and limiting their commercialization. When operated in constant power mode—the most common way of baseload power production—the lifetime of an SOFC is as short as around 1.5 years. As an SOFC starts to degrade, the fuel rate and current density must increase in order to compensate and keep power production at a constant level. This compounds the problem by actually increasing the rate of degradation further, resulting in an exponentially increasing degradation rate and therefore a short lifetime.
It has recently been found that by operating the SOFC differently with constant voltage instead of power, the degradation rate can be slowed such that the cell lifetime can be increased to around 13-14 years. In th... [more]
Rolling Horizon Model for Gasoline Blend Planning under Uncertainty in Demands
mahir jalanko, Vladimir Mahalec
October 30, 2018 (v1)
Keywords: production planning under uncertainty, supply-demand pinch
Use rolling horizon model to solve the gasoline blend planning under uncertainty in products demands. We show that an aggregated model based on supply-demand pinch points can improve executions times greatly
Meta-study of carbon dioxide capture technologies: Finding the signal in the noise.
Thomas Alan Adams II, Leila Hoseinzade, Pranav Bhaswanth Madabhushi, Ikenna J. Okeke
October 31, 2018 (v2)
Keywords: Carbon Capture, Carbon Dioxide Sequestration, Chemical Looping Combustion, CO2 membrane, IGCC, Oxyfuels, Post-combustion capture, Pre-combustion capture, Solid Oxide Fuel Cells
We conducted a meta-study of CO2 capture processes, examining nearly 100 techno-economic analyses published in the recent open literature. Normally, it is difficult to compare one study to another because each study uses its own set of assumptions, such as plant scale, geography, market parameters, and inconsistent definitions of key metrics such as the cost of CO2 avoided (CCA). In this work, we present normalized versions of these studies using a consistent basis of comparison, such as net power delivered, base year of operation, pipeline CO2 pressure, currency, country of construction, and so on. In so doing, we are able to draw meaningful conclusions and direct comparisons between different classes of CO2 capture technology. The technologies considered include coal and gas-based processes using capture strategies including solvent-based post-combustion carbon capture, gasification-based strategies, membrane-based approaches, oxyfuel combustion, chemical looping combustion, calcium... [more]
Coke Oven Gas Conversion Efficiency Improvement by System Upgrading to Combined Cycle Power Plant
Lingyan Deng, Thomas Adams II
October 25, 2018 (v4)
Keywords: Coke oven gas, combined cycle power plant, GAMS optimization, MDEA desulphurization
Coke oven gas (COG) is one of the main by-products generated from steel refineries. In most cases, COG is used only to generate low pressure steam for process heat needs or for small amounts of electricity production. Carbon emissions are inevitable in this COG utilization method. However, carbon emissions are no longer free: the federal government has proposed a minimum carbon tax scheme which incentivises the steel industry to upgrade their present system in order to maintain their profitability. Based on a local steel refinery case study, we propose retrofitting the plant with a combined cycle power plant (CCPP) using COG as fuel input in order to help reduce CO2 emissions and increase energy efficiency. However, COG contains a significant amount of sulphur compounds which have to be removed before it can be used as fuel input for CCPP. Therefore, a MDEA based desulphurization process is proposed to reduce the main sulphur content (H2S) in COG to less than 1 ppmv. ProMax is used to... [more]
Acknowledgement to Reviewers of Energies in 2015
Energies Editorial Office
October 23, 2018 (v1)
Subject: Other
The editors of energies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015.
Correction: Ding, X.; Liu, G.; Du, M.; Guo, H.; Qiao, H. and Gerada, C. Development of an Axial Flux MEMS BLDC Micromotor with Increased Efficiency and Power Density. Energies 2015, 8, 6608⁻6626
Xiaofeng Ding, Guanliang Liu, Min Du, Hong Guo, Hao Qian, Christopher Gerada
October 23, 2018 (v1)
Subject: Other
We wish to make the following change to the published paper [1]. The name of the corresponding author should be “Hao Qian” instead of “Hao Qiao”. [...]
Erratum: Ellegård, K. and Palm, J. Who Is Behaving? Consequences for Energy Policy of Concept Confusion. Energies 2015, 8, 7618⁻7637
Energies Editorial Office
October 23, 2018 (v1)
Subject: Energy Policy
We wish to make the following correction to the published paper [1]. [...]
Correction: Jiménez, F., et al. System for Road Vehicle Energy Optimization Using Real Time Road and Traffic Information. Energies 2014, 7, 3576-3598
Felipe Jiménez, Wilmar Cabrera-Montiel, Santiago Tapia-Fernández
October 23, 2018 (v1)
In the original version of the article [1], insufficient acknowledgement was given for the original Dynamic Programming optimization tool. We apologize for this error. To correct this fact, Santiago Tapia-Fernández has been added as an author, and the acknowledgements and authors contributions have been corrected.
Low Voltage Ride-Through Capability Solutions for Permanent Magnet Synchronous Wind Generators
Victor F. Mendes, Frederico F. Matos, Silas Y. Liu, Allan F. Cupertino, Heverton A. Pereira, Clodualdo V. De Sousa
October 23, 2018 (v1)
Keywords: low voltage ride-through capability (LVRT), permanent magnet synchronous generator (PMSG), voltage sags, wind conversion systems
Due to the increasing number of wind power plants, several countries have modified their grid codes to include specific requirements for the connection of this technology to the power system. One of the requirements is the ride-through fault capability (RTFC), i.e., the system capability to sustain operation during voltage sags. In this sense, the present paper intends to investigate the behavior of a full-converter wind generator with a permanent magnet synchronous machine during symmetrical and asymmetrical voltage sags. Two solutions to improve the low voltage ride-through capability (LVRT) of this technology are analyzed: discharging resistors (brake chopper) and resonant controllers (RCs). The design and limitations of these solutions and the others proposed in the literature are discussed. Experimental results in a 34 kW test bench, which represents a scaled prototype of a real 2 MW wind conversion system, are presented.
A Comparison of Energy Consumption Prediction Models Based on Neural Networks of a Bioclimatic Building
Hamid R. Khosravani, María Del Mar Castilla, Manuel Berenguel, Antonio E. Ruano, Pedro M. Ferreira
October 23, 2018 (v1)
Keywords: data selection, electric power demand, multi objective genetic algorithm (MOGA), neural networks, predictive model
Energy consumption has been increasing steadily due to globalization and industrialization. Studies have shown that buildings are responsible for the biggest proportion of energy consumption; for example in European Union countries, energy consumption in buildings represents around 40% of the total energy consumption. In order to control energy consumption in buildings, different policies have been proposed, from utilizing bioclimatic architectures to the use of predictive models within control approaches. There are mainly three groups of predictive models including engineering, statistical and artificial intelligence models. Nowadays, artificial intelligence models such as neural networks and support vector machines have also been proposed because of their high potential capabilities of performing accurate nonlinear mappings between inputs and outputs in real environments which are not free of noise. The main objective of this paper is to compare a neural network model which was desig... [more]
Optimal Siting and Sizing of Distributed Generators in Distribution Systems Considering Cost of Operation Risk
Qingwu Gong, Jiazhi Lei, Jun Ye
October 23, 2018 (v1)
Keywords: chance constrained programming, distributed generators, distribution systems, hybrid genetic algorithm, point estimate method, siting and sizing
With the penetration of distributed generators (DGs), operation planning studies are essential in maintaining and operating a reliable and secure power system. Appropriate siting and sizing of DGs could lead to many positive effects forthe distribution system concerned, such as the reduced total costs associated with DGs, reduced network losses, and improved voltage profiles and enhanced power-supply reliability. In this paper, expected load interruption cost is used as the assessment of operation risk in distribution systems, which is assessed by the point estimate method (PEM). In light with the costs of system operation planning, a novel mathematical model of chance constrained programming (CCP) framework for optimal siting and sizing of DGs in distribution systems is proposed considering the uncertainties of DGs. And then, a hybrid genetic algorithm (HGA), which combines the GA with traditional optimization methods, is employed to solve the proposed CCP model. Finally,the feasibili... [more]
Capacitor Voltage Ripple Suppression for Z-Source Wind Energy Conversion System
Shoudao Huang, Yang Zhang, Zhikang Shuai
October 23, 2018 (v1)
Keywords: capacitor voltage ripple, pulse width modulation, wind generation system, Z-source inverter
This paper proposes an improved pulse-width modulation (PWM) strategy to reduce the capacitor voltage ripple in Z-source wind energy conversion system. In order to make sure that Z-source capacitor voltage has symmetrical maximum and minimum amplitudes in each active state, the shoot-through time is divided into six unequal parts. According to the active state and zero state, the shoot-through time is rearranged to match the charging time and discharging time of the Z-source capacitors. Theoretically, it is indicated that the voltage ripple of the Z-source capacitors can be reduced effectively by means of the proposed PWM scheme. Finally, simulation and experimental results are given to verify the performance of the presented method.
A Carbon Price Forecasting Model Based on Variational Mode Decomposition and Spiking Neural Networks
Guoqiang Sun, Tong Chen, Zhinong Wei, Yonghui Sun, Haixiang Zang, Sheng Chen
October 23, 2018 (v1)
Keywords: carbon price forecasting, comprehensive evaluation criteria, partial autocorrelation function (PACF), spiking neural network (SNN), variational mode decomposition (VMD)
Accurate forecasting of carbon price is important and fundamental for anticipating the changing trends of the energy market, and, thus, to provide a valid reference for establishing power industry policy. However, carbon price forecasting is complicated owing to the nonlinear and non-stationary characteristics of carbon prices. In this paper, a combined forecasting model based on variational mode decomposition (VMD) and spiking neural networks (SNNs) is proposed. An original carbon price series is firstly decomposed into a series of relatively stable components through VMD to simplify the interference and coupling across characteristic information of different scales in the data. Then, a SNN forecasting model is built for each component, and the partial autocorrelation function (PACF) is used to determine the input variables for each SNN model. The final forecasting result for the original carbon price can be obtained by aggregating the forecasting results of all the components. Actual... [more]
Diesel-Minimal Combustion Control of a Natural Gas-Diesel Engine
Florian Zurbriggen, Richard Hutter, Christopher Onder
October 23, 2018 (v1)
Keywords: closed-loop control, combustion control, Diesel, dual fuel, engine control, extremum seeking, internal combustion engine, Natural Gas, Optimization
This paper investigates the combustion phasing control of natural gas-diesel engines. In this study, the combustion phasing is influenced by manipulating the start and the duration of the diesel injection. Instead of using both degrees of freedom to control the center of combustion only, we propose a method that simultaneously controls the combustion phasing and minimizes the amount of diesel used. Minimizing the amount of diesel while keeping the center of combustion at a constant value is formulated as an optimization problem with an equality constraint. A combination of feedback control and extremum seeking is used to solve this optimization problem online. The necessity to separate the different time scales is discussed and a structure is proposed that facilitates this separation for this specific example. The proposed method is validated by experiments on a test bench.
A Hierarchical Approach Using Machine Learning Methods in Solar Photovoltaic Energy Production Forecasting
Zhaoxuan Li, SM Mahbobur Rahman, Rolando Vega, Bing Dong
October 23, 2018 (v1)
Keywords: artificial neural network (ANN), photovoltaic (PV) forecasting, support vector regression (SVR)
We evaluate and compare two common methods, artificial neural networks (ANN) and support vector regression (SVR), for predicting energy productions from a solar photovoltaic (PV) system in Florida 15 min, 1 h and 24 h ahead of time. A hierarchical approach is proposed based on the machine learning algorithms tested. The production data used in this work corresponds to 15 min averaged power measurements collected from 2014. The accuracy of the model is determined using computing error statistics such as mean bias error (MBE), mean absolute error (MAE), root mean square error (RMSE), relative MBE (rMBE), mean percentage error (MPE) and relative RMSE (rRMSE). This work provides findings on how forecasts from individual inverters will improve the total solar power generation forecast of the PV system.
Vibration Durability Testing of Nickel Manganese Cobalt Oxide (NMC) Lithium-Ion 18,650 Battery Cells
James Michael Hooper, James Marco, Gael Henri Chouchelamane, Christopher Lyness
October 23, 2018 (v1)
Subject: Materials
Keywords: durability, electric vehicle (EV), Li-ion battery ageing, vehicle vibration
Electric vehicle (EV) manufacturers are employing cylindrical format cells in the construction of the vehicles’ battery systems. There is evidence to suggest that both the academic and industrial communities have evaluated cell degradation due to vibration and other forms of mechanical loading. The primary motivation is often the need to satisfy the minimum requirements for safety certification. However, there is limited research that quantifies the durability of the battery and in particular, how the cells will be affected by vibration that is representative of a typical automotive service life (e.g., 100,000 miles). This paper presents a study to determine the durability of commercially available 18,650 cells and quantifies both the electrical and mechanical vibration-induced degradation through measuring changes in cell capacity, impedance and natural frequency. The impact of the cell state of charge (SOC) and in-pack orientation is also evaluated. Experimental results are presented... [more]
Progress of Space Charge Research on Oil-Paper Insulation Using Pulsed Electroacoustic Techniques
Chao Tang, Bo Huang, Miao Hao, Zhiqiang Xu, Jian Hao, George Chen
October 23, 2018 (v1)
Keywords: insulation oil, insulation paper, moisture content, pulsed electroacoustic technique (PEA), Simulation, space charge, temperature
This paper focuses on the space charge behavior in oil-paper insulation systems used in power transformers. It begins with the importance of understanding the space charge behavior in oil-paper insulation systems, followed by the introduction of the pulsed electrostatic technique (PEA). After that, the research progress on the space charge behavior of oil-paper insulation during the recent twenty years is critically reviewed. Some important aspects such as the environmental conditions and the acoustic wave recovery need to be addressed to acquire more accurate space charge measurement results. Some breakthroughs on the space charge behavior of oil-paper insulation materials by the research team at the University of Southampton are presented. Finally, future work on space charge measurement of oil-paper insulation materials is proposed.
A Lithium-Ion Battery Simulator Based on a Diffusion and Switching Overpotential Hybrid Model for Dynamic Discharging Behavior and Runtime Predictions
Lan-Rong Dung, Hsiang-Fu Yuan, Jieh-Hwang Yen, Chien-Hua She, Ming-Han Lee
October 23, 2018 (v1)
Keywords: battery simulator, diffusion model, equivalent circuit model (ECM), linear extrapolation, overpotential, rate capacity effect, recovery effect
A new battery simulator based on a hybrid model is proposed in this paper for dynamic discharging behavior and runtime predictions in existing electronic simulation environments, e.g., PSIM, so it can help power circuit designers to develop and optimize their battery-powered electronic systems. The hybrid battery model combines a diffusion model and a switching overpotential model, which automatically switches overpotential resistance mode or overpotential voltage mode to accurately describe the voltage difference between battery electro-motive force (EMF) and terminal voltage. Therefore, this simulator can simply run in an electronic simulation software with less computational efforts and estimate battery performances by further considering nonlinear capacity effects. A linear extrapolation technique is adopted for extracting model parameters from constant current discharging tests, so the EMF hysteresis problem is avoided. For model validation, experiments and simulations in MATLAB a... [more]
An Algorithm to Translate Building Topology in Building Information Modeling into Object-Oriented Physical Modeling-Based Building Energy Modeling
WoonSeong Jeong, JeongWook Son
October 23, 2018 (v1)
Keywords: building energy modeling, Building Information Modeling, building topology, object-oriented physical modeling
This paper presents an algorithm to translate building topology in an object-oriented architectural building model (Building Information Modeling, BIM) into an object-oriented physical-based energy performance simulation by using an object-oriented programming approach. Our algorithm demonstrates efficient mapping of building components in a BIM model into space boundary conditions in an object-oriented physical modeling (OOPM)-based building energy model, and the translation of building topology into space boundary conditions to create an OOPM model. The implemented command, TranslatingBuildingTopology, using an object-oriented programming approach, enables graphical representation of the building topology of BIM models and the automatic generation of space boundaries information for OOPM models. The algorithm and its implementation allow coherent object-mapping from BIM to OOPM and facilitate the definition of space boundaries information during model translation for building thermal... [more]
Optimal Bidding Strategy for Renewable Microgrid with Active Network Management
Seung Wan Kim, Jip Kim, Young Gyu Jin, Yong Tae Yoon
October 23, 2018 (v1)
Keywords: active network management, market participation of microgrid, microgrid operation, renewable microgrid
Active Network Management (ANM) enables a microgrid to optimally dispatch the active/reactive power of its Renewable Distributed Generation (RDG) and Battery Energy Storage System (BESS) units in real time. Thus, a microgrid with high penetration of RDGs can handle their uncertainties and variabilities to achieve the stable operation using ANM. However, the actual power flow in the line connecting the main grid and microgrid may deviate significantly from the day-ahead bids if the bids are determined without consideration of the real-time adjustment through ANM, which will lead to a substantial imbalance cost. Therefore, this study proposes a formulation for obtaining an optimal bidding which reflects the change of power flow in the connecting line by real-time adjustment using ANM. The proposed formulation maximizes the expected profit of the microgrid considering various network and physical constraints. The effectiveness of the proposed bidding strategy is verified through the simul... [more]
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