Records Added in December 2018
Records added in December 2018
Change month: June | July | August | September | October | November | December
Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer
Po Hu, Jieshuai Ren, Wenan Li
December 3, 2018 (v1)
Keywords: close coupling, frequency-splitting, Hamel locus, self-oscillation, synchronous tuning, wireless power transfer (WPT)
The synchronous tuning of the self-oscillating wireless power transfer (WPT) in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX) rather than the transmitter (TX) current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT sy... [more]
Optimal Planning of Sustainable Buildings: Integration of Life Cycle Assessment and Optimization in a Decision Support System (DSS)
Fabio Magrassi, Adriana Del Borghi, Michela Gallo, Carlo Strazza, Michela Robba
December 3, 2018 (v1)
Keywords: decision support system (DSS), life cycle assessment (LCA), nearly-zero energy buildings, Optimization, sustainable buildings
Energy efficiency measures in buildings can provide for a significant reduction of greenhouse gas (GHG) emissions. A sustainable design and planning of technologies for energy production should be based on economic and environmental criteria. Life Cycle Assessment (LCA) is used to quantify the environmental impacts over the whole cycle of life of production plants. Optimization models can support decisions that minimize costs and negative impacts. In this work, a multi-objective decision problem is formalized that takes into account LCA calculations and that minimizes costs and GHG emissions for general buildings. A decision support system (DSS) is applied to a real case study in the Northern Italy, highlighting the advantage provided by the installation of renewable energy. Moreover, a comparison among different optimal and non optimal solution was carried out to demonstrate the effectiveness of the proposed DSS.
State Estimation of Permanent Magnet Synchronous Motor Using Improved Square Root UKF
Bo Xu, Fangqiang Mu, Guoding Shi, Wei Ji, Huangqiu Zhu
December 3, 2018 (v1)
Keywords: permanent magnet synchronous motor, square root unscented Kalman filter, state estimation
This paper focuses on an improved square root unscented Kalman filter (SRUKF) and its application for rotor speed and position estimation of permanent magnet synchronous motor (PMSM). The approach, which combines the SRUKF and strong tracking filter, uses the minimal skew simplex transformation to reduce the number of the sigma points, and utilizes the square root filtering to reduce computational errors. The time-varying fading factor and softening factor are introduced to self-adjust the gain matrices and the state forecast covariance square root matrix, which can realize the residuals orthogonality and force the SRUKF to track the real state rapidly. The theoretical analysis of the improved SRUKF and implementation details for PMSM state estimation are examined. The simulation results show that the improved SRUKF has higher nonlinear approximation accuracy, stronger numerical stability and computational efficiency, and it is an effective and powerful tool for PMSM state estimation u... [more]
Insights on Energy Transitions in Mexico from the Analysis of Useful Exergy 1971⁻2009
Zeus Guevara, Tânia Sousa, Tiago Domingos
December 3, 2018 (v1)
Subject: Energy Policy
Keywords: energy decoupling, energy transitions, useful exergy
The analysis of useful exergy (UE), which is the minimum amount of work required to produce a given end-use, provides insights on the relationships between structural changes and energy transitions because it focuses on what energy is used for, i.e., energy services, rather than where it comes from, i.e., energy carriers. In this paper, UE was accounted for Mexico in 1971⁻2009. It was found that UE experienced a six-fold growth, led by the increasing share of mechanical drive and electric energy uses. Structural changes such as industrialization and complete electrification mainly drove UE transitions. Technological progress, mainly driven by the industrial sector, and electricity availability caused an improvement in the aggregate final-to-useful efficiency of the economy. In addition, the trend of increasing UE economic intensity shows that Mexico became more dependent on UE per unit of economic output during industrialization. The results suggest that UE trends were more influenced... [more]
A Study on a Linear Magnetic-Geared Interior Permanent Magnet Generator for Direct-Drive Wave Energy Conversion
Ningjun Feng, Haitao Yu, Minqiang Hu, Chunyuan Liu, Lei Huang, Zhenchuan Shi
December 3, 2018 (v1)
Subject: Other
Keywords: finite element analysis, linear permanent magnet generator, magnetic gear, wave energy conversion
The conventional linear permanent magnet generator (CLPMG) for direct-drive wave energy conversion (WEC) has experienced many drawbacks that are difficult to overcome such as low power density and bulky system volume. To improve power density, this paper proposes a linear magnetic-geared interior permanent magnet generator (LMGIPMG) with tubular topology, which artfully incorporates a linear magnetic gear into a linear permanent magnet generator. The operating principle of the LMGIPMG is introduced, and a detailed analysis of air gap flux density, thrust force characteristics, and no-load and load performances are presented and discussed by using finite element method. The CLPMG, which produces the same power as the LMGIPMG, has about four times the volume of the latter. A prototype CLPMG is manufactured to verify simulation results against experimental tests. The design method and the operation conditions of LMGIPMG and CLPMG are both consistent; thus, the performance of LMGIPMG meets... [more]
Dicyanovinyl and Cyano-Ester Benzoindolenine Squaraine Dyes: The Effect of the Central Functionalization on Dye-Sensitized Solar Cell Performance
Simone Galliano, Vittoria Novelli, Nadia Barbero, Alessandra Smarra, Guido Viscardi, Raffaele Borrelli, Frédéric Sauvage, Claudia Barolo
December 3, 2018 (v1)
Subject: Materials
Keywords: central functionalization, dye-sensitized solar cells, NIR-sensitizers, squaraines
In order to achieve a greater light absorption in the near-infrared (NIR) region with a panchromatic spectral response and to suppress the photo-isomerisation phenomenon, we herein report the design, synthesis, spectroscopic and electrochemical characterization of novel centrally functionalized symmetric benzoindolenine squaraine dyes. These molecules have shown different photoelectrical conversion properties, depending on the dicyanovinyl and cyano-ester group substitution on the squaric core unit and on the extension of the π-conjugation.
Comparison of a Novel Organic-Fluid Thermofluidic Heat Converter and an Organic Rankine Cycle Heat Engine
Christoph J.W. Kirmse, Oyeniyi A. Oyewunmi, Andrew J. Haslam, Christos N. Markides
December 3, 2018 (v1)
Keywords: combined heat and power (CHP), economic comparison, low-grade heat, non-linear, off-grid power generation, organic Rankine cycle (ORC), performance analysis, thermofluidic oscillator, two-phase, unsteady
The Up-THERM heat converter is an unsteady, two-phase thermofluidic oscillator that employs an organic working fluid, which is currently being considered as a prime-mover in small- to medium-scale combined heat and power (CHP) applications. In this paper, the Up-THERM heat converter is compared to a basic (sub-critical, non-regenerative) organic Rankine cycle (ORC) heat engine with respect to their power outputs, thermal efficiencies and exergy efficiencies, as well as their capital and specific costs. The study focuses on a pre-specified Up-THERM design in a selected application, a heat-source temperature range from 210 °C to 500 °C and five different working fluids (three n-alkanes and two refrigerants). A modeling methodology is developed that allows the above thermo-economic performance indicators to be estimated for the two power-generation systems. For the chosen applications, the power output of the ORC engine is generally higher than that of the Up-THERM heat converter. However... [more]
Cost Engineering Techniques and Their Applicability for Cost Estimation of Organic Rankine Cycle Systems
Sanne Lemmens
December 3, 2018 (v1)
Keywords: case study, cost estimate, heat recovery, investment costs, organic Rankine cycle (ORC)
The potential of organic Rankine cycle (ORC) systems is acknowledged by both considerable research and development efforts and an increasing number of applications. Most research aims at improving ORC systems through technical performance optimization of various cycle architectures and working fluids. The assessment and optimization of technical feasibility is at the core of ORC development. Nonetheless, economic feasibility is often decisive when it comes down to considering practical instalments, and therefore an increasing number of publications include an estimate of the costs of the designed ORC system. Various methods are used to estimate ORC costs but the resulting values are rarely discussed with respect to accuracy and validity. The aim of this paper is to provide insight into the methods used to estimate these costs and open the discussion about the interpretation of these results. A review of cost engineering practices shows there has been a long tradition of industrial cost... [more]
A Review of CO₂-Enhanced Oil Recovery with a Simulated Sensitivity Analysis
Mandadige Samintha Anne Perera, Ranjith Pathegama Gamage, Tharaka Dilanka Rathnaweera, Ashani Savinda Ranathunga, Andrew Koay, Xavier Choi
December 3, 2018 (v1)
Subject: Energy Policy
Keywords: CO2-EOR, effective factors, immiscible recovery, miscible recovery, numerical modelling, review study
This paper reports on a comprehensive study of the CO₂-EOR (Enhanced oil recovery) process, a detailed literature review and a numerical modelling study. According to past studies, CO₂ injection can recover additional oil from reservoirs by reservoir pressure increment, oil swelling, the reduction of oil viscosity and density and the vaporization of oil hydrocarbons. Therefore, CO₂-EOR can be used to enhance the two major oil recovery mechanisms in the field: miscible and immiscible oil recovery, which can be further increased by increasing the amount of CO₂ injected, applying innovative flood design and well placement, improving the mobility ratio, extending miscibility, and controlling reservoir depth and temperature. A 3-D numerical model was developed using the CO₂-Prophet simulator to examine the effective factors in the CO₂-EOR process. According to that, in pure CO₂ injection, oil production generally exhibits increasing trends with increasing CO₂ injection rate and volume (in H... [more]
Energy Transitions in Nigeria: The Evolution of Energy Infrastructure Provision (1800⁻2015)
Norbert Edomah, Chris Foulds, Aled Jones
December 3, 2018 (v1)
Subject: Energy Policy
Keywords: Africa, developing countries, energy demand, Energy Efficiency, energy histories, energy policy, energy transitions
The provision of energy infrastructure is essential for economic growth, social cohesion, and environmental sustainability. Understanding the multiple functions and services it provides us requires firstly a deeper understanding of the factors that influence energy infrastructure itself. This paper focusses on the factors that influence the evolution of energy infrastructure in Nigeria. By studying different eras of energy use according to the technologies that were being implemented, resources that were available, and the political practice of the time it is possible to better frame the drivers of energy infrastructure. The paper explores the transitions of how Nigerians managed to obtain the vast majority of energy from food calories and traditional biomass, to the broad portfolio of energy sources that is in use today.
Initial Energy Logistics Cost Analysis for Stationary, Quasi-Dynamic, and Dynamic Wireless Charging Public Transportation Systems
Young Jae Jang, Seungmin Jeong, Min Seok Lee
December 3, 2018 (v1)
Subject: Energy Policy
Keywords: alternative fuel vehicles, dynamic wireless charging electric vehicle, electric vehicles, investment cost analysis, road charging vehicle, systems optimization, wireless power transfer
This paper presents an initial investment cost analysis of public transportation systems operating with wireless charging electric vehicles (EVs). There are three different types of wireless charging systems, namely, stationary wireless charging (SWC), in which charging happens only when the vehicle is parked or idle, quasi-dynamic wireless charging (QWC), in which power is transferred when a vehicle is moving slowly or in stop-and-go mode, and dynamic wireless charging (DWC), in which power can be supplied even when the vehicle is in motion. This analysis compares the initial investment costs for these three types of charging systems for a wireless charging-based public transportation system. In particular, this analysis is focused on the energy logistics cost in transportation, which is defined as the cost of transferring and storing the energy needed to operate the transportation system. Performing this initial investment analysis is complicated, because it involves considerable tra... [more]
The Regulatory Noose: Logan City’s Adventures in Micro-Hydropower
Megan Hansen, Randy T. Simmons, Ryan M. Yonk
December 3, 2018 (v1)
Subject: Energy Policy
Keywords: hydropower, micro-hydropower, regulation, Renewable and Sustainable Energy
Recent growth in the renewable energy industry has increased government support for alternative energy. In the United States, hydropower is the largest source of renewable energy and also one of the most efficient. Currently, there are 30,000 megawatts of potential energy capacity through small- and micro-hydro projects throughout the United States. Increased development of micro-hydro could double America’s hydropower energy generation, but micro-hydro is not being developed at the same rate as other renewable sources. Micro-hydro is regulated by the Federal Energy Regulatory Commission and subject to the same regulation as large hydroelectric projects despite its minimal environmental impact. We studied two cases of micro-hydro projects in Logan, Utah, and Afton, Wyoming, which are both small rural communities. Both cases showed that the web of federal regulation is likely discouraging the development of micro-hydro in the United States by increasing the costs in time and funds for d... [more]
State of Charge-Based Active Power Sharing Method in a Standalone Microgrid with High Penetration Level of Renewable Energy Sources
Yun-Su Kim, Chul-Sang Hwang, Eung-Sang Kim, Changhee Cho
December 3, 2018 (v1)
Keywords: constant frequency (CF), renewable energy source, standalone microgrid, state of charge (SOC)-based active power sharing, zero frequency deviation
Standalone microgrids, which are mainly constructed on island areas have low system inertia, may result large frequency deviations even for small load change. Moreover, increasing penetration level of renewable energy sources (RESs) into standalone microgrids makes the frequency stability problem even worse. To overcome this problem, this paper proposes an active power sharing method with zero frequency deviations. To this end, a battery energy storage system (BESS) is operated as constant frequency (CF) control mode, whereas the other distributed generations (DGs) are operated as an active and reactive power (PQ) control mode. As a result, a state of charge (SOC) of the BESS is changed as the system load varies. Based on the SOC deviation, DGs share the load change. The SOC data is assumed to be sent via communication system, hence the communication time delay is considered. To enhance reliability, controllers of DGs are designed to take account of the failure of communication system.... [more]
Slide Valves for Single-Screw Expanders Working Under Varied Operating Conditions
Yuting Wu, Ruiping Zhi, Biao Lei, Wei Wang, Jingfu Wang, Guoqiang Li, Huan Wang, Chongfang Ma
December 3, 2018 (v1)
Subject: Other
Keywords: organic Rankine cycle (ORC), part-load, single-screw expander, slide valve
This paper fully describes the working principle of slide valves in single-screw expanders (SSEs). A geometric analysis of suction and volume ratio slide valves is presented to determine the relations between volume ratio, suction closure volume, discharge opening volume and slide valves displacement. An organic Rankine cycle (ORC) thermodynamic model with SSE integrated with slide valves is developed to analyze the power output of SSE and the net power output of ORC system and variation law of slide valves displacement. Analysis of a typical ORC system under changing operating conditions shows that the power output of the expander and the net output power of the ORC system with slide valves are much better than those without slide valves. When the condensing temperature is 40 °C and the waste availability is 80 kW, the increase in output power and net output power are approximately 3.4 kW and 5 kW, respectively. The presented geometric analysis of slide valves and the thermodynamic mo... [more]
Change month: June | July | August | September | October | November | December