Frontiers in Energy

ISSN 2095-1701 (Print)
ISSN 2095-1698 (Online)
CN 11-6017/TK
Postal Subscription Code 80-972
Formerly Known as Frontiers of Energy and Power Engineering in China
2018 Impact Factor: 1.701
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Macroeconomic impacts of oil price volatility: mitigation and resilience
Zoheir EBRAHIM, Oliver R. INDERWILDI, David A. KING
Front Energ    2014, 8 (1): 9-24.   https://doi.org/10.1007/s11708-014-0303-0
Abstract   HTML   PDF (611KB)

Dependency on oil-derived fuels in various sectors, most notably in mobility, has left the global economy vulnerable to several macroeconomic economic side effects. Numerous studies have addressed the effect of price volatility on specific economic parameters. However, the current literature lacks a comprehensive review of the interactions between global macroeconomic performance and oil price volatility (OPV). Price volatility is intrinsic in commodity markets, but has been advancing at a faster rate in the crude oil market in comparison to other commodities over the past decade, reflecting the status of oil as the most globalised commodity. In this paper, the analytical literature review and analysis of the behavioral responses of macroeconomic agents to OPV shows that such volatility has several damaging and destabilizing macroeconomic impacts that will present a fundamental barrier to future sustainable economic growth if left unchecked. To ensure macroeconomic isolation from OPV, a combination of supply and demand-side policies have been recommended that can help to mitigate and build resilience to the economic uncertainty advanced by OPV.

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Direct writing of electronics based on alloy and metal (DREAM) ink: A newly emerging area and its impact on energy, environment and health sciences
Qin ZHANG, Yi ZHENG, Jing LIU
Front Energ    2012, 6 (4): 311-340.   https://doi.org/10.1007/s11708-012-0214-x
Abstract   HTML   PDF (1678KB)

Electronics, such as printed circuit board (PCB), transistor, radio frequency identification (RFID), organic light emitting diode (OLED), solar cells, electronic display, lab on a chip (LOC), sensor, actuator, and transducer etc. are playing increasingly important roles in people’s daily life. Conventional fabrication strategy towards integrated circuit (IC), requesting at least six working steps, generally consumes too much energy, material and water, and is not environmentally friendly. During the etching process, a large amount of raw materials have to be abandoned. Besides, lithography and microfabrication are typically carried out in “Cleanroom” which restricts the location of IC fabrication and leads to high production costs. As an alternative, the newly emerging ink-jet printing electronics are gradually shaping modern electronic industry and its related areas, owing to the invention of a series of conductive inks composed of polymer matrix, conductive fillers, solvents and additives. Nevertheless, the currently available methods also encounter some technical troubles due to the low electroconductivity, complex sythesis and sintering process of the inks. As an alternative, a fundamentally different strategy was recently proposed by the authors’ lab towards truly direct writing of electronics through introduction of a new class of conductive inks made of low melting point liquid metal or its alloy. The method has been named as direct writing of electronics based on alloy and metal (DREAM) ink. A series of functional circuits, sensors, electronic elements and devices can thus be easily written on various either soft or rigid substrates in a moment. With more and more technical progresses and fundamental discoveries being kept made along this category, it was found that a new area enabled by the DREAM ink electronics is emerging, which would have tremendous impacts on future energy and environmental sciences. In order to promote the research and development along this direction, the present paper is dedicated to draft a comprehensive picture on the DREAM ink technology by summarizing its most basic features and principles. Some important low melting point metal ink candidates, especially the room temperature liquid metals such as gallium and its alloy, were collected, listed and analyzed. The merits and demerits between conventional printed electronics and the new direct writing methods were comparatively evaluated. Important scientific issues and technical strategies to modify the DREAM ink were suggested and potential application areas were proposed. Further, digestions on the impacts of the new technology among energy, health, and environmental sciences were presented. Meanwhile, some practical challenges, such as security, environment-friendly feature, steady usability, package, etc. were summarized. It is expected that the DREAM ink technology will initiate a series of unconventional applications in modern society, and even enter into peoples’ daily life in the near future.

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Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression
Bin HU, Di WU, L.W. WANG, R.Z. WANG
Front. Energy    2017, 11 (4): 493-502.   https://doi.org/10.1007/s11708-017-0510-6
Abstract   HTML   PDF (394KB)

In this paper, the simulation approach and exergy analysis of multi-stage compression high temperature heat pump (HTHP) systems with R1234ze(Z) working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120°C pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compression system. The multi-stage compression system has better energy and exergy efficiencies with the increase of compression stage number. Compared with the single-stage compression system, the coefficient of performance (COP) improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60°C, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respectively.

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Characteristics of force acting on adjustable axial flow pump blade
WEI Peiru, CHEN Hongxun, LU Wei
Front. Energy    2008, 2 (4): 508-513.   https://doi.org/10.1007/s11708-008-0054-x
Abstract   HTML   PDF (226KB)
The internal three-dimensional turbulent flow of adjustable axial-flow pump arrangement was simulated, and the force acting on the blade surface was calculated under different operating conditions. Based on the calculated results, finite element method (FEM) was adopted to analyze stress and strain distributions of the adjustment blade in different operations. Hydraulic moment, centrifugal moment and friction moment which must be conquered by adjusting the blades were also calculated.
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Modeling and control of photovoltaic energy conversion connected to the grid
Rebei NAJET, Ben Ghanem BELGACEM, Hasnaoui OTHMAN
Front Energ    2012, 6 (1): 35-46.   https://doi.org/10.1007/s11708-012-0169-y
Abstract   HTML   PDF (475KB)

This paper presents modeling and control of a photovoltaic generator (PVG) connected to the grid. The parameters of the PVG have been identified in previous work (series and parallel resistance, reverse saturation current and thermal voltage) using Newton-Raphston and the gradient algorithm. The electrical energy from a PVG is transferred to the grid via two static converters (DC/DC and DC/AC). The objective of the proposed control strategy is to maximize energy captured from the PVG. The adapted control law for extracting maximum power from the PVG is based on the incremental conductance algorithm. The developed algorithm has the capability of searching the maximum photovoltaic power under variable irradiation and temperature. To control the DC/AC inverter, an intelligent system based on two structures is constructed: a current source control structure and a voltage source control structure. The system has been validated by numerical simulation using data obtained from the PVG installed in the laboratory research (INSAT, Tunisia).

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Performance prediction of switched reluctance generator with time average and small signal models
Jyoti KOUJALAGI, B. UMAMAHESWARI, R. ARUMUGAM
Front Energ    2013, 7 (1): 56-68.   https://doi.org/10.1007/s11708-012-0216-8
Abstract   HTML   PDF (620KB)

This paper presents the complete mathematical model and predicts the performance of switched reluctance generator with time average and small signal models. The complete mathematical model is developed in three stages. First, a switching model is developed based on quasi-linear inductance profile. Next, based on the switching behaviour, a time average model is obtained to measure the difference between the excitation and generation time in each switching cycle. Finally, to track control voltage and current wave shapes, a small signal model is designed. The effectiveness of the complete multilevel model combining electrical machine, power converter, load and control with programming language is demonstrated through simulations. A PI controller is used for controlling the voltage of the generator. The results presented show that the controller exhibits accurate tracking control of load voltage under different operating conditions. This demonstrates that the proposed model is able to perform an accurate control of the generated output voltage even in transient situations. The simulation is performed to choose the control parameters and study the performance of switched reluctance generator prior to its actual implementation. Initial experimental results are presented using NI-Data acquisition card to control the output power according to load requirements.

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Hydrogen production from water splitting on CdS-based photocatalysts using solar light
Xiaoping CHEN, Wenfeng SHANGGUAN
Front Energ    2013, 7 (1): 111-118.   https://doi.org/10.1007/s11708-012-0228-4
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Hydrogen energy has been regarded as the most promising energy resource in the near future due to that it is a clean and sustainable energy. And the heterogeneous photocatalytic hydrogen production is increasingly becoming a research hotspot around the world today. As visible light response photocatalysts for hydrogen production, cadmium sulfide (CdS) is the most representative material, the research of which is of continuing popularity. In the past several years, there has been significant progress in water splitting on CdS-based photocatalysts using solar light, especially in the development of co-catalysts. In this paper, recent researches into photocatalytic water splitting on CdS-based photocatalysts are reviewed, including controllable synthesis of CdS, modifications with different kinds of cocatalysts, solid solution, intercalated with layered nanocomposites and metal oxides, and hybrids with graphenes etc. Finally, the problems and future challenges in photocatalytic water splitting on CdS-based photocatalysts are described.

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Full lifetime cost analysis of battery, plug-in hybrid and FCEVs in China in the near future
Zhihua CAI, Xunmin OU, Qian ZHANG, Xiliang ZHANG
Front Energ    2012, 6 (2): 107-111.   https://doi.org/10.1007/s11708-012-0182-1
Abstract   HTML   PDF (135KB)

This paper analyzes the full lifetime cost of battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs) in China in the near future. The full lifetime cost comprises the initial and periodic cost of owning and operating the vehicle. Compared with the conventional gasoline vehicles, the full lifetime cost of the BEVs, PHEVs and FCEVs are approximately 1.5, 0.5 and 2.3 times more in the short term, respectively, due to the higher initial costs and higher non-energy-related costs though the fuel costs are lower. The results also suggest that with reasonably anticipatable technological progress in the long term, the lifetime cost of advanced electric vehicles (EVs) can be close to that of gasoline vehicles. It is found that two aspects of action are most important to make BEVs cost-effective: to support technology improvement to decrease the high cost of BEV and to formulate high energy cost of operating the conventional gasoline car. Moreover, it is important to decrease the non-energy operating costs including registration fee, tax rate and etc., of BEVs at the same time.

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Ultrafast solid-liquid-vapor phase change of a thin gold film irradiated by femtosecond laser pulses and pulse trains
Jing HUANG, Yuwen ZHANG, J. K. CHEN, Mo YANG
Front Energ    2012, 6 (1): 1-11.   https://doi.org/10.1007/s11708-012-0179-9
Abstract   HTML   PDF (335KB)

Effects of different parameters on the melting, vaporization and resolidification processes of thin gold film irradiated by femtosecond pulses and pulse train were systematically studied. The classical two-temperature model was adopted to depict the non-equilibrium heat transfer in electrons and lattice. The melting and resolidification processes, which was characterized by the solid-liquid interfacial velocity, as well as elevated melting temperature and depressed solidification temperature, was obtained by considering the interfacial energy balance and nucleation dynamics. Vaporization process which leads to ablation was described by tracking the location of liquid-vapor interface with an iterative procedure based on energy balance and gas kinetics law. The parameters in discussion included film thickness, laser fluence, pulse duration, pulse number, repetition rate, pulse train number, etc. Their effects on the maximum lattice temperature, melting depth and ablation depth were discussed based on the simulation results.

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Fuzzy stochastic long-term model with consideration of uncertainties for deployment of distributed energy resources using interactive honey bee mating optimization
Iraj AHMADIAN,Oveis ABEDINIA,Noradin GHADIMI
Front. Energy    2014, 8 (4): 412-425.   https://doi.org/10.1007/s11708-014-0315-9
Abstract   HTML   PDF (492KB)

This paper presents a novel modified interactive honey bee mating optimization (IHBMO) base fuzzy stochastic long-term approach for determining optimum location and size of distributed energy resources (DERs). The Monte Carlo simulation method is used to model the uncertainties associated with long-term load forecasting. A proper combination of several objectives is considered in the objective function. Reduction of loss and power purchased from the electricity market, loss reduction in peak load level and reduction in voltage deviation are considered simultaneously as the objective functions. First, these objectives are fuzzified and designed to be comparable with each other. Then, they are introduced into an IHBMO algorithm in order to obtain the solution which maximizes the value of integrated objective function. The output power of DERs is scheduled for each load level. An enhanced economic model is also proposed to justify investment on DER. An IEEE 30-bus radial distribution test system is used to illustrate the effectiveness of the proposed method.

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A unified power electronic controller for wind driven grid connected wound rotor induction generator using line commutated inverter
D. R. BINU BEN JOSE, N. AMMASAI GOUNDEN, Raavi SRI NAGA RAMESH
Front Energ    2013, 7 (1): 39-48.   https://doi.org/10.1007/s11708-012-0229-3
Abstract   HTML   PDF (233KB)

The implementation of a simple power converter for a wound rotor induction generator employing a three phase diode bridge rectifier and a line commutated inverter in the rotor circuit for super synchronous speeds has been proposed. The detailed working of the system in power smoothing mode and maximum power point tracking mode is presented. The current flow in the rotor circuit is controlled (by controlling the firing angle of the line commutated inverter) for controlling the stator power in both the modes. An 8 bit PIC microcontroller has been programmed to vary the firing angle of the line commutated inverter. Experiments have been carried out on a 3-phase, 3.73 kW, 400 V, 50 Hz, 4-pole, 1500 r/min wound rotor induction generator and the results obtained with the generator supplying power in both the modes are furnished. The complete scheme has been modeled using MATLAB/SIMULINK blocks and a simulation study has been conducted. The experimental waveforms are compared with the simulation results and a very close agreement between them is observed.

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Structural modeling of a typical gas turbine system
Naresh YADAV, Irshad Ahmad KHAN, Sandeep GROVER
Front Energ    2012, 6 (1): 57-79.   https://doi.org/10.1007/s11708-011-0164-8
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This paper presents an approach for the structural modeling and analysis of a typical gas turbine system. This approach has been applied to the systems and subsystems, which are integral parts of a typical gas turbine system. Since a gas turbine system performance is measured in terms of fluid flow energy transformations across its various assemblies and subassemblies, the performance of such subsystems affects the overall performance of the gas turbine system. An attempt has been made to correlate the associativity of such subsystems contributing to overall gas turbine system functional evaluation using graph theoretic approach. The characteristic equations at the system level as well as subsystem level have been developed on the basis of associativity of various factors affecting their performance. A permanent function has been proposed for the functional model of a gas turbine system, which further leads to selection, identification and optimal evaluation of gas turbine systems.

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Intelligent algorithm for optimal meter placement and bus voltage estimation in ring main distribution system
L. RAMESH, N. CHAKRABORTY, S. P. CHOWDHURY
Front Energ    2012, 6 (1): 47-56.   https://doi.org/10.1007/s11708-011-0159-5
Abstract   HTML   PDF (410KB)

The advancement in power distribution system poses a great challenge to power engineering researchers on how to best monitor and estimate the state of the distribution network. This paper is executed in two stage processes. The first stage is to identify the optimal location for installation of monitoring instrument with minimal investment cost. The second stage is to estimate the bus voltage magnitude, where real time measurement is conducted and measured through identified meter location which is more essential for decision making in distribution supervisory control and data acquisition system (DSCADA). The hybrid intelligent technique is applied to execute the above two algorithms. The algorithms are tested with institute of electrical and electronics engineers (IEEE) and Tamil Nadu electricity board (TNEB) benchmark systems. The simulated results proves that the swarm tuned artificial neural network (ANN) estimator is best suited for accurate estimation of voltage with different noise levels.

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Design and operational considerations for selective catalytic reduction technologies at coal-fired boilers
Jeremy J. SCHREIFELS, Shuxiao WANG, Jiming HAO
Front Energ    2012, 6 (1): 98-105.   https://doi.org/10.1007/s11708-012-0171-4
Abstract   HTML   PDF (200KB)

By the end of 2010, China had approximately 650 GW of coal-fired electric generating capacity producing almost 75% of the country’s total electricity generation. As a result of the heavy reliance on coal for electricity generation, emissions of air pollutants, such as nitrogen oxides (NOx), are increasing. To address these growing emissions, the Ministry of Environmental Protection (MEP) has introduced new NOx emission control policies to encourage the installation of selective catalytic reduction (SCR) technologies on a large number of coal-fired electric power plants. There is, however, limited experience with SCR in China. It is therefore useful to explore the lessons from the use of SCR technologies in other countries. This paper provides an overview of SCR technology performance at coal-fired electric power plants demonstrating emission removal rates between 65% and 92%. It also reviews the design and operational challenges that, if not addressed, can reduce the reliability, performance, and cost-effectiveness of SCR technologies. These challenges include heterogeneous flue gas conditions, catalyst degradation, ammonia slip, sulfur trioxide (SO3) formation, and fouling and corrosion of plant equipment. As China and the rest of the world work to reduce greenhouse gas emissions, carbon dioxide (CO2) emissions from parasitic load and urea-to-ammonia conversion may also become more important. If these challenges are properly addressed, SCR can reliably and effectively remove up to 90% of NOx emissions at coal-fired power plants.

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Structural dynamic analysis of the orbiting scroll wrap in the scroll compressor
Yicai LIU, Yubo XIA, Peng YAN, Yinbin LI, Haibo XIE
Front Energ    2013, 7 (1): 19-25.   https://doi.org/10.1007/s11708-012-0223-9
Abstract   HTML   PDF (514KB)

A deep analysis of orbiting scroll wraps was conducted in this paper by using ANSYS and SolidWorks. Through the modal analysis, the involute of the circle profile orbiting scroll wrap demonstrated a large span in natural frequencies, which led to more superiority in avoiding structural resonances. Based on the dynamic harmonic analysis, loads of frequency changes were gained and the stress and strain distribution of the orbiting scroll wrap in the most dangerous working conditions were obtained, which determined the segments with maximum stress and strain-displacement properties. Two paths defined to elucidate further the structural characteristics of the exhaust chamber provided evidence for the initial correction of orbiting wraps. The results of the present study offer a theoretical basis for the design and manufacture of scroll wraps, and providing a new way to evaluate different scroll wraps.

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Application of fuzzy logic control algorithm as stator power controller of a grid-connected doubly-fed induction generator
Ridha CHEIKH, Arezki MENACER, Said DRID, Mourad TIAR
Front Energ    2013, 7 (1): 49-55.   https://doi.org/10.1007/s11708-012-0217-7
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This paper discusses the power outputs control of a grid-connected doubly-fed induction generator (DFIG) for a wind power generation systems. The DFIG structure control has a six diode rectifier and a PWM IGBT converter in order to control the power outputs of the DFIG driven by wind turbine. So, to supply commercially the electrical power to the grid without any problems related to power quality, the active and reactive powers (Ps, Qs) at the stator side of the DFIG are strictly controlled at a required level, which, in this paper, is realized with an optimized fuzzy logic controller based on the grid flux oriented control, which gives an optimal operation of the DFIG in sub-synchronous region, and the control of the stator power flow with the possibility of keeping stator power factor at a unity.

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Accelerated life-time test of MEA durability under vehicle operating conditions in PEM fuel cell
Tian TIAN, Jianjun TANG, Wei GUO, Mu PAN
Front. Energy    2017, 11 (3): 326-333.   https://doi.org/10.1007/s11708-017-0489-z
Abstract   HTML   PDF (395KB)

In this paper, a novel accelerated test method was proposed to analyze the durability of MEA, considering the actual operation of the fuel cell vehicle. The proposed method includes 7 working conditions: open circuit voltage (OCV), idling, rated output, overload, idling-rated cycle, idling-overload cycle, and OCV-idling cycle. The experimental results indicate that the proposed method can effectively destroy the MEA in a short time (165 h). Moreover, the degradation mechanism of MEA was analyzed by measuring the polarization curve, CV, SEM and TEM. This paper may provide a new research direction for improving the durability of fuel cell.

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Cited: Crossref(2) WebOfScience(1)
Load shedding scheme for the two-area system with linear quadratic regulator
D. TYAGI, Ashwani KUMAR, Saurabh CHANANA
Front Energ    2013, 7 (1): 90-102.   https://doi.org/10.1007/s11708-012-0224-8
Abstract   HTML   PDF (337KB)

The power system is prone to many emergency conditions which may lead to emergency state of operation with decay in the system frequency. The dramatic change in the frequency can result in cascaded failure of the system. In order to avoid power system collapse, load shedding (LS) schemes are adopted with the optimal amount of load shed. This paper proposed a methodology in a two-area thermal-thermal system for finding the required amount of load to be shed for setting the frequency of the system within minimum allowable limits. The LS steps have been obtained based on the rate of change of frequency with the increase in load in steps. A systematic study has been conducted for three scenarios: the scheme with a conventional integral controller; the scheme with a linear quadratic regulator (LQR); and the scheme with an LQR and superconducting magnetic energy storage devices (SMES). A comparison of the results has been presented on the two-area system.

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Numerical simulation and analysis of periodically oscillating pressure characteristics of inviscid flow in a rolling pipe
Yan GU, Yonglin JU
Front Energ    2012, 6 (1): 21-28.   https://doi.org/10.1007/s11708-012-0173-2
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Floating liquefied natural gas (LNG) plants are gaining increasing attention in offshore energy exploitation. The effects of the periodically oscillatory motion on the fluid flow in all processes on the offshore plant are very complicated and require detailed thermodynamic and hydrodynamic analyses. In this paper, numerical simulations are conducted by computational fluid dynamics (CFD) code combined with user defined function (UDF) in order to understand the periodically oscillating pressure characteristics of inviscid flow in the rolling pipe. The computational model of the circular pipe flow is established with the excitated rolling motion, at the excitated frequencies of 1–4 rad/s, and the excitated amplitudes of 3°–15°, respectively. The influences of flow velocities and excitated conditions on pressure characteristics, including mean pressure, frequency and amplitude are systematically investigated. It is found that the pressure fluctuation of the inviscid flow remains almost constant at different flow velocities. The amplitude of the pressure fluctuation increases with the increasing of the excitated amplitude, and decreases with the increasing of the excitated frequency. It is also found that the period of the pressure fluctuation varies with the excitated frequency. Furthermore, theoretical analyses of the flow in the rolling circular pipe are conducted and the results are found in qualitative agreement with the numerical simulations.

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Solving multi-objective optimal power flow problem considering wind-STATCOM using differential evolution
Belkacem MAHDAD, K. SRAIRI
Front Energ    2013, 7 (1): 75-89.   https://doi.org/10.1007/s11708-012-0222-x
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In this paper, a simple strategy based differential evolution was proposed for solving the problem of multi-objective environmental optimal power flow considering a hybrid model (Wind-Shunt-FACTS). The DE algorithm optimized simultaneously a combined vector control based active power of wind sources and reactive power of multi STATCOM exchanged with the electrical power system to minimize fuel cost and emissions. The proposed strategy was examined and applied to the standard IEEE 30-bus with smooth cost function to solve the problem of security environmental economic dispatch considering multi distributed hybrid model based wind and STATCOM controllers. In addition, the proposed approach was validated on a large practical electrical power system 40 generating units considering valve point effect. Simulation results demonstrate that choosing the installation of multi type of FACTS devices in coordination with many distributed wind sources is a vital research area.

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Development of oxide dispersion strengthened ferritic steels with and without aluminum
Jae Hoon LEE
Front Energ    2012, 6 (1): 29-34.   https://doi.org/10.1007/s11708-012-0178-x
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Pure Fe, Cr, Al, Ti elemental powders and pre-alloyed Y2O3 powder were processed by high energy mechanical milling. The compositions of the mixed powders are designed as Fe-18Cr-0.2Ti-0.35Y2O3 and Fe-18Cr-5Al-0.2Ti-0.35Y2O3 in weight percent. The as-milled powders were consolidated by hot extrusion at 1423 K. The dispersed oxide particles were identified to be titania+ yttria for Al-free oxide dispersion strengthened (ODS) steel and alumina+ yttria for Al-added ODS steel, respectively. The ultimate tensile strength of Al-free ODS steel was higher than that of Al-added ODS steel over the temperature range of 298–973 K, because of the difference in number density and size of thermally stable oxide particles dispersed in both steel matrices. The strength in the longitudinal direction was lower than that in the transverse direction, probably due to anisotropy of the microstructure with elongated grains in the hot-extrusion direction for the 18%Cr-ODS steels with and without 5%Al.

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Wearable thermal energy harvester powered by human foot
Guodong XU, Yang YANG, Yixin ZHOU, Jing LIU
Front Energ    2013, 7 (1): 26-38.   https://doi.org/10.1007/s11708-012-0215-9
Abstract   HTML   PDF (614KB)

With explosive applications of many advanced mobile electronic devices, a pervasive energy system with long term sustainability becomes increasingly important. Among the many efforts ever tried, human power is rather unique due to its independence of weather or geographical conditions and is therefore becoming a research focus. This paper is dedicated to demonstrate the possibility and feasibility of harvesting thermal energy from human body by sandwiching a thermoelectric generator (TEG) between human shoe bottom and ground, aiming to power a portable electronic device. Through the conceptual experiments conducted on adults, a maximum 3.99 mW steady state power output at a ground temperature with 273 K is obtained, which is sufficient enough to drive a lot of micro-electronic devices. Also, parametric simulations are performed to systematically clarify the factors influencing the TEG working performance. To further reveal the mechanism of this power generation modality, analytical solutions to the coupled temperature distributions for human foot and TEG module are obtained and the correlation between TEG characteristics and the output power are studied. It was demonstrated that, the TEG working as a wearable power resource by utilizing thermal energy of human foot shows enormous potential and practical values either under normal or extreme conditions.

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Survey and analysis of energy consumption in office buildings in Tianjin
Junlong LI, Huan ZHANG, Shijun YOU, Zhenhui XIE
Front Energ    2013, 7 (1): 69-74.   https://doi.org/10.1007/s11708-012-0221-y
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An energy audit of 24 office buildings was conducted in Tianjin, including basic information of buildings, building energy system and energy bills. The investigation results showed that the average intensity of energy consumption in office buildings in Tianjin accounts for 161.51 kW·h/(m2·a). By breaking the energy consumption down into detailed items, it was found that the heating system consumed the highest amount of energy (46.6%), followed by equipment (35.9%), cooling system (11%) and lighting system (6.69%). The main factors for office building energy consumption were found and some feasible measures to save energy were proposed.

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Anion-exchange membrane direct ethanol fuel cells: Status and perspective
T.S. Zhao, Y.S. Li, S.Y. Shen
Front Energ Power Eng Chin    2010, 4 (4): 443-458.   https://doi.org/10.1007/s11708-010-0127-5
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Direct ethanol fuel cells (DEFCs) are a promising carbon-neutral and sustainable power source for portable, mobile, and stationary applications. However, conventional DEFCs that use acid proton-exchange membranes (typically Nafion type) and platinum-based catalysts exhibit low performance (i.e., the state-of-the-art peak power density is 79.5 mW/cm2 at 90°C). Anion-exchange membrane (AEM) DEFCs that use low-cost AEM and non-platinum catalysts have recently been demonstrated to yield a much better performance (i.e., the state-of-the-art peak power density is 160 mW/cm2 at 80°C). This paper provides a comprehensive review of past research on the development of AEM DEFCs, including the aspects of catalysts, AEMs, and single-cell design and performance. Current and future research challenges are identified along with potential strategies to overcome them.

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Combined heat and power economic dispatch problem using the invasive weed optimization algorithm
T. JAYABARATHI, Afshin YAZDANI, V. RAMESH, T. RAGHUNATHAN
Front Energ    2014, 8 (1): 25-30.   https://doi.org/10.1007/s11708-013-0276-4
Abstract   HTML   PDF (138KB)

Cogeneration units which produce both heat and electric power are found in many process industries. These industries also consume heat directly in addition to electricity. The cogeneration units operate only within a feasible zone. Each point within the feasible zone consists of a specific value of heat and electric power. These units are used along with other units which produce either heat or power exclusively. Hence the economic dispatch problem for these plants optimizing the fuel cost is quite complex and several classical and meta-heuristic algorithms have been proposed earlier. This paper applies the invasive weed optimization algorithm which is inspired by the ecological process of weed colonization and distribution. The results obtained have been compared with those obtained by other methods earlier and showed a marked improvement over earlier ones.

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Lightening structure optimization on turbine wheel of vehicular turbocharger
ZHAO Junsheng, MA Chaochen, HU Liaoping
Front. Energy    2008, 2 (4): 422-426.   https://doi.org/10.1007/s11708-008-0098-y
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Based on basic principle of optimization design, structure optimization of turbine is conducted using optimization module of ANSYS and APDL in order to get the minimum turbine weight. Meanwhile, the original blade profile and flow passage are maintained, and the structural strength of the turbine are guaranteed. Considering assembly technique and cast requirement, the structure of the modified turbine is determined which can save 6.91 percent of the material compared with the original one. The modified turbine not only saved material, but also gained better effect of mass distribution between the turbine and the compressor impeller. The result can provide useful reference to engineering application of turbocharger.
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Thermal radiative properties of metamaterials and other nanostructured materials: A review
Ceji FU, Zhuomin M. ZHANG
Front Energ Power Eng Chin    2009, 3 (1): 11-26.   https://doi.org/10.1007/s11708-009-0009-x
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The ability to manufacture, control, and manipulate structures at extremely small scales is the hallmark of modern technologies, including microelectronics, MEMS/NEMS, and nano-biotechnology. Along with the advancement of microfabrication technology, more and more investigations have been performed in recent years to understand the influence of microstructures on radiative properties. The key to the enhancement of performance is through the modification of the reflection and transmission properties of electromagnetic waves and thermal emission spectra using one-, two-, or three-dimensional micro/nanostructures. This review focuses on recent developments in metamaterials–manmade materials with exotic optical properties, and other nanostructured materials, such as gratings and photonic crystals, for application in radiative energy transfer and energy conversion systems.

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Experimental investigation on heat transfer effect of conical strip inserts in a circular tube under laminar flow
M. ARULPRAKASAJOTHI,K. ELANGOVAN,K. HEMA CHANDRA REDDY,S. SURESH
Front. Energy    2016, 10 (2): 136-142.   https://doi.org/10.1007/s11708-015-0389-z
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The aim of this paper is to observe the Nusselt number and friction factor behavior of the circular tube with conical strip inserts as turbulators in a laminar flow condition, using staggered and non-staggered conical strips with three different twist ratios (Y = 2, 3 and 5). The conical strip is inserted in the forward and backward direction individually compared to the flow of water which is the working fluid. The results indicate that the conical strip inserts increases the Nusselt number when compared to the plain surface tube. It is observed that the strip geometry has a major effect on the thermal performance of the circular tube. On examination of different strips for determining the enhancement of Nusselt number, the staggered conical strip with the twist ratio of Y = 3 has given a better result compared to the other two strips. Finally, correlations have been derived using regression analysis for predicting the Nusselt number and friction factor.

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Economic analysis of a hybrid solar-fuel cell power delivery system using tuned genetic algorithm
Trina SOM, Niladri CHAKRABORTY
Front Energ    2012, 6 (1): 12-20.   https://doi.org/10.1007/s11708-012-0172-3
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An economic evaluation of a network of distributed energy resources (DERs) comprising a microgrid structure of power delivery system in an Indian scenario has been made. The mathematical analysis is based on the application of tuned genetic algorithm (TGA). The analyses for optimal power operation pertaining to minimum cost have been made for two cases in Indian power delivery system. The first case deals with the consumers’ individual optimal operation of DERs, while in the second one, consumers altogether form a microgrid with the optimal supply of power from DERs. The total annual costs for these two cases are found to be economically competitive and encouraging. A reduction of approximately 5.7% in the annual cost has been obtained in the case of microgid system than that in the separately operating consumers’ system for a small locality of India. It is observed that the application of TGA results in a reduction of the minimum cost depicting an improved outcome in terms of energy economy.

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Human power-based energy harvesting strategies for mobile electronic devices
Dewei JIA, Jing LIU
Front Energ Power Eng Chin    2009, 3 (1): 27-46.   https://doi.org/10.1007/s11708-009-0002-4
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Energy problems arise with the proliferation of mobile electronic devices, which range from entertainment tools to life saving medical instruments. The large amount of energy consumption and increasing mobility of electronic devices make it urgent that new power sources should be developed. It has been gradually recognized that the human body is highly flexible in generating applicable power from sources of heat dissipation, joint rotation, enforcement of body weight, vertical displacement of mass centers, and even elastic deformation of tissues and other attachments. These basic combinations of daily activities or metabolic phenomena open up possibilities for harvesting energy which is strong enough to power mobile or even implantable medical devices which could be used for a long time or be recharged permanently. A comprehensive review is presented in this paper on the latest developed or incubating electricity generation methods based on human power which would serve as promising candidates for future mobile power. Thermal and mechanical energy, investigated more thoroughly so far, will particularly be emphasized. Thermal energy relies on body heat and employs the property of thermoelectric materials, while mechanical energy is generally extracted in the form of enforcement or displacement excitation. For illustration purposes, the piezoelectric effect, dielectric elastomer and the electromagnetic induction couple, which can convert force directly into electricity, were also evaluated. Meanwhile, examples are given to explain how to adopt inertia generators for converting displacement energy via piezoelectric, electrostatic, electromagnetic or magnetostrictive vibrators. Finally, future prospects in harvesting energy from human power are made in conclusion.

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