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Showing records 346 to 370 of 370. [First] Page: 1 11 12 13 14 15 Last
Field Study on Humidification Performance of a Desiccant Air-Conditioning System Combined with a Heat Pump
Koichi Kawamoto, Wanghee Cho, Hitoshi Kohno, Makoto Koganei, Ryozo Ooka, Shinsuke Kato
November 16, 2018 (v1)
Keywords: dedicated outdoor air system (DOAS), desiccant, heat pump, humidification
A desiccant air-conditioning system was developed as a latent-load-processing air conditioner in a dedicated outdoor air system during the summer. This study investigated the application of this air-conditioning system to humidification during the winter without using make-up water, thereby eliminating the cause of microbial contamination in air-conditioning systems. The experiments were conducted with a system used for summer applications to determine the feasibility of adsorbing vapor from outdoor air and supplying it to an indoor space. The humidification performance, energy efficiency, and operating conditions were examined. Although the conditions were subpar because the experiments were performed with an actual dedicated outdoor air system, the results showed that it is possible to supply air with a minimum humidity ratio of 5.8 g/kg dry air (DA) when the humidity ratio of outdoor air ranges from 1.8 to 2.3 g/kg DA. The minimum humidification performance required for a dedicated... [more]
Field Experiments on 10 kV Switching Shunt Capacitor Banks Using Ordinary and Phase-Controlled Vacuum Circuit Breakers
Wenxia Sima, Mi Zou, Qing Yang, Ming Yang, Licheng Li
November 16, 2018 (v1)
Subject: Other
Keywords: field tests, phase selection, shunt capacitor banks, vacuum circuit breakers (VCBs)
During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the equipment. This study presents a complete comparison study of ordinary and phase-controlled VCBs on switching 10 kV shunt capacitor banks. An analytical analysis for switching 10 kV shunt capacitor banks is presented on the basis of a reduced circuit with an ungrounded neutral. A phase selection strategy for VCBs to switch 10 kV shunt capacitor banks is proposed. Switching on current waveforms and switching off overvoltage waveforms with, and without, phase selection were measured and discussed by field experiments in a 110 kV substation in Chongqing, China. Results show that the operation of phase-controlled VCBs for 10 kV switching shunt capacitor banks is stable, and phase-controlled VCBs can be used to implement the 10 kV... [more]
Influence of Fine Metal Particles on Surface Discharge Characteristics of Outdoor Insulators
Yong Liu, Bowen Xia, Boxue Du, Masoud Farzaneh
November 16, 2018 (v1)
Subject: Materials
Keywords: discharge luminesce, fine metal particles, flashover voltage, micrometer-level size, outdoor insulator, particle amount, surface discharge characteristic
Focusing on the influence of fine metal particles on the insulation characteristics of outdoor insulators, spherical micrometer-level iron powders were used to represent fine metal particles of different parameters on a polymer insulator specimen surface. Dynamic movement and lift-off behavior of fine particles, as well as the triggered surface discharges under AC voltage were investigated in a uniform electric field under different experimental conditions. The results reveal that the inception, propagation and intensity of surface discharges are significantly affected by the particle parameters, including particle size, amount and distributing characteristic. Based on the measurement of light emission during the flashover process using a high-speed camera, the process of surface discharge to flashover triggered by the fine metal particles were investigated to obtain a relationship between flashover voltage, discharge light intensity and particle parameters. It is suggested that partic... [more]
Environmental Analysis of Petrol, Diesel and Electric Passenger Cars in a Belgian Urban Setting
Nils Hooftman, Luis Oliveira, Maarten Messagie, Thierry Coosemans, Joeri Van Mierlo
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: electric vehicle, emissions, life cycle assessment, non-exhaust, urban
The combustion of fossil fuels in the transport sector leads to an aggravation of the air quality along city roads and highways. Urban air quality is a serious problem nowadays as the number of vehicles increases on a yearly basis. With stricter Euro emission regulations, vehicle manufacturers are not meeting the imposed limits and are also disregarding the non-exhaust emissions. This paper highlights the relevance of non-exhaust emissions of passenger vehicles, both conventional (diesel and petrol) or electric vehicles (EV), on air quality levels in an urban environment in Belgium. An environmental life cycle assessment was carried out based on a real-world emission model for passenger cars and fuel refinery data. A cut-off was applied to the models to highlight what emissions, both from the refinery to the exhaust and electricity production for EV, do actually occur within Belgium’s borders. Results show that not much progress has been made from Euro 4 to 6 for conventional vehicles.... [more]
Implementing a Novel Hybrid Maximum Power Point Tracking Technique in DSP via Simulink/MATLAB under Partially Shaded Conditions
Shahrooz Hajighorbani, Mohd Amran Mohd Radzi, Mohd Zainal Abidin Ab Kadir, Suhaidi Shafie, Muhammad Ammirrul Atiqi Mohd Zainuri
November 16, 2018 (v1)
Keywords: digital signal processing (DSP), global maximum power point (GMPP), O), partial shadow (PS), perturb and observation (P&, photovoltaic (PV), Simulink/MATLAB
This paper presents a hybrid maximum power point tracking (MPPT) method to detect the global maximum power point (GMPP) under partially shaded conditions (PSCs), which have more complex characteristics with multiple peak power points. The hybrid method can track the GMPP when a partial shadow occurs either before or after acquiring the MPP under uniform conditions. When PS occurs after obtaining the MPP during uniform conditions, the new operating point should be specified by the modified linear function, which reduces the searching zone of the GMPP and has a significant effect on reducing the reaching time of the GMPP. Simultaneously, the possible MPPs are scanned and stored when shifting the operating point to a new reference voltage. Finally, after determining the possible location of the GMPP, the GMPP is obtained using the modified P&O. Conversely, when PS occurs before obtaining the MPP, the referenced MPP should be specified. Thus, after recognizing the possible location of... [more]
Electric Vehicles in Logistics and Transportation: A Survey on Emerging Environmental, Strategic, and Operational Challenges
Angel Alejandro Juan, Carlos Alberto Mendez, Javier Faulin, Jesica de Armas, Scott Erwin Grasman
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: electric vehicles, green vehicle routing problems, logistics and transportation
Current logistics and transportation (L&T) systems include heterogeneous fleets consisting of common internal combustion engine vehicles as well as other types of vehicles using “green” technologies, e.g., plug-in hybrid electric vehicles and electric vehicles (EVs). However, the incorporation of EVs in L&T activities also raise some additional challenges from the strategic, planning, and operational perspectives. For instance, smart cities are required to provide recharge stations for electric-based vehicles, meaning that investment decisions need to be made about the number, location, and capacity of these stations. Similarly, the limited driving-range capabilities of EVs, which are restricted by the amount of electricity stored in their batteries, impose non-trivial additional constraints when designing efficient distribution routes. Accordingly, this paper identifies and reviews several open research challenges related to the introduction of EVs in L&T activities, inclu... [more]
Numerical Investigation of a Tuned Heave Plate Energy-Harvesting System of a Semi-Submersible Platform
Kun Liu, Haizhi Liang, Jinping Ou
November 16, 2018 (v1)
Keywords: heave plate, semi-submersible, tuned mass damper (TMD), Wave Energy, wave energy converter
A novel tuned heave plate energy-harvesting system (THPEH) is presented for the motion suppressing and energy harvesting of a semi-submersible platform. This THPEH system is designed based on the principle of a tuned mass damper (TMD) and is composed of spring supports, a power take-off system (PTO) and four movable heave plates. The permanent magnet linear generators (PMLG) are used as the PTO system in this design. A semi-submersible platform operating in the South China Sea is selected as the research subject for investigating the effects of the THPEH system on motion reduction and harvesting energy through numerical simulations. The numerical model of the platform and the THPEH system, which was established based on hydrodynamic analysis, is modified and validated by the results of the flume test of a 1:70 scale model. The effects of the parameters, including the size, the frequency ratio and the damping ratio of the THPEH system, are systematically investigated. The results show t... [more]
The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles
Zheng Wang, Bochen Liu, Yue Zhang, Ming Cheng, Kai Chu, Liang Xu
November 16, 2018 (v1)
Keywords: bidirectional DC/DC converter, chaotic modulation, electric and hybrid vehicles, Energy Conversion, shifted-phase angle based control
Three-port isolated (TPI) bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI) is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.
The Health Costs of Revised Coal Mining Limits in Northern Bohemia
Vojtěch Máca, Jan Melichar
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: airborne pollution, coal mining, coal-fired power plant, external costs, impact-pathway approach
Brown coal has been the major source of energy for more than 150 years for the Czech economy, but its role in the coming decades is nowadays the source of heated debate. Many of the recurring discussions address the coal reserves that were set aside in 1991 in order to halt the massive destruction of the landscape and the unprecedented deterioration of the human environment in Northern Bohemia. We study the proposed variants of the revised mining limits using the impact-pathway approach in order to quantify and monetize the health effects of airborne emissions from coal mining and the use of extracted coal for the production of electricity and heat. We find that the dominant health impacts associated with the revision of the limits, estimated to be up to 7 billion euros over the 2015⁻2050 period, will stem from the use of coal for the production of electricity and heat and that a large part of the impact will be borne by populations outside the Czech Republic.
A Sectoral Micro-Economic Approach to Scenario Selection and Development: The Case of the Greek Power Sector
Alexandros Flamos
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: actor-based modeling and analysis, generation capacity adequacy, policy assessment, power market, scenario development
Generating policy-relevant scenarios is instrumental for understanding and developing policy measures. These are especially relevant to the power sector. Practitioners have been working on policy-relevant scenarios for the ex-ante assessment of policy measures in a meaningful way for end-users related to climate change mitigation and adaptation strategies. This paper presents a method for generating such policy relevant scenarios by focusing on the actor-contingent elements of the scenarios, i.e., the developments that are within the control of system actors to change or bring about. Several scenario techniques focusing on systematic-formalized or quantitative approaches have been published on this front over the past few years. Here, we introduce a methodology that is best suited for the assessment of the expected effect of different policy measures on the involved stakeholders’ behavior as well as for the analysis of the interactions between different policy measures as reflected on... [more]
Multi-Objective Demand Response Model Considering the Probabilistic Characteristic of Price Elastic Load
Shengchun Yang, Dan Zeng, Hongfa Ding, Jianguo Yao, Ke Wang, Yaping Li
November 16, 2018 (v1)
Keywords: demand response, electricity consumption satisfaction (ECS), interaction benefit satisfaction (IBS), price elastic load (PEL), Stochastic Optimization, uncertainty
Demand response (DR) programs provide an effective approach for dealing with the challenge of wind power output fluctuations. Given that uncertain DR, such as price elastic load (PEL), plays an important role, the uncertainty of demand response behavior must be studied. In this paper, a multi-objective stochastic optimization problem of PEL is proposed on the basis of the analysis of the relationship between price elasticity and probabilistic characteristic, which is about stochastic demand models for consumer loads. The analysis aims to improve the capability of accommodating wind output uncertainty. In our approach, the relationship between the amount of demand response and interaction efficiency is developed by actively participating in power grid interaction. The probabilistic representation and uncertainty range of the PEL demand response amount are formulated differently compared with those of previous research. Based on the aforementioned findings, a stochastic optimization mode... [more]
Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 2: Numerical Modeling
Sona Kazemi, Melissa Barazandegan, Madjid Mohseni, Khalid Fatih
November 16, 2018 (v1)
Subject: Biosystems
Keywords: crossover, electrode spacing, flat-plate microbial fuel cell (FPMFC), mixed potential theory, numerical model, passive air-breathing, separator
The separator plays a key role on the performance of passive air-breathing flat-plate MFCs (FPMFC) as it isolates the anaerobic anode from the air-breathing cathode. The goal of the present work was to study the separator characteristics and its effect on the performance of passive air-breathing FPMFCs. This was performed partially through characterization of structure, properties, and performance correlations of eight separators presented in Part 1. Current work (Part 2) presents a numerical model developed based on the mixed potential theory to investigate the sensitivity of the electrode potentials and the power output to the separator characteristics. According to this numerical model, the decreased peak power results from an increase in the mass transfer coefficients of oxygen and ethanol, but mainly increasing mixed potentials at the anode by oxygen crossover. The model also indicates that the peak power is affected by the proton transport number of the separator, which affects t... [more]
A Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 1: Structure, Properties, and Performance Correlations
Sona Kazemi, Madjid Mohseni, Khalid Fatih
November 16, 2018 (v1)
Subject: Biosystems
Keywords: crossover, electrode spacing, flat-plate microbial fuel cell, passive air-breathing, separator
Passive air-breathing microbial fuel cells (MFCs) are a promising technology for energy recovery from wastewater and their performance is highly dependent on characteristics of the separator that isolates the anaerobic anode from the air-breathing cathode. The goal of the present work is to systematically study the separator characteristics and its effect on the performance of passive air-breathing flat-plate MFCs (FPMFCs). This was performed through characterization of structure, properties, and performance correlations of eight separators in Part 1 of this work. Eight commercial separators were characterized, in non-inoculated and inoculated setups, and were examined in passive air-breathing FPMFCs with different electrode spacing. The results showed a decrease in the peak power density as the oxygen and ethanol mass transfer coefficients in the separators increased, due to the increase of mixed potentials especially at smaller electrode spacing. Increasing the electrode spacing was... [more]
Analysis of a Solar Cooling System for Climatic Conditions of Five Different Cities of Saudi Arabia
M. Mujahid Rafique, Shafiqur Rehman, Aref Lashin, Nassir Al Arifi
November 16, 2018 (v1)
Subject: Other
Keywords: clean technology, desiccant wheel, energy saving, evaporative cooling, Saudi Arabia, thermal cooling
Air high in humidity leads to uncomfortable conditions and promotes the growth of different fungi and bacteria, which may cause health problems. The control of moisture content in the air using traditional air conditioning techniques is not a suitable option due to large consumption of primary energy and hence emission of greenhouse gases. The evaporative cooling technology is a cost effective and eco-friendly alternative but can provide thermal comfort conditions only under low humidity conditions. However, the evaporative cooling method can be used effectively in conjunction with desiccant dehumidifiers for better control of humidity. Such systems can control the temperature and humidity of the air independently and can effectively utilize the low-grade thermal energy resources. In this paper, the theoretical analysis of desiccant based evaporative cooling systems is carried out for five cities in Saudi Arabia (Jeddah, Jazan, Riyadh, Hail, and Dhahran). It has been observed that the... [more]
Economic Viability Study of an On-Road Wireless Charging System with a Generic Driving Range Estimation Method
Aditya Shekhar, Venugopal Prasanth, Pavol Bauer, Mark Bolech
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: analysis, charging, contactless, cost, driving range, dynamic, economic, electric vehicle (EV), emissions, extension, inductive power transfer (IPT), static, viability, wireless
The economic viability of on-road wireless charging of electric vehicles (EVs) strongly depends on the choice of the inductive power transfer (IPT) system configuration (static or dynamic charging), charging power level and the percentage of road coverage of dynamic charging. In this paper, a case study is carried out to determine the expected investment costs involved in installing the on-road charging infrastructure for an electric bus fleet. Firstly, a generic methodology is described to determine the driving range of any EV (including electric buses) with any gross mass and frontal area. A dynamic power consumption model is developed for the EV, taking into account the rolling friction, acceleration, deceleration, aerodynamic drag, regenerative braking and Li-ion battery behavior. Based on the simulation results, the linear dependence of the battery state of charge (SoC) on the distance traveled is proven. Further, the impact of different IPT system parameters on driving range is i... [more]
Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case
Chirag Trivedi, Michel J. Cervantes, Ole G. Dahlhaug
November 16, 2018 (v1)
Keywords: computational fluid dynamic (CFD), Francis turbine, hydropower, pressure, turbulence, uncertainty, velocity
Hydraulic turbines are widely used to meet real-time electricity demands. Computational fluid dynamic (CFD) techniques have played an important role in the design and development of such turbines. The simulation of a complete turbine requires substantial computational resources. A specific approach that is applied to investigate the flow field of one turbine may not work for another turbine. A series of Francis-99 workshops have been planned to discuss and explore the CFD techniques applied within the field of hydropower with application to high-head Francis turbines. The first workshop was held in December 2014 at the Norwegian University of Science and Technology, Norway. The steady-state measurements were conducted on a model Francis turbine. Three operating points, part load, best efficiency point, and high load, were investigated. The complete geometry, meshing, and experimental data concerning the hydraulic efficiency, pressure, and velocity were provided to the academic and indu... [more]
Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine
Peter Bachant, Martin Wosnik
November 16, 2018 (v1)
Keywords: cross-flow turbine, marine hydrokinetic energy, Reynolds number, scale model, turbine performance, vertical-axis wind turbine (VAWT), wind energy
Experiments were performed with a large laboratory-scale high solidity cross-flow turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-flow turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R eD ≈ 10⁶ or an approximate average Reynolds number based on the blade chord length R ec ≈ 2 × 10⁵ . A simple model that calculates the peak torque coefficient from static foil data and cross-flow turbine kinematics was shown to be a reasonable predictor for... [more]
A Large Scale Daylighting System Based on a Stepped Thickness Waveguide
Ngoc Hai Vu, Seoyong Shin
November 16, 2018 (v1)
Keywords: linear Fresnel lens, optical fiber daylighting system, plastic optical fiber, stepped thickness waveguide
This paper presents a study on the use of optical fiber and a solar concentrator for a building daylighting system. Daylighting is essential for improving indoor environments and reducing electric lighting power consumption in office buildings. Traditionally, optical fiber daylighting systems were implemented only on a small scale. More complicated technologies are required for more amounts of daylight over further distance via a smaller light guider. The proposed solar lighting system with optical fiber is composed of an array of linear Fresnel lenses and a stepped thickness waveguide. The linear Fresnel lenses collect light into the stepped thickness waveguide. The stepped-thickness waveguide is an optical component which redirects focused sunlight from the vertical direction to the horizontal direction, and it guides light to the attached optical fiber. Simulation models were developed using commercial optical simulation tools (LightTools™). The optical efficiency and angular tolera... [more]
Visualization of International Energy Policy Research
Xiaoling Wang, Jatin Nathwani, Chunyou Wu
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: energy policies, historical perspective, literature metrology, research evolutionary path, visualization analysis
The complexity of policy decision making is well recognized. It is not clear, however, what role academic policy research has played in influencing the directions of policy outcomes and how the research has intertwined with notable issues globally. Given the importance of energy choices on sustainable development, we have developed a comprehensive and powerful visualization of the research trends worldwide in energy policy studies over the past five decades using the literature metrology theory and its techniques. The analytical framework provides a visual tracking of research activity, directional flow and a robust basis for judging progress. The emergent findings are an aid to decision makers drawing insights from specific policy studies within a fully transparent view of the historical context on a global scale.
Electric Load Forecasting Based on a Least Squares Support Vector Machine with Fuzzy Time Series and Global Harmony Search Algorithm
Yan Hong Chen, Wei-Chiang Hong, Wen Shen, Ning Ning Huang
November 16, 2018 (v1)
Keywords: electric load forecasting, fuzzy c-means (FCM), fuzzy time series (FTS), global harmony search algorithm (GHSA), least squares support vector machine (LSSVM)
This paper proposes a new electric load forecasting model by hybridizing the fuzzy time series (FTS) and global harmony search algorithm (GHSA) with least squares support vector machines (LSSVM), namely GHSA-FTS-LSSVM model. Firstly, the fuzzy c-means clustering (FCS) algorithm is used to calculate the clustering center of each cluster. Secondly, the LSSVM is applied to model the resultant series, which is optimized by GHSA. Finally, a real-world example is adopted to test the performance of the proposed model. In this investigation, the proposed model is verified using experimental datasets from the Guangdong Province Industrial Development Database, and results are compared against autoregressive integrated moving average (ARIMA) model and other algorithms hybridized with LSSVM including genetic algorithm (GA), particle swarm optimization (PSO), harmony search, and so on. The forecasting results indicate that the proposed GHSA-FTS-LSSVM model effectively generates more accurate predi... [more]
An Innovative Control Strategy to Improve the Fault Ride-Through Capability of DFIGs Based on Wind Energy Conversion Systems
Vandai Le, Xinran Li, Yong Li, Tran Le Thang Dong, Caoquyen Le
November 16, 2018 (v1)
Keywords: doubly fed induction generator (DFIG), low voltage ride-through (LVRT), passivity-based control (PBC), wind energy conversion systems (WECS)
An innovative control strategy is proposed for enhancing the low voltage ride-through (LVRT) capability of a doubly fed induction generator based on wind energy conversion systems (DFIG-WECS). Within the proposed control method, the current control loops of the rotor side converter (RSC) are developed based on passivity theory. The control scheme for the grid side converter (GSC) is designed based on a two-term approach to keep the DC-link voltage close to a given value. The first term based on the maximal voltage of GSC is introduced in the GSC control loops as a reference reactive current. The second one reflecting the instantaneous unbalanced power flow between the RSC and GSC is also introduced in the GSC control loops as a disturbance considering the instantaneous power of the grid filter to compensate the instantaneous rotor power. The effectiveness of the proposed control strategy is verified via time domain simulation of a 2.0 MW-575 V DFIG-WECS using PSCAD/EMTP. Simulation res... [more]
The Concept, Design and Performance of a Novel Rotary Kiln Type Air-Staged Biomass Gasifier
Huiyuan Shi, Wen Si, Xi Li
November 16, 2018 (v1)
Keywords: air staged, biomass gasification, energy balance, partial oxidation, rotary kiln
Tar formation is the main bottleneck for biomass gasification technology. A novel rotary kiln type biomass gasification process was proposed. The concept design was based on air staging and process separation. This concept was demonstrated on a pilot scale rotary kiln reactor under ambient pressure and autothermic conditions. The pilot scale gasifier was divided into three different reaction regions, which were oxidative degradation, partial oxidation and char gasification. A series of tests was conducted to investigate the effect of key parameters. The results indicate that under optimum operating conditions, a fuel gas with high heat value of about 5500 kJ/Nm³ and gas production rate of 2.32 Nm³/kg could be produced. Tar concentration in the fuel gas could be reduced to 108 mg/Nm³ (at the gasifier outlet) and 38 mg/Nm³ (after gas conditioning). The cold gas efficiency and carbon conversion rate reached 75% and 78%, respectively. The performance of this gasification system shows consi... [more]
Device Performance Improvement of Double-Pass Wire Mesh Packed Solar Air Heaters under Recycling Operation Conditions
Chii-Dong Ho, Hsuan Chang, Chun-Sheng Lin, Chun-Chieh Chao, Yi-En Tien
November 16, 2018 (v1)
Keywords: double-pass, heat-transfer efficiency, recycling, solar air heater, wire mesh packing
The improvement of device performance of a recycling solar air heater featuring a wire mesh packing was investigated experimentally and theoretically. The application of the wire mesh packing and recycle-effect concept to the present study were proposed aiming to strengthen the convective heat-transfer coefficient due to increased turbulence. Comparisons were made among different designs, including the single-pass, flat-plate double-pass and recycling double-pass wire mesh packed operations. The collector efficiency of the recycling double-pass wire mesh packed solar air heater was much higher than that of the other configurations for various recycle ratios and mass flow rates scenarios. The power consumption increment due to implementing wire mesh in solar air heaters was also discussed considering the economic feasibility. A fairly good agreement between theoretical predictions and experimental measurements was achieved with an analyzed error of 1.07%⁻9.32%.
Aerodynamic and Structural Integrated Optimization Design of Horizontal-Axis Wind Turbine Blades
Jie Zhu, Xin Cai, Rongrong Gu
November 16, 2018 (v1)
Keywords: annual energy production, blade mass, horizontal axis wind turbine, integrated optimization design, multi-objective optimization
A procedure based on MATLAB combined with ANSYS is presented and utilized for the aerodynamic and structural integrated optimization design of Horizontal-Axis Wind Turbine (HAWT) blades. Three modules are used for this purpose: an aerodynamic analysis module using the Blade Element Momentum (BEM) theory, a structural analysis module employing the Finite Element Method (FEM) and a multi-objective optimization module utilizing the non-dominated sorting genetic algorithm. The former two provide a sufficiently accurate solution of the aerodynamic and structural performances of the blade; the latter handles the design variables of the optimization problem, namely, the main geometrical shape and structural parameters of the blade, and promotes function optimization. The scope of the procedure is to achieve the best trade-off performances between the maximum Annual Energy Production (AEP) and the minimum blade mass under various design requirements. To prove the efficiency and reliability of... [more]
Quantifying the Water-Energy-Food Nexus: Current Status and Trends
Yuan Chang, Guijun Li, Yuan Yao, Lixiao Zhang, Chang Yu
November 16, 2018 (v1)
Keywords: footprint quantification, interconnection, water-energy-food (WEF) system
Water, energy, and food are lifelines for modern societies. The continuously rising world population, growing desires for higher living standards, and inextricable links among the three sectors make the water-energy-food (WEF) nexus a vibrant research pursuit. For the integrated delivery of WEF systems, quantifying WEF connections helps understand synergies and trade-offs across the water, energy, and food sectors, and thus is a critical initial step toward integrated WEF nexus modeling and management. However, current WEF interconnection quantifications encounter methodological hurdles. Also, existing calculation results are scattered across a wide collection of studies in multiple disciplines, which increases data collection and interpretation difficulties. To advance robust WEF nexus quantifications and further contribute to integrated WEF systems modeling and management, this study: (i) summarizes the estimate results to date on WEF interconnections; (ii) analyzes methodological an... [more]
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