Journal Sciences News
Ultrasonics
15 July 2018
Efficiency performance and cost structure of Portuguese energy “utilities” – Non-parametric and parametric analysis
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Rui Rita, Vitor Marques, Ana L
15 July 2018
Melamine-nitrogenated mesoporous activated carbon derived from rice husk for carbon dioxide adsorption in fixed-bed
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): A.L. Yaumi, M.Z. Abu Bakar, B.H. Hameed This work presents the preparation of melamine-nitrogenated mesoporous activated carbon from rice husk via single step chemical activation with phosphoric acid and subsequent modification with melamine for efficient carbon dioxide adsorption. The nitrogen-containing carbons were characterized for their textural and chemical properties and thereafter tested for carbon dioxide adsorption in fixed-bed adsorption system. Characterization of the prepared adsorbent reveals better textural properties with high basicity, porosity and nitrogen functionalities indicating that nitrogen was successfully incorporated on to the surface of activated carbons. The nitrogen-containing activated carbon exhibited a maximum carbon dioxide capacity of 5.43
15 July 2018
Comparative study on lignocellulose liquefaction in water, ethanol, and water/ethanol mixture: Roles of ethanol and water
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Shanghuan Feng, Rufei Wei, Mathew Leitch, Chunbao Charles Xu This study aimed to investigate the roles of ethanol and water in the water/ethanol mixed solvent in liquefaction of lignocellulose biomass. To this end, an organosolv lignin, cellulose, cellulose/lignin (50:50, w/w) mixture and an acetone extracted white birch bark (EWBB) were comparatively liquefied in pure water, water/ethanol mixture (50:50, v/v) and pure ethanol at fixed condition (300
15 July 2018
Analysis of two-phase injection heat pump using artificial neural network considering APF and LCCP under various weather conditions
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Dongwoo Kim, Kang Sub Song, Junyub Lim, Yongchan Kim The objective of this study is to optimize the performance of a two-phase injection (TPI) heat pump considering annual performance factor (APF) and life cycle climate performance (LCCP). The performances of non-injection (NI), vapor injection (VI), and TPI heat pumps are measured under various outdoor temperatures. Based on the measured data, artificial neural network models for the NI, VI, and TPI heat pumps are developed to predict the performance indexes during cooling and heating seasons. As a result, the TPI heat pump shows higher heating capacity than the NI and VI heat pumps with a lower compressor discharge temperature in cold weather conditions. Therefore, the application of the TPI has a merit on reducing the size of the heat pump due to its lower back-up heater loss and over-capacity penalty. When the objective function maximizes the APF for system optimization in three climate regions, the TPI heat pump shows a 1.4–2.7% higher APF than the NI heat pump, and a 11.1%–18.1% smaller optimum rated heating capacity.
15 July 2018
Well-being analysis of distribution network in the presence of electric vehicles
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Habiballah Kheradmand-Khanekehdani, Mohsen Gitizadeh Environmental concerns, limitations of fossil fuels and their pollution are among the most important challenges of societies today. To overcome these challenges, the penetration rate of electric vehicles and renewable energy resources has highly increased. But the use of plug-in hybrid electric vehicles with unmanaged charging exerts a negative impact on the electric grid reliability. The current study presents a comprehensive investigation of the reliability of distribution grid based on stochastic behavior of plug-in hybrid electric vehicles and renewable energy resources. Moreover, a new method is introduced for grid well-being management in the presence of plug-in hybrid electric vehicles. The proposed method includes the managed charging and vehicle to grid scenarios and is tested through improved of Roy Billinton test system bus 2. The presented method manages the plug-in hybrid electric vehicles charging and power injection to the grid using system well-being analysis. The simulation results indicate that adequacy of distribution grid is put at risk state in the presence of plug-in hybrid electric vehicles with unmanaged charging, whereas the use of the proposed method not only does not deteriorate the system reliability but also improves well-being criteria and adequacy indices.
15 July 2018
Improved design of supercritical CO2 Brayton cycle for coal-fired power plant
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Yifan Zhang, Hongzhi Li, Wanlong Han, Wengang Bai, Yu Yang, Mingyu Yao, Yueming Wang As an advanced power cycle, supercritical CO2 (sCO2) Brayton cycle has been considered as a promising alternative of conventional steam Rankine cycle for coal-fired power plants. The sCO2 power cycle must be improved to deal with coal-fired system integration constraints since coal-fired boiler is significantly different from nuclear and CSP heaters. The inlet temperature of the working fluid entering coal-fired boiler in sCO2 cycle is much higher than that in steam cycle, as it can be preheated more sufficiently in recuperators. Hence, the exhaust heat of coal-fired boiler flue gas cannot be fully utilized itself. It is of great importance to study on how to make good use of the exhaust heat of flue gas. An in-house code of sCO2 Brayton cycle tailored for coal-fired power plant was developed at first. Then, three improved cycle layouts for better utilization of the exhaust heat of flue gas were proposed, which were assessed in depth based on comprehensive analyses of both sCO2 boiler and cycle layout. The improved cycle with a second split flow to the boiler was proved to be the most effective one. With parameters of 31MPa/600
15 July 2018
Thermodynamic analysis of a novel hybrid liquid air energy storage system based on the utilization of LNG cold energy
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Tong Zhang, Laijun Chen, Xuelin Zhang, Shengwei Mei, Xiaodai Xue, Yuan Zhou Liquid air energy storage (LAES) is a promising solution for electricity energy storage and grid load shifting. The storage and application of cold energy can significantly affect the performance of LAES systems. A stable and sufficient source of cold energy in the liquefaction process is the key factor for the stable and efficient operation of an LAES system. Hence, a novel hybrid LAES system combined with organic Rankine cycle (ORC) systems based on the utilization of liquefied natural gas (LNG) cold energy is proposed in this paper. In the charging process, the LNG helps cool the compressed air, and the cold energy of the liquid air and excess compression heat are utilized in a two-stage ORC system to generate additional electricity during the discharging process. A mathematical model comprising energy and exergy analyses was developed to analyze the performance of the proposed system and the influence of key parameters. Compared to standalone LAES systems, the cold energy storage system is extremely simplified in the proposed system, and higher electricity storage efficiency and density are obtained. Therefore, the proposed system has a promising prospect in LNG terminals owing to its stability and ease of implementation.
15 July 2018
Improvement on the energy performance of a refrigeration system adapting a plate-type heat exchanger and low-GWP refrigerants as alternatives to R134a
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Atilla G. Devecio
15 July 2018
An improvement crossover operation method in genetic algorithm and spatial optimization of heliostat field
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Jianxing Wang, Liqiang Duan, Yongping Yang The heliostat field of solar power tower (SPT) system occupies a large proportion of both the total investment and total energy losses of a plant. However, the optimization design of a heliostat field is a challenging work, because there are too many parameters to be optimized. In this paper, a new high-dimensional genetic algorithm toolbox (HDGA) is developed in Visual Studio Community 2015 for the heliostat field design, in which a new crossover strategy is employed for the high-dimensional optimization. The algorithm is verified by both mathematical models and engineering cases, the results show that HDGA is more effective for the high-dimensional problem, and its convergence speed is much faster than that of the genetic algorithm toolbox developed by the University of Sheffield (Sheffield GA). The new algorithm is explained in detail and the optimal field layout is presented. With the new algorithm, a heliostat field referencing to the Gemasolar plant is optimized in this paper. The results show that the optical performance of the heliostat field is improved significantly than that of the un-optimized case, and the optical efficiency of 63.7% is reachable at the design point. At the same time, the annual insolation weighted efficiency is 56.9%.
15 July 2018
Forecasting energy demand, wind generation and carbon dioxide emissions in Ireland using evolutionary neural networks
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Karl Mason, Jim Duggan, Enda Howley The ability to accurately predict future power demands, power available from renewable resources and the environmental impact of power generation is vital to the energy sector for the purposes of planning, scheduling and policy making. Machine learning techniques, neural networks in particular, have proven to be very effective methods for addressing these challenging forecasting problems. This research utilizes the powerful evolutionary optimisation algorithm, covariance matrix adaptation evolutionary strategy, as a means of training neural networks to predict short term power demand, wind power generation and carbon dioxide intensity levels in Ireland over a two month period. The network is trained over one month and then tested over the following month. A neural network trained with covariance matrix adaptation evolutionary strategy performs very competitively when compared to other state of the art prediction methods when forecasting Ireland's energy needs, providing fast convergence, more accurate predictions and robust performance. The covariance matrix adaptation evolutionary strategy trained network also gives accurate predictions when predicting multiple time steps into the future.
15 July 2018
Optimal design and operating strategies for a biomass-fueled combined heat and power system with energy storage
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Yingying Zheng, Bryan M. Jenkins, Kurt Kornbluth, Alissa Kendall, Chresten Tr
15 July 2018
Experimental investigation on the CaO/CaCO3 thermochemical energy storage with SiO2 doping
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Xiaoyi Chen, Xiaogang Jin, Zhimin Liu, Xiang Ling, Yan Wang Thermochemical systems offer high energy densities and the possibility of long-term storage for the promotion of renewable energy utilization. In particular, CaO/CaCO3 is a very promising system in the field of thermochemical energy storage due to its high energy density, widespread availability and low cost. However, this system makes stringent demands on the performance of CaO/CaCO3 energy storage, including the high reactivity and robust cycling stability. In this study, thermodynamics, kinetics and cycling stability of SiO2-doped CaCO3 are investigated by thermogravimetric analysis and differential scanning calorimetry. The obtained results show that SiO2 has a slightly negative effect on heat storage capacity, but the amount of released heat is increased, and the specific heat capacity is improved by 20% due to the high thermal conductivity of SiO2. Additionally, samples with an optimal mass ratio of 5% SiO2 show a decrease in the activation energy by approximately 40
15 July 2018
Thermal oil recovery from fractured reservoirs: Energy and emissions intensities
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): C.C. Ezeuko, I.D. Gates Increasingly, more focus has been placed on recovering heavy oil from fractured reservoirs. The key challenge of these reservoirs is the nature of the rock with its geological and rock-fluid complexities as well as the viscosity of the oil itself and the difficulties of lowering the viscosity of the oil. The research documented here presents an analysis of the energy and emissions impact of thermal (steam-based) oil recovery from naturally fractured carbonate reservoirs. By using a combination of the dual porosity concept and energy balance, the method offers a solid analytical approach to evaluate the ideal performance in terms of both energy utilization and greenhouse gas (GHG) emissions for thermal recovery from naturally fractured reservoirs. The results provide a limit on energy efficiency and emissions when recovering oil from these systems by using steam. The results reveal that the energy efficiency and GHG emissions per unit oil produced should be improved for thermal recovery processes operated in fractured reservoirs.
15 July 2018
An improved incentive-based demand response program in day-ahead and intra-day electricity markets
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): E. Shahryari, H. Shayeghi, B. Mohammadi-ivatloo, M. Moradzadeh By advancement and vogue of smart grid technologies, there is a strong attitude toward utilizing different strategies for participating in demand response (DR) programs in electricity markets. DR programs can be classified into two main categories namely incentive-based programs (IBPs) and time-based rate programs (TBRPs). In this paper, an improved incentive-based DR (IBDR) model is proposed. In our proposed IBP, the concept of elasticity is improved where it depends not only on the electricity price, but also is a function of consumption hour and customer type. In this program, the incentive value which is paid to the participating consumers is not a fix value and relates to the peak intensity of each hour. The proposed IBP can participate in both of day-ahead and intra-day electricity markets. The property of considering intra-day market enables consumers to provide maximum DR if possible. The proposed model is implemented on peak load curve of Spanish electricity market and a 200-unit residential complex. Different scenarios are considered to show effectiveness of the proposed DR model from various aspects including peak shaving as well as economic indices.
15 July 2018
Bangladesh power supply scenarios on renewables and electricity import
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Anjana Das, Arideep Halder, Rahul Mazumder, Vinay Kumar Saini, Jyoti Parikh, Kirit S. Parikh Bangladesh, currently a low middle-income economy aspires to become a high middle income country by 2021. To achieve such aspiration, the country will have to ensure adequate power supply for its fast growing economy. Bangladesh lacks energy resources for power generation. This paper explores some of the power supply scenarios with special focus on power imports and higher use of renewables. Using the technology rich, least cost optimization model 'The Integrated MARKAL-EFOM System (TIMES)', the authors developed four possible future power supply scenarios for Bangladesh. These scenarios include an energy security framework (based on the Power System Master Plan (PSMP) 2016 report), a high power import scenario, a scenario with higher use of renewables and a combined high power import - high renewables development scenario. The analysis indicates that the present energy security framework ensures energy security with diversifying fuels used for power generation, however, scenarios with high power imports and a high share of renewables (including the combined scenario) bring down the cost of supplying power along with a reduction in expensive fossil fuel imports while maintaining energy security as fuel sources for power generation still remain diversified.
15 July 2018
Statistical modeling and optimization of the combustion efficiency in cement kiln precalciner
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): S. Fellaou, A. Harnoune, M.A. Seghra, T. Bounahmidi Cement industry is highly energy and emissions intensive. Thermal energy is majorly used in the kiln and calciner systems, accounting for over 90% of total energy use in cement plant, and virtually all of the fuel use. Therefore, the precalciner is one of the key equipment in cement manufacturing process impacting the energy efficiency of the pyroprocessing unit. The purpose of this paper is to demonstrate the potential of statistical modeling to support the optimization of precalciners. According to the current knowledge of the authors, this is the first investigation using statistical models to optimize combustion system operating conditions by analyzing historical and experimental design data. Multiple linear regressions were obtained for each of the two approaches with statistically comparable variances. It should be noted that the optimum obtained with the experimental design is better because the corresponding model describes a larger range of operating variables. On the basis of the experiment-based model, 60% of the total unburned organic carbon could be reduced.
15 July 2018
Heat transfer of calcined petroleum coke and heat exchange tube for calcined petroleum coke waste heat recovery
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Bin Zheng, Peng Sun, Yongqi Liu, Qiang Zhao This paper reports the results of heat transfer of calcined petroleum coke and heat exchange tube. The unsteady heat transfer 3D model of single calcined petroleum coke particle layer was set up. The model had been used to investigate detailed heat transfer pathways. The calculated values of calcined petroleum coke temperature showed good agreement with the corresponding available experimental data. The temperature distribution, the heat quantity, the heat flux and the heat transfer contribution rate were studied with different heat transfer times. The results showed that the temperature of the particles near the heat exchange wall decreases rapidly in the early stage of the heat-transfer process, but the temperature of the particles far from the heat exchange wall is almost unchanged. the heat change process can be divided into high-speed stage, fast stage and slow stage. The average heat transfer contribute rate of solid phase is 92.79% and greater than that of gas phase. The contact heat conduction between particles is dominant at any position of the particle layer. The unconventional heat transfer direction distribution was found at the beginning of the heat transfer process. The detailed heat transfer mechanism of calcined petroleum coke and heat exchange tube was clarified.
15 July 2018
Envisioning a low-cost solar future: Exploring the potential impact of Achieving the SunShot 2030 targets for photovoltaics
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Wesley Cole, Bethany Frew, Pieter Gagnon, Andrew Reimers, Jarett Zuboy, Robert Margolis In the context of recent dramatic solar energy cost reductions, the U.S. Department of Energy set new levelized cost of energy goals for photovoltaics (PV) to achieve by 2030 to enable significantly greater PV adoption: $0.03/kWh for utility-scale, $0.04/kWh for commercial, and $0.05/kWh for residential PV systems. We analyze the potential impacts of achieving these “SunShot 2030” cost targets for the contiguous United States using the Regional Energy Deployment System (ReEDS) and Distributed Generation (dGen) capacity expansion models. We consider the impacts under a wide range of future conditions. We find that PV could provide 13%–18% of U.S. electricity demand in 2030 and 28%–64% of demand if the SunShot 2030 goals are achieved, with PV deployment increasing in every state. The availability of low-cost storage has the largest impact on projected deployment, followed by natural gas prices and electricity demand. For comparison, PV deployed under a business-as-usual scenario could provide only 5% of generation in 2030 and 17% in 2050. We find that the high levels of PV deployment explored here lead to lower electricity prices and system costs, lower carbon dioxide emissions, lower water consumption, increased renewable energy curtailment, and increased storage deployment compared with the business-as-usual scenario.
15 July 2018
Fatigue analysis of the steam generator of a parabolic trough solar power plant
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): P.A. Gonz
15 July 2018
Estimating residential energy consumption in metropolitan areas: A microsimulation approach
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Wenwen Zhang, Caleb Robinson, Subhrajit Guhathakurta, Venu M. Garikapati, Bistra Dilkina, Marilyn A. Brown, Ram M. Pendyala Prior research has shown that land use patterns and the spatial configurations of cities have a significant impact on residential energy demand. Given the pressing issues surrounding energy security and climate change, there is renewed interest in developing and retrofitting cities to make them more energy efficient. Yet deriving micro-scale residential energy footprints of metropolitan areas is challenging because high resolution data from energy providers is generally unavailable. In this study, a bottom-up model is proposed to estimate residential energy demand using datasets that are commonly available in the United States. The model applies novel machine learning methods to match records in the Residential Energy Consumption Survey with Public Use Microdata samples. This matching and machine learning produce a synthetic household energy distribution at a neighborhood scale. The model was tested and validated with data from the Atlanta metropolitan region to demonstrate its application and promise.
15 July 2018
Investigation of n-dodecane pyrolysis at various pressures and the development of a comprehensive combustion model
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Meirong Zeng, Wenhao Yuan, Wei Li, Yan Zhang, Yizun Wang n-Dodecane combustion was investigated experimentally and numerically in present study. Pyrolysis experiments of n-dodecane at pressures of 0.0066, 0.039, 0.197 and 1
15 July 2018
Experimental validation of an air-PCM storage unit comparing the effective heat capacity and enthalpy methods through CFD simulations
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Muriel Iten, Shuli Liu, Ashish Shukla Two computational fluid dynamics (CFD) models were developed for the simulation of an air- thermal energy storage (TES) unit. The TES unit was experimentally tested with air flowing over horizontal metallic panels filled with phase change material (PCM). The commercial PCM was characterised by differential scanning calorimetry (DSC), namely: phase change temperature range, specific heat and enthalpy values. These properties were coupled to the CFD models in order to setup the two most common methods for phase change problems: enthalpy and the effective heat capacity methods. Both models predicted the PCM temperature and air outlet temperature and were compared with the experimental results. The PCM temperature presented the major differences. The enthalpy method shows the phase change stage by a quasi-horizontal curve, appropriate for pure PCMs. However, most of the commercial PCMs are composed by different compounds and hence this is not linear during the phase change as presented by the experimental results. The smooth increase over the phase change was accurately predicted by the effective heat capacity method. For the air outlet temperature, both methods present good agreements with the experimental results. Hence, for analysis requiring particular attention on the PCM behaviour the effective heat capacity method is recommended.
15 July 2018
Comparative analysis of different surfaces for integrated solar heating and radiative cooling: A numerical study
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Mingke Hu, Bin Zhao, Xianze Ao, Yuehong Su, Yunyun Wang, Gang Pei The spectral selectivity of solar selective absorbing coatings enhances coating performance in diurnal heating collection but also limits the potential application of these materials in nocturnal radiative cooling. A radiative cooling surface shows poor solar heating performance due to the same reason. The present study proposed a novel surface that combines solar heating and radiative cooling (SH-RC) considering the spectral selectivity of photo-thermic conversion and radiative cooling. A hypothetical SH-RC surface was also proposed. This hypothetical surface had an absorptivity of 0.92 in the solar radiation band, emissivity of 0.70 in the “atmospheric window” band, and absorptivity (emissivity) of 0.05 in other bands. The thermal performance of this spectrally selective SH-RC surface (SH-RCs surface) was numerically investigated by comparing it with three surfaces, namely, solar selective absorbing coating surface (SH surface), spectrally selective radiative cooling surface (RC surface), and spectrally non-selective black surface (SH-RCblack surface). Results indicated that the SH-RCs surface is most suitable for achieving integrated SH and RC. In a typical summer day, the heat gains of the SH, RC, SH-RCblack, and SH-RCs surfaces are 17.14, 0, 15.57, and 13.22
15 July 2018
Turbine investment optimisation for energy recovery plants by utilising historic steam flow profiles
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Philip van Zyl Venter, Stephanus Esias Terblanche, Martin van Eldik Burnable off-gases generated in engineering process plants are regularly utilised as energy sources. A common use is for steam production, where excess steam is allocated to power generation turbines. Fluctuating off-gas productions may, however, result in power generation losses from turbine trips, due to insufficient steam. Numerous power co-generation investment models exist, which are typically based on cost minimisations or meeting energy demands. These models do not, however, incorporate plant-specific historic steam profiles and typically use average-based patterns for decision making. This paper presents a novel stochastic mixed integer linear programming model that utilises historic steam profiles to determine optimal turbine investments in terms of the net present value. A further advantage is the ability to investigate the investment and procurement of a, typically very expensive, supplementary energy resource to assist during low off-gas flow periods. The proposed model is solved to optimise over 10 years for an engineering factory seeking to invest into an energy recovery plant. Optimal results demonstrate how natural gas in a fluctuating off-gas environment can increase power generation profits and should be invested in, together with a 30
15 July 2018
Process simulation, analysis and optimization of a coal to ethylene glycol process
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Qingchun Yang, Dawei Zhang, Huairong Zhou, Chenwei Zhang With the rapid development of polyester industry, the increasing demand of ethylene glycol (EG) is in conflict with the shortage of supply in China. Large project of EG production from coal has been receiving more and more attention. However, little work has been done to model and simulate the complete coal to ethylene glycol (CtEG) process, and there is a lack of research analyzing or optimizing its system performance. In this paper, the CtEG process was modeled and simulated to calculate and analyze its mass and energy balance. The models were validated by comparison with industrial data. The element balance and thermodynamic performance of the CtEG process were analyzed to identify the technical bottleneck and provide theoretical support for the actual production. Key parameters were investigated and optimized for increasing the yield of product as well as improving the system performance of the CtEG process. Results indicate that, the process produce 37.50
15 July 2018
An experimental study of a thermochemical regeneration waste heat recovery process using a reformer unit
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Christian Gaber, Martin Demuth, Ren
15 July 2018
Particulate emissions from urban bus fueled with biodiesel blend and their reducing characteristics using particulate after-treatment system
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Yunhua Zhang, Diming Lou, Piqiang Tan, Zhiyuan Hu Particulate emissions from an urban bus fueled with B20 (20% biodiesel from waste cooking oil and 80% diesel by volume) were investigated using portable emissions measurement system (PEMS), then the effect of a catalyzed continuously regeneration trap (CCRT) on the particulate emissions of the B20-fueled bus were ascertained. Results show that compared with a D100 (pure diesel), B20 reduced particulate number (PN) and particulate mass (PM) emission rates of the bus by 13.9% and 24.3% under cruise control. Under transient condition, B20 reduced the PN and PM emission rates by 18.4% and 16.3%. B20 decreased the total PN concentration by 6.6% whereas increased the proportion of nucleation particles from 89.0% to 92.0%. Correspondingly causing a decrease in the GMD (geometric mean diameter) from 43.02
15 July 2018
Gravitational search algorithm applied to fixed head hydrothermal power system with transmission line security constraints
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Serdar
15 July 2018
From laboratory to pilot: Design concept and techno-economic analyses of the fluidized bed fast pyrolysis of biomass
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Wei-Cheng Wang, Jyun-Jhih Jan For scaling up a lab-designed process of fluidized bed fast pyrolysis, a design concept and techno-economic analysis were both conducted in this study, including system development, experimental investigations and process evaluation. Rice husk was chosen as the feedstock based on its availability in Taiwan. The product distributions were studied with varying temperature, carrier gas flow rate and biomass feeding. The results showed that the optimal experimental conditions for obtaining the maximum bio-oil yield were at the temperature between 400
15 July 2018
Developing a successive linear programming model for head-sensitive hydropower system operation considering power shortage aspect
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Zhong-kai Feng, Wen-jing Niu, Sen Wang, Chun-tian Cheng, Zhi-qiang Jiang, Hui Qin, Yi Liu The power industry is playing an increasingly important role in the world economy, and insufficient power supply may lead to huge enormous economic loss throughout the world. Then, the problem of power shortage is receiving a great deal of attention from operators and managers in electrical power system. With the merits of fast startup-shutdown, hydropower is regarded as one of the most reliable renewable energy sources to smooth the electricity shortage of power grid. Thus, this paper focuses on the operation of head-sensitive hydropower system considering power shortage aspect. To effectively address this problem, a novel method based on linear programming and successive approximation is proposed, where the initial hydraulic heads of each hydroplants is generated based on the actual working condition, and then the linear programming method is used to solve the fixed-head hydropower optimization problem involving a carefully-designed min-max optimization objective, while the successive approximation strategy is employed to incrementally improve the solution's quality by dynamically updating water heads of all the hydropower plants. The simulations demonstrate that compared with the original load demand, our method can make an average of approximate 20% reduction in electricity shortage of power system, demonstrating its effectiveness and practicability.
15 July 2018
A novel Heat Exchanger Network Bridge Retrofit method using the Modified Energy Transfer Diagram
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Nathan S. Lal, Timothy G. Walmsley, Michael R.W. Walmsley, Martin J. Atkins, James R. Neale The aim of this paper is to develop a novel method for the retrofit of Heat Exchanger Networks based on Bridge Retrofit analysis. The method identifies Retrofit Bridges that correspond to energy saving modifications using two new proposed tools: The Heat Surplus-Deficit Table and the Modified Energy Transfer Diagram. These tools both allow the identification and quantification of Retrofit Bridges. These tools have been developed following conventional Pinch Analysis tools such as the Composite Curve and Grand Composite Curve. The connection between the conventional Heat Exchanger Network synthesis tools and the proposed retrofit tools is established to improve understanding of the method and relate it to what is currently used in both literature and industry. The method is demonstrated with a simple illustrative example and a more detail paper mill case study. The paper mill incorporates a paper machine and paper recycling plant and is co-located with a Kraft pulp mill in New Zealand. Results from the retrofit method suggest a retrofit design that will achieve an annualised profit of NZD 570,000/y (USD 414,000/y) with a payback of 2.4
15 July 2018
Method of C groove on vortex suppression and energy performance improvement for a NACA0009 hydrofoil with tip clearance in tidal energy
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Yabin Liu, Lei Tan Tidal energy induced by the gravitation between the earth and moon is the most widespread energy with great development potential by hydraulic machineries. Tip leakage vortex (TLV) has significant influence on the flow pattern and energy performance of hydraulic machineries. In the present work, a C groove method is proposed to suppress the TLV and improve the energy performance of a NACA0009 hydrofoil in tidal energy conversion. The numerical approach with mesh generation and Navior-Stokes equation solution is employed to evaluate the effect of C groove. The geometric and flow parameters including groove width, groove edge rotation, groove position, tip clearance size, and inlet velocity are systematically investigated. The function of the C groove is to suppress the primary TLV by groove jet impingement and weaken the secondary TLV by groove breaking flow, and then improve the flow pattern resulting in a higher energy performance. Results show that the C groove can suppress the vortex area under all conditions, and the maximum decrease of vortex area is 66.55% and 67.94% under tip clearance of 0.2 and 0.4, respectively. The C groove can improve the lift drag ratio of foil under all conditions, and the maximum increase of lift drag ratio is 2.79% and 2.10% under tip clearance of 0.2 and 0.4, respectively. With the C groove, newborn vortexes are induced, which can be classified into three types: newborn groove vortex (NGV) in groove, newborn primary TLV (NPTLV) above suction side downstream groove, and newborn secondary TLV (NSTLV) in tip clearance downstream groove.
15 July 2018
Solar driven net zero emission electricity supply with negligible carbon cost: Israel as a case study for Sun Belt countries
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): A.A. Solomon, Dmitrii Bogdanov, Christian Breyer A high temporal and spatial resolution energy transition study was performed using a linear optimization based energy system transition model. The study uses Israel's electricity sector dataset, which has important characteristics typical for several Sun Belt countries. It has 7 scenarios aimed at assessing the impacts of various policy factors, such as carbon cost and coupling to the water sector. Under the present renewable electricity technology cost projections, a carbon cost only speeds up the transitions into renewable electricity. However, a No Carbon Cost scenario also achieves comparable results by 2050 (with only 2% fossil). The levelized cost of electricity in 2050 was shown to be less than that of 2015 in all scenarios except under the Current Policy. The Current Policy scenario will significantly increase the cost of electricity in the post-2020 period even when a carbon cost is ignored. The observed emission reduction comes after 2030 but there are still significant emissions by 2050. This shows that Israel's present energy policy carries multiple risks to the nation. Alternatively, Sun Belt countries, such as Israel, can speed the transition of the electricity sector without the need to implement carbon cost, only by promoting solar photovoltaics and supporting batteries.
15 July 2018
Process integration of Calcium-Looping thermochemical energy storage system in concentrating solar power plants
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): C. Ortiz, M.C. Romano, J.M. Valverde, M. Binotti, R. Chacartegui The Calcium-Looping process is a promising thermochemical energy storage method based on the multicycle calcination-carbonation of CaCO3-CaO to be used in concentrated solar power plants. When solar energy is available, the CaCO3 solids are calcined at high temperature to produce CaO and CO2, which are stored for subsequent utilization. When power is needed, these reaction by-products are fed into a carbonator reactor where energy is released from the exothermic carbonation reaction. In comparison with currently commercial energy storage systems, such as solar salts, the Calcium-Looping process presents several benefits such as the feasibility to work at significantly higher power cycle temperatures, a higher energy storage density and the possibility to store energy in the medium-long term. The present manuscript analyzes a number of novel Calcium-Looping configurations for energy storage combined with CO2 cycles in a solar tower plant. The high overall efficiencies achieved (32–44%, defined as the ratio of net electric power production to net solar thermal power entering the calciner) indicate a potential interest for the integration of the Calcium-Looping process in Concentrating Solar Power Plants, although major technological challenges related to the design of the solar receiver and of the high temperature solids handling devices remain to be faced.
15 July 2018
Alternative designs of evacuated receiver for parabolic trough collector
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Ramchandra G. Patil, Sudhir V. Panse, Jyeshtharaj B. Joshi, Vishwanath H. Dalvi The paper discusses alternative designs of receivers for parabolic trough collectors with smaller rim angles. The Half Insulation Filled Receiver (HIFR) and Linear Cavity Receiver (LCR) designs have been studied and optimized for minimum heat loss. Different combinations of insulations and annulus gasses have been evaluated. From this study, the best combination of insulation material and annulus gas and its pressure has been obtained for geometry optimization of the receiver. Configuration of SCHOTT PTR 70 receiver has been considered as the base case for this study. Heat losses from the HIFR and LCR for the microtherm – air (at 0.1
15 July 2018
A hybrid renewable system based on wind and solar energy coupled with an electrical storage: Dynamic simulation and economic assessment
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Annamaria Buonomano, Francesco Calise, Massimo Dentice d'Accadia, Maria Vicidomini This work presents a thermo-economic simulation model of a hybrid renewable power plant based on wind turbine and photovoltaic technologies, coupled to an energy storage system. The total plant capacity is 200
15 July 2018
Multi-period energy targeting for Total Site and Locally Integrated Energy Sectors with cascade Pinch Analysis
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Peng Yen Liew, Sharifah Rafidah Wan Alwi, Wai Shin Ho, Zainuddin Abdul Manan, Petar Sabev Varbanov, Ji
15 July 2018
Forecasting crude oil price: Does exist an optimal econometric model?
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Vin
15 July 2018
Experimental investigation of breakwater-type WEC composed of both stationary and floating pontoons
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Xuanlie Zhao, Dezhi Ning Improving the energy conversion performance, especially in shorter waves, may enhance the competitiveness of wave energy converters (WECs) deployed at sea with medium wave conditions. In this paper, a novel system consisting of a front oscillating buoy type WEC and a rear fixed pontoon is proposed to improve the energy conversion performance of the original single pontoon breakwater -type WEC system by Ning et al. (2016). For the purpose of comparison, the experiments for both single pontoon system and two-pontoon system are conducted. Note that, to avoid the significant increase of the construction cost, the total pontoon volume (i.e., the displacement of the pontoon) of the proposed system remains the same with that of the single pontoon system. The two-pontoon system with different draft ratios d 1/d 2 (where d 1 and d 2 are the draft of the front pontoon and rear pontoon) are considered. The experiment shows that the system with smaller draft ratio gives more excellent energy conversion performance. The current controller-magnetic powder brake system is selected and used as the power take-off (PTO) system. The characteristics of the PTO system are investigated, which shows that the approximate Coulomb damping force can be simulated very well. The results also reveal that the proposed breakwater-type WEC with proper configuration improves the capture width ratio (CWR) effectively without compromising the coastal protection performance (i.e., the transmission coefficient K T
15 July 2018
Stochastic day-ahead scheduling of multiple energy Carrier microgrids with demand response
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Mohammad H. Shams, Majid Shahabi, Mohammad E. Khodayar Microgrids are indispensable components of active energy systems that supply diverse electrical and thermal demands. A microgrid is composed of distributed energy resources (DER) including renewable resources, combined heat and power generation (CHP) and conventional generation resources that rely on fossil fuels. Energy hubs in microgrids facilitate the conversion of different types of energy resources. The coupling among natural gas and electricity distribution networks introduces new challenges to the short-term operation planning of microgrids. In this paper, a two-stage stochastic optimization problem is formulated for the short-term operation planning of microgrids with multiple-energy carrier networks to determine the scheduled energy and reserve capacity. The problem is formulated as a mixed integer linear programming problem in which the objective function is to minimize the expected operation cost in the short-term operation horizon. The uncertainties in the renewable generation including the wind and solar photovoltaic generation, and electrical and thermal demands are captured by introducing scenarios with respective probabilities. The proposed solution framework ensures the reliability and security of energy supply in multiple scenarios. The advantage of capturing the interdependence among the electricity and natural gas systems to promote energy efficiency is presented. Furthermore, the effectiveness of demand response programs to reduce the operation costs and improve the security measures is investigated. The sensitivity of the operation costs to the variation of natural gas flow and congestion in pipelines and energy prices is addressed to highlight the interdependence among natural gas and electricity infrastructure systems.
15 July 2018
Exploiting dependence: Day-ahead volatility forecasting for crude oil and natural gas exchange-traded funds
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s):
15 July 2018
Prevention of boiler performance degradation under large primary air ratio scenario in a 660
15 July 2018
Biochar contribution in biomass reburning technology and transformation mechanism of its nitrogen foundational groups at different oxygen contents
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Songshan Cao, Feng Duan, Ping Wang, ChienSong Chyang Biomass has been considered as an alternative fuel through reburning in utility boilers because of its vast availability and renewable nature. The biochar contribution in biomass reburning technology and the transformation mechanism of its nitrogen foundational groups at different oxygen contents were investigated in this study. Results demonstrate that the biochar contribution rate increased first and then decreased as the oxygen content increased. The peak value appeared at an oxygen content of 1.5%. As the oxygen content increases from 0 to 6%, the pyridine N (N-6) content gradually decreased from 47.73% to 36.86%, and the contents of pyridine N (N-5), quaternary N (N-Q), and nitrogen oxides N (N-X) increased by 2.67%, 2.88%, and 5.33%, respectively, in the sewage sludge char. In the peanut-shell char, the N-6 content decreased from 42.54% to 35.89%, the N-Q content increased from 19.11% to 24.59%. N-5 content has the minimum value, while N-X content has the maximum value at the oxygen content of 3%.
15 July 2018
Potential energy directly conversion and utilization methods used for heavy duty lifting machinery
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Yunxiao Hao, Long Quan, Hang Cheng, Lianpeng Xia, Lei Ge, Bin Zhao Hydraulic driven heavy duty lifting machinery is widely applied in mobile machinery. In traditional systems, the gravitational potential energy (GPE) is usually dissipated as heat through the throttling effect of the control valve, resulting in huge energy waste. To address the above issue, this paper proposes two direct GPE recovery (GPER) solutions based on hydraulic-pneumatic energy storage (HPES) principle. For system driven by double hydraulic cylinders, an independent HPES hydraulic cylinder is added to the system. For system driven by single hydraulic cylinder, the HPES is integrated into the original single rod hydraulic cylinder, functioning as a storage chamber. In both schemes, the HPES hydraulic cylinder or chamber is directly connected to an accumulator. With the self-weight of the lifting machinery is balanced by the precharge pressure of the accumulator, the GPE and hydraulic energy can be directly converted mutually. Both schemes have been analyzed in detail. Experimental prototypes have been constructed based on one 76-ton and one 6-ton hydraulic excavator. Experimental results indicate that as compared to the original system, 49.1% GPE recovery rate and 26.2% energy consumption reduction per operation cycle can be achieved for the 76-ton excavator. For the 6-ton excavator, the GPE recovery rate reaches 70.9% and 44.4% energy consumption reduction rate can be achieved for each operation cycle. Besides hydraulic excavator, the proposed solutions can also bring significant energy saving for all other lifting machinery.
15 July 2018
Assessing the combined influence of fluid-rock interactions on reservoir properties and injectivity during CO2 storage in saline aquifers
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Guodong Cui, Yi Wang, Zhenhua Rui, Bailian Chen, Shaoran Ren, Liang Zhang Complex fluid-rock interactions can occur during the injection of carbon dioxide (CO2) into saline aquifers for sequestration, which may affect CO2 injectivity and storage capacity. In this paper, a comprehensive reactive transport model is established to analyze salt precipitation, CO2-water-rock geochemical reactions, and their effects on reservoir physical properties and injectivity. In addition, sensitivity analyses are conducted to investigate the main factors that affect fluid-rock interactions and injectivity with relevance for site selection for CO2 storage. Results show that the back flow of formation water not only affects the salt precipitation but also affects the CO2-water-rock geochemical reactions, resulting in salt and calcite precipitations mainly occurring in the dry-out zone. However, most of the mineral dissolution/precipitation caused by CO2-water-rock reaction occurs in the two-phase and aqueous-phase zones, and their effect on reservoir porosity and permeability are small. A considerable amount of sodium chloride precipitates in the dry-out zone as brine is drawn by capillary action into this zone, with significant consequences for porosity, permeability and injectivity. The injection rate, salinity, capillary pressure–saturation relationships, and reservoir permeability strongly affect the distribution of salt precipitation. Moderate injection rates, salinities, capillary pressures, and permeabilities all lead to favorable CO2 injectivity.
15 July 2018
Optimization of regional water - power systems under cooling constraints and climate change
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Raphael Payet-Burin, Federica Bertoni, Claus Davidsen, Peter Bauer-Gottwein Thermo-electric generation represents 70% of Europe's electricity production and 43% of water withdrawals, and is therefore a key element of the water-energy nexus. In 2003, 2006 and 2009, several thermal power plants had to be switched off in Europe because of heat waves, showing the need to assess the impact of climate change on cooling constraints of thermal power plants. An integrated water-power model of the Iberian Peninsula was developed in this study. It includes a physical hydrologic representation, spatially and temporally resolved water demands, management of water infrastructure and a simple power system model. The system was evaluated under present and future climatic conditions using different climate change scenarios. The cost of cooling constraints is found to increase by 220–640 million ˆ/year, for the period 2046–2065 depending on the climate change scenario. Average available capacity of freshwater-cooled thermal power plants is reduced by 16–30% while production is reduced by 5–12% in summer. The power production is shifted from plants equipped with once-through cooling systems (
15 July 2018
Unconventional biomass fuels for steam gasification: Kinetic analysis and effect of ash composition on reactivity
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): M.P. Gonz
15 July 2018
Economic assessment of large power photovoltaic irrigation systems in the ECOWAS region
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): C. Lorenzo, R.H. Almeida, M. Mart
15 July 2018
Assessing oil supply security of South Asia
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): M. Mohsin, P. Zhou, N. Iqbal, S.A.A. Shah Energy security assessment provides a benchmark for policy analysis and identifies the challenges for ensuring energy supplies as well. This paper develops a composite index for assessing the oil supply risk of South Asian countries. The index is based on a comprehensive set of indicators including the ratio of imported oil over GDP, geopolitical risk, market liquidity, GDP per capita, ratio of oil imports over consumption, diversification, oil price volatility, US$ volatility and transportation risk. Results reveal that India is the least oil vulnerable country while Afghanistan and Bangladesh are the most oil vulnerable countries. India's leading score reflects a higher potential to change the oil suppliers while Afghanistan, Bangladesh, Bhutan, and Nepal have the least score confirming them as the highest supply risk associated countries. Policies such as adopting renewable energy technologies, generating nuclear power, diversifying export sources and cutting down oil subsidies can help reduce the impact of oil supply risk.

Can microalgae biodiesel contribute to achieve the sustainability objectives in the transport sector in France by 2030? A comparison between first, second and third generation biofuels though a range-based Multi-Actor Multi-Criteria Analysis
Publication date: 15 July 2018
Source:Energy, Volume 155 Author(s): Gino Baudry, Cathy Macharis, Thomas Vall
view: 303

$1 OFF $10, $2 OFF $19, offer valid until 04/30/2018.

Code: SHOPTD1

Start: 29 Oct 2017 | End: 30 Apr 2018

Save Up to 50% Off Winter Tires Plus Free Shipping at BestUsedTires.com!

Start: 03 Oct 2017 | End: 30 Apr 2018

(US) Garage Studio - Join the Loyalty Program and Receive 30% off 1 Regular Price Item on Your Birthday!

Start: 18 Aug 2017 | End: 01 May 2018

Search All Amazon* UK* DE* FR* JP* CA* CN* IT* ES* IN* BR* MX
Booking.com B.V. is based in Amsterdam in the Netherlands. Ready for some statistics? Our 1,534,024 properties, including 860,482 holiday rentals, are located in 123,105 destinations in 229 countries and territories, and are supported internationally by 198 offices in 70 countries.
2013 Copyright © Techhap.com Mobile version 2015 | PeterLife & company
Skimlinks helps publishers monetize editorial content through automated affiliate links for products.
Terms of use Link at is mandatory if site materials are using fully or particulary.
Were treated to the site administrator, a cup of coffee *https://paypal.me/peterlife
Yandex.ru