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  • Evaluating social sustainability of bioeconomy value chains through integrated use of local and global methods
    Biomass Bioenergy (IF 3.219) Pub Date : 2018-01-17
    Tuomas J. Mattila, Jáchym Judl, Catherine Macombe, Pekka Leskinen

    A bioeconomy is an economic system, which replaces fossil resources with renewable biological resources. As strategies are implemented, new bio-based value chains are created and others expand to replace fossil fuel based supply chains. Understanding the sustainability impacts of this development requires tools for assessing the impacts. The environmental impacts of bioeconomies have been studied through life cycle assessment, but the social impacts are poorly understood. Commonly applied social sustainability methods are local in scope and lack a life cycle perspective. The aim of this paper was to compare the priority setting in global and local approaches to social sustainability assessment and to explore possibilities for integrating them. A multi-region input-output model was used to estimate the social life cycle impacts of Finnish wood products. The main social issues were found in health and safety and gender inequality, with a large part of the impacts occurring outside the forest sector and outside Finnish boundaries. In contrast, local stakeholders views on social sustainability focused mostly on local conditions, employment and co-operation between companies. Ways to combine the contrasting results were explored and a framework for integrating the local and global approaches was outlined.

    更新日期:2018-01-17
  • Experimental study of a designed solar parabolic trough with large rim angle
    Renew. Energy (IF 4.357) Pub Date : 2018-01-17
    Djelloul Azzouzi, Houssam eddine Bourorga, Khathir abdelrahim Belainine, Boussad Boumeddane

    In this paper, the design process steps of a conventional solar parabolic trough with large rim angle are presented. The various parameters which intervene to obtain the suitable parabolic trough form of the concentrator are applied. Through an experimental characterization, the real focal distance and the focal zone size of the designed concentrator have been determined and compared with those calculated theoretically. Then, its concentration ratio is evaluated and the focused solar flux at the focal zone along the absorber tube is calculated using Soltrace code. It should be noted that the wind speed effect was not taken into account in the experimental tests which are conducted under a solar irradiation of 970 W/m2 and a receiver inclination angle of 36° which corresponds to the experimentation site latitude.

    更新日期:2018-01-17
  • Experimental investigation of physicochemical properties of diesel, biodiesel and TBK-biodiesel fuels and combustion and emission analysis in CI internal combustion engine
    Renew. Energy (IF 4.357) Pub Date : 2018-01-17
    György Szabados, Ákos Bereczky

    Nowadays, there is a lot of research done with renewable diesel fuels. The number of parent materials (especially sludge oil, used oil, edible and non-edible oils), production technologies, and additives of biodiesel is increasing. In our work a comprehensive comparison test series of three fuels (fossil diesel, conventional biodiesel (rapeseed oil methyl ester), and a new type of biodiesel (which is called Triglycerides of Modified Structure)) have been performed. Comparison tests have been conducted with respect to their physicochemical properties and their effect on the combustion and emission of a bus engine. Referring to the physicochemical properties, the tested biodiesel fulfil all the requirements of the EN (European Norm) 14214 standard, but the tested TBK (Thész-Boros-Király) doesn't fit some of the requirements of the EN standard. Based on the indicator and heat release results it can be established, that there is no significant, but a moderate improvement of the combustion process with bio fuels. As for the emission it can be stated, that bio fuels are advantageous as well, but the results are near to measurement accuracy, except smoke and opacity, which decreased in a high degree in case of the two tested bio fuel compared to the fossil one.

    更新日期:2018-01-17
  • Comparison of late PCCI combustion, performance and emissions of diesel engine for B20 and B100 fuels by KIVA-CHEMKIN coupling
    Renew. Energy (IF 4.357) Pub Date : 2018-01-17
    Alborz Zehni, Rahim Khoshbakhti Saray

    A numerical study is performed by KIVA-CHEMKIN code to compare the combustion, performance and emission characteristics of neat biodiesel (B100) and biodiesel blend including a mixture of 20% biodiesel and 80% diesel (B20) resulting from the PCCI combustion mode in a light-duty diesel engine. For the biodiesel reaction mechanism, multi-chemistry surrogate mechanism using methyl decanoate (MD) and methyl-9-decenoate (MD9D) is used in this study. The results show that PCCI combustion like high temperature conventional combustion cannot cover the lower ISFC of the biodiesel blend fuel compared to the diesel fuel. A detailed analysis of combustion and emissions, involving the role of formaldehyde (CH2O) and hydroxyl (OH) radicals as well as O and H radicals, was performed in the PCCI combustion stages and emissions formation for the B100 and B20 fuels. The results indicate that higher concentration of formaldehyde as well as lower concentration of hydroxyl radicals for the B20 case advances low temperature heat release (LTHR) and retards high temperature heat release (HTHR) respectively compared to the B100 case. In addition, O and OH radicals as well as cylinder temperature are effective parameters regarding higher NO and CO concentrations for the B20 case compared to the B100 case.

    更新日期:2018-01-17
  • Dynamic modeling of vortex induced vibration wind turbines
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    A. Chizfahm, E. Azadi Yazdi, M. Eghtesad
    更新日期:2018-01-17
  • Catalytic gasification characteristics of cellulose, hemicellulose and lignin
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    Haimiao Yu, Zilu Wu, Geng Chen

    In this paper, catalytic gasification experiments of three major biomass components (cellulose, hemicellulose, and lignin), straw, and pine were performed with dolomite and Na2CO3 as catalysts on a small-scale entrained-flow gasifier. We focused on the differences of catalytic gasification characteristics among three major biomass components. Sodium carbonate and dolomite largely positively promoted hemicellulose gasification, significantly improved the gasification efficiency, calorific value of gas, and carbon conversion, and significantly reduced the tar yield. Sodium carbonate showed the optimal catalytic effect. Dolomite positively catalyzed the gasification of cellulose, hemicellulose, lignin, straw, and pine. Sodium carbonate significantly catalyzed the gasification of hemicellulose, but it inhibited the gasification of cellulose, lignin, straw, and pine. Sodium carbonate is suitable to catalyze the gasification of biomass with a high content of hemicellulose. The influences of different catalysts on the catalytic gasification characteristics of cellulose, hemicellulose and lignin were different. Therefore, the selection of biomass gasification catalyst should be based on the components and properties of biomass.

    更新日期:2018-01-17
  • Heat Recovery from Multiple-Fracture Enhanced Geothermal Systems: The Effect of Thermoelastic Fracture Interactions
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    Hedda Slatlem Vik, Saeed Salimzadeh, Hamidreza M. Nick
    更新日期:2018-01-17
  • Utilization of de-oiled algal biomass for enhancing vehicular quality biodiesel production from Chlorella sp. in mixotrophic cultivation systems
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    Richa Katiyar, Randhir K. Bharti, B.R. Gurjar, Amit Kumar, Shalini Biswas, Vikas Pruthi
    更新日期:2018-01-17
  • Evaluation of classification methods according to solar radiation features from the viewpoint of the production of Parabolic Trough CSP plants
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    S. Moreno-Tejera, M.A. Silva-Pérez, L. Ramírez-Santigosa, I. Lillo-Bravo

    In this work, the representativeness of the day-types classified according to the solar radiation features by two classification methods is evaluated from the perspective of the production of two parabolic trough plants. A new methodology to characterize the representativeness of the day-types using a novel index is proposed, based on the characterization of the daily production. As a previous step to the use of a classification method, the evaluation methodology helps to select the most adequate model and to improve it from the perspective of a concentrated solar power project. This methodology is applied to 16 years of measurements from Seville (Spain) classified by two methods: a method based on daily clearness index values (kt), and a method that uses clustering techniques to define the day-types. From the application of the methodology to the clustering classification some improvements are identified and applied. As a result, from the 10 day-types identified by the clustering classification method a new classification based on 8 day-types with different features for each type of plant is proposed. The use of this classification to estimate the daily yield outperforms the results obtained with the kt classification, with a mean yearly RMSE value more than 20 % lower.

    更新日期:2018-01-17
  • The integration of Semi-transparent photovoltaics on greenhouse roof for energy and plant production
    Renew. Energy (IF 4.357) Pub Date : 2018-01-16
    Reda Hassanien Emam Hassanien, Ming Li, Fang Yin

    The aim of this study was to investigate the effect of semi-transparent building integrated photovoltaics (BIPV) mounted on top of a greenhouse, on the growth of tomatoes and microclimate conditions as well as to estimate the generated energy and the payback period of this system. Three modules were settled at 20 % of the greenhouse roof area at a tilt angle of 30º facing south at a distance of 0.08 m between the plastic cover and the BIPV. Each module has a peak power of 170 Wp and efficiency of 8.25 %. Results revealed that the annual generated electric energy of the BIPV was 637 kWh. Furthermore, there were no significant differences (P< 0.05) in the growth of tomatoes between shaded greenhouse by the BIPV and the un-shaded greenhouse. The reduction of solar radiation under the BIPV was 35 % - 40 % more than the Polyethylene covers on clear days. The BIPV shading decreases the air temperature by (1 ºC - 3 ºC) on clear days and has no effect on relative humidity. The payback period was found to be 9 years. Moreover, this system can provide most of the annual energy demands for the greenhouse environmental control systems.

    更新日期:2018-01-17
  • Experimental investigation on effect of ethanol and di-ethyl ether addition on the spray characteristics of diesel/biodiesel blends under high injection pressure
    Fuel (IF 4.601) Pub Date : 2018-01-11
    Cheng Zhan, Zehao Feng, Wen'an Ma, Mingzhi Zhang, Chenglong Tang, Zuohua Huang

    In this work, a comprehensive experimental investigation on spray characteristics of four blended fuels, including diesel (D100), diesel-biodiesel (DB), diesel-biodiesel- ethanol (DBE), and diesel-biodiesel-diethyl ether (DBDE) has been conducted by using high pressure common rail injection system (up to 200 MPa). The transient spray behavior under various conditions was recorded by high speed photography with scattering light illumination. It is shown that higher injection pressure significantly accelerates the spray tip penetration (STP) evolution due to increased inertia of spray while increase in ambient pressure reduces the STP evolution due to higher gas resistance. With the addition of diethyl ether (DEE) into biodiesel, the STP of blended fuel tends to go down and corresponding projected area increases a lot when compared to DB. By means of particle droplet image analysis (PDIA) optical diagnostic method, spray microscopic parameters such as Sauter Mean Diameter (SMD), droplet diameter distribution probability curve, cumulative volume curve and characteristic diameter have been investigated. Results show that both the injection pressure and ambient pressure have significant influence on the spray microscopic characteristics. In addition, for fixed injection pressure and ambient pressure, when DEE is added into DB blends, the number fraction of smaller droplets increases, though the statistic diameter with peak probability is fixed at a certain value. Furthermore, SMD of the four tested fuels decreases sequentially in the order of DB, D100, DBE, and DBDE, indicating that DEE addition favors the atomization process.

    更新日期:2018-01-17
  • Viscosity models for pure hydrocarbons at extreme conditions: A review and comparative study
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Hseen O. Baled, Isaac K. Gamwo, Robert M. Enick, Mark A. McHugh

    Viscosity is a critical fundamental property required in many applications in the chemical and oil industries. In this review the performance of seven select viscosity models, representative of various predictive and correlative approaches, is discussed and evaluated by comparison to experimental data of 52 pure hydrocarbons including straight-chain alkanes, branched alkanes, cycloalkanes, and aromatics. This analysis considers viscosity data to extremely high-temperature, high-pressure conditions up to 573 K and 300 MPa. Unsatisfactory results are found, particularly at high pressures, with the Chung-Ajlan-Lee-Starling, Pedersen-Fredenslund, and Lohrenz-Bray-Clark models commonly used for oil reservoir simulation. If sufficient experimental viscosity data are readily available to determine model-specific parameters, the free volume theory and the expanded fluid theory models provide generally comparable results that are superior to those obtained with the friction theory, particularly at pressures higher than 100 MPa. Otherwise, the entropy scaling method by Lötgering-Lin and Gross is recommended as the best predictive model.

    更新日期:2018-01-17
  • Experimental study on impingement spray and near-field spray characteristics under high-pressure cross-flow conditions
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Zhanbo Si, Nagisa Shimasaki, Keiya Nishida, Youichi Ogata, Min Guo, Chenglong Tang, Zuohua Huang

    The fuel spray injected into a direct injection (DI) engine is substantially affected by both the in-cylinder air flow and the piston cavity wall impingement. The combined effect of the air flow and the wall impingement plays an important role on the spray development, mixture formation, and subsequent combustion. In this study, the effects of cross-flow and flat wall impingement on the spray development and dispersion were investigated. The spray was injected by a valve covered orifice (VCO) nozzle under various cross-flow velocities and ambient pressures. Impingement spray images in a vertical plane and several horizontal planes were obtained by a high speed video camera and a continuous wave laser sheet. A high speed video camera connected with a long-distance microscope was employed to obtain the near-field spray images. The results show that cross-flow favors spray dispersion while the high ambient pressure tends to compress the spray profiles. Additionally, under an approximate liquid-to-air momentum flux ratio q, when the ambient pressure and cross-flow velocity were varied, at 2 ms ASOI the outlines of the spray in the windward side agree well, whereas the spray extended further in the leeward side at a lower ambient pressure. At the plane of y = 25 mm, a complex vortex movement was observed that resulted in a non-uniform distribution of droplets in the upper part of the spray in the leeward side. In addition, at the plane of y = 45 mm, an empty belt area occurred in the vortex core region revealing that the density of the droplets in this region was quite low. The quantitative analysis shows that with increasing cross-flow velocity, the spray tip penetration decreases slightly before impingement while the spray tip penetrates further on the wall surface after impingement. The high cross-flow velocity favors the spray breakup and dispersion leading to a larger wall-jet vortex while the high ambient pressure restrains the spray dispersion leading to a smaller spray tip penetration and vortex height. For near-field spray, the spray image at higher ambient pressure shows fewer ligaments. With increasing cross-flow velocity, the whole spray shifted downstream. The spray outline was wider at the initial stage (0.05 ms ASOI) than that at steady stage (2 ms ASOI) of spray evolution.

    更新日期:2018-01-17
  • Nanoscale rock mechanical property changes in heterogeneous coal after water adsorption
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Yihuai Zhang, Maxim Lebedev, Ahmed Al-Yaseri, Hongyan Yu, Xiaomeng Xu, Mohammad Sarmadivaleh, Ahmed Barifcani, Stefan Iglauer

    Rock mechanical properties are of key importance in coal mining exploration, coal bed methane production and CO2 storage in deep unmineable coal seams; accurate data is required so that geohazards (e.g. layer collapse or methane/CO2 leakage) can be avoided. In this context it is well established that coal matrix swelling due to water adsorption significantly changes the coal microstructure. However, how water adsorption and the associated with microstructural changes affect the mechanical properties is only poorly understood, despite the fact that micro-scale mechanical properties determine the overall geo-mechanical response as failure initiates at the weakest point. Thus, we measured nanoscale rock mechanical properties via nanoindentation tests and compared the results with traditional acoustic methods on heterogeneous medium rank coal samples in both dry and brine saturated conditions. The microscale heterogeneity of the rock mechanical properties was mapped and compared with the morphology of the sample (measured by SEM and microCT). While the nanoindentation tests measured decreasing indentation moduli after water adsorption (−60% to −66%), the traditional acoustic tests measured an increase (+17%). We concluded that acoustic tests failed to capture the accurate rock mechanical properties changes for the heterogeneous coal during water adsorption. It is thus necessary to measure the coal rock mechanical properties at the microscale to obtain more accurate data and reduce the risk of geohazards.

    更新日期:2018-01-17
  • Enhancing energy production from waste textile by hydrolysis of synthetic parts
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Elnaz Hasanzadeh, Safoora Mirmohamadsadeghi, Keikhosro Karimi
    更新日期:2018-01-17
  • Morphological and structural evolution of bituminous coal slime particles during the process of combustion
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Hui Wang, Songlin Liu, Xiaotong Li, Dawei Yang, Xiangyu Wang, Chang Song
    更新日期:2018-01-17
  • Catalytic cracking of Swida wilsoniana oil for hydrocarbon biofuel over Cu-modified ZSM-5 zeolite
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Changzhu Li, Jiangshan Ma, Zhihong Xiao, Stanton B. Hector, Rukuan Liu, Shuangmiao Zuo, Xinfeng Xie, Aihua Zhang, Hong Wu, Qiang Liu

    Catalytic cracking of Swida wilsoniana oil over non-catalyst and various Cu-modified ZSM-5 catalysts doped with different concentration of Cu (0, 5, 10, 20 and 30 wt%) was studied. The physicochemical properties of the prepared catalysts were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) model, Transmission electron microscopy (TEM) and temperature-programmed desorption of ammonia (NH3-TPD) analysis. Results showed that the introduction of Cu did not change the crystalline structure of ZSM-5 and CuO might deposit on the surface or inside the pores. The numbers of ZSM-5 total acidic sites were increased after it was loaded with 5 wt% and 10 wt% concentration of Cu. The overall hydrocarbon biofuels yields obtained from Cu-modified ZSM-5 catalysts were improved relative to parent ZSM-5. Determination of composition of the hydrocarbon biofuels showed that the hydrocarbon fractions were the main components produced. The optimum Cu concentration used for ZSM-5 modification was 10 wt%, which obtained the highest hydrocarbon biofuels yield (68.20 wt%) and percentage of hydrocarbon fractions content (89.07 wt%). The reuse of Cu-modified ZSM-5 catalysts results showed acceptable levels of reusability after three times regeneration. In addition, the physical properties of the Cu-modified ZSM-5 catalysts produced hydrocarbon biofuels were improved compared to non-catalytic cracking of S. wilsoniana oil. This work showed that the newly developed 10 wt% concentration Cu-modified ZSM-5 was an efficient catalyst for cracking of S. wilsoniana oil for the production of hydrocarbon biofuels.

    更新日期:2018-01-17
  • Determination of the absolute adsorption/desorption isotherms of CH4 and n-C4H10 on shale from a nano-scale perspective
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Yueliang Liu, Huazhou Andy Li, Yuanyuan Tian, Zhehui Jin, Hucheng Deng

    Accurate description of absolute adsorption/desorption behavior for hydrocarbons on shale is of critical importance to the understanding of the fundamental mechanisms governing the storage, transport, and recovery of shale gas or shale gas condensate in shale reservoirs. By applying a thermogravimetric method, we first measure the excess adsorption/desorption isotherms of pure CH4 and n-C4H10 on shale samples over the temperature range of 303.15–393.15 K. The maximum test pressures considered for CH4 and n-C4H10 are 50 bar and 2 bar, respectively. Grand Canonical Monte Carlo (GCMC) simulations are then applied to calculate the density of the adsorption phase by considering the fluid-pore surface interactions. We use such calculated density of the adsorption phase to calibrate the excess adsorption/desorption isotherms, which enables us to eventually obtain the absolute adsorption/desorption isotherms. Such approach for estimating the density of the adsorption phase is essentially different from the commonly used approaches in which the density of the adsorption phase is considered to be independent of temperature, pressure, and pore size. The adsorption/desorption test results show that both CH4 and n-C4H10 exhibit more adsorption as temperature decreases or pressure increases. Their adsorption/desorption isotherms exhibit hysteresis phenomenon and this phenomenon weakens as temperature increases. Comparatively, the hysteresis behavior observed for n-C4H10 is more obvious than that for CH4. Compared with CH4, n-C4H10 has higher adsorption capacity under the same condition, indicating its higher affinity towards the shale with organic matters. As for the conventional approaches, the density calculated from the van der Waals constant b or the liquid hydrocarbon density can be used to reasonably well evaluate the absolute adsorption isotherms of n-C4H10 on shale, but tends to underestimate the absolute adsorption of CH4 on shale. GCMC simulations show that the density of the adsorption phase is strongly correlated with system pressure, temperature, and pore size. Compared to the conventional approaches, GCMC simulations can better capture the in-situ density of adsorption phase; on the basis of the in-situ density of adsorption phase, we can then achieve more accurate determination of the absolute adsorption isotherms of a given hydrocarbon on shale. This study raises the imperativeness of leveraging more sophisticated simulation tools (such as GCMC) for more accurate determination of absolute adsorption isotherms.

    更新日期:2018-01-17
  • Catalytic upgrading of pyrolysis vapors from lignite over mono/bimetal-loaded mesoporous HZSM-5
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Xue-Yu Ren, Jing-Pei Cao, Xiao-Yan Zhao, Zhen Yang, Tian-Long Liu, Xing Fan, Yun-Peng Zhao, Xian-Yong Wei

    HZSM-5 was modified via alkaline treatment and wet impregnation method which loading transition metals (Co, Mo–Co and Ni–Co). The performance of catalysts for the catalytic fast pyrolysis of lignite was tested in a drop tube reactor at 600 °C. In comparison to non-catalytic experiment, the chemical composition of upgrading tar was obviously simplified, which mainly contains light aromatics such as benzene, toluene, ethylbenzene, xylene and naphthalene (BTEXN). The yield of BTEXN was significantly increased from 12.9 to 26.4 mg/g when Ni/Co-H-5 was used. Meanwhile, the Ni/Co-H-5 treated by NaOH solution achieved considerable deoxygenation performance (86.6%) than other ones. The addition of bimetallic Mo–Co or Ni–Co significantly enhanced the BTEXN selectivity of HZSM-5. Ni promoted H2 formation in gaseous product and caused the decrease of naphthalenes yield. Whereas the yields of toluene and o-xylene increased after the pyrolysis vapors pass through Mo/Co-H-5. The zeolite treated by NaOH solution (AT-HZSM-5) favors the generation of aromatics and phenolics, conversely naphthalene derivatives. Moreover, AT-Mo/Co-H-5 and AT-Ni/Co-H-5 inhibited the coke formation. A catalytic pathway was also proposed to describe the diffusion process of pyrolysis vapors on the active site of catalyst.

    更新日期:2018-01-17
  • Conversion of petroleum emulsion into light fraction-rich upgraded oil in supercritical methanol
    Fuel (IF 4.601) Pub Date : 2018-01-12
    Muhammad Kashif Khan, Winarto Kwek, Jaehoon Kim
    更新日期:2018-01-17
  • Computational optimization of the combustion system of a heavy duty direct injection diesel engine operating with dimethyl-ether
    Fuel (IF 4.601) Pub Date : 2018-01-16
    Jesús Benajes, Ricardo Novella, Jose Manuel Pastor, Alberto Hernández-López, Sage L. Kokjohn

    A genetic algorithm optimization methodology is applied to the design of the combustion system of a heavy-duty diesel engine fueled with dimethyl ether (DME). The optimization includes the key combustion system related hardware, bowl geometry and injection nozzle design, together with the most relevant air management and injection settings. The GA was linked to the KIVA computational fluid dynamics code and an automated grid generation tool to perform a single-objective optimization. The optimization target focused on maximizing efficiency, while keeping NOx emissions, peak pressure and maximum pressure rise rate under the baseline engine levels. This research work not only provides the optimum combustion system definition, but also the cause-effect relation between the inputs and outputs under investigation, identifying the most relevant parameters controlling the performance of a DME fueled engine. Piston bowl geometry is found to primarily influence heat transfer and combustion efficiency due to its impact on the surface area and fuel distribution, respectively. Mixing is most affected by the injection system parameters. Finally, the optimum DME engine configuration provides 6.9% absolute net indicated efficiency improvement over the baseline engine fueled with DME. This study confirms the potential of DME as a promising fuel for the future generation of compression ignition engines and demonstrates the need to co-optimize the fuel and combustion system.

    更新日期:2018-01-17
  • MOF for Template-Directed Growth of Well-Oriented Nanowire Hybrid Arrays on Carbon Nanotube Fibers for Wearable Electronics Integrated with Triboelectric Nanogenerators
    Nano Energy (IF 12.343) Pub Date : 2018-01-17
    Jingxin Zhao, Huayang Li, Chaowei Li, Qichong Zhang, Juan Sun, Xiaona Wang, Jiabin Guo, Liyan Xie, Jixun Xie, Bing He, Zhenyu Zhou, Conghua Lu, Weibang Lu, Guang Zhu, Yagang Yao
    更新日期:2018-01-17
  • Hybrid Thermoelectric Battery Electrode FeS2 Study
    Nano Energy (IF 12.343) Pub Date : 2018-01-17
    Chao Wang, Yi Niu, Jing Jiang, Yide Chen, Hanqing Tian, Rui Zhang, Ting Zhou, Junfeng Xia, Yan Pan, Shuangyin Wang
    更新日期:2018-01-17
  • Copper indium selenide water splitting photoanodes with artificially designed heterophasic blended structure and their high photoelectrochemical performances
    Nano Energy (IF 12.343) Pub Date : 2018-01-17
    Joo Sung Kim, Seung Ki Baek, Young Been Kim, Hyun Woo Do, Yong Hun Kwon, Sung Woon Cho, Young Dae Yun, Jae Hong Yoon, Han-Bo-Ram Lee, Sang-Woo Kim, Hyung Koun Cho
    更新日期:2018-01-17
  • Oxygen-Deficient Ta2O5 Nanoporous Films as Self-Supported Electrodes for Lithium Microbatteries
    Nano Energy (IF 12.343) Pub Date : 2018-01-17
    Senlin Xia, Jiangfeng Ni, Serguei V. Savilov, Liang Li
    更新日期:2018-01-17
  • 更新日期:2018-01-17
  • Electrochemical Desalination of Seawater and Hypersaline Brines with Coupled Electricity Storage
    ACS Energy Lett. Pub Date : 2018-01-16
    Divyaraj Desai, Eugene S. Beh, Saroj Sahu, Vedasri Vedharathinam, Quentin van Overmeere, Charles F. de Lannoy, Arun P. Jose, Armin R. Völkel, Jessy B. Rivest
    更新日期:2018-01-17
  • Water-in-Salt Electrolyte for Potassium-Ion Batteries
    ACS Energy Lett. Pub Date : 2018-01-16
    Daniel P. Leonard, Zhixuan Wei, Gang Chen, Fei Du, Xiulei Ji
    更新日期:2018-01-17
  • Evaluation of hydrogen production from harvesting wind energy at high altitudes in Iran by three extrapolating Weibull methods
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Zabihollah Najafian Ashrafi, Masoud Ghasemian, Misagh Irandoost Shahrestani, Erfan Khodabandeh, Ahmad Sedaghat

    One of the most appropriate ways for energy storage is producing hydrogen from renewable resources. Wind energy is recognized as one of the widely used renewable energy resources. This paper investigates the use of wind energy for producing hydrogen in Iran. To achieve this, the country is divided into five major regions: center, north, south, east and west. The performance of three large-scale commercial wind turbines, ranging from 1500 kW to 3000 kW at hub height of 80 m and four large-scale wind turbine ranging from 2000 kW to 4500 kW at hub height of 120 m are evaluated for producing hydrogen in 150 wind stations in Iran. All wind data were recorded based on 10-min time intervals for more than one year at different wind mast heights. For estimating Weibull parameters, the Standard Deviation Method (SDM), Empirical Method of Lysen (EML) and Power Density Method (PDM) are used. An extrapolation method is used to determine the shape and the scale parameters of the Weibull distribution at the high attitudes of 80 m and 120 m. Then, power law and surface roughness exponents, capacity factor, annual energy production and annual hydrogen production for the wind sites are determined. The results indicate that rated power is not the only determinative parameter and the highest hydrogen production is from the GW-109/2500 wind turbine at the hub height of 80 m and from E112/4500 at the hub height of 120 m. For better assessment, the amount of hydrogen production is depicted in Geographic Information Science (GIS) maps using power production of the seven wind turbine models. Next by analyzing these GIS maps, it is found that there are significant potentials in north, north-west, east and south of Iran for producing hydrogen from wind energy.

    更新日期:2018-01-17
  • 更新日期:2018-01-17
  • Exploring the role of the spacers and acceptors on the triphenylamine-based dyes for dye-sensitized solar cells
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Jagadeeswari Sivanadanam, Ramesh Mukkamala, Sudip Mandal, Raman Vedarajan, Noriyoshi Matsumi, Indrapal Singh Aidhen, Kothandaraman Ramanujam

    Six triphenylamine-based dyes were explored for their application in dye-sensitized solar cells (DSSCs). Dyes 1–3 and dyes 4–6 possess cyanoacrylic acid (C-acceptor) and rhodanine-3-acetic acid (R-acceptor), respectively. Stilbene (in dyes 2 and 5) and bis(styryl)benzene (in dyes 3 and 6) were used as π-spacers. There is no π-spacer in the dye 1 and 4. To elucidate the role of π-spacers, optical, electrochemical, and photovoltaic properties of the dyes were studied. Among C-acceptor dyes, dye 2 exhibits the highest light-to-electricity conversion efficiency of 4.45%, followed by dye 3 (4.16%). Similarly, among R-acceptor dyes, dye 5 is the best. These results indicate that stilbene is a better π-spacer over bis(styryl)benzene. Although bis(styryl)benzene could extend the light absorption range (in dye-adsorbed TiO2 film), its tendency to promote intermolecular π-π stacking is possibly the reason for its poor performance in DSSCs. Furthermore, the conjugation break in the R-acceptor moiety attached to the TiO2 surface limits the electron injection of R-acceptor dyes poorer than C-acceptor dyes. Density functional theory calculations were performed for the dye-(TiO2)8 cluster, assuming a bidentate chelation of a carboxylic acid group with Ti4+ of TiO2 anatase. The natural bond orbital (NBO) analysis indicated relatively more electron-accepting ability of cyanoacrylic acid over rhodanine-3-acetic acid.

    更新日期:2018-01-17
  • Characterization of Fe2O3/CeO2 oxygen carriers for chemical looping hydrogen generation
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Shiwei Ma, Shiyi Chen, Ahsanullah Soomro, Min Zhu, Wenguo Xiang

    Fe2O3 is currently the most proper active metal oxide for chemical looping hydrogen generation (CLHG). However, supports are necessary to improve the reactivity and redox stability. CeO2 can enhance the oxygen mobility, leading to high redox reactivity and carbon deposition resistance, which can be an excellent alternative support for oxygen carriers. In this paper, Fe2O3/CeO2 oxygen carriers prepared by the co-precipitation method with different Fe2O3 loadings were investigated on a batch fluidized bed regarding the hydrogen yield and purity, redox reactivity and stability in CLHG with CO as fuel. The results showed that Fe6Ce4 is the best given comprehensive performance with no CO or CO2 observed in the obtained hydrogen (detection limit 0.01% in volume). The oxygen mobility property for the reducible support CeO2 and the physical contact between un-integrated Fe2O3 and CeO2 could improve the reduction of Fe2O3. In addition, the formation of the hematite-like solid solution and perovskite-type CeFeO3 could bring about abundant oxygen vacancies and promote the oxygen mobility, which contributes to the elimination of carbon deposition, counteracts the negative effect of serious sintering and guarantees the reactivity and redox stability of the Fe2O3/CeO2 oxygen carriers. The Fe2O3/CeO2 oxygen carriers were characterized by carbon monoxide temperature-programmed reduction measurement and X-ray diffraction patterns, and Fe6Ce4 was also selected to be characterized by scanning electron microscopy images and energy dispersive X-ray spectrometer analysis.

    更新日期:2018-01-17
  • (Pr0.9La0.1)2(Ni0.74Cu0.21Nb0.05)O4+δ-Ce0.9Gd0.1O2−δ (GDC) as an active and CO2-tolerant nano-composite cathode for intermediate temperature solid oxide fuel cells
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Geng Li, Hongyun Jin, Liangqi Gui, Beibei He, Ling Zhao

    Nano composite of Ruddlesden-Popper electrocatalyst-oxygen ionic conductor, (Pr0.9La0.1)2(Ni0.74Cu0.21Nb0.05)O4+δ (PLNCN)-Ce0.9Gd0.1O2−δ (GDC), is developed as composite cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) via a infiltration way. The electrochemical behavior of PLNCN-GDC nanostructured electrode is assessed with respect to infiltration loading and oxygen partial pressure. The optimized PLNCN loading can improve charge transfer dynamics for electrochemical oxygen reduction reaction, thus promoting cathode performance. Importantly, the encouraging results of single cell highlight high activity and good CO2 tolerance of PLNCN-GDC nanostructured cathode.

    更新日期:2018-01-17
  • Hydrogen separation by thin vanadium-based multi-layered membranes
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Stefano Fasolin, Simona Barison, Stefano Boldrini, Alberto Ferrario, Matteo Romano, Francesco Montagner, Enrico Miorin, Monica Fabrizio, Lidia Armelao

    Thanks to their high hydrogen permeability, vanadium based alloys can be a valuable and sustainable alternative to palladium alloys, commonly employed in commercial membranes for hydrogen purification/separation. In this work, the unprecedented deposition of micrometric vanadium-based multilayers and their investigation as hydrogen selective membranes have been reported. In particular, this work describes the use of High Power Impulse Magnetron Sputtering, a technique easily scalable also for complex geometries, for the deposition of dense and crystalline Pd/V93Pd7/Pd multilayers with total thickness <7 μm onto porous alumina. These membranes showed high hydrogen fluxes in the 300–400 °C range, up to 0.26 mol m−2 s−1 at 300 kPa pressure difference and 375 °C, as well as an unexpected and significant resistance to hydrogen embrittlement and to syngas in operating conditions.

    更新日期:2018-01-17
  • Effects of surface coating with Cu-Pd on electrochemical properties of A2B7- type hydrogen storage alloy
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Yibo Wang, Wukui Tang, Feng Wang, Cuiping Ding, Shimeng Xu, Ronghai Yu

    La0.75Mg0.25Ni3.2Co0.2Al0.1 hydrogen storage alloy, the nickel-metal hydride (MH/Ni) secondary battery negative electrode, was modified by CuSO4 solution (3 wt% in Cu in contrast with alloy weight) and PdCl2 solution varied from 1 wt% to 4 wt% in Pd in contrast with alloy weight with a simplified pollution-free replacement plating method, aiming at improving its comprehensive electrochemical properties. The XRD analysis and SEM images combined with EDS results reveal that Cu and Pd nanoparticles are uniformly plated on the pristine alloy surface. The relative amount of Pd on the Cu-Pd coated alloy surface increases notably as the PdCl2 concentration increases in the plating solution. Electrochemical tests indicate that alloy electrodes modified by Cu-Pd composite coating show perfect activation performance, which achieve the maximum discharge capacity at the first charge-discharge cycle. Moreover, alloy electrodes coated with Cu-Pd perform dramatically enhanced high rate dischargeability (HRD). The enhancement increases firstly and then decreases as the content of Pd increases in the Cu-Pd coating. Meanwhile, the cycle life of modified alloys is also improved significantly. Among all the samples, the Cu-Pd coated alloy with 3 wt% Pd content in the PdCl2 solution reinforces the comprehensive electrochemical properties most sufficiently, with dischargeability of 86.4% under 1500 mA/g and remaining capacity of 82.7% after 100 cycles.

    更新日期:2018-01-17
  • One-pot hydrothermal synthesis of supported CoS electrocatalysts: The effect of support nature on oxygen reduction reaction activity in alkaline medium
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    S.M. Senthil Kumar, K. Selvakumar, R. Thangamuthu

    The development of efficient and durable earth-abundant electrocatalysts for the oxygen reduction reaction (ORR) is an ongoing challenge. In this work, we directly anchored CoS nanocatalysts (20 wt%) on different supports, namely, carbon nanotubes (CNTs) and reduced graphene oxide by a single-pot hydrothermal route. The developed synthesis processes enabled us to alter the composite nature of CoS by changing the sulfur precursor used. The corresponding electrocatalytic performance of these composite catalysts toward the ORR was studied in alkaline medium. The increase in the effective electrode surface area that accompanies the CoS nanocomposite substantially boosts its ORR catalytic performance. The CoS-CNT-Cy hybrid material shows an onset potential of 0.85 V, which is 60–200 mV less negative than that of other catalysts tested. The catalytic current density achieved with the hybrid material at 0.2 mg cm−2 is comparable with that of commercial Pt/C (20%). The synergistic effect of CNTs and CoS enhances the overall performance of the hybrid catalyst. Extension of this nanocomposite strategy to other earth-abundant materials could similarly enable inexpensive electrocatalysts that lack the high intrinsic activity of the noble metals.

    更新日期:2018-01-17
  • An investigation of efficient microstructured reactor with monolith Co/anodic γ-Al2O3/Al catalyst in Fischer-Tropsch synthesis
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Li Zhang, Hualong Chu, Hao Qu, Qi Zhang, Hong Xu, Jun Cao, Zhiyong Tang, Jin Xuan

    A new type of microstructured reactor was applied in Fischer-Tropsch synthesis (FTS). Monolith Co/anodic γ-Al2O3 plate type catalyst was adopted in the microstructured reactor which has the advantage that the microchannel was achieved through the gap between the catalyst plates, not machining. The γ- Al2O3 support was prepared on aluminum plate following the anodization method. And the cobalt was loaded on the anodic γ-Al2O3 support by impregnation. The thickness, morphology, structure, reduction behavior and the catalytic performance of the catalyst were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), as well as the H2 temperature-programmed reduction (H2-TPR). The performance of the catalyst and the microstructured reactor was experimentally characterized in FTS. The CO conversion (19.42%) with 2.7% of CH4 selectivity and 95.77% of C5+ selectivity was obtained with the newly designed microstructured reactor at 220 °C and 2.0 MPa under a gas hourly space velocity (GHSV) of 5,000 h−1. And the activity of the catalyst can be shown greatly in this microstructured reactor. Furthermore, the new developed microreactor is simpler in structure and easier to manufacture at low cost compared with the microchannel reactors requiring precise machining. And the deactivation catalyst after long period operation can be easily replaced for this kind of microstructured reactor.

    更新日期:2018-01-17
  • Preparation and performances of Cu single bond Co spinel coating on ferritic stainless steel for solid oxide fuel cell interconnect
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    X. Zhang, P.F. You, H.L. Zhang, X.G. Yang, M.Q. Luo, Chaoliu Zeng

    A compact and adherent Co single bond Cu spinel coating on ferritic stainless steel was developed by electroplating a Co single bond Cu alloy layer followed by oxidation. The Co single bond Cu alloy was oxidized into a three-layer structure consisted of a thinner CuO outer layer, a middle thicker Cu0.92Co2.08O4 layer and an inner Co3O4 layer after an oxidation treatment of 2 h at 800 °C in air. The three-layer oxide structure was transformed into a double-layer scale with a (Co,Cr,Cu,Mn,Fe)3O4 spinel outer layer and an inner Cr-rich oxide layer after an oxidation of 500 h at 800 °C in air. The Cu single bond Co coating enhanced the oxidation resistance of the alloy and served as a diffusion barrier against the outward migration of Cr elements. Meanwhile, the area specific resistance (ASR) of the scale for the Cu single bond Co coated alloy was significantly lower than that for the bare sample.

    更新日期:2018-01-17
  • Sustainable hydrogen production options from food wastes
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Gozde Duman, Koray Akarsu, Alper Yilmazer, Tugba Keskin Gundogdu, Nuri Azbar, Jale Yanik

    In this study, two thermochemical processes, namely steam gasification and supercritical water gasification (SCWG), were comparatively studied to produce hydrogen from food wastes containing about 90% water. The SCWG experiments were performed at 400 and 450 °C in presence of catalyst (Trona, K2CO3 and seaweed ash). The maximum hydrogen yield was obtained at 450 °C in presence of K2CO3 catalyst. In second process, hydrothermal carbonization was used to convert food wastes into a high-quality solid fuel (hydrochar) that was further gasified in a dual-bed reactor in presence of steam. The steam gasification of hydrochar was carried out with and without catalysts (iron−ceria catalyst and dolomite). The maximum hydrogen yield obtained from steam gasification process was 28.08 mmol/g dry waste, about 7.7 times of that from SCWG. This study proposed a new concept for hydrogen production from wet biomass, combination of hydrothermal carbonization following steam gasification.

    更新日期:2018-01-17
  • Preparation of metal-free electrocatalysts from cassava residues for the oxygen reduction reaction: A sulfur functionalization approach
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Cinthia J. Mena-Durán, I.L. Alonso-Lemus, P. Quintana, Romeli Barbosa, L.C. Ordoñez, B. Escobar
    更新日期:2018-01-17
  • Numerical optimization of channel to land width ratio for PEM fuel cell
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Mohammad Ziauddin Chowdhury, Omer Genc, Serkan Toros
    更新日期:2018-01-17
  • The effect of metal type on the sulfur tolerance of catalysts supported on niobia for sour water-gas shift reaction
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    Ludmila P.C. Silva, Marina M. Freitas, Rachel M. Santos, Geronimo Perez, Luís E. Terra, Ana C.S.L.S. Coutinho, Fabio B. Passos
    更新日期:2018-01-17
  • Catalysts based on Co-Birnessite and Co-Todorokite for the efficient production of hydrogen by ethanol steam reforming
    Int. J. Hydrogen Energy (IF 3.582) Pub Date : 2018-01-17
    J.F. Da Costa-Serra, A. Chica

    Two structured manganese oxides (Birnessite and Todorokite) containing Co have been studied in the steam reforming of ethanol. It has been found that both materials are active in the hydrogen production, exhibiting high values of conversion of ethanol and selectivities to hydrogen (100% and 70%, respectively). The best results have been obtained with the catalyst based on Todorokite material. Characterization by DRX, BET area, TPR and TEM has allowed to find that the excellent performance exhibited by this material could be attributed to the lower size of the Co metallic particles present in this sample (6 nm vs 12 nm in Birnessite). This lower size could be related to the especial microporous structure of Todorokite precursor, which could provide high-quality positions for the stabilization of the Co metal particles during calcination and reduction steps. Catalytic deactivation has also been considered. Deactivation was found higher for Todorokite-based catalyst, which presented the largest amount of deposited carbon (26.2 wt% for Co-TOD vs 10.6 wt% for Co-BIR). On the other hand, the degree of metal sintering was found similar in both catalysts. Therefore, the deactivation of the catalysts has been attributed primarily to the deposition of coke. The results presented here show that it is possible to prepare new catalysts based on manganese oxides with Birnessite and Todorokite structure and promoted with Co with high catalytic performance in the steam reforming of ethanol.

    更新日期:2018-01-17
  • The Spatial Collection Efficiency of Charge Carriers in Photovoltaic and Photoelectrochemical Cells
    Joule Pub Date : 2018-01-16
    Gideon Segev, Hen Dotan, David S. Ellis, Yifat Piekner, Dino Klotz, Jeffrey W. Beeman, Jason K. Cooper, Daniel A. Grave, Ian D. Sharp, Avner Rothschild
    更新日期:2018-01-16
  • Unlocking the potential of graphene for water oxidation using an orbital hybridization strategy
    Energy Environ. Sci. (IF 29.518) Pub Date : 2018-01-04
    Yingfang Yao, Zhe Xu, Feng Cheng, Wenchao Li, Peixin Cui, Guangzhou Xu, Sheng Xu, Peng Wang, Guodong Sheng, Yadong Yan, Zhentao Yu, Shicheng Yan, Zhaoxu Chen, Zhigang Zou
    更新日期:2018-01-16
  • Mechanically-stacked perovskite/CIGS tandem solar cells with efficiency of 23.9% and reduced oxygen sensitivity
    Energy Environ. Sci. (IF 29.518) Pub Date : 2018-01-02
    Heping Shen, The Duong, Jun Peng, Daniel Jacobs, Nandi Wu, Junbo Gong, Yiliang Wu, Siva Krishna Karuturi, Xiao Fu, Klaus Weber, Xudong Xiao, Thomas P. White, Kylie Catchpole
    更新日期:2018-01-16
  • 更新日期:2018-01-16
  • Partial Oxidation of Filter Cake Particles from Biomass Gasification Process in the Simulated Product Gas Environment
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Jun-fei Jiang, Lin Lang, Le-teng Lin, Hua-cai Liu, Xiu-li Yin, Chuang-zhi Wu

    Filtration failure occurs when filter media are blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCPs) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermogravimetric analysis through a temperature-programmed route in a 2 vol % O2–N2 environment. Partial oxidation of the FCPs in the simulated product gas environment was examined at 300–600 °C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely, drying, preoxidation, complex oxidation, and nonoxidation, occurred in the FCP partial oxidation when the temperature increased from 30 to 800 °C in a 2 vol % O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725 °C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400 °C and 1.59 g/cm2, respectively. The FCPs were characterized before and after partial oxidation by Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunaeur–Emmett–Teller analysis. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCPs can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C═O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analyses suggest that, during partial oxidation, the FCPs underwent pore or pit formation, expansion, amalgamation, and destruction.

    更新日期:2018-01-16
  • Pyrolysis Kinetics of Heavy Oil Asphaltenes under Steam Atmosphere at Different Pressures
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Alexandra Boytsova, Natalia Kondrasheva, Jorge Ancheyta

    Thermogravimetric analysis was used to study the pressure effect on the activation energy during asphaltene gasification. The experiments were carried out under steam atmosphere at different pressures (1–80 bar) and temperatures (100–900 °C). The measured values of the total mass loss of asphaltenes are pressure dependent. They increase with rising pressure. Kinetic parameters were determined using a first-order kinetic model and integral method with thermogravimetric analysis data. The activation energy was found to vary from 189.6 to 130.4 kJ/mol and frequency factor from 4.1 × 1010 to 1.2 × 106 min–1. A decrease of both parameters was observed with an increasing pressure. Coke produced during the gasification is obviously characterized by the bigger pore size and weaker mechanical strength as the pressure increases from 1 to 80 bar. The structure of the produced coke becomes more crumbly with raising pressure. The formation of spherical carbon particles with a radius of around 5 μm was observed at high pressure (20–80 bar). The elemental composition of these particles is roughly equal: C (∼97%), S (∼2%), and O (∼1%).

    更新日期:2018-01-16
  • Characteristics of Methane (CH4) Diffusion in Coal and Its Influencing Factors in the Qinshui and Ordos Basins
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Junlong Zhao, Dazhen Tang, Yong Qin, Hao Xu, Yulong Liu, Haiyong Wu

    Diffusion coefficient is usually used to evaluate the methane (CH4) diffusion properties in the coal matrix and is vital to coalbed methane (CBM) development. Although extensive literature on the CH4 diffusion coefficient can be obtained, most of them aim at the whole coal or coal rank instead of the macrolithotype. Additionally, the primary structure of coal was destroyed with the common determination technologies (e.g., the particle, steady-state, and inverse diffusion methods) which could result in great errors. In this work, to avoid the shortcomings of the above methods, nine flake coal samples from six coal mines in the Qinshui and Ordos Basins were prepared to determine the CH4 diffusion coefficient with the slab calculation model. Meanwhile, the effects on the diffusion from the gas pressure, temperature, water saturability, and coal pore structure, and the gas adsorption capacity controlled by the coal rank and macrolithotype, were analyzed to reveal the diffusion mechanism (mode) at the CBM reservoir and laboratory conditions. Results show that the CH4 diffusion coefficient, at an order of magnitude of 10–10 m2/s measured with the flake coal sample, is more truthful. High temperature and gas pressure, low water saturability, developed pore structure, and high gas adsorption capacity contribute to large CH4 diffusion coefficient. Although the higher rank coal has the larger gas adsorption capacity, the CH4 diffusion coefficient exhibits a “U” shape (first decreasing and then increasing) with the increase of coal rank due to more micropores in low- and high-rank coals than the middle-rank coal. From the bright to dull coals at the same coal rank, the decreasing development of pore structure and gas adsorption capacity causes the decreasing CH4 diffusion coefficient. But compared to the coal rank, the influence of coal macrolithotype on CH4 diffusion coefficient is weaker. In addition, the CH4 diffusion modes in coal mainly are transitional and Fick diffusions in the CBM reservoir and laboratory.

    更新日期:2018-01-16
  • Effects of Hydrogen Addition on the Standoff Distance of Premixed Burner-Stabilized Flames of Various Hydrocarbon Fuels
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Lei Xu, Fuwu Yan, Yu Wang

    The quenching distance of premixed hydrocarbon flames is of significant importance for studying flame/wall interactions and for understanding the unburned hydrocarbon emissions of internal combustion engines. Motivated by the fact that the standoff distance of premixed burner-stabilized flames could be used to investigate the behavior of head-on quenching distance of freely propagating flames despite the different physics involved, a parametric investigation on the standoff distances of methane, ethane, and propane burner-stabilized flames was conducted numerically using a detailed chemical kinetic mechanism, with a focus on the effects of hydrogen addition. Specifically, the minimum standoff distance was found to quantitatively correlate with the head-on quenching distance of premixed flames. The variations of the minimum standoff distance as a function of hydrogen fractions were then investigated in detail. The results showed that as hydrogen fraction increased, the minimum standoff distances decreased monotonously for all the hydrocarbon/air flames, with the reduction being most significant for methane fuel. Accompanying kinetic analysis showed that hydrogen addition enhances the heat release process, which promotes the reduction of minimum standoff distance. Subsequently, the dependences of the minimum standoff distance on fuel dilution, equivalence ratios, unburned gas temperatures, and pressures were explored. In addition, the potential to study the parametric dependence on unburned hydrocarbons emissions induced by near-wall flame quenching using the burner-stabilized flame model was discussed. The current study provides a useful approach to quantify the quenching distance of premixed flames, which has practical applications in internal combustion engines. Moreover, the dependence of standoff distance on hydrogen addition and other varying flame parameters can now be more fundamentally understood with the help of detailed chemical kinetics.

    更新日期:2018-01-16
  • Acid-Catalyzed Ring Opening of Furan in Aqueous Solution
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Xiao Liang, Brian S. Haynes, Alejandro Montoya
    更新日期:2018-01-16
  • Simultaneous Removal of SO2 and NOx from Coal-Fired Flue Gas Using Steel Slag Slurry
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Ziheng Meng, Chenye Wang, Xingrui Wang, Yan Chen, Huiquan Li
    更新日期:2018-01-16
  • Adsorption and Dissolution Behaviors of Carbon Dioxide and n-Dodecane Mixtures in Shale
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Chaofan Zhu, Yajun Li, Houjian Gong, Qian Sang, Zijin Li, Mingzhe Dong

    CO2 cyclic injection is a promising method for enhanced shale oil recovery. However, the enhanced shale oil recovery mechanism is unclear, especially the adsorption and dissolution of CO2 and oil in kerogen. Therefore, it is of great importance to study the adsorption and dissolution mechanisms of CO2 and oil mixtures in shale. In this study, a new experimental apparatus was designed to test the change in the mole fractions of CO2 and oil before and after adsorption and dissolution at equilibrium conditions. For simplicity, n-dodecane (n-C12) was used as the oil. The adsorption and dissolution amounts of CO2 and n-C12 were obtained using a mathematical method. Moreover, the adsorption and dissolution characteristics of the CO2 and n-C12 mixtures in shale and the effect of pressure on the adsorption and dissolution amounts were studied. Finally, the swelling factor of the shale, which was caused by the dissolution of the mixtures, was calculated from the experimental results. The results show that dissolved n-C12 in shale could be replaced by CO2 when the mole fraction of CO2 in the free phase was larger than a threshold. The adsorption and dissolution amounts of CO2 and n-C12 increased with pressure. The lower pressure and larger mole fraction of CO2 enabled a lower swelling factor of shale. This study provides a straightforward method to experimentally determine the adsorption and dissolution properties of shale, which can be used to evaluate enhanced shale oil recovery by CO2 injection and the geological storage of CO2.

    更新日期:2018-01-16
  • Asphaltene Deposition during Bitumen Extraction with Natural Gas Condensate and Naphtha
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    ZhenBang Qi, Ali Abedini, Atena Sharbatian, Yuanjie Pang, Adriana Guerrero, David Sinton

    Solvent bitumen extraction processes are alternatives to thermal processes with potential for improved economic and environmental performance. However, solvent interaction with bitumen commonly results in in situ asphaltene precipitation and deposition, which can hinder flow and reduce the process efficiency. Successful implementation requires one to select a solvent that improves recovery with minimal flow assurance problems. The majority of candidate industrial solvents are in the form of mixtures containing a wide range of hydrocarbon fractions, further complicating the selection process. In this study, we quantify the pore-scale asphaltene deposition using two commonly available solvent mixtures, natural gas condensate and naphtha, using a microfluidic platform. The results are also compared with those of two typical pure solvents, n-pentane and n-heptane, with all cases evaluated with both 50 and 100 μm pore-throat spacing. The condensate produced more asphaltenes and pore-space damage than the naphtha and exhibited deposition dynamics similar to that of pentane and heptane. This similarity is due to the presence of a large amount of light hydrocarbon fractions in condensate (∼85 wt % of C5s–C7s) dictating the overall deposition dynamics. Naphtha, which contains heavier fractions (∼70 wt % of C8s–C11s) and aromatic/naphthenic components, generated less asphaltenes and exhibited a slower deposition rate, resulting in less pore damage and overall better performance.

    更新日期:2018-01-16
  • What Fraction of the Asphaltenes Stabilizes Water-in-Bitumen Emulsions?
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    J. A. Rocha, E. N. Baydak, H. W. Yarranton

    It is hypothesized that only a fraction of the asphaltenes acts to stabilize emulsions and that this fraction consists of the most self-associated (least soluble) asphaltenes. To test the hypothesis, the effects of removing the least soluble versus the most interfacially adsorbed asphaltenes on emulsion stability, film properties, and mass surface coverage were compared. The least soluble asphaltenes were removed by precipitation from solutions of asphaltenes in heptane and toluene. The most adsorbed asphaltenes were removed by separating an asphaltene-stabilized emulsion from its continuous phase. Brine-in-oil emulsions were prepared using organic phases of 10 g/L of the residual asphaltene fractions from the supernatant or continuous phase. The stability of the emulsions was assessed in terms of percentage of water resolved after repeated treatment cycles involving heating at 60 °C and centrifugation at 3500 rpm. The three asphaltenes examined were extracted from a mined oil sand bitumen, a bitumen from a cyclic steam process, and a bitumen from a SAGD process. Only some of the species in the asphaltenes were found to strongly stabilize emulsion, and the size of this fraction ranged from 2% to >65% in the three samples of this study. The most adsorbed, highly stabilizing material tended to be concentrated in the least soluble fraction of the asphaltenes, consistent with the proposed hypothesis. The emulsion stability data were generally consistent with a previously observed threshold of 5 mg/m2 asphaltene surface coverage for stable emulsions. Fractionating the asphaltenes eventually removed enough of the self-associated material that the surface coverage dropped below the threshold and unstable emulsions were observed.

    更新日期:2018-01-16
  • Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils
    Energy Fuels (IF 3.091) Pub Date : 2018-01-16
    Yuzhuo Li, Shanpeng Han, Yingda Lu, Jinjun Zhang

    We report for the first time the results from a systematic investigation of how asphaltenes of different polarity affect crystallization and gelation of waxy oils. The more polar asphaltenes were found to be more aromatic in nature and more highly self-aggregated in the solvent. The presence of less polar asphaltenes in the waxy oil reduced the wax appearance temperature and wax precipitation to a greater degree compared to more polar asphaltenes, which was mainly attributed to the difference in the aggregation state of asphaltenes of different polarity. Reducing the polarity of asphaltenes present in the oil also resulted in a lower gelation temperature, lower storage modulus, and lower yield stress, which was probably because the less polar asphaltenes were more similar to wax on the molecular level and, thus, more readily interacting with wax. Notably, a 99% reduction in the yield stress was observed upon the addition of the least polar asphaltenes examined in the present work, in contrast to the 62% yield stress reduction upon the addition of the most polar asphaltenes. This observation may be of industrial significance because it suggests that the crude oil containing less polar asphaltenes may form a softer gel or deposit that is more easily broken or removed. Microscopic analysis showed that the wax crystals precipitated in the presence of less polar asphaltenes have a smaller aspect ratio.

    更新日期:2018-01-16
  • The Interplay of Oxygen Functional Groups and Folded Texture in Densified Graphene Electrodes for Compact Sodium-Ion Capacitors
    Adv. Energy Mater. (IF 16.721) Pub Date : 2018-01-16
    Jun Zhang, Wei Lv, Dequn Zheng, Qinghua Liang, Da-Wei Wang, Feiyu Kang, Quan-Hong Yang
    更新日期:2018-01-16
  • Wettability of reservoir rocks having different polarity by a model nonionic surfactant: fluid imbibition study into crushed rock packs
    Energy Fuels (IF 3.091) Pub Date : 2018-01-15
    Andrei Zelenev, Zlata Grenoble

    The imbibition of solutions of a model nonionic surfactant into packed beds of crushed reservoir rocks was studied using the Washburn technique. A linear dependence between the equivalent height of capillary rise and the square root of imbibition time was observed at different stages of imbibition experiments. It has been shown that under the conditions when surfactants did not alter the polarity of rocks, the imbibition rate of surfactant solutions correlated well with the polar non-dispersion component of surface free energy of the rocks. It was possible to compare data obtained for different rocks by normalizing the slopes of imbibition curves over the corresponding slopes determined for a completely wetting fluid, hexamethyldisiloxane (HMDS). Such normalization allowed one to account for substantial differences in the morphology of crushed rock powders. Overall, the observed trends in the imbibition behavior were qualitatively similar to the trends reported previously for the rise of surfactant solutions in single capillaries. The largest qualitative impact of nonionic surfactant was observed in the imbibition into hydrophobic oily sandstone, in which case a surfactant-induced shift to hydrophilicity was observed. Overall, high concentrations were needed in order to observe the impact of surfactant on the imbibition rate.

    更新日期:2018-01-16
  • Gold plasmon-induced photocatalytic dehydrogenative coupling of methane to ethane on polar oxide surfaces
    Energy Environ. Sci. (IF 29.518) Pub Date : 2017-12-22
    Lingshu Meng, Zhenye Chen, Zhiyun Ma, Sha He, Yidong Hou, Hao-Hong Li, Rusheng Yuan, Xi-He Huang, Xuxu Wang, Xinchen Wang, Jinlin Long
    更新日期:2018-01-15
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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