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  • Effects of metals in wastewater on hydrogen gas production using electrohydrolysis
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-21
    Ebru Çokay; Yasin Gürler

    Hydrogen gas was produced from metal plating wastewater by electro hydrolysis. Wastewater contains chrome, copper and nickel metals which can accelerate the production of hydrogen gas. Effects of kind of metals, the voltage and reaction time on percent hydrogen gas (HGP) were investigated. After application of different DC voltages on each metallic wastewater, percent hydrogen gas (HGP), cumulative hydrogen gas volume (CHGV), hydrogen gas formation rate (HFR) and total organic carbon (TOC) removal were also evaluated. Hydrogen gas percent was obtained as %99 at 4 V for chrome plating wastewater while percent hydrogen gas was achieved as 50% H2 gas at 4 V for copper and nickel metal plating wastewater. Maximum CHGV achieved with 4 V DC voltage for all metal plating wastewater. Maximum CHGV (4000 mL), HFR (985 mL H2 d−1) and percent hydrogen gas (99%) was observed with chrome plating wastewater at 4 V DC voltage. Hydrogen gas produced from chrome metal plating wastewater using electro hydrolysis method can be efficiently used for fuel cells as a source due to nearly pure hydrogen gas.

    更新日期:2020-01-17
  • The potential role of hydrogen as a sustainable transportation fuel to combat global warming
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2018-11-23
    Canan Acar; Ibrahim Dincer

    Hydrogen is recognized as a key source of the sustainable energy solutions. The transportation sector is known as one of the largest fuel consumers of the global energy market. Hydrogen can become a promising fuel for sustainable transportation by providing clean, reliable, safe, convenient, customer friendly, and affordable energy. In this study, the possibility of hydrogen as the major fuel for transportation systems is investigated comprehensively based on the recent data published in the literature. Due to its several characteristic advantages, such as energy density, abundance, ease of transportation, a wide variety of production methods from clean and renewable fuels with zero or minimal emissions; hydrogen appears to be a great chemical fuel which can potentially replace fossil fuel use in internal combustion engines. In order to take advantage of hydrogen as an internal combustion engine fuel, existing engines should be redesigned to avoid abnormal combustion. Hydrogen use in internal combustion engines could enhance system efficiencies, offer higher power outputs per vehicle, and emit lower amounts of greenhouse gases. Even though hydrogen-powered fuel cells have lower emissions than internal combustion engines, they require additional space and weight and they are generally more expensive. Therefore, the scope of this study is hydrogen-fueled internal combustion engines. It is also highlighted that in order to become a truly sustainable and clean fuel, hydrogen should be produced from renewable energy and material resources with zero or minimal emissions at high efficiencies. In addition, in this study, conventional, hybrid, electric, biofuel, fuel cell, and hydrogen fueled ICE vehicles are comparatively assessed based on their CO2 and SO2 emissions, social cost of carbon, energy and exergy efficiencies, fuel consumption, fuel price, and driving range. The results show that when all of these criteria are taken into account, fuel cell vehicles have the highest average performance ranking (4.97/10), followed by hydrogen fueled ICEs (4.81/10) and biofuel vehicles (4.71/10). On the other hand, conventional vehicles have the lowest average performance ranking (1.21/10), followed by electric vehicles (4.24/10) and hybrid vehicles (4.53/10).

    更新日期:2020-01-17
  • A review on the catalysts used for hydrogen production from ammonia borane
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-19
    Ceren Yüksel Alpaydın; Senem Karahan Gülbay; C. Ozgur Colpan

    Boron compounds have recently attracted attention in hydrogen production since they contain many hydrogen atoms. Among these compounds, ammonia borane, which has high hydrogen density (in weight basis), can be used to produce hydrogen through a hydrolysis reaction. However, since the ammonia borane solution is highly resistant to hydrolysis under ambient conditions, there is a need for active and stable catalysts to accelerate the reaction. In this review paper, unsupported and carbon-based supported metal catalysts used for hydrogen production through the hydrolysis of ammonia borane are presented. Noble metal catalysts (Ru, Rh, Pd, Pt and their binary and ternary alloys) and non-noble metal catalysts (Co, Ni, Fe, Cu and their binary and ternary alloys) were examined. The activation energy of reaction and turnover frequency (TOF) values were compared for these catalysts. Among the unsupported catalysts, it was concluded that the multi-metal catalyst systems (binary, ternary and quaternary) have higher catalytic activity than a single use of the same metals. In addition, the comparison showed that the supported catalysts are more resistant to catalytic cycles and suitable for long-term use. It was observed that CNT supported Rh (TOF = 706 mol H2 mol cat−1 min−1) and graphene supported Ru (TOF = 600 mol H2 mol cat−1 min−1) catalysts are the most active catalysts for the hydrogen generation from the ammonia borane at room temperature.

    更新日期:2020-01-17
  • Effect of fuel blend composition on hydrogen yield in co-gasification of coal and non-woody biomass
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-15
    Busra Cabuk; Gozde Duman; Jale Yanik; Hayati Olgun

    In this study, torrefaction of sunflower seed cake and hydrogen production from torrefied sunflower seed cake via steam gasification were investigated. Torrefaction experiments were performed at 250, 300 and 350 °C for different times (10–30 min). Torrefaction at 300 °C for 30 min was selected to be optimum condition, considering the mass yield and energy densification ratio. Steam gasification of lignite, raw- and torrefied biomass, and their blends at different ratios were conducted at downdraft fixed bed reactor. For comparison, gasification experiments with pyrochar obtained at 500 °C were also performed. The maximum hydrogen yield of 100 mol/kg fuel was obtained steam gasification of pyrochar. The hydrogen yields of 84 and 75 mol/kg fuel were obtained from lignite and torrefied biomass, respectively. Remarkable synergic effect exhibited in co-gasification of lignite with raw biomass or torrefied biomass at a blending ratio of 1:1. In co-gasification, the highest hydrogen yield of 110 mol/kg fuel was obtained from torrefied biomass-lignite (1:1) blend, while a hydrogen yield from pyrochar-lignite (1:1) blend was 98 mol/kg. The overall results showed that in co-gasification of lignite with biomass, the yields of hydrogen depend on the volatiles content of raw biomass/torrefied biomass, besides alkaline earth metals (AAEMs) content.

    更新日期:2020-01-17
  • Hydrogen production via thermochemical H2O splitting using CaSO4 – CaO redox reactions
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-27
    Rahul R. Bhosale

    By applying the principles of the second law of thermodynamics and utilizing the HSC Chemistry software, the thermodynamic equilibrium and efficiency analysis of the CaSO4CaO water splitting cycle was performed in this investigation. The temperatures desirable and the equilibrium compositions allied with the thermal reduction of CaSO4 and the re-oxidation of CaO via water splitting reaction were estimated. The obtained results indicate that the thermal reduction temperature (TH) required to completely decompose the CaSO4 was decerased from 2220 to 1890 K due to the rise in the molar flow rate of (n˙Ar) from 1 to 50 mol/s. In addition, the consequence of the TH, n˙Ar, and the water splitting temperature (TL) on the process parameters such as total amount of solar energy needed, re-radiation losses, energy dissipated by the water splitting reactor and others associated with the CaSO4CaO water splitting cycle was scrutinized. By utilizing higher n˙Ar from 1 to 50 mol/s, the TH was decreased from 2200 to 1890 K. However, as the n˙Ar was increased from 1 to 50 mol/s, the amount of heat energy needed to heat the Ar was also upsurged from 12.5 to 625.6 kW. This rise in the Q˙Ar−heating, directly reflected into an increase in the Q˙solar−cycle from 1063.4 up to 2653.9 kW. The findings of this study further confirms that the maximum solar-to-fuel energy conversion efficiency (ηsolar−to−fuel) equal to 27.4% was realized by conducting the CaSO4CaO water splitting cycle at TH = 2220 K, n˙Ar = 1 mol/s, and TL = 1100 K. By using 50% of the recuperable heat, the ηsolar−to−fuel of the CaSO4CaO water splitting cycle can be enhanced up to 36.2%.

    更新日期:2020-01-17
  • Design and analysis of a combined floating photovoltaic system for electricity and hydrogen production
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-01-30
    Mert Temiz; Nader Javani

    The current study deals with a potential solution for the replacement of fossil fuel based energy resources with a sustainable solar energy resource. Electrical energy demand of a small community is investigated where a floating photovoltaic system and integrated hydrogen production unit are employed. Data are taken from Mumcular Dam located in Aegean Region of Turkey. PvSyst software is used for the simulation purposes. Furthermore, the obtained results are analyzed in the HOMER Pro Software. Photovoltaic (PV) electricity provides the required load and excess electricity to be used in the electrolyzer and to produce hydrogen. Saving lands by preventing their usage in conventional PV farms, saving the water due to reducing evaporation, and compensating the intermittent availability of solar energy are among the obtained results of the study for the considered scenario. Stored hydrogen is used to compensate the electric load through generating electricity by fuel cell. Floating PV (FPV) system decreases the water evaporation of water resources due to 3010 m2 shading area. FPV and Hydrogen Systems provides %99.43 of the electricity demand without any grid connection or fossil fuel usage, where 60.30 MWh/year of 211.94 MWh/year produced electricity is consumed by electric load at $0.6124/kWh levelized cost of electricity (LCOE).

    更新日期:2020-01-17
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  • Biohydrogen production from acid hydrolyzed wastewater treatment sludge by dark fermentation
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-04-17
    Karapinar Ilgi; Balcan Onur

    Waste generation, waste management, sustainable energy production, and global warming are interrelated environmental issues to be considered together. Wastewater treatment sludge is an organic substance rich waste which causes significant environmental problems. However, these wastes can be used as raw material in biofuel generation. This study was designed to investigate the possible utilization of waste sludge in biohydrogen production by taking these facts into consideration. For this purpose, the sludge was first pre-treated with acid and then, the solid (sludge) and liquid (filtrate) phases of acid pre-treated sludge were used as the substrates for biohydrogen generation dark fermentation. Two-factor factorial experimental design method was used in acid hydrolysis of sludge to determine the effect of pH (pH = 2–6) and reaction period (time, min) elution of chemical oxygen demand (COD), total organic carbon (TOC) and total sugar (TS), NH4N and PO4P. Statistical evaluation of the results indicated that pH significantly affects the elution of organic carbon and nutrient content of sludge while the reaction time is significant for only organic carbon content. The optimum pretreatment conditions for maximum organic and nutrient elution were determined as pH = 2 and t = 1440 min. The pretreated products, named as filtrate sludge and sludge, conducted to dark fermentation under mesophilic conditions for biohydrogen generation showed that pretreatment of waste sludge at pH = 6 is the best condition giving the maximum yields (YH2) as YH2 = 24 mmol g−1 Total Sugar consumed and YH2 = 41 mmol g−1 Total sugar consumed, for filtrate and sludge, respectively.

    更新日期:2020-01-17
  • Application of aspen plus to renewable hydrogen production from glycerol by steam reforming
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-09
    Derya Unlu; Nilufer Durmaz Hilmioglu

    Steam reforming is the most favored method for the production of hydrogen. Hydrogen is mostly manufactured by using steam reforming of natural gas. Due to the negative environmental impact and energy politics, alternative hydrogen production methods are being explored. Glycerol is one of the bio-based alternative feedstock for hydrogen production. This study is aimed to simulate hydrogen production from glycerol by using Aspen Plus. First of all, the convenient reactor type was determined. RPlug reactor exhibited the highest performance for the hydrogen production. A thermodynamic model was determined according to the formation of byproduct. The reaction temperature, water/glycerol molar feed ratio as reaction parameters and reactor pressure were investigated on the conversion of glycerol and yield of hydrogen. Optimum reaction parameters are determined as 500 °C of reaction temperature, 9:1 of water to glycerol ratio and 1 atm of pressure. Reactor design was also examined. Optimum reactor diameter and reactor length values were determined as 5 m and 50 m, respectively. Hydrogen purification was studied and 99.9% purity of H2was obtained at 25 bar and 40 °C. The obtained results were shown that Aspen Plus has been successfully applied to investigate the effects of reaction parameters and reactor sizing for hydrogen production from glycerol steam reforming.

    更新日期:2020-01-17
  • Microarray analysis of high light intensity stress on hydrogen production metabolism of Rhodobacter capsulatus
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-01-22
    Muazzez Gürgan; Harun Koku; Inci Eroglu; Meral Yücel

    Biohydrogen obtained from purple non sulfur bacteria (PNSB) is an environmentally friendly alternative for hydrogen production. PNSB can be employed in large scale outdoor photobioreactors to produce hydrogen by photofermentation with sunlight as the light source. In external environmental conditions, however, bacteria can experience stress due to high light intensities, which can inhibit or slow down hydrogen production. Previous studies with other PNSB showed varying responses to light intensities (above 4000 lux), in some cases improving, and in others adversely affecting hydrogen production. In this study, Rhodobacter capsulatus, a PNSB species that produce hydrogen efficiently from dark fermenter effluents containing acetate, was used to investigate the effects of high light intensity stress on the hydrogen production metabolism at the gene expression level. A microarray analysis was carried out using a custom-design Affymetrix GeneChip TR_RCH2a520699F. R. capsulatus DSM1710 was grown under a cyclic illumination of 2000 and 7000 lux (12 h light/12 h dark) in a hydrogen production medium having 30 mM acetate and 2 mM glutamate, and was exposed to a high light intensity (10,000 lux) for 1 h in the middle of a light period. The results reveal that photosynthetic reaction center genes were down-regulated in order to protect the photosynthetic membrane from damage. On the other hand, the expression of nitrogenase and electron transport system genes were enhanced by high light intensity. These results show that a high light intensity stress drives R. capsulatus to direct gene expression towards hydrogen production, which supports the hypothesis that hydrogen production is a way for the disposal of excess reducing equivalents to maintain the internal redox balance.

    更新日期:2020-01-17
  • The effect of hydraulic retention time on thermophilic dark fermentative biohydrogen production in the continuously operated packed bed bioreactor
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-01-23
    Ilgi Karapinar; Pelin Gokfiliz Yildiz; Recep Tugcan Pamuk; Firuze Karaosmanoglu Gorgec
    更新日期:2020-01-17
  • Enhanced hydrogen purification by graphene - Poly(Dimethyl siloxane) membrane
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-01-29
    Filiz Ugur Nigiz; Nilufer Durmaz Hilmioglu

    In this study, a nanocomposite graphene oxide (GO) incorporated poly (dimethyl siloxane) (PDMS) membrane was produced and used for the purification of hydrogen (H2) by separating the (CO2). The produced membrane was characterized and the single-gas permeability test was performed. Effects of GO addition, trans-membrane pressure and membrane thickness on the gas separation performance of membrane were evaluated as a function of permeability and CO2/H2 selectivity. GO addition increased the CO2/H2 selectivity and H2 purification performance. The highest CO2 permeability of 3670 Barrer and CO2/H2 selectivity of 11.7 were obtained when the GO loading was 0.5 wt% when the trans-membrane pressure was 0.2 Mpa.

    更新日期:2020-01-17
  • Numerical modeling of a downdraft plasma coal gasifier with plasma reactions
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-01-24
    Beycan Ibrahimoglu; M. Zeki Yilmazoglu

    In this paper, a 3D numerical simulation of a downdraft plasma gasifier with plasma reactions is conducted. The effects of the equivalence ratio (ER) on the syngas properties in the presence of the plasma reactions are investigated. The boundary conditions for the air plasma inlet of the gasifier are obtained from the outlet of a 10 kW microwave plasma generator. A conventional gasification analysis is carried out to validate the model. In the second part of the study, plasma reactions are added to conventional gasification equations. Mole fractions of the constituents of the syngas and temperature contours are obtained for different ER values. According to the results, with the increase of ER from 0.20 to 0.45 the lower heating value of the produced syngas decreased from 1536.6 kcal/m3 to 751.8 kcal/m3.

    更新日期:2020-01-17
  • Optimum energy evaluation and life cycle cost assessment of a hydrogen liquefaction system assisted by geothermal energy
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-04-15
    Ceyhun Yilmaz

    In this study, analyses of the thermodynamic performance and life cycle cost of a geothermal energy-assisted hydrogen liquefaction system were performed in a computer environment. Geothermal water at a temperature of 200 °C and a flow rate of 100 kg/s was used to produce electricity. The produced electricity was used as a work input to liquefy the hydrogen in the advanced liquefaction cycle. The net work requirement for the liquefaction cycle was calculated as 8.6 kWh/kg LH2. The geothermal power plant was considered as the work input in the liquefaction cycle. The hydrogen could be liquefied at a mass flow rate of 0.2334 kg/s as the produced electricity was used directly to produce liquid hydrogen in the liquefaction cycle. The unit costs of electricity and liquefied hydrogen were calculated as 0.012 $/kWh and 1.44 $/kg LH2. As a result of the life cycle cost analysis of the system, the net present value (NPV) and levelized annual cost (LAC) were calculated as 123,100,000 and 14,450,000 $/yr. The simple payback period (Nspp) and discount payback period (Ndpp) of the system were calculated as 2.9 and 3.6 years, respectively.

    更新日期:2020-01-17
  • Bimetallic palladium-cobalt nanomaterials as highly efficient catalysts for dehydrocoupling of dimethylamine borane
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-15
    Betül Şen; Ayşenur Aygün; Aysun Şavk; Mehmet Harbi Çalımlı; Senem Karahan Gülbay; Fatih Şen

    In this work, we report the synthesis, characterization and application of graphene oxide stabilized PdCo nanoparticles ([email protected]) for the dehydrocoupling of dimethylamine borane (DMAB) as a model reaction. Bimetallic graphene oxide stabilized PdCo nanoparticles were readily synthesized using an ultrasonic reduction technique, in which both metals of Pd and Co were reduced with GO. The dispersion of PdCo nanoparticles on the surface of GO was enhanced with the help of the ultrasonic reduction method which result in the enhancing of dispersion of both metals without any agglomeration problem. The characterization studies revealed that graphene oxide stabilized PdCo nanoparticles have a uniform, homogeneous distribution on graphene oxide and an average particle size of 3.48 ± 0.22 nm. After fully characterization of graphene oxide stabilized PdCo nanoparticles, they have been tried in model reaction as a catalyst and exhibited a high catalytic performance compared the previous catalysts in literature with a TOF value of 226.80 h−1. The investigation of kinetic parameters showed that graphene oxide stabilized PdCo nanoparticles have very high negative entropy (ΔS: −170.85 J mol−1 K−1) value and a low activation energy value (Ea: 17.53 ± 2 kJ mol−1) for the model reaction.

    更新日期:2020-01-17
  • Modeling and analysis of a model solid oxide fuel cell running on low calorific value coal gases
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-23
    Mustafa İlbaş; Berre Kümük

    Solid oxide fuel cell (SOFC) is a device that produces electricity directly from oxidizing a fuel. Some of the advantages are operating at high temperatures and converting various hydrocarbon fuels directly into electricity. This study investigates the parameters that influence the cell characteristics of a cathode-supported SOFC (CSSOFC) model. Numerical modeling has been performed utilizing low calorific value coal gases, generator gas, and water gas by deriving an SOFC model based on finite element method (FEM). The effects of fuel compositions, temperature, pressure, and porosity on the performance of the developed SOFC have been examined using COMSOL software. These effects are presented by polarization and power curves. A mathematical model has been developed to determine the performance of a CSSOFC with low calorific value coal gases that were obtained from Turkey/Turk coal. It is predicted that the performance of CSSOFC is higher than that of the electrolyte-supported SOFC (ES-SOFC) for all studied fuels. Besides this, the cost of the cathode supporting materials for high-performance CSSOFC is low. The performance of SOFC using water gas is higher than that of the generator gas. This being maybe the hydrogen content of the water gas is higher compared with the generator gas. Therefore, the result confirmed that low calorific value coal gases could be used in SOFCs as a source of fuel. Moreover, the power of the CSSOFC increases as the pressure, temperature, and hydrogen content increase.

    更新日期:2020-01-17
  • Energy and exergy performance assessments of a high temperature-proton exchange membrane fuel cell based integrated cogeneration system
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-22
    Yagmur Nalbant; C. Ozgur Colpan; Yilser Devrim

    High-temperature proton exchange membrane fuel cell (HT-PEMFC), which operates between 160 °C and 200 °C, is considered to be a promising technology, especially for cogeneration applications. In this study, a mathematical model of a natural gas fed integrated energy system based on HT-PEMFC is first developed using the principles of electrochemistry and thermodynamics (including energy and exergy analyses). The effects of some key operating parameters (e.g., steam-to-carbon ratio, HT-PEMFC operating temperature, and anode stoichiometric ratio) on the system performance (electrical, cogeneration, and exergetic efficiencies) are examined. The exergy destruction rates of each component in the integrated system are found for different values of these parameters. The results show that the most influential parameter which affects the performance of the integrated system is the anode stoichiometric ratio. For the baseline conditions, when the anode stoichiometric ratio increases from 1.2 to 2, the electrical, cogeneration, and exergetic efficiencies decrease by 42.04%, 33.15%, and 37.39%, respectively. The highest electrical power output of the system is obtained when the SCR, operating temperature, and anode stoichiometric ratio are taken as 2, 160 °C, and 1.2, respectively. For this case, the electrical, cogeneration, and exergetic efficiencies are found as 26.20%, 70.34%, and 26.74%, respectively.

    更新日期:2020-01-17
  • The effects of driving patterns and PEM fuel cell degradation on the lifecycle assessment of hydrogen fuel cell vehicles
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-13
    Pouria Ahmadi; Seyed Hosein Torabi; Hadi Afsaneh; Yousef Sadegheih; Hadi Ganjehsarabi; Mehdi Ashjaee

    This research paper mainly deals with the realistic simulation of hydrogen fuel cell vehicles and the development of a lifecycle assessment (LCA) tool to calculate and compare the environmental impacts of hydrogen fuel cell passenger vehicles with conventional vehicles. Since fuel cell vehicles are equipped with regenerative braking, they have strong potential to recover an ample portion of the energy being wasted in the braking system. Thus, the driving cycle can significantly affect the performance of fuel cell vehicles. In order to investigate the effect of driving patterns, several driving patterns are considered, and both vehicle fuel economy and lifecycle emissions are calculated and compared. Fuel cell degradation, on the other hand, is another major problem fuel cell vehicles face. This is mainly caused by the starts/stops, acceleration/deceleration, membrane humidity variation and a high load of the engine. When the vehicle operates on various driving patterns, the fuel cell will degrade which eventually affects the fuel economy. The effect of fuel cell degradation is also investigated for these driving patterns, and the results are compared. The results showed that the highway driving cycle has the lowest total lifecycle emission compared to New York city driving cycle, the city of Surrey (CoS) driving cycle, and the UDDS driving cycles. The results also indicate that fuel cell degradation undesirably affected the average fuel economy of the vehicle for about 23%.

    更新日期:2020-01-17
  • Investigation of the effect of graphitized carbon nanotube catalyst support for high temperature PEM fuel cells
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-06
    Yılser Devrim; Elif Damla Arıca

    In this study, it is aimed to investigate the graphitization effect on the performance of the multi walled carbon nanotube catalyst support for high temperature proton exchange membrane fuel cell (HT-PEMFC) application. Microwave synthesis method was selected to load Pt nanoparticles on both CNT materials. Prepared catalyst was analyzed thermal analysis (TGA), Transmission Electron Microscopy (TEM) and corrosion tests. TEM analysis proved that a distribution of Pt nanoparticles with a size range of 2.8–3.1 nm was loaded on the Pt/CNT and Pt/GCNT catalysts. Gas diffusion electrodes (GDE) were manufactured by an ultrasonic spray method with synthesized catalyst. Polybenzimidazole (PBI) membrane based Membrane Electrode Assembly (MEA) was prepared for observe the performance of the prepared catalysts. The synthesized catalysts were also tested in a HT-PEMFC environment with a 5 cm2 active area at 160 °C without humidification. This study demonstrates the feasibility of using the microwave synthesis method as a fast and effective method for preparing high performance Pt/CNT and Pt/GCNT catalyst for HT-PEMFC. The HT-PEMFC performance evaluation shows current densities of 0.36 A/cm20.30 A/cm2 and 0.20 A/cm2 for the MEAs prepared with Pt/GCNT, Pt/CNT and Pt/C catalysts @ 0.6 V operating voltage, respectively. AST (Accelerated Stress Test) analyzes of MEAs prepared with Pt/GCNT and Pt/CNT catalysts were also performed and compared with Pt/C catalyst. According to current density @ 0.6 V after 10,000 potential cycles, Pt/GCNT, Pt/CNT and Pt/C catalysts can retain 61%, 67% and 60% of their performance, respectively.

    更新日期:2020-01-17
  • Degradations in porous components of a proton exchange membrane fuel cell under freeze-thaw cycles: Morphology and microstructure effects
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2018-11-22
    Adnan Ozden; Samaneh Shahgaldi; Jian Zhao; Xianguo Li; Feridun Hamdullahpur

    In this study, porous components of a proton exchange membrane (PEM) fuel cell, i.e., single-layer gas diffusion layer (GDL, carbon paper), double-layer GDL (microporous layer (MPL) deposited carbon papers), and catalyzed electrodes, are subjected to 60 repetitive freeze-thaw cycles between −40 °C and 30 °C under water-submerged conditions; and their morphological and microstructural characteristics are investigated at each 15 cycles and compared with those of virgin materials. The results indicate that consecutive cycling of temperature causes different degradation patterns in different components. The single-layer GDL shows a unique degradation mechanism, in which macro-scale pores volumetrically expand, and relatively small-scale hollows and cracks form on the polymeric binder and carbon fiber interfaces, respectively. For the double-layer GDL, large-scale surface cracks form on the MPL surface after 15 cycles, and the morphology and microstructure degradation gains momentum with the formation of these cracks, and upon completion of 30 cycles, large-scale carbon/hydrophobic agent flakes start to detach from the surface. For the catalyzed electrodes, due to their inherently cracked surface, the catalyst layers (CLs) degrade first through expansion of the cracks in the in- and through-plane directions, and then through swelling and agglomeration of the ionomer; and combination of these two patterns triggers detachment of large CL flakes from the surface, negatively affecting the microstructure.

    更新日期:2020-01-17
  • Assessment of NOx emissions of the Scimitar engine at Mach 5 based on a thermodynamic cycle analysis
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-14
    Tayfun Tanbay; Muhammed Bişar Uca; Ahmet Durmayaz

    The Scimitar engine is a new advanced propulsion system designed to propel the aircraft A2 of the LAPCAT project. It is a hybrid system that utilizes the features of turbofan, ramjet and air-turborocket. Hydrogen and air are used as the fuel and oxidant, respectively, while helium is used to transfer heat from the hot incoming air to the hydrogen in the engine. In this study, we present a thermodynamic cycle analysis of the Scimitar engine for the assessment of NOx emissions. The combustion of fuel is studied in detail with an equilibrium model taking into account various dissociation and formation reactions since high levels of temperatures are achieved in its combustion chamber. The NOx emissions of the engine at Mach 5 and the effects of fuel and air flow rates, cruise speed and altitude on these emissions are presented by solving a nonlinear system of equations formed through our novel thermodynamic model. The results show that the NO emissions of the engine can be diminished significantly by decreasing air flow rate, cruise speed and altitude and by increasing the fuel flow rate. The variations of NO2 emissions with these parameters are similar except the variation with altitude which has an inverse effect as compared to the variation of NO.

    更新日期:2020-01-17
  • Application of distributed combustion technique to hydrogen-rich coal gases: A numerical investigation
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-03-04
    Serhat Karyeyen; Mustafa Ilbas

    Distributed combustion has been a promising combustion technique, for enabling a more uniform thermal field, resulting in ultra-low pollutant emissions, reduced combustion noise, and enhanced combustion efficiency. This work examines combustion of hydrogen-rich coal gases derived from Turkish coal under distributed combustion conditions. Focus here is on obtaining a broadened flame and reducing pollutant emissions. Numerical modelling was carried out using a commercial code in order to predict the thermal field and pollutant emissions of the hydrogen-rich coal gases under distributed combustion conditions. A gas mixture (90% N2 and 10% CO2) was utilized to simulate controlled entrainment of hot reactive product gases into the fresh mixture prior to ignition in order to seek distributed combustion. The results showed that distributed combustion provided far more uniform thermal field that resulted in greatly reduced NOx emissions. The results also showed that the temperature difference between the maximum and exit temperature was reduced to approximately 200 K under distributed conditions. In addition, the NOx pollutant emissions predicted for each gas were reduced to near zero levels under high intensity distributed combustion conditions supporting the available experimental data. It has been concluded that enhanced thermal field uniformity and significantly reduced NOx emissions were achieved for hydrogen-rich coal gases under distributed conditions.

    更新日期:2020-01-17
  • Analysis of the effect of H2O content on combustion behaviours of a biogas fuel
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-02-27
    Murat Sahin; Mustafa Ilbas

    The present work deals with the biogas in a combustor with regard to its combustion features under differing conditions of H20 content and H2S. The content of water (H2O) vapour has been changed from 0% to 10% and a CFD code has been employed while implementing numerical investigations. In modelling, a combustion model (the PDF/Mixture Fraction) along with a turbulence model (the k-Ɛ standard turbulence model) has been utilised. This study also deals with the combustion performances of the biogas by the addition of a different quantity of H2O into the biogas. The Emissions and the flame temperature of the biogas through the combustor apparently seem to be strikingly affected by the changes in H2O contents. It is interesting to note that the flame temperature zones change their positions and advance to the burner's downstream. The rise in flame temperatures of the biogas can be attributed to the change in H2O content caused by a better fuel-air mixture. It is also observed that adding H2O into the biogas lowers the axial temperature levels.

    更新日期:2020-01-17
  • The changing role of diesel oil-gasoil-LPG and hydrogen based fuels in human health risk: A numerical investigation in ferry ship operations
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2019-04-03
    Ender Yalcin; Munir Suner

    The ships and on-road vehicles are two main emission sources in transportation. In the special form of the ships such as ferry ship, the passengers face with both of two sources because the passengers and vehicles could be proceeding simultaneously. Hence, the exposed emission value in g/m³ by passengers has rapidly increased in the ferries. In this study, the authors found that the vehicles produced emission average 1515 g/s. The calculated value of CO2, SO2, NO2, NO forms respectively, 153.6, 1.37, 0.138, 0.12 g/s. The impatient passengers could be exposed to these emissions more than the reference dose limits within a certain time period. Among these forms, we revealed SO2, NO2 and NO have health risk with HQ value within the 1-year period. The expected symptoms could be summarized respiratory paralysis, damage to liver, lung, spleen, and blood, respiratory and CNS involvement, cancer in long-term.

    更新日期:2020-01-17
  • 更新日期:2020-01-17
  • Interfaces engineering of MoNi-based sulfides electrocatalysts for hydrogen evolution reaction in both acid and alkaline media
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Yan Xie; Yuanwei Liu; Zhongnian Yang

    Searching for efficiently noble-metal-free hydrogen evolution catalysts is critical to the development of hydrogen energy. In this work, we report an in-situ growing defect-rich heterointerfaces structure MoNi-based sulfides on carbon cloth via a facile and controllable hydrothermal process. The interface structure in [email protected]/CC can not only provide suffcient channel for transportation of electrolyte, but also release of produced gases in the catalytic process, thence enhance the sluggish hydrogen evolution efficiency. Furthermore, the defects in [email protected]/CC have significant impacts on hydrogen evolution behavior. Therefore, the as-synthesied [email protected]/CC shows a low overpotential of 33 mV to deliver a current density of 10 mAcm−2 and a small tafel slope of 80 mVdec−1, and also exhibits an excellent long-term stability in 0.5 M H2SO4. Additionaly, the [email protected]/CC offers outstanding hydrogen evolution reaction performances in 1 M KOH.

    更新日期:2020-01-17
  • Hybrid niobium and titanium nitride nanotube arrays implanted with nanosized amorphous rhenium–nickel: An advanced catalyst electrode for hydrogen evolution reactions
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Huibin Zhang; Xuanhan Chen; Zhimao Lin; Liqiang Zhang; Huazhen Cao; Linping Yu; Guoqu Zheng
    更新日期:2020-01-17
  • Effect of non-solvent from the phase inversion method on the morphology and performance of the anode supported microtubular solid oxide fuel cells
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Cong Ren; Yanxiang Zhang; Qi Xu; Tian Tian; Fanglin Chen

    The microstructure of the anode in anode-supported solid oxide fuel cells has significant influence on the cell performance. In this work, microtubular Ni-yttria stabilized zircona (Zr0.8 Y0.2O2, YSZ) anode support has been prepared by the phase inversion method. Different compositions of non-solvent have been used for the fabrication of the Ni-YSZ anode support, and the correlation between non-solvent composition and characteristics of the microstructure of the anode support has been investigated. The presence of ethanol or isopropanol in the non-solvent can inhibit the growth of the finger-like pores in the anode support. With the increase of the concentration of ethanol or isopropanol in the non-solvent, a thin dense layer can be observed on the top of the prepared tubular anode support. In addition, the mechanism of pore formation is explained based on the inter-diffusivity between the solvent and the non-solvent. The prepared microtubular solid oxide fuel cells (MT-SOFCs) have been tested, and the influence of the anode microstructure on the cell electrochemical performance is analyzed based on a polarization model.

    更新日期:2020-01-17
  • 更新日期:2020-01-17
  • Sequential dark and photo-fermentative hydrogen gas production from agar embedded molasses
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Muhammet Enes Mıynat; İkbal Ören; Ebru Özkan; Hidayet Argun

    In this study, molasses and dark fermentation effluent were solidified using agar and used for H2 production by dark and photo-fermentation. During dark fermentation, the solid jelly form of molasses enabled a slow release of the substrate to the liquid broth hindering fast pH decreases. The initial total sugar concentration, H2 yield, H2 rate and lag phase in dark fermentation were 36.2 g/L, 226.24 mL H2/g TS, 29.85 mL H2/h and 4.37 h, respectively. Photo-fermentation of 5.77 g TVFA/L embedded dark fermentation effluent did not lead to efficient H2 production. The best performance in photo-fermentation was obtained with 1.55 g TVFA/L containing diluted dark fermentation effluent. The H2 yield, H2 rate and lag phase in photo-fermentation were 870.26 mL H2/g TVFA, 0.913 mL H2/h and 54.07 h, respectively. Embedding concentrated substrate using agar can enhance H2 production performance but only if the release of the substrate does not exceed inhibitory levels and if the rate of diffusion is tolerable for microbial activity.

    更新日期:2020-01-17
  • High-performance solid oxide fuel cells with fiber-based cathodes for low-temperature operation
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Joseph Parbey; Qin Wang; Jialong Lei; Mayken Espinoza-Andaluz; Feng Hao; Yong Xiang; Tingshuai Li; Martin Andersson

    Low-temperature operation of solid oxide fuel cells (SOFCs) results in deterioration in electrochemical performance due to sluggish oxygen reduction reaction (ORR) at the cathode. To enhance the reaction pathway for ORR, La0.8Sr0.2MnO3 (LSM) nanofibers were fabricated by electrospinning and used for low-temperature solid oxide fuel cells operated at 600–700 °C. The morphological and structural characteristics show that the electrospun LSM nanofiber has a highly crystallized perovskite structure with a uniform elemental distribution. The average diameter of the LSM nanofiber after sintering is 380 nm. A symmetric cell of nanofiber-based LSM cathode on scandia-stabilized zirconia (SSZ) electrolyte pellet exhibits much lower area specific resistances compared to commercial LSM powder-based cathode. A single cell based on the nanofiber LSM cathode on yttrium-doped barium cerate-zirconia (BCZY) electrolyte exhibits a power density of 0.35 Wcm−2 at 600 °C, which increases to 0.85 Wcm−2 at 700 °C. The cell has an area specific resistance (ASR) of 0.46 Ωcm2 at 600 °C, which decreases to 0.07 Ωcm2 at 700 °C. The results indicate that the LSM electrode fabricated by the electrospinning process produces a nanostructured porous electrode which optimizes the microstructure and significantly enhances the ORR at the cathode of SOFCs.

    更新日期:2020-01-17
  • Methods for measuring the effective thermal conductivity of metal hydride beds: A review
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Wenli Zhao; Yi Yang; Zewei Bao; Dong Yan; Zezhi Zhu

    The effective thermal conductivity of metal hydride beds is a crucial parameter for metal hydride reactor design. In this review, methods and principles for the measurement of the effective thermal conductivity of metal hydride beds are discussed, including steady-state techniques (the radial heat flow, comparative cut bar, guarded heat flow meter, and guarded hot plate methods) and transient techniques (the hot-wire, thermal probe, transient plane source, and laser flash methods). Reports of effective thermal conductivity measurements for characterizing metal hydride beds have been reviewed, including the measurement methods, material composition, measurement results, temperature, and gas pressure. The advantages, disadvantages, and applications of each measurement method have been presented, and an assessment regarding different techniques of measurement has been conducted. Laser flash and transient plane source are found to be the most frequently used methods, and have been increasingly applied in recent years. Finally, a brief discussion of recommended future development of effective thermal conductivity measurement is presented.

    更新日期:2020-01-17
  • Effect of retrograde condensation on the production performance of organic hydrogen compounds energy
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Yue Peng; Tao Bu; Zhenyun Shi; Qing Tian; Wanjing Luo

    The gas-condensate reservoirs are typical organic fossil reservoirs of hydrogen compounds energy. With the development of gas-condensate reservoirs, a part of condensate liquid of hydrogen compounds will appear under the influence of retrograde condensation mechanism. However, the effects of retrograde condensation on the production performance of organic hydrogen compound energy with different well types are still not clear. In this study, a series of numerical simulation models were established to investigate the law of retrograde condensation with different well types and reservoir permeabilities. Furthermore, the effects of retrograde condensation on gas well productivity were analyzed by the comparison between the compositional modeling and black oil modeling results. Results show that the condensate oil for the fractured wells is mainly distributed around the fracture tips instead of the perforation intervals for the unfractured wells. The maximum oil saturation and condensate area of two fractures at ends are much larger than those of middle fractures. The retrograde condensation exhibits a negligible impact on the production of multiple fractured horizontal wells with a cumulative gas production reduction 0.87%–1.57%. Hydraulic fracturing, multiple fractures and high reservoir permeability are conducive to lower the impact of retrograde condensation on the production of organic hydrogen compounds energy.

    更新日期:2020-01-17
  • Intensifying vehicular proton exchange membrane fuel cells for safer and durable, design and operation
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Nilesh Ade; Benjamin Wilhite; Henry Goyette; M. Sam Mannan

    The explosion in a proton exchange membrane fuel cell (PEMFC) powered forklift in Louisiana, USA in May 2018 and the resulting fatality highlights the need for the improved safety of this technology. Apart from the safety concerns, PEMFC durability has been an important issue towards its further commercialization. Both the safety and durability concerns associated with this technology can be attributed to the temporal degradation of its components. In this study, we have developed a mathematical model that relates the microscale PEMFC degradation to the probability of a macroscale explosion in a Fuel Cell Electric Vehicle (FCEV). Using the model and the inherent safety principle of intensification, it was observed that increasing the operating temperature of the PEMFC system can significantly improve both its safety and durability while intensifying membrane design parameters i.e. membrane thickness and membrane conductivity do not provide any significant improvements. A key inference from this study is that the durability (expressed in voltage loss) and safety (expressed in explosion probability) of a PEMFC system are not perfectly correlated.

    更新日期:2020-01-17
  • Multi-objective optimization for efficient modeling and improvement of the high temperature PEM fuel cell based Micro-CHP system
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Yu Yang; Hao Zhang; Ping Yan; Kittisak Jermsittiparsert

    Fuel cells due to different useful features such as high efficiency, low pollution, noiselessness, lack of moving parts, variety of fuels used and wide range of capacity of these sources can be the main reasons for their tendency to use them in different applications. In this study, the application of a high temperature proton exchange membrane fuel cell (HT-PEMFC) in a combined heat and power (CHP) plant has been analyzed. This study presents a multi-objective optimization method to provide an optimal design parameters for the HT-PEMFC based micro-CHP during a 14,000 h lifetime by considering the effect of degradation. The purpose is to optimize the net electrical efficiency and the electrical power generation. For the optimization process, different design parameters including auxiliary to process fuel ratio, anodic stoichiometric ratio, steam to carbon ratio, and fuel partialization level have been employed. For optimization, A new technique based on Tent mapping and Lévy flight mechanism, called improved collective animal behavior (ICAB) algorithm has been employed to solve the algorithm premature convergence shortcoming. Experimental results of the proposed method has been applied to the data of a practical plant (Sidera30) for analyzing the efficiency of the proposed ICAB based system, it is compared with normal condition and another genetic algorithm based method for this purpose. Final results showed that the difference between the maximum electrical power production under normal condition and ICAB based condition changes from 2.5 kW when it starts and reaches to its maximum value, 3.0 kW, after 14,000 h lifetime. It is also concluded that the cumulative average for the normal and the ICAB based algorithm are 24.01 kW and 27.04 kW, respectively which showed about 3.03 kW cumulative differences.

    更新日期:2020-01-17
  • 更新日期:2020-01-17
  • Highly efficient methanol oxidation on durable PtxIr/MWCNT catalysts for direct methanol fuel cell applications
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-17
    Narayanamoorthy Bhuvanendran; Sabarinathan Ravichandran; Weiqi Zhang; Qiang Ma; Qian Xu; Lindiwe Khotseng; Huaneng Su
    更新日期:2020-01-17
  • The role of oxygen vacancies in the CO2 methanation employing Ni/ZrO2 doped with Ca
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-16
    Oliver E. Everett; Priscila C. Zonetti; Odivaldo C. Alves; Roberto R. de Avillez; Lucia G. Appel

    The Ni/ZrO2 catalyst doped with Ca and Ni/ZrO2 were employed in the CO2 methanation, a reaction which will possibly be used for storing intermittent energy in the future. The catalysts were characterized by X-ray photoelectron spectroscopy (XPS, reduction in situ), X-ray diffraction (XRD, reduction in situ and Rietveld refinement), electron paramagnetic resonance (EPR), temperature-programmed surface reaction, cyclohexane dehydrogenation model reaction, temperature-programmed desorption of CO2 and chemical analysis. The catalytic behavior of these catalysts in the CO2 methanation was analyzed employing a conventional catalytic test. Adding Ca to Ni/ZrO2, the metallic surface area did not change whereas the CO2 consumption rate almost tripled. The XRD, XPS and EPR analyses showed that Ca+2 but also some Ni2+ are on the ZrO2 surface lattice of the Ni/CaZrO2 catalyst. These cations form pairs which are composed of oxygen vacancies and coordinatively unsaturated sites (cus). By increasing the number of these pairs, the CO2 methanation rate increases. Moreover, the number of active sites of the CO2 methanation rate limiting step (CO and/or formate species decomposition, rls) is enhanced as well, showing that the rls occurs on the vacancies-cus sites pairs.

    更新日期:2020-01-17
  • Synthesis and characterization of Nanocrystalline Ba0·6Sr0·4Co0·8Fe0·2O3 for application as an efficient anode in solid oxide electrolyser cell
    Int. J. Hydrogen Energy (IF 4.084) Pub Date : 2020-01-16
    Shoroshi Dey; Jayanta Mukhopadhyay; Raja Kishora Lenka; Pankaj Kumar Patro; Abhijit Das Sharma; Tarasankar Mahata; Rajendra N. Basu

    Nanocrystalline Ba0·6Sr0·4Co0·8Fe0·2O3 (BSCF-6482) powder is synthesized by combustion synthesis technique. Powder calcined at 1000 °C reveals phase pure cubic perovskite. Transmission electron microscopic (TEM) analysis exhibits soft agglomerates of average size ∼50 nm wherein interplanar spacing for (110) and (221) resembles to the cubic lattice. While DC electrical conductivity of 23 S cm−1@800 °C is observed, interfacial polarization measured by electrochemical impedance spectroscopy is found to be the least @850 °C (0.18 Ω cm2). Cell performance has been compared among BSCF-6482, BSCF-5582 and LSCF-6482 mixed ionic and electronic conducting (MIEC) and conventional electrode (LSM). Higher performance (1.37 A/cm2@1.3 V,800 °C) with high hydrogen generation rate (0.57 Nl/cm2/h) is found during steam electrolysis with cell fabricated using BSCF-6482 having minimal area specific resistance 0.33 Ω cm2. Under similar operating condition, BSCF-5582, LSCF-6482 and LSM exhibit hydrogen generation rate of 0.35, 0.28 and 0.23 Nl/cm2/h respectively. Cell microstructure is clinically correlated with the higher reactivity of BSCF-6482 air electrode in steam electrolysis.

    更新日期:2020-01-17
  • Enhanced SO2 tolerance of FeCeOx/CNTs catalyst for NO and Hg0 removal by coating shell SiO2
    Fuel Process. Technol. (IF 4.507) Pub Date : 2020-01-17
    Huawei Zhang; Mingzhu Zhang; Lifeng Hao; Juan Wang; Yaguang Ma; Yaqing Zhang; Tiantian Jiao; Wenrui Zhang; Shaojie Chen; Peng Liang
    更新日期:2020-01-17
  • Investigation on the behavior of mercury across the flue gas treatment of coal combustion power plants using a lab-scale firing system
    Fuel Process. Technol. (IF 4.507) Pub Date : 2020-01-17
    Ida Masoomi; Hiroyuki Kamata; Akinori Yukimura; Kiyohito Ohtsubo; Marc Oliver Schmid; Günter Scheffknecht
    更新日期:2020-01-17
  • Experimental and CFD survey of indirect solar dryer modified with low-cost iron mesh
    Sol. Energy (IF 4.674) Pub Date : 2020-01-17
    Hande Özge Güler; Adnan Sözen; Azim Doğuş Tuncer; Faraz Afshari; Ataollah Khanlari; Ceylin Şirin; Afsin Gungor

    In the present work, double-pass indirect solar dryer (DPISD) and double-pass indirect solar dryer with mesh absorber modification (DPISDMA) have been designed, analyzed, manufactured and tested. The main aim of this study is improving the thermal efficiency of double-pass solar air collector by integrating iron meshes. Pepino fruit (Solanum muricatum L.) samples in two thicknesses have been used in the experimental study. Also, CFD analysis of both solar air collectors and drying chamber and quality metrics such as phenolic, total flavonoid contents and antioxidant activity have been conducted. Numerical simulation and experimental results showed that using mesh modification has positive influence on the performance of the collector. The highest value of the average efficiency of the dryer was obtained in DPISDMA for the thin sample thickness as 23.08%. According to quality analyses, the experiments which done in DPISDMA gave the best results with highest values of TPC, TFC and antioxidant activity values (p < 0.05). Drying data of the pepino fruit for different experiments were modelled according to 8 different most used mathematical models. Accordingly, the best fitted kinetics model was determined as Logarithmic model for all experiments which gave the most accurate statistical values.

    更新日期:2020-01-17
  • Interfacial engineering and down-conversion of ultraviolet light for efficient perovskite solar cells
    Sol. Energy (IF 4.674) Pub Date : 2020-01-17
    Srinivasa Rao Pathipati; Muhammad Naeem Shah; Xiaofang Pan

    The addition of a tiny amount of fluorescent organic material N, N′-di (naphtha-1-yl)-N, N′-diphenyl-benzidine (NPB) into polymeric hole transport layer (HTL) is shown to yield a significant enhancement in down-conversion of ultraviolet (UV) light into visible light. As a result, NPB incorporated HTL based devices exhibit enhancement in power conversion efficiency (PCE) of 18.2% compared to 15.1% for pristine devices. This work demonstrated that fluorescent down-conversion of UV light based on doped HTLs is a novel and effective approach for enhanced performance of perovskite solar cells (PSCs). In addition, the incorporated fluorescent material NPB provides a favorable energetic alignment at the interface for low voltage loss. These results are further supported by time-resolved photoluminescence (TRPL) measurements that are performed on perovskite layers deposited on top of NPB doped Poly (triaryl amine) (PTAA), which shows an improvement in lifetime of the charge carriers with increasing concentration of NPB. An increase in the lifetime of the charge carriers is observed on the perovskite layer that is deposited on top of 2.5 wt% NPB doped PTAA layer. The lifetime enhancement is due to additional charge carriers that are generated from the conversion of high energy photons to low energy photons. These additional charge carriers that are generated in HTL occupy the charge transport states after filling the trap states in the perovskite layer and hence the lifetime of the charge carriers increases. The TRPL lifetime decreases with further increase in the NPB concentration more than 2.5 wt% due to efficient charge carrier extraction.

    更新日期:2020-01-17
  • Gassing Behavior of High‐Entropy Oxide Anode and Oxyfluoride Cathode Probed Using Differential Electrochemical Mass Spectrometry
    Batteries Supercaps Pub Date : 2020-01-16
    Ben Breitung; Qingsong Wang; Alexander Schiele; Đorđije Tripković; Abhishek Sarkar; Leonardo Velasco; Di Wang; Subramshu S. Bhattacharya; Horst Hahn; Torsten Brezesinski

    Multicomponent materials may exhibit favorable Li‐storage properties because of entropy stabilization. While the first examples of high‐entropy oxides and oxyfluorides show good cycling performance, they suffer from various problems. Here, we report on side reactions leading to gas evolution in Li‐ion cells using rock‐salt (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O (HEO) or Li(Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)OF (Li(HEO)F). Differential electrochemical mass spectrometry indicates that a robust solid electrolyte interphase layer is formed on the HEO anode, even when using an additive‐free electrolyte. For the Li(HEO)F cathode, the cumulative amount of gases is found by pressure measurements to depend strongly on the upper cutoff potential used during cycling. Cells charged to 5.0 V versus Li+/Li show the evolution of O2, H2, CO2, CO and POF3, with the latter species being indirectly due to lattice O2 release as confirmed by electron energy loss spectroscopy. This result attests to the negative effect that lattice instability at high potentials has on the gassing.

    更新日期:2020-01-17
  • Electric double‐layer capacitors based on non‐aqueous electrolytes: A comparative study of potassium and quaternary ammonium salts
    Batteries Supercaps Pub Date : 2020-01-16
    Satoshi Uchida; Titus Masese

    Immense attention has been drawn towards electric double layer capacitors (EDLCs) as a viable intermittent energy storage solution, owing to their ultra‐fast charge/discharge rates and long cycle life. However, the high activation energy of ionic conductivity innate in conventional aprotic organic electrolytes has greatly impeded the feasibility of high‐performance EDLCs. Herein, we investigate and compare the physicochemical properties and performance of electrolytes based on potassium hexafluorophosphate (KPF 6 ) and commercial triethylmethy‐lammonium tetra‐fluoroborate (TEMABF 4 ) salts in EDLCs. Compared to commercial TEMABF 4 ‐based electrolytes, KPF 6 salt‐based electrolytes (in acetonitrile solvent) demonstrate outstanding rate performance. The KPF 6 salt‐based electrolyte further manifests lower ionic resistance within activated carbon pores as well as lower interfacial resistance between electrode and electrolyte; an affirmation of not the high ionic conductivity but rather the eminence of low activation energy. The low activation energy can be attributed to the low effective nuclear charge of the K + cations that allow anions to transverse easily in solvent state. This study not only underpins potassium‐ion (K + ) as a fast charge carrier, but also a viable solution for the next‐generation non‐aqueous power devices relying on monovalent alkali cations.

    更新日期:2020-01-17
  • 更新日期:2020-01-17
  • Surface-Dominated Storage of Heteroatoms-Doping Hard Carbon for Sodium-Ion Batteries
    Energy Storage Mater. Pub Date : 2020-01-17
    Qianzheng Jin; Kangli Wang; Pingyuan Feng; Zhuchan Zhang; Shijie Cheng; Kai Jiang
    更新日期:2020-01-17
  • An Ultra-durable Gel electrolyte Stabilizing Ion Deposition and Trapping Polysulfides for Lithium-sulfur Batteries
    Energy Storage Mater. Pub Date : 2020-01-16
    Chenfeng Ding; Lingbo Huang; Yiran Guo; Jin-le Lan; Yunhua Yu; Xuewei Fu; Wei-Hong Zhong; Xiaoping Yang
    更新日期:2020-01-17
  • 更新日期:2020-01-17
  • Fluorine‐Substituted Benzotriazole Core Building Block‐Based Highly Efficient Hole‐Transporting Materials for Mesoporous Perovskite Solar Cells
    Solar RRL Pub Date : 2020-01-16
    Li Tao; Cheng Chen; Cheng Wu; Xingdong Ding; Mengmeng Zheng; Hongping Li; Gongqiang Li; Hongfei Lu; Ming Cheng
    更新日期:2020-01-17
  • Solar‐Inspired Water Purification Based on Emerging 2D Materials: Status and Challenges
    Solar RRL Pub Date : 2020-01-16
    Zhongjian Xie; Ya-Pei Peng; Li Yu; Chenyang Xing; Meng Qiu; Junqing Hu; Han Zhang
    更新日期:2020-01-17
  • Intensification of Vertical Phase Separation for Efficient Polymer Solar Cell via Piecewise Spray Assisted by a Solvent Driving Force
    Solar RRL Pub Date : 2020-01-16
    Jiang Cheng; Shenghao Wang; Yang Tang; Rong Hu; Xingwu Yan; Zhen Zhang; Lu Li; Qibing Pei
    更新日期:2020-01-17
  • Transparent silicon carbide/tunnel SiO2 passivation for c‐Si solar cell front side: Enabling Jsc > 42 mA/cm2 and iVoc of 742 mV
    Prog. Photovoltaics (IF 7.776) Pub Date : 2020-01-16
    Manuel Pomaska; Malte Köhler; Paul Procel Moya; Alexandr Zamchiy; Aryak Singh; Do Yun Kim; Olindo Isabella; Miro Zeman; Shenghao Li; Kaifu Qiu; Alexander Eberst; Vladimir Smirnov; Friedhelm Finger; Uwe Rau; Kaining Ding
    更新日期:2020-01-17
  • Plant hormone induced enrichment of Chlorella sp. omega-3 fatty acids
    Biotechnol. Biofuels (IF 5.452) Pub Date : 2020-01-17
    Ramachandran Sivaramakrishnan; Aran Incharoensakdi

    Omega-3 fatty acids have various health benefits in combating against neurological problems, cancers, cardiac problems and hypertriglyceridemia. The main dietary omega-3 fatty acids are obtained from marine fish. Due to the pollution of marine environment, recently microalgae are considered as the promising source for the omega-3 fatty acid production. However, the demand and high production cost associated with microalgal biomass make it necessary to implement novel strategies in improving the biomass and omega-3 fatty acids from microalgae. Four plant hormones zeatin, indole acetic acid (IAA), gibberellic acid (GBA) and abscisic acid (ABA) were investigated for their effect on the production of biomass and lipid in isolated Chlorella sp. The cells showed an increase of the biomass and lipid content after treatments with the plant hormones where the highest stimulatory effect was observed in ABA-treated cells. On the other hand, IAA showed the highest stimulatory effect on the omega-3 fatty acids content, eicosapentaenoic acid (EPA) (23.25%) and docosahexaenoic acid (DHA) (26.06%). On the other hand, cells treated with ABA had highest lipid content suitable for the biodiesel applications. The determination of ROS markers, antioxidant enzymes, and fatty acid biosynthesis genes after plant hormones treatment helped elucidate the mechanism underlying the improvement in biomass, lipid content and omega-3 fatty acids. All four plant hormones upregulated the fatty acid biosynthesis genes, whereas IAA particularly increased omega-3-fatty acids as a result of the upregulation of omega-3 fatty acid desaturase. The contents of omega-3 fatty acids, the clinically important compounds, were considerably improved in IAA-treated cells. The highest lipid content obtained from ABA-treated biomass can be used for biodiesel application according to its biodiesel properties. The EPA and DHA enriched ethyl esters are an approved form of omega-3 fatty acids by US Food and Drug Administration (FDA) which can be utilized as the therapeutic treatment for the severe hypertriglyceridemia.

    更新日期:2020-01-17
  • Quantitative visualization of subcellular lignocellulose revealing the mechanism of alkali pretreatment to promote methane production of rice straw
    Biotechnol. Biofuels (IF 5.452) Pub Date : 2020-01-17
    Xiaoli Li; Junjing Sha; Yihua Xia; Kuichuan Sheng; Yufei Liu; Yong He

    As a renewable carbon source, biomass energy not only helps in resolving the management problems of lignocellulosic wastes, but also helps to alleviate the global climate change by controlling environmental pollution raised by their generation on a large scale. However, the bottleneck problem of extensive production of biofuels lies in the filamentous crystal structure of cellulose and the embedded connection with lignin in biomass that leads to poor accessibility, weak degradation and digestion by microorganisms. Some pretreatment methods have shown significant improvement of methane yield and production rate, but the promotion mechanism has not been thoroughly studied. Revealing the temporal and spatial effects of pretreatment on lignocellulose will greatly help deepen our understanding of the optimization mechanism of pretreatment, and promote efficient utilization of lignocellulosic biomass. Here, we propose an approach for qualitative, quantitative, and location analysis of subcellular lignocellulosic changes induced by alkali treatment based on label-free Raman microspectroscopy combined with chemometrics. Firstly, the variations of rice straw induced by alkali treatment were characterized by the Raman spectra, and the Raman fingerprint characteristics for classification of rice straw were captured. Then, a label-free Raman chemical imaging strategy was executed to obtain subcellular distribution of the lignocellulose, in the strategy a serious interference of plant tissues’ fluorescence background was effectively removed. Finally, the effects of alkali pretreatment on the subcellular spatial distribution of lignocellulose in different types of cells were discovered. The results demonstrated the mechanism of alkali treatment that promotes methane production in rice straw through anaerobic digestion by means of a systemic study of the evidence from the macroscopic measurement and Raman microscopic quantitative and localization two-angle views. Raman chemical imaging combined with chemometrics could nondestructively realize qualitative, quantitative, and location analysis of the lignocellulose of rice straw at a subcellular level in a label-free way, which was beneficial to optimize pretreatment for the improvement of biomass conversion efficiency and promote extensive utilization of biofuel.

    更新日期:2020-01-17
  • Lignin degradation and detoxification of eucalyptus wastes by on-site manufacturing fungal enzymes to enhance second-generation ethanol yield
    Appl. Energy (IF 8.426) Pub Date : 2020-01-16
    Willian Daniel Hahn Schneider; Roselei Claudete Fontana; Henrique Macedo Baudel; Félix Gonçalves de Siqueira; Jorge Rencoret; Ana Gutiérrez; Laura Isabel de Eugenio; Alicia Prieto; María Jesús Martínez; Ángel T. Martínez; Aldo José Pinheiro Dillon; Marli Camassola
    更新日期:2020-01-17
  • Machine-learning based hybrid demand-side controller for high-rise office buildings with high energy flexibilities
    Appl. Energy (IF 8.426) Pub Date : 2020-01-17
    Yuekuan Zhou; Siqian Zheng

    The accurate demand prediction with high efficiency and advanced demand-side controller are essential for the enhancement of energy flexibility provided by buildings, whereas the current literature fails to present the mechanism on modelling development and demand-side control. This paper aims to deal with the complexity of building demand prediction with supervised machine learning method, including the multiple linear regression, the support vector regression and the backpropagation neural network. The regularization, adding the sum of the weights to the learning function, is utilized to improve the training speed and to solve the overfitting by eliminating the unnecessary connections with small weights. The configuration of the artificial neural network was presented, and sensitivity analysis has been conducted on the learning performance regarding different training times. Energy flexibilities of sophisticated building energy systems (including renewable system, electric and thermal demands and building services systems) were quantitatively characterised with a series of quantifiable indicators. Moreover, several advanced controllers have been developed and contrasted, in regard to the flexibility utilisation of building energy systems. Results showed that, the developed hybrid controller with short-term prediction through the cross-entropy function is more technically competitive than other controllers. With the implementation of the developed hybrid controller, the peak power of the grid importation can be reduced from 500.3 to 195 kW by 61%. This study formulates a data-driven model with an advanced machine learning algorithm for the accurate building demand prediction and a hybrid advanced controller with short-term prediction for the energy management, which are critical for the promotion of energy flexible buildings.

    更新日期:2020-01-17
  • Multi-objective economic dispatch of a microgrid considering electric vehicle and transferable load
    Appl. Energy (IF 8.426) Pub Date : 2020-01-16
    Hui Hou; Mengya Xue; Yan Xu; Zhenfeng Xiao; Xiangtian Deng; Tao Xu; Peng Liu; Rongjian Cui

    In order to investigate the impact of electric vehicles’ charging-discharging behaviour and demand side response resources on the economic operation of photovoltaic grid-connected microgrid system, a multi-objective model of microgrid economic dispatching with electric vehicles, transferable load and other distributed generations (diesel engines and energy storage unit) is proposed in this paper. The model takes the comprehensive operating cost of microgrid, the utilization rate of photovoltaic energy and the power fluctuation between the microgrid and main grid as objectives. Moreover, four different cases of microgrid economic dispatch considering electric vehicles and transferable load are put forward, which are electric vehicles’ orderly charging and discharging and transferable load participating in demand response in Case 1, electric vehicles’ charging randomly and the transferable load participating in demand response in Case 2, electric vehicles orderly charging and discharging and transferable load not participating in demand response in Case 3, electric vehicles’ charging randomly and the transferable load not participating in the demand response in Case 4. Multi-objective Seeker Optimization Algorithm and the method of fuzzy membership function are applied in this study to obtain the optimal results. The simulation analysis shows that the orderly charging-discharging behaviour of electric vehicles and the participation of transferable load can effectively improve the economic costs, efficiency and security of microgrid economic operation.

    更新日期:2020-01-17
  • 更新日期:2020-01-17
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