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Dynamic modeling of a NG-fueled SOFC-PEMFC hybrid system coupled with TSA process for fuel cell vehicle

Energy Procedia 2019年 158卷 2215-2224页

作者： Zhen Wu Meng Ni Pengfei Zhu Zaoxiao Zhang Building Energy Research Group Department of Building and Real Estate The Hong Kong Polytechnic University Hong Kong P.R. China State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an 710049 P.R. China

Fuel cell power technology has drawn extensive attentions due to its high efficiency, low emission and noise. Solid oxide fuel cell (SOFC) could generate the power by diverse fuels, such as natural gas (NG), while proton exchange membrane fuel cell (PEMFC) only feeds on pure H 2 . More and more attentions are paid on the combination of SOFC and PEMFC for high efficiency and convenient refueling in the practical applications. To obtain H 2 fuel with high purity from SOFC as a reformer, the gas processing subsystem for H 2 separation and purification should be applied between SOFC and PEMFC. In this present study, the gas processing subsystem, consisting of water gas shift (WGS) and thermal swing adsorption (TSA), is introduced into the SOFC-PEMFC hybrid system. Then, the SOFC-WGS-TSA-PEMFC hybrid system is modelled to investigate the transient behaviors under different operations. The simulation results show that the SOFC-WGS-TSA-PEMFC hybrid system has an improved energy conversion efficiency of approximately 64%, which is higher than the only-SOFC and the reform-PEMFC. The waste heat recovery for driving the TSA reaction accounts for the higher net electricity efficiency compared with the SOFC-PEMFC hybrid system based on the pressure swing adsorption (PSA) for H 2 separation. Since the SOFC and PEMFC have completely different transient responses to the change of the loading, the influences of operating conditions of fuel cell vehicles on the transient behaviors of single SOFC and PEMFC and the overall performance of the SOFC-WGS-TSA-PEMFC hybrid system are further investigated. Through the analysis and discussion based on the dynamic modelling, the operation strategy is unveiled in this paper for the performance optimization of the hybrid system when installed in the fuel cell vehicles.

关键词： SOFC PEMFC Metal hydride Transient behavior High efficiency

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Influence of(Mg_(1/3)Nb_(2/3))complex substitutions on crystal structures and microwave dielectric properties of Li2TiO3 ceramics with extreme low loss

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Journal of Materiomics 2018年第4期4卷 368-382页

作者： Huan-Huan Guo Di Zhou Li-Xia Pang Jin-Zhan Su Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education&International Center for Dielectric ResearchSchool of Electronic and Information EngineeringXi'an Jiaotong UniversityXi'an710049China Micro-optoelectronic Systems Laboratories Xi'an Technological UniversityXi'an710032ShaanxiChina International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'anShaanxi710049China

A systematic investigation of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)(0.1≤x≤0.35)solid solutions synthesized by traditional solid-state reaction method is reported in this *** the composition range of 0.1≤x≤0.25,a monoclinic rock salt structured solid solution was *** x increased to 0.3,a phase transition from monoclinic to cubic phase,along with an order-disorder phase transition,was *** x increased from 0.1 to 0.35,the microwave permittivity(εr)and temperature coefficient of resonant frequency(TCF)of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)ceramics decreased linearly from 21.0 to 18.6,+27.1 to-19.4 ppm/℃,*** Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic sintered at 1170℃shows high performance of microwave dielectric properties with aεr~19.6,a Qf(Q=quality factor=1/dielectric loss;f=resonant frequency)~109,770 GHz(at 7.7 GHz)and a near zero TCF~t 1.2 ppm/℃.Moreover,the burying sintering process can reduce the volatilization of lithium so that the porosity of Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic was reduced effectively,which made Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic promising for future *** area electron diffraction patterns,high-resolution transmission electron microscopy,Raman and far-infrared spectra were employed to study the relation between crystal structure and microwave dielectric properties in detail.

关键词： Microwave dielectric properties Phase evolution Crystal structure High quality

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Research on the Influence of Helical Strakes on Dynamic Response of Floating Wind Turbine Platform

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China Ocean engineering 2017年第2期31卷 131-140页

作者： DING Qin-wei LI Chun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 China

The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform with the supplement of helical strakes for the purpose to analyze the impact of helical strakes on the dynamic response of the floating wind turbine Spar platform. The dynamic response of floating wind turbine Spar platform under wind, wave and current loading from the impact of number, height and pitch ratio of the helical strakes is analysed by the radiation and diffraction theory, the finite element method and orthogonal design method. The result reveals that the helical strakes can effectively inhibit the dynamic response of the platform but enlarge the wave exciting force; the best parameter combination is two pieces of helical strakes with the height of 15%D （D is the diameter of the platform） and the pitch ratio of 5; the height of the helical strake and its pitch ratio have significant influence on pitch response.

关键词： floating wind turbine platform helical strakes orthogonal design

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Three-dimensional analysis of condensation nanofluid film on an inclined rotating disk by efficient analytical methods

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Arab Journal of Basic and Applied Sciences 2018年第1期25卷 28-37页

作者： Hatami, M. Jing, D. Yousif, Majeed A. Department of Mechanical Engineering Esfarayen University of Technology Esfarayen Iran State Key Laboratory of Multiphase Flow in Power Engineering & International Research Center for Renewable Energy Xi’an Jiaotong University Xi’an China Department of Mathematics Faculty of Science University of Zakho Zakho Iraq

In this study, least square method (LSM) and differential transform method (DTM) applied to solve the three dimensional problem of steady nanofluid deposition on an inclined rotating disk is illustrated. The governing non-linear partial differential equations are reduced to the nonlinear ordinary differential equations system by similarity transform. There is a good agreement between the present analytical and numerical results. Results indicate that increasing nanofluid volume fraction leads to increase in temperature profile and highest temperature obtained for aluminium oxide (Al₂O₃)-water case. © 2018, © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of the University of Bahrain.

关键词： condensation film DTM film thickness LSM Nanofluid rotating disk

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Synthesis and application of transition metal phosphides as electrocatalyst for water splitting

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Science Bulletin 2017年第9期62卷 633-644页

作者： Jinzhan Su Jinglan Zhou Lu Wang Cong Liu Yubin Chen International Research Center for Renewable Energy (IRCRE) State Key Laboratory for Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

With continuous research on photocatalytic water splitting, searching for efficient catalyst for hydrogen evolution reaction(HER) becomes popular topic in addition to main catalyst research. Transition metal phosphides are receiving intense attention due to its abundance in the Earth's crust and comparable catalytic properties to noble metals. In this review, the synthesis approaches, HER reaction mechanism,photocatalytic activity, approaches to improve the activity of transition metal phosphides were reviewed and discussed. It was showed that the transition metal phosphides have great potential to reduce the cost of photocatalyst and promising application on water splitting. The stability problem and participation of poisonous reactant and product in its synthesis reaction limit its application and developing in a certain extent, but with the continuous efforts on the development and improvement of the synthesis methods,transition metal phosphides will find wide application in water splitting.

关键词： Transition metal phosphide Electrocatalyst HER Photocatalytic water splitting

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Calcined [email protected] @Rh x Ni 1- x : A novel hierarchically oriented composition tunable catalyst for green and sustainable hydrogen generation

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Journal of Environmental Chemical engineering 2022年第3期10卷

作者： Yasir Abbas Zareen Zuhra Sahresh Majeed Muhammad Shuaib Khan Majid Basharat Deependra Tyagi Shafqat Ali Zhanpeng Wu Zhaojun Liu Department of Electrical and Electronic Engineering Southern University of Science and Technology 1088 Xueyuan Blvd Nanshan District Shenzhen 518055 PR China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical Technology Beijing 100029 PR China Department of Environment and Civil Engineering Dongguan University of Technology Dongguan 523808 PR China Institute of Chemical Sciences Bahauddin Zakariya University Multan 60800 Pakistan International Research Center for Renewable Energy (IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering (MPFE) Xi’an Jiaotong University Xi’an 710049 PR China Institute for Advanced Study Shenzhen University Nanhai Avenue 3688 Shenzhen 518060 PR China

The ever decreasing amount of fossil fuels and increasing environmental pollution are alarming threats for green and sustainable future. Designing a new catalyst is, therefore, of paramount significance in the quest to discover sustainable, robust, and environmentally benign materials for clean and sustainable energy generation. Herein, we developed a hierarchically oriented catalyst of calcined poly(ferrocenedimethano)-cyclotriphosphazene-microspheres (CPFC-MS) supported with nickel-aluminum layered double hydroxide and decorated with nanoparticles (NPs) of rhodium-nickel, [email protected] x Ni 1 - x ( x = 2.06–6.75), for H 2 generation from ammonia borane (AB) hydrolysis . The highly active catalyst was characterized by scanning electron microscopy (SEM), Raman spectroscopy , high-resolution transmission electron microscopy (HRTEM) and TEM, energy dispersive X-ray spectroscopy (EDX), fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). The as-fabricated [email protected] @Rh x Ni 1- x ( x = 2.06–6.75) catalysts were tested for AB hydrolysis and the results showed remarkable performance and higher stability for H 2 generation. The [email protected] @Rh 2.06 Ni 7.32 catalyst, having the lowest Rh-contents, exhibited maximum H 2 generation with a turn over frequency (TOF) of 780 mol H 2 hr −1 mol Rh −1 and an activation energy (E a ) of 40.3 kJ/mol with excellent sustainability . The superior activity is ascribed to the synergetic effect between RhNi NPs and their well-dispersion over hierarchically oriented [email protected] support, while higher stability due to LDH-AlNi/RhNi attractions. This work will provide new opportunities for polyphosphazenes and LDH derived hierarchically oriented sustainable catalysts for green energy production for sustainable future.

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Multi-scale reconstruction of porous media from low-resolution core images using conditional generative adversarial networks

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Journal of Natural Gas Science and engineering 2022年 99卷

作者： Yongfei Yang Fugui Liu Jun Yao Stefan Iglauer Mozhdeh Sajjadi Kai Zhang Hai Sun Lei Zhang Junjie Zhong Vadim Lisitsa Key Laboratory of Unconventional Oil & Gas Development (China University of Petroleum (East China)) Ministry of Education Qingdao 266580 PR China Research Center of Multiphase Flow in Porous Media School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 PR China Petroleum Engineering Department Edith Cowan University Joondalup Western Australia 6027 Australia Institute of Petroleum Engineering College of Engineering University of Tehran Tehran *** Iran Institute of Mathematics SB RAS Novosibirsk 630090 Russia

Various rocks such as carbonate, coal or shale contain both micro- and macro-pores. To accurately predict the fluid flow and mechanical properties of these porous media, a multi-scale characterization of the pore space is of key importance. Hybrid superposition methods perform well in such multi-scale reconstructions, however, input images with two resolutions (high and low) and different reconstruction methods are required. In addition, the superposition algorithms are complex and human factors can introduce serious bias. Here we thus propose an effective approach based on conditional generative adversarial network (cGAN) for efficient and reliable multi-scale digital rock reconstruction based only on low-resolution core images. High-resolution core images with narrow field of view (FOV) and their corresponding large structure images were thus used to train the cGAN model. The model was validated with real sample images, and the model-generated images exhibited great agreement with the real pore structures. We also demonstrate that the proposed method can generate images independent of the structure size to some extent. This work provides an advanced image-generating model based on deep learning, and therefore aids in better and wider pore-scale characterization and process modeling, to improve understanding of subsurface science and engineering processes.

关键词： Multi-scale Digital rock Generative adversarial network Porous media reconstruction Deep learning

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Cobalt oxide and carbon modified hematite nanorod arrays for improved photoelectrochemical water splitting

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Chinese Chemical Letters 2017年第12期28卷 2207-2211页

作者： Miao Wang Meng Wang Yanming Fu Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an fiaotong UniversityXi'on 710049China

Given the proper band gap, low cost and good stability, hematite （α-Fe2O3） has been considered as a promising candidate for photoelectrochemical （PEC） water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide （COOx） and carbon （C） for the improved PEC performance, with a photocurrent density at 1.6V （vs. reversible hydrogen electrode, RHE） increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.

关键词： Hematite nanorodsSurface modificationPhotoelectrochemical water splittingWater oxidationElectrochemical impedance spectroscopy

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Exploration over combined impacts of modified piston bowl geometry and tert -butyl hydroquinone additive-included biodiesel/diesel blend on diesel engine behaviors

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Fuel 2022年 322卷

作者： Krupakaran Radhakrishnan Lawrence Zuohua Huang Xuan Phuong Nguyen Dhinesh Balasubramanian Vidyasagar Reddy Gangula Raghurami Reddy Doddipalli Van Vang Le Sachuthananthan Bharathy Anh Tuan Hoang Department of Mechanical Engineering Sree Vidyanikethan Engineering College Tirupati Andhra Pradesh India State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an 710049 China PATET Research Group Ho Chi Minh City University of Transport Ho Chi Minh City Viet Nam Department of Mechanical Engineering Mepco Schlenk Engineering College Sivakasi India Mechanical Engineering Faculty of Engineering Khon Kaen University Khon Kaen Thailand Center for Alternative Energy Research and Development Khon Kaen University Khon Kaen Thailand Institute of Maritime Ho Chi Minh City University of Transport Ho Chi Minh City Viet Nam Institute of Engineering HUTECH University Ho Chi Minh City Viet Nam

Nowadays, the use of biodiesel for diesel engines has been attracting researchers aiming to improve engine characteristics although the engine performance could be decreased while utilizing biodiesel. In this aspect, optimizing the piston bowl geometry is one of the useful approaches to enhance the efficiency of the biodiesel-powered diesel engine. In this study, the standard piston of an existing diesel engine was modified into two different combustion bowls, namely Symmetrical Stepped Curved-V (SSCV) and Symmetrical Spline-V (SSV), to evaluate the CI engine performance powered with mixtures of sesame-originated biodiesel, diesel fuel, and tert -butyl hydroquinone (TBHQ) additive through two-stage experiment. In the first phase, experiments were carried out on two modified piston bowls powered by diesel and S20 (20% sesame biodiesel + 80% diesel fuel). Resultantly, SSV piston revealed superior engine characteristics to SSCV piston and standard piston due to enhanced air–fuel mixing and more complete combustion of SSV piston-based engine. Indeed, SSV piston operation exhibited an 8.68% of increased brake thermal efficiency (BTE), 6.54% of curtailed brake-specific fuel consumption (BSFC), 4.76% of lowered carbon monoxide (CO), 4.84% of decreased unburnt hydrocarbon (HC), and 2.22% of lowered smoke opacity but with increased nitrogen oxide (NOx) by 14.14% in comparison to diesel. In the 2nd phase, to control the NOx emission effectively, a TBHQ additive was added to the S20 sample at different proportions (500 mg and 1000 mg) to analyze the test engine behaviors with modified piston shapes. As a result, S20 + 500 mg TBHQ at 100% load improved BTE by 5.79% and reduced BSFC by 4.36% in the case of SSV piston. Moreover, it curtailed emissions of CO, HC, NOx, and smoke opacity by 13.33%, 15.49%, 12.09%, and 9.44%, respectively, when equated with diesel. Overall, S20 + 500 mg TBHQ could be thought of as a possible alternative fuel on SSV piston as it resulted in superior p

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A mixed discontinuous Galerkin method with symmetric stress for Brinkman problem based on the velocity-pseudostress formulation

arXiv

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arXiv 2019年

作者： Qian, Yanxia Wu, Shuonan Wang, Fei Wang, Fei School of Mathematics and Statistics Xi'An Jiaotong University Xi'an Shaanxi710049 China School of Mathematical Sciences Peking University Beijing100871 China School of Mathematics and Statistics State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi710049 China

The Brinkman equations can be regarded as a combination of the Stokes and Darcy equations which model transitions between the fast flow in channels (governed by Stokes equations) and the slow flow in porous media (governed by Darcy?fs law). The numerical challenge for this model is the designing of a numerical scheme which is stable for both the Stokes-dominated (high permeability) and the Darcy-dominated (low permeability) equations. In this paper, we solve the Brinkman model in n dimensions (n = 2, 3) by using the mixed discontinuous Galerkin (MDG) method, which meets this challenge. This MDG method is based on the pseudostress-velocity formulation and uses a discontinuous piecewise polynomial pair PSk+1-Pk(k ≥ 0), where the stress field is symmetric. The main unknowns are the pseudostress and the velocity, whereas the pressure is easily recovered through a simple postprocessing. A key step in the analysis is to establish the parameter-robust inf-sup stability through specific parameter-dependent norms at both continuous and discrete levels. Therefore, the stability results presented here are uniform with respect to the permeability. Thanks to the parameter-robust stability analysis, we obtain optimal error estimates for the stress in broken H(div)-norm and velocity in L2-norm. Furthermore, the optimal L2 error estimate for pseudostress is derived under certain conditions. Finally, numerical experiments are provided to support the theoretical results and to show the robustness, accuracy, and flexibility of the MDG method. Copyright © 2019, The Authors. All rights reserved.

关键词： Stability

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