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Modelling of a tubular solid oxide fuel cell with different designs of indirect internal reformer 被引量:3
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作者 P.Kim-Lohsoontorn F.Priyakorn +1 位作者 U.Wetwatana N.Laosiripojana 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2014年第2期251-263,共13页
The cell performance and temperature gradient of a tubular solid oxide fuel cell with indirect internal reformer (IIR-SOFC) fuelled by natural gas, containing a typical catalytic packed-bed reformer, a catalytic coa... The cell performance and temperature gradient of a tubular solid oxide fuel cell with indirect internal reformer (IIR-SOFC) fuelled by natural gas, containing a typical catalytic packed-bed reformer, a catalytic coated wall reformer, a catalytic annular reformer, and a novel catalytic annular-coated wall reformer were investigated with an aim to determine the most efficient internal reformer system. Among the four reformer designs, IIR-SOFC containing an annular-coated wall reformer exhibited the highest performance in terms of cell power density (0.67 W.cm 2) and electrical efficiency (68%) with an acceptable temperature gradient and a moderate pressure drop across the reformer (3.53 × 10 5 kPa). IIR-SOFC with an annular-coated wall reformer was then studied over a range of operating conditions: inlet fuel temperature, operating pressure, steam to carbon (S : C) ratio, gas flow pattern (co-flow and counter-flow pattern), and natural gas compositions. The simulation results showed that the temperature gradient across the reformer could not be decreased using a lower fuel inlet temperature (1223 K-1173 K) and both the power density and electrical efficiency of the cell also decreased by lowering fuel inlet temperature. Operating in higher pressure mode (1-10 bar) improved the temperature gradient and cell performance. Increasing the S : C ratio from 2 : 1 to 4:1 could decrease the temperature drop across the reformer but also decrease the cell performance. The average temperature gradient was higher and smoother in IIR-SOFC under a co-flow pattern than that under a counter-flow pattern, leading to lower overpotential and higher cell performance. Natural gas compositions significantly affected the cell performance and temperature gradient. Natural gas containing lower methane content provided smoother temperature gradient in the system but showed lower power density and electrical efficiency. 展开更多
关键词 indirect internal reforming solid oxide fuel cell annular-coated wall reformer packed-bed reformer catalytic coated wall reformer catalyticannular reformer
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One-dimensional Dynamic Modeling and Simulation of a Planar Direct Internal Reforming Solid Oxide Fuel Cell 被引量:2
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作者 康英伟 李俊 +3 位作者 曹广益 屠恒勇 李箭 杨杰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2009年第2期304-317,共14页
This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell (DIR-SOFC) comprehensively. A one-dimensional dynamic model of a planar D1R-SOFC is first developed... This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell (DIR-SOFC) comprehensively. A one-dimensional dynamic model of a planar D1R-SOFC is first developed based on mass and energy balances, and electrochemical principles. Further, a solution strategy is presented to solve the model, and the International Energy Agency (IEA) benchmark test is used to validate the model. Then, through model-based simulations, the steady-state performance of a co-flow planar DIR-SOFC under specified initial operating conditions and its dynamic response to introduced operating parameter disturbances are studied. The dynamic responses of important SOFC variables, such as cell temperature, current density, and cell voltage are all investigated when the SOFC is subjected to the step-changes in various operating parameters including both the load current and the inlet fuel and air flow rates. The results indicate that the rapid dynamics of the current density and the cell voltage are mainly influenced by the gas composition, particularly the H2 molar fraction in anode gas channels, while their slow dynamics are both dominated by the SOLID (including the PEN and interconnects) temperature. As the load current increases, the SOLID temperature and the maximum SOLID temperature gradient both increase, and thereby, the cell breakdown is apt to occur because of excessive thermal stresses. Changing the inlet fuel flow rate might lead to the change in the anode gas composition and the consequent change in the current density distribution and cell voltage. The inlet air flow rate has a great impact on the cell temperature distribution along the cell, and thus, is a suitable manipulated variable to control the cell temperature. 展开更多
关键词 solid oxide fuel cell direct internal reforming PLANAR dynamic model SIMULATION
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Numerical simulation of a direct internal reforming solid oxide fuel cell using computational fluid dynamics method
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作者 Jun LI Ying-wei KANG +3 位作者 Guang-yi CAO Xin-jian ZHU Heng-yong TU Jian LI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第7期961-969,共9页
A detailed mathematical model of a direct internal reforming solid oxide fuel cell(DIR-SOFC) incorporating with simulation of chemical and physical processes in the fuel cell is presented. The model is developed based... A detailed mathematical model of a direct internal reforming solid oxide fuel cell(DIR-SOFC) incorporating with simulation of chemical and physical processes in the fuel cell is presented. The model is developed based on the reforming and electrochemical reaction mechanisms,mass and energy conservation,and heat transfer. A computational fluid dynamics(CFD) method is used for solving the complicated multiple partial differential equations(PDEs) to obtain the numerical approximations. The resulting distributions of chemical species concentrations,temperature and current density in a cross-flow DIR-SOFC are given and analyzed in detail. Further,the influence between distributions of chemical species concentrations,temperature and current density during the simulation is illustrated and discussed. The heat and mass transfer,and the kinetics of reforming and electrochemical reactions have significant effects on the parameter distributions within the cell. The results show the particular characteristics of the DIR-SOFC among fuel cells,and can aid in stack design and control. 展开更多
关键词 Direct internal reforming (DIR) Solid oxide fuel cell (SOFC) Computational fluid dynamics (CFD) Numerical simulation
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Analysis of Heat and Mass Transfer for a Single-Planar-Anode-Supported Solid Oxide Fuel Cell Considering Internal Reforming 被引量:3
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作者 ZHANG Zhuqian WANG Yulei BA Liming 《Journal of Thermal Science》 SCIE EI CAS CSCD 2020年第3期697-707,共11页
The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-... The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-fluid numerical model including electrochemical reactions and water-gas-shift(WGS)reaction for a single channel solid oxide fuel cell was developed to study the steady-state characteristics,which include distributions of the temperature(T),temperature gradient((35)T/(35)x),and fuel utilization.It was shown that the maximum temperature(Tmax)changed with operating voltage and the maximum temperature gradient(((35)T/(35)x)max)occurred at the inlet of the channel of a solid oxide fuel cell by simulation.Moreover,the natural convection condition had a great influence on T and(35)T/(35)x.The thermal stress generated by temperature differences was the key parameter and increasing the convection heat-transfer coefficient can greatly reduce the thermal stress.In addition,the results also showed that there were lower temperature gradients and lower current density at high working voltage;therefore,choosing the proper operating voltage can obtain better cell performance. 展开更多
关键词 three-dimensional numerical simulation internal reforming reaction solid oxide fuel cell temperature gradient fuel utilization
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Predictive control of a direct internal reforming SOFC using a self recurrent wavelet network model 被引量:1
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作者 Jun LI Nan GAO +4 位作者 Guang-yi CAO Heng-yong TU Ming-ruo HU Xin-jian ZHU Jian LI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2010年第1期61-70,共10页
In this paper,an application of a nonlinear predictive controller based on a self recurrent wavelet network (SRWN) model for a direct internal reforming solid oxide fuel cell (DIR-SOFC) is presented. As operating temp... In this paper,an application of a nonlinear predictive controller based on a self recurrent wavelet network (SRWN) model for a direct internal reforming solid oxide fuel cell (DIR-SOFC) is presented. As operating temperature and fuel utilization are two important parameters,the SOFC is identified using an SRWN with inlet fuel flow rate,inlet air flow rate and current as inputs,and temperature and fuel utilization as outputs. To improve the operating performance of the DIR-SOFC and guarantee proper operating conditions,the nonlinear predictive control is implemented using the off-line trained and on-line modified SRWN model,to manipulate the inlet flow rates to keep the temperature and the fuel utilization at desired levels. Simulation results show satisfactory predictive accuracy of the SRWN model,and demonstrate the excellence of the SRWN-based predictive controller for the DIR-SOFC. 展开更多
关键词 Direct internal reforming (DIR) Solid oxide fuel cell (SOFC) Predictive control Self recurrent wavelet network (SRWN)
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Temperature Gradient Analyses of a Tubular Solid Oxide Fuel Cell Fueled by Methanol
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作者 Qidong Xu Meiting Guo +5 位作者 Lingchao Xia Zheng Li Qijiao He Dongqi Zhao Keqing Zheng Meng Ni 《Transactions of Tianjin University》 EI CAS 2023年第1期14-30,共17页
Thermal management in solid oxide fuel cells(SOFC)is a critical issue due to non-uniform electrochemical reactions and convective fl ows within the cells.Therefore,a 2D mathematical model is established herein to inve... Thermal management in solid oxide fuel cells(SOFC)is a critical issue due to non-uniform electrochemical reactions and convective fl ows within the cells.Therefore,a 2D mathematical model is established herein to investigate the thermal responses of a tubular methanol-fueled SOFC.Results show that unlike the low-temperature condition of 873 K,where the peak temperature gradient occurs at the cell center,it appears near the fuel inlet at 1073 K because of the rapid temperature rise induced by the elevated current density.Despite the large heat convection capacity,excessive air could not eff ectively eliminate the harmful temperature gradient caused by the large current density.Thus,optimal control of the current density by properly selecting the operating potential could generate a local thermal neutral state.Interestingly,the maximum axial temperature gradient could be reduced by about 18%at 973 K and 20%at 1073 K when the air with a 5 K higher temperature is supplied.Additionally,despite the higher electrochemical performance observed,the cell with a counter-fl ow arrange-ment featured by a larger hot area and higher maximum temperature gradients is not preferable for a ceramic SOFC system considering thermal durability.Overall,this study could provide insightful thermal information for the operating condition selection,structure design,and stability assessment of realistic SOFCs combined with their internal reforming process. 展开更多
关键词 Solid oxide fuel cell MODELING Methanol fuel Temperature gradient internal reforming
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金融危机以来国内金融市场风险传导机制研究——基于偏t-APARCH模型的实证分析 被引量:9
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作者 蔡则祥 曹源芳 《审计与经济研究》 CSSCI 北大核心 2014年第5期88-96,共9页
基于金融市场波动有偏、尖峰、厚尾的特征,利用有偏t分布APARCH模型和Granger因果关系检验,对我国债券市场、股票市场、外汇市场和货币市场之间的风险传导问题进行考察。研究结果显示:在上涨和下跌阶段,各金融市场的风险传导能力具有个... 基于金融市场波动有偏、尖峰、厚尾的特征,利用有偏t分布APARCH模型和Granger因果关系检验,对我国债券市场、股票市场、外汇市场和货币市场之间的风险传导问题进行考察。研究结果显示:在上涨和下跌阶段,各金融市场的风险传导能力具有个体差异;债券市场、股票市场和货币市场在上涨和下跌阶段具有非常强烈的风险传导能力;外汇市场在上涨阶段对其他市场不具有显著的风险传导能力,而在下跌阶段,对所有市场均具有风险传导能力;从整体上看,我国金融市场在下跌阶段的风险传导能力要强于上涨阶段的风险传导能力。 展开更多
关键词 金融市场风险传导 市场波动 金融风险管理 金融危机 金融改革 金融国际化 次贷危机
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A Regional Repo Market Initiative for Global Financial Stability
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作者 GongpilChoi 《Economics World》 2017年第1期16-33,共18页
The prevailing global financial system suffers from a shortage of good collateral for increased reliance on nonbank secured lending. Given that the global financial crisis was mainly triggered by the collapse of the c... The prevailing global financial system suffers from a shortage of good collateral for increased reliance on nonbank secured lending. Given that the global financial crisis was mainly triggered by the collapse of the collateral pool for dealer-based credit intermediation, this issue needs to be resolved quickly for normalized credit supply. Primarily, increased supply capacity for safe assets that can serve as valid collateral is the key agenda. This would be possible with a better use of USTs that are kept in EME silos and a broader recognition of an emerging market sovereign collateral pool. The inclusion of new collateral into the expanded and invigorated repo system that includes Asia would stabilize global capital flows and improve financial stability. In a related context, a market-driven, risk-mitigating regional repo market initiative would also bring balance to an increasingly market-driven financial ecosystem and mitigate the global shortage of safe assets. 展开更多
关键词 international monetary system reform regional repo market COLLATERALS cross-border capital flows
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Worldwide Inflation and International Monetary Reform:Exchange Rates or Interest Rates? 被引量:1
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作者 Ronald McKinnon 《China & World Economy》 SCIE 2011年第5期1-16,共16页
The international dollar standard is malfunctioning. Near-zero US short-term interest rates launch massive hot money outflows into emerging markets (EM) in Asia and Latin America. Each EM central bank buys dollars t... The international dollar standard is malfunctioning. Near-zero US short-term interest rates launch massive hot money outflows into emerging markets (EM) in Asia and Latin America. Each EM central bank buys dollars to prevent its currency from appreciating but loses monetary control. Despite some appreciation, average inflation in EMs is now much higher than in the old industrial economies and world commodity prices are bid up sharply. This inflation on the dollar 's periphery only registers in the US CPI with a long lag. However, the more immediate effect of the Fed's zero interest rate is to upset the process of bank intermediation within the American economy. Bank credit continues to decline while employment languishes. Therefore, constructive international monetary reform calls for the Fed to abandon its zero-interest rate policy, which is best done in cooperation with the European Central Bank, the Bank of Japan, and the Bank of England also abandoning their ultra low interest rates. 展开更多
关键词 exchange rate global inflation international monetary reform interest rate
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Functional ceramic support as an independent catalyst layer for direct liquid fuel solid oxide fuel cells 被引量:1
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作者 Jie Luo Kai Zhao +5 位作者 Jishi Zhao Jun Li Yihui Liu Dongchu Chen Qing Xu Min Chen 《Journal of Advanced Ceramics》 SCIE EI CAS CSCD 2023年第3期474-486,共13页
A porous ceramic support is designed as a multi-functional independent catalyst layer for solid oxide fuel cells(SOFCs)running on liquid hydrocarbon fuel.The layer consists of a highly porous Ce_(0.9)Ca_(0.1)O_(2−δ)c... A porous ceramic support is designed as a multi-functional independent catalyst layer for solid oxide fuel cells(SOFCs)running on liquid hydrocarbon fuel.The layer consists of a highly porous Ce_(0.9)Ca_(0.1)O_(2−δ)ceramic backbone and active NiMo catalysts,which could be integrated into the conventional Ni metal containing the anode for internal reforming of the hydrocarbon fuel.Compared to conventional catalyst layers sintered on the anodes,this independent catalyst layer could be simply assembled on top of the anode without additional sintering,thereby avoiding the mismatch of the thermal expansion coefficient between the catalyst layer and the anode and improving stability of a single cell.Moreover,a current collector layer could be inserted between the catalyst and the anode to enhance current collection efficiency and electrochemical performance of the single cell.At 750℃,the independent catalyst layer displays high activity towards the catalytic decomposition of methanol,and the single cell could achieve the maximum power density of 400–500 mW·cm^(−2)in dry methanol.Furthermore,by employing the independent catalyst layer,the single cell offers additional in-situ catalyst regeneration capability under the methanol operation mode.Feeding 10 mL·min−1 air into an anode channel for 5 min is found to be effective to burn out carbon species in the catalyst layer,which reduces the degradation rate of the cell voltage by orders of magnitude from 2.6 to 0.024 mV·h−1 during the operation of 360 h in dry methanol.The results demonstrate the significance of the independent catalyst layer design for direct internal reforming methanol fuel cells. 展开更多
关键词 independent catalyst layer NiMo-Ce_(0.9)Ca_(0.1)O_(2−δ)catalyst internal reforming METHANOL solid oxide fuel cell(SOFC)
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Reforming the International Order
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作者 Lan Xinzhen 《Beijing Review》 2018年第6期48-48,共1页
The accusation that China is seeking to overhaul the current international order is often lobbied by Western nations in their attempts at provocationand containment. But is China really fomenting such a change? The r... The accusation that China is seeking to overhaul the current international order is often lobbied by Western nations in their attempts at provocationand containment. But is China really fomenting such a change? The remarks of Chinese President Xi Jinping on numerous international occasions suggest not. China is in fact a beneficiary of the current international system, and the process of reform and opening up continues to adapt China's domestic conditions to better fit this global order. 展开更多
关键词 reforming the International Order
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BRICS Mechanism and International Financial Governance Reform
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作者 Li Wei 《Peace》 2013年第2期11-19,共9页
The global financial crisis in 2008 thoroughly exposed the shortcomings of the existing international financial system, followed by rising initiatives on the international financial governance system reform. Unlike pr... The global financial crisis in 2008 thoroughly exposed the shortcomings of the existing international financial system, followed by rising initiatives on the international financial governance system reform. Unlike previous reforms, emerging economies as a group have gradually become an important participant in the current round of international financial reform, especially with the BRICS countries as the main representative. This paper argues that the BRICS mechanism is in a trial period, and whether it is capable to form a cohesive institutional actor to participate in international financial governance, and to completely change the long-term situation of international financial affairs dominated by developed countries under the framework of the G-20 depends on whether BRICS member states can continue to maintain a rapid economic development, to create a strong convergence of interests and to maintain a relatively closed nature of the mechanism. 展开更多
关键词 BRICS Mechanism and International Financial Governance reform
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Transfer Pricing,Taxing Rights over Cross-Border Sales Income and the OECD Two-Pillar Response
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作者 Kerrie Sadiq Richard Krever 《Belt and Road Initiative Tax Journal》 2023年第2期74-81,共8页
The confluence of several factors including government fiscal pressures and growing opportunities for tax minimization in a digital economy prompted the OECD to embark on a program to reduce base erosion and profit sh... The confluence of several factors including government fiscal pressures and growing opportunities for tax minimization in a digital economy prompted the OECD to embark on a program to reduce base erosion and profit shifting(BEPS).At the same time,countries became increasingly unhappy about international tax rules that left them unable to impose income taxes on companies earning profits by selling to customers inside their country without establishing a taxable presence there.The frustration led to unilateral responses that prompted the OECD to develop proposals to address this problem as well.The OECD’s proposals to reduce profit shifting and enhance taxing rights of sales destination countries evolved into what are now known as Pillar One and Pillar Two international tax reforms.This paper provides an overview of the operation of each of the Pillars and notes the limitations that prevent them from addressing the underlying causes of profit shifting and providing full taxing rights to sales destination jurisdictions. 展开更多
关键词 Transfer pricing Taxing rights Base erosion and profit shifting International tax reform Two-Pillar reform SALES
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