Temperature Gradient Analyses of a Tubular Solid Oxide Fuel Cell Fueled by Methanol

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.

Modelling of a tubular solid oxide fuel cell with different designs of indirect internal reformer

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.

Worldwide Inflation and International Monetary Reform:Exchange Rates or Interest Rates?

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.

Reforming the International Order

The accusation that China is seeking to overhaul the current international order is often lobbied by Western nations in their attempts at provocation and 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

BRICS Mechanism and International Financial Governance Reform

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.

Functional ceramic support as an independent catalyst layer for direct liquid fuel solid oxide fuel cells

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.

Transfer Pricing,Taxing Rights over Cross-Border Sales Income and the OECD Two-Pillar Response

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.

Analysis of Heat and Mass Transfer for a Single-Planar-Anode-Supported Solid Oxide Fuel Cell Considering Internal Reforming

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.