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Search Results: 1 - 10 of 25638 matches for " solid oxide fuel cell "
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Measuring Porosity of Anodes in Solid Oxide Fuel Cell (SOFC) through Water Archimedeans Porosimetry  [PDF]
Syed Mubashar Hassan, Syed Ali Hasnain
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.36005
Abstract: The present research is aimed to measure the porosity of anodes in solid oxide fuel cell through water Archimedeans method. There are various alternatives available to replace fossil fuel cells like nuclear power, wind energy, solar energy, bio fuel, and geothermal and fuel cells. Among all the alternatives of fossil fuel, one form of energy production that stands out from the rest and promises a sustainable future energy is fuel cell. Moreover, it offers many advantages in contrast to other forms of energy generation. An Archimedean approach for water immersion porosimetry is carried out. Some of the results are beyond rational limits, and given negative and sometime above 100 percent porosity. The reasons for these unacceptable results are either due to water ingress into the sample or the sample turns into buoyant due to air in the cling film. The results from Archimedean porosimetry should only be used qualitatively due to errors associated with the results. It is also noted that Archimedean porosimetry is not the ideal technique for measuring the porosity of coated samples. It is suggested that larger samples should be analyzed that will help to minimize the weighing errors.
Performance Assessment of SOFC Systems Integrated with Bio-Ethanol Production and Purification Processes
Issara Choedkiatsakul,Kanokporn Sintawarayan,Tanya Prawpipat,Apinan Soottitantawat
Engineering Journal , 2010, DOI: 10.4186/ej.2010.14.1.1
Abstract: The overall electrical efficiencies of the integrated systems of solid oxide fuel cell (SOFC) and bio-ethanol production with purification processes at different heat integration levels were investigated. The simulation studies were based on the condition with zero net energy. It was found that the most suitable operating voltage is between 0.7 and 0.85 V and the operating temperature is in the range from 973 to 1173 K. For the effect of percent ethanol recovery, the optimum percent ethanol recovery is at 95%. The most efficient case is the system with full heat integration between SOFC and bio-ethanol production and purification processes with biogas reformed for producing extra hydrogen feed for SOFC which has the overall electrical efficiency = 36.17%. However more equipment such as reformer and heat exchangers are required and this leads to increased investment cost.
Influence of Dry Methane Reactions on the Cell Output Characteristics of Solid Oxide Fuel Cells  [PDF]
Hongxin You, Bin Qu, Guoqing Guan, Abudula Abuliti
American Journal of Analytical Chemistry (AJAC) , 2015, DOI: 10.4236/ajac.2015.64024
Abstract: In order to study the influence of dry methane concentration on outputs in solid oxide fuel cells (SOFCs), the output performance was obtained for dry methane of different concentrations on a Ni-ScSZ anode in solid oxide fuel cells, and the anode exhaust gas was measured by online chromatography. The underlying causes of the output performance change were analyzed from the anode reactions by summarizing the anode exhaust gas regular pattern for different reactions, and analyzing the electrochemical reaction kinetics of methane with oxygen ion. As the oxygen ion concentration at the anode three-phase boundary proportionally increased with current density, the following reactions occurred for different dry methane concentrations in sequence CH4 + O2﹣ → CO + 2H2 + 2e, CH4 + 2O2 → CO + H2O + H2 + 4e, CH4 + 3O2 → CO + 2H2O + 6e, CH4 + 4O2 → CO2 + 2H2O + 8e. With various concentrations of methane at a low current, the outlet methane continuously reduced with the increase of the current density. Meanwhile, CO and H2 exhaust gas increased with increasing current density for low concentration of methane. With methane concentrations at 3.85% and 5.66%, the cell output voltage dropped rapidly. For concentrations of 29.7% and 3.85%, the anode exhaust residual methane changed irregularly with current density and this phenomenon was associated with the dry methane that reacted on anode of the cell. The transformation of reactions, the water produced in the electrochemical reactions and the polarization in response to the change of reactions maybe induced the output voltage and power density reducing as low concentrations of dry methane were used.
An Isothermal Study of the Electrochemical Performance of Intermediate Temperature Solid Oxide Fuel Cells  [PDF]
O. O. Ighodaro, K. Scott, L. Xing
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.52006
Abstract: A two-dimensional along the channel micro-scale isothermal model of a SOFC is developed and validated against experimental data and other simulated results from literature. The steady state behaviour of the cell was determined by numerical solution of the combined transport, continuity and kinetic equations. An important characteristic of the model is the consideration of the triple phase boundary as a distinct layer. The model is capable of predicting the cell performance including polarisation behaviour and power output. The model is used to study the effect of the support structure, geometric parameters and the effect of operating conditions on cell performance. Several parametric studies include the effect of operating conditions and geometric parameters on cell performance with a view to optimising the cell. The simulation results showed that the anode supported SOFC displayed the best performance with the activation and ohmic overpotentials being responsible for most of the voltage losses in the cell.
The influence of fuel composition on Solid Oxide Fuel Cell obtained by using the advanced mathematical model
Jaroslaw Milewski
Journal of Power Technologies , 2011,
Abstract: The advanced mathematical model of Solid Oxide Fuel Cell (SOFC) is presented. The governing equations of the model are presented and described. Based on the model the influence of fuel composition on SOFC performance is shown. Hydrogen is used as reference fuel.
Microstructure and electrical properties of SrTi0.98Nd0.02O3-δ -based composites applied as porous layers for SOFCs
Beata Bochentyn,Bogus?aw Kusz
Processing and Application of Ceramics , 2012,
Abstract: SrTi0.98Nb0.02O3-δ-CeO2 and SrTi0.98Nb0.02O3-δ-YSZ composites have been prepared. In order to evaluate the applicability of the material for solid oxide fuel cells (SOFCs) both bulk samples and porous composite layers have been investigated. The electrical conductivity of the bulk samples was measured using the four-terminal DC method, whereas the conductivity of the porous layers was determined using the DC Van der Pauw method in the temperature range of 400–850 °C in humidified hydrogen. The microstructure of the samples was characterized by scanning electron microscopy (SEM) technique. From the fuel cells point of view a significant advantage of the bulk Sr(Ti,Nb)O3-δ-YSZ over Sr(Ti,Nb)O3-δ-CeO2 composite was noticed in the case of microstructure and electrical properties. Ceria grains in the Sr(Ti,Nb)O3-δ-CeO2 composite tend to form large clusters, especially at the grain boundaries. This phenomenon results in sample cracking during redox cycles.
Comparative analysis of time constants in Solid Oxide Fuel Cell processes – selection of key processes for modeling power systems
Jaros?aw Milewski,Janusz Lewandowski
Journal of Power Technologies , 2011,
Abstract: The article presents a comparative analysis of the time constants of the main processes in the SOFC. The analysis was used to determine those processes most relevant to the modeling of an energy system comprising a fuel cell. The hybrid system, in addition to the fuel cell, has other devices (such as compressors, turbines, heat exchangers, etc.) working with it that may limit permissible ranges of parameter changes during transient processes. On the other hand, fuel cells aect other devices making up the system, including by restricting their operation in terms of dynamic responses.Determination of time constants of the main processes in the cell and their analysis and comparison with time constants of other devices will allow selection of the most important processes from modeling point of vies and simplify the dynamic fuel cell model, so the class of fuel cell will match classes of models of other system elements.
Syntheses of Doped-LaCrO3 Nanopowders by Hydrothermal Method  [PDF]
Minkyung Kang, Juyeon Yun, Chiwook Cho, Changyoon Kim, Weonpil Tai
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2013, DOI: 10.4236/ojinm.2013.33007
Abstract:

The effects of additives and precipitants on the syntheses of doped LaCrO3 (lanthanum chromites) were studied by hydrothermal reaction at temperature ranges of 100 to 230. LaCrO3 nanopowders were synthesized by hydrothermal methods using several types of precipitants such as NaOH, KOH, NH4OH, and NH2CONH2. The influence of Sr, Ca and Co doping on the lanthanum chromites prepared by hydrothermal method were investigated. The synthesized nanopowders were characterized by means of XRD, SEM and densitometer. The electrical conductivity of the doped LaCrO3 was studied at 750 in air by a DC four point probe method. The particles size of undoped LaCrO3 nanopowder was approximately 100 nm when using KOH as a precipitant. The relative density of lanthanum chromite doped with calcium and cobalt is over 97%. The highest electrical conductivity of La0.62Ca0.38Co0.18Cr0.82O3 was 32.75 S/cm at 750 in air, which is 30 times higher than undoped LaCrO3. The density and electrical conductivity are increased by doping cobalt and calcium on the LaCrO3.

Effects of ORC Working Fluids on Combined Cycle Integrated with SOFC and ORC for Stationary Power Generation  [PDF]
Osagie Matthew, Sen Nieh
Energy and Power Engineering (EPE) , 2019, DOI: 10.4236/epe.2019.114010
Abstract: The purpose of this study is to explore the effects of working fluid on conventional combined cycle integrated with pressurized solid oxide fuel cell (SOFC) and waste heat recovery organic Rankine cycle (ORC) for stationary utility power generation. The mathematical model of a natural gas fueled design configuration is developed in Matlab and Simulink and simulated with 14 working fluids. The effluent gases of SOFC undergo combustion in the combustion chamber and it is utilized in the gas turbine, steam turbine cycle and ORC. The model is compared with those found in literature and the parametric studies of temperature, flow rate, fuel utilization factor and exhaust gas on the system efficiency are examined. Results revealed that working fluids show a closely related behavior in efficiency at low pressure ratio and high flow fraction, fuel utilization, and temperature. R-123 was found to perform the best among 14 working fluids studied, yielding a system energy efficiency of 70% in the combined cycle integrated with SOFC and ORC.
Effects of Syngas Components on the Carbon Formation in Planar Solid Oxide Fuel Cell
YU Jian-Guo, WANG Yu-Zhang, WENG Shi-Lie
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.01129
Abstract: The utilization of syngas as the fuel of solid oxide fuel cell (SOFC) is one of the main ways to use the coal efficiently and cleanly. However, the possibility of carbon formation in Ni/YSZ anode may reduce the performance of SOFC. According to the fully three―dimensional models of chemical/electrochemical, heat/mass transfer and overpotential, the effects of fuel components on the performance and carbon formation of SOFC were obtained. The results shows that the increments of water steam and carbon dioxide may inhibit the carbon formation activity. However, the massive water steam and carbon dioxide will reduce the output voltage of SOFC as well. The high molar fraction of hydrogen in syngas also reduces the carbon formation activity. The addition of carbon monoxide may narrow down the region of carbon formation, but enhance the carbon formation activity near the fuel inlet of SOFC. Moreover, the existence of methane results in the sharply carbon formation, thus, the methane should be removed as clear as possibly in syngas.
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