401 results found
Shearing PR, Gelb J, Yi J, et al., 2010, Analysis of triple phase contact in Ni-YSZ microstructures using non-destructive X-ray tomography with synchrotron radiation, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 12, Pages: 1021-1024, ISSN: 1388-2481
Shearing PR, Cai Q, Golbert JI, et al., 2010, Microstructural analysis of a solid oxide fuel cell anode using focused ion beam techniques coupled with electrochemical simulation, JOURNAL OF POWER SOURCES, Vol: 195, Pages: 4804-4810, ISSN: 0378-7753
Porous composite electrodes play a critical role in determining the performance and durability of solid oxide fuel cells, which are now emerging as a high efficiency, low emission energy conversion technology for a wide range of applications.In this paper we present work to combine experimental electrochemical and microstructural characterisation with electrochemical simulation to characterise a porous solid oxide fuel cell anode. Using a standard, electrolyte supported, screen printed Ni-YSZ anode, electrochemical impedance spectroscopy has been conducted in a symmetrical cell configuration. The electrode microstructure has been characterised using FIB tomography and the resulting microstructure has been used as the basis for electrochemical simulation. The outputs from this simulation have in turn been compared to the results of the electrochemical experiments.A sample of an SOFC anode of 6.68 mu m x 5.04 mu m x 1.50 mu m in size was imaged in three dimensions using FIB tomography and the total triple phase boundary density was found to be 13 mu m(-2). The extracted length-specific exchange current for hydrogen oxidation (97% H-2, 3% H2O) at a Ni-YSZ anode was found to be 0.94 x 10(-10), 2.14 x 10(-10), and 12.2 x 10(-10) A mu m(-1) at 800, 900 and 1000 degrees C, respectively, consistent with equivalent literature data for length-specific exchange currents for hydrogen at geometrically defined nickel electrodes on YSZ electrolytes. (C) 2010 Elsevier B.V. All rights reserved.
Shearing PR, Gelb J, Brandon NP, 2010, X-ray nano computerised tomography of SOFC electrodes using a focused ion beam sample-preparation technique, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 30, Pages: 1809-1814, ISSN: 0955-2219
Weng X, Brett D, Yufit V, et al., 2010, Highly conductive low nickel content nano-composite dense cermets from nano-powders made via a continuous hydrothermal synthesis route, Solid State Ionics, Vol: 181, Pages: 827-834
Cai Q, Brandon NP, Adjiman CS, 2010, Modelling the dynamic response of a solid oxide steam electrolyser to transient inputs during renewable hydrogen production, Frontiers of Energy and Power Engineering in China, Vol: 4, Pages: 211-222, ISSN: 1673-7504
Hydrogen is regarded as a leading candidate for alternative future fuels. Solid oxide electrolyser cells (SOEC) may provide a cost-effective and green route to hydrogen production especially when coupled to a source of renewable electrical energy. Developing an understanding of the response of the SOEC stack to transient events that may occur during its operation with intermittent electricity input is essential before the realisation of this technology. In this paper, a one-dimensional (1D) dynamic model of a planar SOEC stack has been employed to study the dynamic behaviour of such an SOEC and the prospect for stack temperature control through variation of the air flow rate. Step changes in the average current density from 1.0 to 0.75, 0.5 and 0.2 A/cm2 have been imposed on the stacks, replicating the situation in which changes in the supply of input electrical energy are experienced, or the sudden switch-off of the stack. Such simulations have been performed both for open-loop and closed-loop cases. The stack temperature and cell voltage are decreased by step changes in the average current density. Without temperature control via variation of the air flow rate, a sudden fall of the temperature and the cell potential occurs during all the step changes in average current density. The temperature excursions between the initial and final steady states are observed to be reduced by the manipulation of the air flow rate. Provided that the change in the average current density does not result in a transition from exothermic to endothermic operation of the SOEC, the use of the air flow rate to maintain a constant steady-state temperature is found to be successful.
Brandon NP, 2010, Understanding solid oxide fuel cell microstructure, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 239, ISSN: 0065-7727
Shearing PR, Howard LE, Jorgensen PS, et al., 2010, Characterization of the 3-dimensional microstructure of a graphite negative electrode from a Li-ion battery, ELECTROCHEMISTRY COMMUNICATIONS, Vol: 12, Pages: 374-377, ISSN: 1388-2481
Mermelstein J, Millan M, Brandon N, 2010, The impact of steam and current density on carbon formation from biomass gasification tar on Ni/YSZ, and Ni/CGO solid oxide fuel cell anodes, Journal Power Sources, Vol: 195, Pages: 1657-1666
Maher RC, Brightman E, Heck C, et al., 2010, Monitoring Solid Oxide Fuel Cell Processes Using In-Situ Raman Spectroscopy, 22nd International Conference on Raman Spectroscopy, Publisher: AMER INST PHYSICS, Pages: 550-550, ISSN: 0094-243X
Brandon NP, Matian M, Marquis AJ, et al., 2010, THERMAL MANAGEMENT ISSUES IN FUEL CELL TECHNOLOGY, 14th International Heat Transfer Conference, Publisher: AMER SOC MECHANICAL ENGINEERS, Pages: 591-599
Zhao Y, Shah N, Brandon N, 2010, Performance investigation of a SOFC-GT hybrid system based on thermodynamic optimization strategies, Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010, Vol: 5, Pages: 9-16
A thermodynamic optimization methodology is developed to model, analyze, and predict the system behaviour of a combined SOFC-GT cycle. The system efficiency and power output are used as a basis to optimize the whole hybrid power plant. The optimized performance characteristics are presented and discussed in detail through a parametric analysis. Simulations of the effects that various design and operating parameters have on system performance have led to some interesting results. This study can be considered as a preliminary investigation of more complex fuel cell and gas turbine hybrid systems incorporating additional practical irreversible losses.
Offer GJ, Howey DA, Contestabile M, et al., 2010, Comparative analysis of battery electric, hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system, Energy Policy, Vol: 38, Pages: 24-29
This paper compares battery electric vehicles (BEV) to hydrogen fuel cell electric vehicles (FCEV) and hydrogen fuel cell plug-in hybrid vehicles (FCHEV). Qualitative comparisons of technologies and infrastructural requirements, and quantitative comparisons of the lifecycle cost of the powertrain over 100,000 mile are undertaken, accounting for capital and fuel costs. A common vehicle platform is assumed. The 2030 scenario is discussed and compared to a conventional gasoline-fuelled internal combustion engine (ICE) powertrain. A comprehensive sensitivity analysis shows that in 2030 FCEVs could achieve lifecycle cost parity with conventional gasoline vehicles. However, both the BEV and FCHEV have significantly lower lifecycle costs. In the 2030 scenario, powertrain lifecycle costs of FCEVs range from $7360 to $22,580, whereas those for BEVs range from $6460 to $11,420 and FCHEVs, from $4310 to $12,540. All vehicle platforms exhibit significant cost sensitivity to powertrain capital cost. The BEV and FCHEV are relatively insensitive to electricity costs but the FCHEV and FCV are sensitive to hydrogen cost. The BEV and FCHEV are reasonably similar in lifecycle cost and one may offer an advantage over the other depending on driving patterns. A key conclusion is that the best path for future development of FCEVs is the FCHEV.
Zhao Y, Shah N, Brandon NP, 2010, The Development and Application of a Novel Optimisation Strategy for Solid Oxide Fuel Cell-Gas Turbine Hybrid Cycles, Fuel Cells, Vol: 10, Pages: 181-193
A combined power system with solid oxide fuel cell (SOFC) and gas turbine (GT) is modelled and analysed thermodynamically in this paper. A novel optimisation strategy including the design of optimal parameters is proposed and applied to the hybrid system. Different sources of irreversible losses are specified, and entropy analyses are used to indicate the multi-irreversibilities existing, and to assess the work potentials of the system. Expressions of the power output and efficiency for both the subsystems and the SOFC-GT hybrid system are derived. The optimal performance characteristics are presented and discussed in detail through a parametric analysis. The developed model is expected to provide not only a convenient tool to determine the optimal system performance and component irreversibility, but also an appropriate basis to design similar complex hybrid power plants. This new approach can be further extended to other energy conversion settings and electrochemical systems. Decision makers should therefore find the methodology contained in this paper useful in the comparison and selection of advanced heat recovery systems.
Cordner M, Matian M, Offer GJ, et al., 2010, Designing, building, testing and racing a low-cost fuel cell range extender for a motorsport application, Journal of Power Sources
Panos C, Kouramas KI, Georgiadis MC, et al., 2010, Modelling and Explicit MPC of PEM Fuel Cell Systems, Computer Aided Chemical Engineering, Vol: 28, Pages: 517-522
Matian M, Marquis A, Brett D, et al., 2010, An experimentally validated heat transfer model for thermal management design in polymer electrolyte membrane fuel cells, Journal of Power and Energy
Brett DJL, Kucernak AR, Aguiar P, et al., 2010, What happens inside a fuel cell? Developing an experimental functional map of fuel cell performance, ChemPhysChem, Vol: 11, Pages: 2714-2731
Cai Q, Adjiman CS, Brandon NP, 2010, Modelling the dynamic response of a solid oxide steam electrolyser to transient inputs during renewable hydrogen production, Frontiers of Energy and Power Engineering in China, Vol: 4, Pages: 211-222
Sadhukhan J, Zhao Y, Shah N, et al., 2010, Performance analysis of integrated biomass gasification fuel cell (BGFC) and biomass gasification combined cycle (BGCC) systems, Chemical Engineering Science, Vol: 65, Pages: 1942-1954
Biomass gasification processes are more commonly integrated to gas turbine based combined heat and power (CHP) generation systems. However, efficiency can be greatly enhanced by the use of more advanced power generation technology such as solid oxide fuel cells (SOFC). The key objective of this work is to develop systematic site-wide process integration strategies, based on detailed process simulation in Aspen Plus, in view to improve heat recovery including waste heat, energy efficiency and cleaner operation, of biomass gasification fuel cell (BGFC) systems. The BGFC system considers integration of the exhaust gas as a source of steam and unreacted fuel from the SOFC to the steam gasifier, utilising biomass volatilised gases and tars, which is separately carried out from the combustion of the remaining char of the biomass in the presence of depleted air from the SOFC. The high grade process heat is utilised into direct heating of the process streams, e.g. heating of the syngas feed to the SOFC after cooling, condensation and ultra-cleaning with the Rectisol® process, using the hot product gas from the steam gasifier and heating of air to the SOFC using exhaust gas from the char combustor. The medium to low grade process heat is extracted into excess steam and hot water generation from the BGFC site. This study presents a comprehensive comparison of energetic and emission performances between BGFC and biomass gasification combined cycle (BGCC) systems, based on a 4th generation biomass waste resource, straws. The former integrated system provides as much as twice the power, than the latter. Furthermore, the performance of the integrated BGFC system is thoroughly analysed for a range of power generations, 100–997 kW. Increasing power generation from a BGFC system decreases its power generation efficiency (69–63%), while increasing CHP generation efficiency (80–85%).
Matian M, Marquis A, Brandon NP, 2010, Application of thermal imaging to validate a heat transfer model for polymer electrolyte fuel cells, Int. Journal of Hydrogen Energy
Zhao Y, Shah N, Brandon NP, 2009, Comparison of Two Novel Optimization Strategies for Solid Oxide Fuel Cell-Gas Turbine Hybrid Systems, Third European Fuel Cell Technology & Applications Conference - Piero Lunghi Conference
Clague R, Offer G, Matian M, et al., 2009, Fuel cell racing: Imperial College London presents the Racing Green team, Pages: 302-311
Imperial Racing Green is a major initiative at Imperial College London to design, build and race zero emission vehicles in order to give students hands-on experience in the design, development and construction of fuel cell and battery vehicles, and win competitions like Formula Zero and Formula Student Class 1A, run by the Institute of Mechanical Engineers. The former competition is a time trial series for fuel cell go-carts, the latter is for single seat race cars and accommodates a wider range of technologies. The Imperial Racing Green entry to Formula Zero, codenamed IRG02, is a go-cart powered by a Hydrogenics 8kW PEM fuel cell coupled via a DC/DC converter in a current control loop to two banks of 165F Maxwell ultra-capacitors. Overall vehicle control is achieved with a National Instruments CompactRio, which also acts as a data logger. The Imperial Racing Green entry to Formula Student Class 1A, codenamed IRG03, has a modular 25kW electric drive, braking and suspension assembly at each corner. Racing Green will continue to compete in the Formula Zero Championship throughout 2009, and will compete in Formula Student Class 1A at Silverstone in July 2009. This project has demonstrated that new approaches to project based learning can generate enormous student interest and international media attention, while being rewarding to the academics and researchers involved too. This paper gives detailed information of the design of IRG02 and presents data recorded during the Formula Zero race of August 2008. A summary of the design of IRG03 is also given, concluding with lessons learnt and future plans.
Shearing PR, Gelb J, Brandon NP, 2009, Characterization of SOFC electrode microstructure using nano-scale X-ray Computed Tomography and Focused Ion Beam techniques: A comparative study, Pages: 51-57, ISSN: 1938-5862
In solid oxide fuel cells (SOFC) the redox reactions are supported by composite porous materials and, therefore, the electrochemical activity of an electrode is a direct function of its microstructure. Ni-YSZ (Yttria Stabilized Zirconia) is a common choice for the anode material in SOFC. Recently advances in tomographic techniques have enabled researchers to probe electrode microstructures providing unprecedented access to a wealth of microstructural information regarding the distribution of ionic, electronic and pore phases in three dimensions. In this paper nano-scale X-ray Computed Tomography (nCT) and Focused Ion Beam (FIB) techniques have been used to characterize microstructures from the same Ni-YSZ anode sample, 3D reconstruction from both techniques are presented and a quantitative and qualitative comparison is provided. An advanced technique for sample preparation for nCT is also presented. ©The Electrochemical Society.
Hawkes AD, Brett DL, Brandon NP, 2009, Fuel Cell Micro-CHP Techno-Economics: Part 2 – Model Application to Consider the Economic and Environmental Impact of Stack Degradation, International Journal of Hydrogen Energy, Vol: In Press
Mermelstein J, Millan-Agorio M, Brandon NP, 2009, The impact and mitigation of carbon formation on Ni-YSZ anodes from biomass gasification tars, Pages: 111-117, ISSN: 1938-5862
The combination of Solid Oxide Fuel Cells (SOFCs) and biomass gasification has the potential to become an attractive technology for the production of clean renewable energy. However the impact of tars, formed during biomass gasification, on the performance and durability of SOFC anodes has not been well established experimentally. This paper reports on an experimental study assessment of the performance and mitigation of carbon formation on the anodes of SOFC button cells from synthetic model tars arising from the gasification of biomass material. The anode material was a 60:40 wt.% NiO/YSZ cermet, which was tested in a synthetically generated syngas containing a concentration of up to 15 g/Nm3 biomass gasification tars. It was found that carbon formation in dry conditions significantly damaged the anode of the fuel cell resulting in decreased cell performance and excessive anode polarization resistances. These effects were reduced by applying a load to the cell, and were essentially inhibited once the steam content of the input fuel was > 2%. © The Electrochemical Society.
Hawkes AD, Brett DL, Brandon NP, 2009, Fuel Cell Micro-CHP Techno-Economics: Part 1 - Model Concept and Formulation, International Journal of Hydrogen Energy, Vol: In Press
Mermelstein J, Brandon N, Millan M, 2009, Impact of Steam on the Interaction between Biomass Gasification Tars and Nickel-Based Solid Oxide Fuel Cell Anode Materials, ENERGY & FUELS, Vol: 23, Pages: 5042-5048, ISSN: 0887-0624
Shearing PR, Golbert J, Chater RJ, et al., 2009, 3D reconstruction of SOFC anodes using a focused ion beam lift-out technique, CHEMICAL ENGINEERING SCIENCE, Vol: 64, Pages: 3928-3933, ISSN: 0009-2509
Bidault F, Brett DJL, Middleton PH, et al., 2009, A new application for nickel foam in alkaline fuel cells, 4th Dubrovnik Conference on Sustainable Development of Energy, Water and Environment Systems, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 6799-6808, ISSN: 0360-3199
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