412 results found
Wu B, Yufit V, Campbell J, et al., 2013, Simulated and experimental validation of a fuel cell-supercapacitor passive hybrid system for electric vehicles, IET Conference Publications, Vol: 2013
The concept of a fuel cell-supercapacitor hybrid system involves the direct coupling of the two devices to achieve the same benefits of hybridisation but without the need for costly DCDC converters. Using an experimentally validated steady state fuel cell model and a transmission line based supercapacitor model, it has been shown that the passive hybridisation allows for efficiency gains of approximately 16% compared to a pure fuel cell system. Under load, the supercapacitors meets the peak power requirement due to their lower impedance giving the FC time to ramp up. Under no load conditions, the fuel cell gradually charges the supercapacitors back to the steady state thermodynamic equilibrium potential. A fast fourier transform analysis of the respective loads under an automotive drive cycle showed that the supercapacitors act as a low pass filter, reducing the magnitude of load oscillations from the fuel cell. This therefore addresses two of the main modes of fuel cell degradation in automotive applications: rapid power cycling and no load idling.
Troxler Y, Wu B, Marinescu M, et al., 2013, The effect of thermal gradients on the performance of lithium ion batteries, Journal of Power Sources, Pages: accepted-accepted, ISSN: 0378-7753
Abstract An experimental apparatus is described, in which Peltier elements are used for thermal control of lithium-ion cells under isothermal and non-isothermal conditions, i.e. to induce and maintain thermal gradients. Lithium-ion battery packs for automotive applications consist of hundreds of cells, and depending on the pack architecture, individual cells may experience non-uniform thermal boundary conditions. This paper presents the first study of the impact of artificially induced thermal gradients on cell performance. The charge transfer resistance of a 4.8 Ah is verified to have a strong temperature dependence following the Arrhenius law. Thermal cycling of the cell, combined with slow rate cyclic voltammetry, allows to rapidly identify phase transitions in electrodes, due to the thermal effect of entropy changes. A cell with a temperature gradient maintained across is found to have a lower impedance than one held at the theoretical average temperature. This feature is attributed to details of the inner structure of the cell, and to the non-linear temperature dependence of the charge transfer resistance.
Solid oxide fuel cells (SOFCs) have many advantages when compared to other fuel cell technologies, particularly for distributed stationary applications. As a consequence they are becoming ever more economically competitive with incumbent energy solutions. However, as with all technologies, improvements in durability, efficiency and cost is required before they become feasible alternatives. Such improvements are enabled through improved understanding of the critical material interactions occurring during operation. Raman spectroscopy is a noninvasive and non-destructive optical characterization tool which is ideally suited to the study of these critical chemical processes occurring within operational SOFCs. In this paper we will discuss advantages of using Raman characterization for understanding these important chemical processes occurring within SOFCs. We will present the specific examples of the type of measurement possible and discuss the direction of future research. © 2012 Materials Research Society.
Mazur C, Contestabile M, Offer G, et al., 2012, Comparing electric mobility policies to transition science: Transition management already in action?, Pages: 123-128, ISSN: 2165-4387
Driven by sustainability issues as well as economic aspects, governments have been creating and applying policies and regulations with the aim of shifting national personal transport towards electric mobility. In this context, transition science offers insights into the relevant socio-technological systems and the process of transition. This paper gives an overview of transition science, and furthermore presents current policy making by the UK and German governments that aim to manage the shift to electric mobility. A comparison of the two different policies with transition science shows that there is an overlap between the applied policy making and theory, especially for the case of the UK. Although both governments do not explicitly follow transition management their actions can be explained with the help of transition science. However, it should be noted that transition science is still a young field which needs to be further developed in order to provide policy makers with tools that enable them to manage such transitions. ©2012 IEEE.
Iora P, Taher MAA, Chiesa P, et al., 2012, A one dimensional solid oxide electrolyzer-fuel cell stack model and its application to the analysis of a high efficiency system for oxygen production, CHEMICAL ENGINEERING SCIENCE, Vol: 80, Pages: 293-305, ISSN: 0009-2509
Clague R, Marquis AJ, Brandon NP, 2012, Finite element and analytical stress analysis of a solid oxide fuel cell, JOURNAL OF POWER SOURCES, Vol: 210, Pages: 224-232, ISSN: 0378-7753
Konda NVSNM, Shah N, Brandon NP, 2012, Dutch hydrogen economy: evolution of optimal supply infrastructure and evaluation of key influencing elements, ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Vol: 7, Pages: 534-546, ISSN: 1932-2135
Hawkes AD, Staffell I, Bergman N, et al., 2010, A Change of Scale? Prospects for Distributed Energy Resources, Energy 2050, Editors: Skea, Ekins, Winskel, London, UK, Publisher: Earthscan
Shearing PR, Bradley RS, Gelb J, et al., 2012, Exploring microstructural changes associated with oxidation in Ni-YSZ SOFC electrodes using high resolution X-ray computed tomography, SOLID STATE IONICS, Vol: 216, Pages: 69-72, ISSN: 0167-2738
Brightman E, Maher R, Offer GJ, et al., 2012, Designing a miniaturised heated stage for in situ optical measurements of solid oxide fuel cell electrode surfaces, and probing the oxidation of solid oxide fuel cell anodes using in situ Raman spectroscopy, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 83, ISSN: 0034-6748
Brandon N, 2012, Can we kick our petrol pump habit?, MATERIALS TODAY, Vol: 15, Pages: 182-182, ISSN: 1369-7021
Somalu MR, Brandon NP, 2012, Rheological Studies of Nickel/Scandia-Stabilized-Zirconia Screen Printing Inks for Solid Oxide Fuel Cell Anode Fabrication, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 95, Pages: 1220-1228, ISSN: 0002-7820
Offer GJ, Yufit V, Howey DA, et al., 2012, Module design and fault diagnosis in electric vehicle batteries, Journal of Power Sources
Systems integration issues, such as electrical and thermal design and management of full battery packs–often containing hundreds of cells–have been rarely explored in the academic literature. In this paper we discuss the design and construction of a 9 kWh battery pack for a motorsports application. The pack contained 504 lithium cells arranged into 2 sidepods, each containing 3 modules, with each module in a 12P7S configuration. This paper focuses particularly on testing the full battery pack and diagnosing subsequent problems related to cells being connected in parallel. We demonstrate how a full vehicle test can be used to identify malfunctioning strings of cells for further investigation. After individual cell testing it was concluded that a single high inter-cell contact resistance was causing currents to flow unevenly within the pack, leading to cells being unequally worked. This is supported by a Matlab/Simulink model of one battery module, including contact resistances. Over time the unequal current flowing through cells can lead to significant differences in cells’ state of charge and open circuit voltages, large currents flowing between cells even when the load is disconnected, cells discharging and aging more quickly than others, and jeopardise capacity and lifetime of the pack.
Lorente E, Millan M, Brandon NP, 2012, Use of gasification syngas in SOFC: Impact of real tar on anode materials, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 37, Pages: 7271-7278, ISSN: 0360-3199
Wu B, Offer GJ, Yufit V, et al., 2012, Fault analysis in battery module design for electric and hybrid vehicles, Power Electronics, Machines and Drive
Brett DJL, Manage M, Agante E, et al., 2012, Fuels and fuel processing for low temperature fuel cells, Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology: Fundamentals and Performance of Low Temperature Fuel Cells, Pages: 3-26, ISBN: 9781845697730
This chapter examines the role of the fuel in the operation, performance and degradation of fuel cells. The range of fuels and impurities that are of relevance to low-temperature fuel cells are discussed and the performance from a thermodynamic perspective is analysed. As a route to hydrogen, various fuel processing options are considered along with an overview of the major storage techniques. Issues associated with alternative fuels are covered along with the deleterious properties of fuels and their impurities. © 2012 Woodhead Publishing Limited All rights reserved.
Liu YH, Brandon NP, Liu M, 2012, Electrical models of SOFC for Power Generation, Asia-Pacific Power and Energy Engineering Conference (APPEEC), Publisher: IEEE, ISSN: 2157-4839
Brett DJL, Agante E, Brandon NP, et al., 2012, The role of the fuel in the operation, performance and degradation of fuel cells, Functional Materials for Sustainable Energy Applications, Pages: 249-278, ISBN: 9780857090591
This chapter examines the role of the fuel in the operation, performance and degradation of fuel cells. The range of fuels that are of relevance to fuel cells are discussed and the performance from a thermodynamic perspective is analysed. As a route to hydrogen, various fuel processing options are considered along with an overview of the major storage techniques. Issues associated with alternative fuels are covered along with the deleterious properties of fuels and their impurities. © 2012 Woodhead Publishing Limited All rights reserved.
Shearing PR, Brandon NP, Gelb J, et al., 2012, Multi Length Scale Microstructural Investigations of a Commercially Available Li-Ion Battery Electrode, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 159, Pages: A1023-A1027, ISSN: 0013-4651
Cai Q, Haw AWV, Adjiman CS, et al., 2012, Hydrogen production through steam electrolysis: a model-based study, 22nd European Symposium on Computer Aided Process Engineering (ESCAPE), Publisher: ELSEVIER SCIENCE BV, Pages: 257-261, ISSN: 1570-7946
Lorf C, Martinez-Botas RF, Brandon N, 2012, 26,500km down the Pan-American Highway in an electric vehicle a battery's perspective, SAE Technical Papers, Vol: 1, Pages: 19-26, ISSN: 0148-7191
This paper presents a novel battery degradation model based on empirical data from the Racing Green Endurance project. Using the rainflow-counting algorithm, battery charge and discharge data from an electric vehicle has been studied in order to establish more reliable and more accurate predictions for capacity and power fade of automotive traction batteries than those currently available. It is shown that for the particular lithium-iron phosphate (LiFePO4) batteries, capacity fade is 5.8% after 87 cycles. After 3,000 cycles it is estimated to be 32%. Both capacity and power fade strongly depend on cumulative energy throughput, maximum C-rate as well as temperature. Copyright © 2012 SAE International.
Heat pumps are a promising technology for heating (and cooling) domestic buildings that provide exceptionally high efficiencies compared with fossil fuel combustion. There are in the region of a billion heat pumps in use world-wide, but despite their maturity they are a relatively new technology to many regions. This article gives an overview of the state-of-the-art technologies and the practical issues faced when installing and operating them. It focuses on the performance obtained in real-world operation, surveying the published efficiency figures for hundreds of air source and ground source heat pumps (ASHP and GSHP), and presenting a method to relate these to results from recent UK and German field trials. It also covers commercial aspects of the technologies, the typical savings in primary energy usage, carbon dioxide emissions abatement that can be realised, and wider implications of their uptake.
Ang SMC, Brett DJL, Staffell I, et al., 2012, Design of fuel-cell micro-cogeneration systems through modeling and optimization, WIREs Energy and Environment, Vol: 1, Pages: 181-193
Konda NVSNM, Shah N, Brandon NP, 2011, Design of networks for the large-scale deployment of CO<inf>2</inf>capture, transport and storage using multi-period optimization models: The case for the netherlands, 11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings
Carbon capture and sequestration (CCS) is widely accepted as one of the key technologies in the portfolio of actions that can help mitigate CO2emissions. CCS can play significant role especially in the short/medium term as it offers a seamless and cheaper transition route towards a more sustainable energy economy (e.g., renewables) in the long-term while allowing the continued use of fossil fuels environmentally benignly. However, one of the main stumbling blocks to realize large-scale deployment of carbon capture and storage (CCS) is the huge upfront costs involved. Hence, in this contribution we have proposed a comprehensive optimization framework, that is spatially and temporally explicit, to design the least-cost CCS networks and their optimal evolution with time over the next four decades (i.e., until 2050). This framework establishes optimal transport links amongst most potential sources and sinks (while leaving out the not-so-important ones from a global perspective), as and when they are necessary, to achieve a pre-set CO2reduction target that is to be met by CCS in every decade within this time horizon. We have then demonstrated the applicability and usefulness of our approach with a real case study by applying it to design CCS networks for the Netherlands. As demonstrated by Konda et. al., 2011, CCS must be an integral part of the Dutch CO2mitigation portfolio to comply with the local and regional (i.e., EU level) CO2mitigation targets. Furthermore, the availability of a number of large-scale CO2point-sources and large storage capacity makes CCS an attractive CO2mitigation option for the Netherlands. Potential CO2sources considered within our framework include the existing power plants (including coal/gas-fired plants and Integrated Gasification Combined Cycle plants) and industrial sources (including refineries, cement, steel and chemical plants such as ammonia and hydrogen production plants). In addition to the existing plants, we have also considered th
Cai Q, Adjiman CS, Brandon NP, 2011, Investigation of the active thickness of solid oxide fuel cell electrodes using a 3D microstructure model, Electrochimica Acta, Vol: 56, Pages: 10809-10819, ISSN: 0013-4686
A 3D microstructure model is used to investigate the effect of the thickness of the solid oxide fuel cell (SOFC) electrode on its performance. The 3D microstructure model, which is based on 3D Monte Carlo packing of spherical particles of different types, can be used to handle different particle sizes and generate a heterogeneous network of the composite materials from which a range of microstructural properties can be calculated, including phase volume fraction, percolation and three phase boundary (TPB) length. The electrode model can also be used to perform transport and electrochemical modelling such that the performance of the synthetic electrode can be predicted. The dependence of the active electrode thickness, i.e. the region of the anode, which is electrochemically active, on operating over-potential, electrode composition and particle size is observed. Operating the electrode at an over-potential of above 200 mV results in a decrease in the active thickness with increasing over-potential. Reducing the particle size dramatically enhances the percolating TPB density and thus the performance of the electrode at smaller thicknesses; a smaller active thickness is found with electrodes made of smaller particles. Distributions of local current generation throughout the electrode reveal the heterogeneity of the 3D microstructure at the electrode/electrolyte interface and the dominant current generation in the vicinity of this interface. The active electrode thickness predicted using the model ranges from 5 μm to 15 μm, which corresponds well to many experimental observations, supporting the use of our 3D microstructure model for the investigation of SOFC electrode related phenomena.
Thiedmann R, Stenzel O, Spettl A, et al., 2011, Stochastic simulation model for the 3D morphology of composite materials in Li-ion batteries, COMPUTATIONAL MATERIALS SCIENCE, Vol: 50, Pages: 3365-3376, ISSN: 0927-0256
Zhao Y, Sadhukhan J, Lanzini A, et al., 2011, Optimal integration strategies for a syngas fuelled SOFC and gas turbine hybrid, JOURNAL OF POWER SOURCES, Vol: 196, Pages: 9516-9527, ISSN: 0378-7753
Ang SMC, Fraga ES, Brandon NP, et al., 2011, Fuel cell systems optimisation - Methods and strategies, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 36, Pages: 14678-14703, ISSN: 0360-3199
Zhang X, Su S, Chen J, et al., 2011, A new analytical approach to evaluate and optimize the performance of an irreversible solid oxide fuel cell-gas turbine hybrid system, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 36, Pages: 15304-15312, ISSN: 0360-3199
Clague R, Shearing PR, Lee PD, et al., 2011, Stress analysis of solid oxide fuel cell anode microstructure reconstructed from focused ion beam tomography, JOURNAL OF POWER SOURCES, Vol: 196, Pages: 9018-9021, ISSN: 0378-7753
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