Fuel processors for fuel cell vehicles

Fuel processors for fuel cell vehicles

16 Fuel science and technology (fundamental science, analysis, instrumentation) implemented to the simulator using a non-equilibrium sorption formulat...

158KB Sizes 0 Downloads 108 Views

16 Fuel science and technology (fundamental science, analysis, instrumentation) implemented to the simulator using a non-equilibrium sorption formulation. The sorption model accounts for the non-ideality of the free gas phase, as partial fugacity of the gas component is calculated using the Peng-Robinson equation of state. Model predictions of multicomponent sorption of methane, nitrogen and carbon dioxide mixtures on the coal are found to be in good agreement with experimental measurements. The transport component of the compositional coalbed simulator is verified using an existing two-phase coalbed simulator.

was assumed to be homogeneous for the complete mixing in the lateral direction and no mixing in the longitudinal direction. The particles were monodisperse and stationary relative to the gas in the distance. It was assumed that the combustion of coal particles occurs in the diffusion regime. The binary diffusion coefficients were identical, independent of the concentration of components of gas mixture. The Lewis number was assumed to be 1, and the Soret and Dufour effects were negligibly small. Approximately equations were obtained for the detection of the increment and frequency of acoustic oscillations which explicitly include parameters of fuel and oxidant.

03/00869 Effect of greenhouse design parameters on conservation of energy for greenhouse environmental control

03/00873 Experimental investigation of a downdraft biomass gasifier

Gupta, M. J. and Chandra, P. Energy, 2002, 27, (8), 777-794. A mathematical model was developed and used to study the effect of various energy conservation measures to arrive at a set of design features for an energy efficient greenhouse. The simulation results indicated that under cold climatic conditions of northern India, a gothic arch shaped greenhouse required 2.6% and 4.2% less heating as compared to gable and quonset shapes. An east-west oriented gothic arch greenhouse required 2% less heating as compared to a northsouth oriented one. North wall insulation of an east west oriented gothic arch greenhouse saved 30% in heating costs. The use of night curtains reduced the night-time heating requirement by 70.8% and daily requirement by 60.6%. By replacing the single cover on the southern side with air inflated double wall glazing, the heating requirement was reduced by 23%. The combination of the design features for an energy efficient greenhouse suitable for cold climatic conditions was found to reduce the greenhouse heating needs by 80%. An internal rock bed thermal storage/retrieval system met the remaining heating energy requirements of the energy-conserving greenhouse.

Zainal, Z. A. et al. Biomass and Bioenergy, 2002, 23, (4), 283-289. An experimental investigation of a downdraft biomass gasifier is carried out using furniture wood and wood chips. The effect of equivalence ratio on the gas composition, calorific value and the gas production rate is presented. The calorific value of the producer gas increases with equivalence ratio initially, attains a peak and then decreases with the increase in equivalence ratio. The gas flow rate per unit weight of the fuel increases linearly with equivalence ratio. It is also observed that complete conversion of carbon to gaseous fuel has not taken place even for the optimum equivalence ratio.

03/00874

Fuel processors for fuel cell vehicles

zur Megede, D. Journal of Power Sources, 2002, 106, (1-2), 35~,1. Hydrogen is the fuel of choice for today's fuel cells with polymer electrolyte. However, for its successful application in vehicles there are some open issues, for example the missing hydrogen infrastructure and difficulties with regard to vehicle storage tanks. This makes on-board fuel processors together with liquid fuels both attractive and necessary. Different types of fuel processors for fuel cell vehicles are described. Some examples together with developmental challenges are presented.

03100870 Energetic utilization of used tires Zabaniotou, A. et al. Energy Sources, 2002, 24, (9), 843-854. In this study, used tyre pyrolysis experiments were performed in a captive sample reactor, at atmospheric pressure, under a helium atmosphere. The effects of temperature on the yields and composition of the pyrolysis products were investigated. Char yield decreased with the temperature of pyrolysis, while total gas yield increased. Tar and liquid hydrocarbons increased slightly with temperature. Experiments combined with a first-order kinetic model allowed the estimation of the kinetic parameters for total weight loss. The char produced by pyrolysis was burned and its reactivity was measured as a function of pyrolysis temperature. It was found that there was a decline in reactivity for charring temperatures above 650°C and that char produced at low pyrolysis temperature is preferable for medium heating value solid fuel uses.

03100871 Energy and material management based on a fuzzy-petri net approach Tuma, A. Int. J. Environment and Sustainable Development, 2002, I, (2), 160-170. In model production systems, materials and different forms of energy are provided, converted, stored and transported. Environmental impacts can be identified at any stage of the energy and material flow process. Due to the fact that production units and processes are interconnected with energy and material flows, it is of special interest to implement production control policies, which control the energy and material streams. In this way it is possible that available resources utilized most efficiently and emissions and by-products caused by the production process are reduced. Achieving this goal in one step, the input and output streams of a production system have to be balanced. This can be done with input-output models (e.g. unit operation models) or with simulation systems. Due to the requirements of the modelling of real production systems (simultaneous modelling of structure and state of the production system, availability to describe analytical and synthetical production structure, possibility to model different aggregation levels) a petri net approach seems to be adequate to this task. In a second approach, control strategies concerning economic and ecological goals have to be integrated. In accordance with the structure of the available expert knowledge (fuzzy knowledge) a fuzzy petri net approach for an environmental integrated controlling of interconnected production systems is discussed. Validating this approach an exemplary production system from the textile industry, consisting of a house, a hydropower plant, a boiler dye house, and a flue gas neutralization facility is analysed.

03100872 Excitation of acoustic oscillations during combustion of coal particles Pesochin, V. R. Izvestiya Akademii Nauk, Energetika, 2002, (1), 146151. (In Russian) A theoretical study of excitation of acoustic vibrations during combustion of coal particles in the combustion chamber of a pulse MHD generator was carried out. The flow in the combustion chamber

03100875 Ground-based passive FT-IR spectrometry Knapp, R. B. et al. Proceedings ~?f SPIE-The International Society for Optical Engineering, 2002, (4577), 269-286. Absorbance and transmittance spectra were acquired with groundbased passive Fourier transform IR (FTIR) spectrometry for industrial stack evaluations and open-air controlled vapour generation experiments. Industrial flue gas containing SOz and N20 from a coal-burning power plant and an acid plant, respectively, were analysed with midwave- and long-wave-lR passive sensors. Controlled open-air experiments used only a long wave-IR sensor. Experiments produced methanol and ethanol plumes at 3 and 4 elevated plume temperatures, respectively. Various vapour concentration path length of ethanol and methanol were generated and gravimetrically monitored at 0-300 ppm/ m. Associated absorbance values for these concentration path length products obeyed Beer's Law for each elevate stack temperature of 125, 150, 175, and 200 ° .

03100876 In-situ high-temperature magnetic resonance imaging of coals by using prepared magnetization SPRITE techniques Saito, K. Energy & Fuels, 2002, 16, (3), 575 585. This paper considers the 3D-SPRITE which has been shown to be successful for studying short relaxation time systems and which is free from distortions due to susceptibility variations for coals. The results obtained were discussed in relation to the three-dimensional distribution of mobile components for two kinds of coal. At the same time, inversion recovery preparation experiments are presented in order to clarify the chemical heterogeneity of coals. This paper also documents the first systematic in-situ variable-temperature NMR microimaging study of coals between 25 and 600°C with a newly developed hightemperature microimaging probe and systems. This is in order to clarify the behaviour of mobile components at high temperatures in heterogeneous coal specimens.

03•00877 Measurement of the mass transfer coefficient and Sherwood number for carbon spheres burning in a bubbling fluidized bed Hayhurst, A. N. and Parmar, M. S. Combustion and Flame, 2002, 130, (4), 361-375. In this study a freely moving, machined sphere of graphite (or a rounded particle of a coal char) attached to a very thin, flexible thermocouple is burnt in a bed of silica sand fluidized by air. Simultaneous measurements were made of [CO] and [CO2] in the off-gases, as well as of the temperature of the burning particle. Each sphere of carbon was large enough (>2 mm) for its burning to be controlled by external mass transfer. These measurements, together with the relative rates of formation of CO and COz obtained previously, enabled mass transfer coefficients and Sherwood numbers to be derived. Such measurements were made for different temperatures in the bed, sizes of sand, superficial velocities, and initial diameters of a graphite sphere. Only a slight decrease in Sh was found

Fuel and Energy Abstracts

March 2003 115