The operation of solid oxide fuel cells on various fuels, such as natural gas, biogas and gases derived from biomass or coal gasification and distillate fuel reforming has been an active area of SOFC research in recent years. In this study, we develop a theoretical understanding and thermodynamic simulation capability for investigation of an integrated SOFC reformer system operating on various fuels. The theoretical understanding and simulation results suggest that significant thermal management challenges may result from the use of different types of fuels in the same integrated fuel cell reformer system. Syngas derived from coal is simulated according to specifications from high-temperature entrained bed coal gasifiers. Diesel syngas is approximated from data obtained in a previous NFCRC study of JP-8 and diesel operation of the integrated 25 kW SOFC reformer system. The syngas streams consist of mixtures of hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. Although the SOFC can tolerate a wide variety in fuel composition, the current analyses suggest that performance of integrated SOFC reformer systems may require significant operating condition changes and/or system design changes in order to operate well on this variety of fuels.

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A low-swirl burner (LSB) developed for laboratory research has been scaled to the thermal input levels of a small industrial burner. The purpose was to demonstrate its viability for commercial and industrial furnaces and boilers. The original 5.28 cm i.d. LSB using an air-jet swirler was scaled to 10.26 cm i.d. and investigated up to a firing rate of Q ‫ס‬ 586 kW. The experiments were performed in water heater and furnace simulators. Subsequently, two LSBs (5.28 and 7.68 cm i.d.) configured to accept a novel vaneswirler design were evaluated up to Q ‫ס‬ 73 kW and 280 kW, respectively. The larger vane-LSB was studied in a boiler simulator. The results show that a constant velocity criterion is valid for scaling the burner diameter to accept higher thermal inputs. However, the swirl number needed for stable operation should be scaled independently using a constant residence time criterion. NO x emissions from all the LSBs were found to be independent of thermal input and were only a function of the equivalence ratio. However, emissions of CO and unburned hydrocarbons were strongly coupled to the combustion chamber size and can be extremely high at low thermal inputs. The emissions from a large vane-LSB were very encouraging. Between 210 and 280 kW and 0.8 Ͻ Ͻ 0.9, NO x emissions of Ͻ15 ppm and CO emissions of Ͻ10 ppm were achieved. These results indicate that the LSB is a simple, low-cost, and promising environmental energy technology that can be further developed to meet future air-quality rules.

The physical, thermal, and chemical behavior of pulverized coal particles during thermal decomposition are examined for five coal types and two particle sizes for one of the bituminous coals. Particles were injected axially into a lean (35% excess air) methane/air fiat flame with a nominal peak temperature of 1750~ The significant events observed are classified by three time scales. Particles heat to the gas temperature in less than 10 msec, devolatilization occurs between 10 and 75 msec and, under the appropriate conditions, large soot particles are formed WRS and grow for times exceeding 75 msec.The events that accompany devolatilization are dependent upon coal type and particle size. For large bituminous particles (ca., 80 Izm) a significant volatile fraction is ejected from the particle as a jet. This volatile jet reacts close to the particle producing a trail of small solid particles. The local heat released during the reaction of the volatiles, in combination with heterogeneous oxidation, increases the particle temperature and raises it above that of the bulk gas stream. At later times, large soot structures are formed which are attributed to the agglomeration of small, homogeneously formed soot on the volatile trail structures.Small bituminous particles (ca., 40 Ixm) burn with a higher intensity (i.e., higher temperature and more rapidly) with few trails and do not produce soot structures probably because of the more diffuse nature of the devolatilization process.Other ranks of coal exhibit different physical, thermal, and chemical behavior. For example, neither the lignites nor the anthracite produce volatile trails. Further, the particle temperature for the lignites is only slightly shifted above the bulk gas temperature in the devolatilization region while anthracite takes 50 msec to reach the bulk gas temperature level. This is attributable to the relatively low heat content of the volatiles in the former case and the low volatile content in the latter.The impact of the above observations on the formation of fuel NO is discussed.

Power and temperature control of fluctuating biomass gas fueled solid oxide fuel cell and micro gas turbine hybrid system AbstractThis paper addresses how the power and temperature are controlled in a biomass gas fueled solid oxide fuel cell (SOFC) and micro gas turbine (MGT) hybrid system. A SOFC and MGT dynamic model are developed and used to simulate the hybrid system performance operating on biomass gas. The transient behavior of both the SOFC and MGT are discussed in detail.An unstable power output is observed when the system is fed biomass gas. This instability is due to the fluctuation of gas composition in the fuel. A specially designed fuel controller succeeded not only in allowing the hybrid system to follow a step change of power demand from 32 to 35 kW, but also stably maintained the system power output at 35 kW. In addition to power control, fuel cell temperature is controlled by introduction and use of a bypass valve around the recuperator. By releasing excess heat to the exhaust, the bypass valve provided the control means to avoid the self-exciting behavior of system temperature and stabilized the temperature of SOFC at 850• C.

IntroductionGas turbine combustors are receiving increased attention with respect to design, internal flowfield structure, and dome region mixing processes between the fuel and air. A greater understanding of the processes associated with gas turbine engine combustion is required as designers address problems due to increasing demands on combustor performance and the move toward the use of relaxed specification fuels and alternative fuels. Little is understood about the interaction between fuel spray injection and a swirl-induced aerodynamic field or the interaction of wall jets with a swirl-stabilized flowfield.As an aid to understanding the complex flowfield, in-situ and nonintrusive, spatially resolved measurements of gas velocity, temperature, droplet size, droplet velocity, soot distribution, and species concentration must be provided. Although experimental research has been conducted in both laboratory bench-scale and full-scale hardware (e.g., Brum and Samuelsen, 1987;Gouldin et al., 1985; Lilly, 1985), the required data base is still not available. This is due to several factors. First, the relatively simple model combustors amenable to modeling and optical access for laser diagnostics typically do not exhibit some of the geometrical and operational features characteristic of practical combustors. Second, full-scale combustor beds preclude the use of optical diagnostics, have poorly defined boundary conditions, and have prohibitive operating costs.

a b s t r a c tThe constantly evolving western grid of the United States is characterized by complex generation dispatch based on economics, contractual agreements, and regulations. The future electrification of transportation via plug-in electric vehicles calls for an energy and emissions analysis of electric vehicle (EV) penetration scenarios based on realistic resource dispatch. A resource dispatch and emissions model for the western grid is developed and a baseline case is modeled. Results are compared with recorded data to validate the model and provide confidence in the analysis of EV-grid interaction outlooks. A modeled dispatch approach, based on a correlation between actual historical dispatch and system load data, is exercised to show the impacts (emission intensity, temporally resolved load demand) associated with EV penetration on the western grid. The plug-in hybrid electric vehicle (PHEV) and selected charging scenarios are the focus for the analysis. The results reveal that (1) a correlation between system load and resource group capacity factor can be utilized in dispatch modeling, (2) the hourly emissions intensity of the grid depends upon PHEV fleet charge scenario, (3) emissions can be reduced for some species depending on the PHEV fleet charge scenario, and (4) the hourly model resolution of changes in grid emissions intensity can be used to decide on preferred fleet-wide charge profiles.