W SOFC-System

DEVELOPMENT OF A PORTABLE PROPANE DRIVEN 300 W SOFC-SYSTEM... 

Development of a Portable Propane Driven 300 W SOFC-System... 

As for the power density of SOFC systems, a comparison between the different kinds of cells has been made (Vora, 2006). The measured specific power (at 1000 K, fuel utilization ratio of 80% and 0.65 V) of a tubular SOFC bundle (24 cells) is around 0.13 in W/cm3, whereas that of an HPD5 bundle (six cells) is of 0.17 in W/cm3. The Delta9 configuration, with bundles of nine cells, reaches over 0.4 W/cm3. A comparison is shown in Figure 7.9. 

Small SOFC systems in the 10-500 W power range operating on hydrocarbon fuels have been considered and developed for portable applications. Examples of portable apphcations are battery charging, remote power, and low-level auxiliary power [50, 51]. Portable SOFC systems are particularly suitable for tactical military applications (e.g., soldier power and unmanned vehicle power) due to its potential for operation on logistics fuels such as JP-8 [52]. 

Solid Oxide Fuel Cells, History, Fig. 8 Ultra Electronics AMI s 50 W (left) and 250 W (right) portable SOFC systems... 

Microtubular SOFCs have been successfully integrated into portable power xmits by Ultra Electronics AMI (USA). Figure 8 shows its 50 W and 250 W systems that use propane as the fuel to produce continuous power. The 50 W systems, miming on propane, provide power for ground sensors, unmanned aerial vehicles, and robots. The 250 W systems are fueled by propane or LPG and are used to extend military mission durations and deliver off-grid power for electronics, radios, and computers. The use of globally available fuels in such portable SOFC systems eliminates complicated logistics. 

In SOFC systems several cells are connected through series or parallel interconnections to form a so-called stack. A single SOFC exhibits voltages of 1 V and an average power density of 1 W/cm note that up to 2 W/cm has also been reported for lab cells [3, 4]. Cell stacks allow accommodation for a wide range of power needs, system weights, and volumes. 

W. The SOFC system supplies 1 kW, and the rest of the power demand is supplied from grid electricity. The characteristic load-following feature of the cogeneration system is shown in Fig. 2.11. These tests confirm that the system efficiency for a residential house is 43%-48% LHV as an average value for the 24-h test period. 

Several other manufacturers are developing SOFC systems based on planar SOFCs. Figure 13.14 shows a photograph of a portable 50 W system, developed by GE Power Systems (formerly Honeywell) that incorporates a planar SOFC stack and other components for a self-contained power unit [56]. GE Power Systems also plans to produce larger size atmospheric and hybrid SOFC systems using planar cells. 

Padulles J., Ault G.W., McDonald J.R. (2000) An integrated SOFC plant dynamic model for power systems simulation. Journal of Power Sources 86, 495-500. 

In recent years, SOFC technology has been developed over a broad spectrum of power generation applications, with systems ranging from portable devices (e.g., 500 W battery charger) to small power systems (e.g., 5kW residential power or automobile auxiliary power units), and to distributed generation power plants (e.g., 100-500 kw systems). SOFCs can also be integrated with a gas turbine to form large (several hundred kW to multi-MW) pressurized hybrid systems [87]. 

The development of such SOFC is promoted by a Swiss consortium led by ETH Zurich [23] and in Germany, a new start-up company named eZelleron presented micro tubular SOFC [24] which can be scaled from 1/5 (nominal/peak load) W for battery chargers for mobile phones etc., to 25/125 W for laptop computers and leisure applications and finally also by connecting high numbers of small cells to 75/375 W-systems. As advantages, the company advertises fast start-up times and fuel flexibility. 

W.A., and Tietz, F. (2008) Screening of A-substitution in the system Ao.esSro.sFeo.gCoo.iOj-j for SOFC cathodes. J. Electrochem. Soc., 155 (2), B204-B214. 

Veyo, S.E., Lundberg, W.L., Vora, S.D., and Litzinger, K.P. (2003) Tubular SOFC hybrid power system status. Proceedings of ASME Turbo Expo 2003 Power for Land, Sea, and Air, Atlanta, Georgia, ASME Paper 2003-GT-38943. 

Solid oxide fuel cells (SOFQ are promising electrochemical energy conversion systems to produce power for portable, mobile, and stationary apphcations ranging from several W to MW. The advantage that SOFCs have over other fuel cell systems is their direct operation on hydrocarbons and air (without being restricted to a hydrogen distribution net). Operation principle, temperature regime, and materials were introduced and are detailed in further articles. 

Blum L, Peters Ro, David P, Au SF, Deja R, Tiedemann W (2004) Integrated stack module development for a 20 kW system. In Proceedings of the 6th European SOFC forum. Lucerne, 30 June - 2 July 2004... 

Farhad and Hamdullahpur (2010) propose a novel portable fuel cell plant fueled by ammonia. In this plant a solid-oxide fuel cell (SOFC) stack consisting of anode-supported planar cells with an Ni-YSZ anode, YSZ electrolyte, and YSZ-LSM cathode is used to generate electric power. An ammonia cylinder with a capacity of 0.8 L is sufficient to sustain full-load operation of the portable system for 9 hours and 34 minutes. Computer simulation of this system predicts that for a 100-W portable device operating at a voltage of 25.6 V (a single-cell voltage of 0.73 V), an energy efficiency of 41.1% and a fuel utilization ratio of 80% are attainable. 

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