High power density SOFC

Y. Jatsuzaki, et ah, "High Power Density SOFC Development at Tokyo Gas," Fuel Cell Program and Abstracts, 1992 Fuel Cell Seminar, Tucson, Arizona, November 29 -December 2, 1992. 

Patel. Thermally Integrated High Power Density SOFC Generator, in SEC A 2004 Annual Meeting and Core Program Review. 2004. Boston US DOENETL. 

Patel, R, Maru, H.C., Borglum, B., Stokes, R.A., Petri, R., Remick, R.J., Sishtla, C., Krist, K., Armstrong, T. and Virkar, A. (2(K)4) Thermally integrated power systems (TIPS), high power density SOFC generator. Proceedings of the Fuel Cell Seminar 2004, November 1-5 2004, San Antonio, TX, pp. 132-135. 

A more recent development in high power density large-scale tubular SOFCs is that of flat tubes, which consist of a tube with two flat, parallel sides, and two rounded sides, with cross-connected current paths connecting the two flat faces of the tubes through the interior to minimize the length of the current path, as shown schematically in Figure 6.6 [48],... 

FIGURE 6.6 High power density (HPD) SOFC, consisting of a flattened tube with two flat faces. The vertical struts between the two flat faces provide shorter paths for the electronic current collection, eliminating the need for all of the electronic current to travel around the circumference of the cathode, as in the standard tubular cell design shown in Figure 6.5 [48], Reprinted from [48] with permission from Elsevier. 

A SOFC usually operates at temperatures between 800°C (1,472°F) and 1,000°C (1,832°F). It has major advantages such as high power density (typically 200-2,000 mW/cm2), fuel flexibility and the possibility of internal reforming. The latter means hydrogen is generated in the anode volume basically on its porous surface by steam reforming (SR) of, for example, methane (MSR)... 

In the same way, the result of competition amongst the three surviving PEFC, SOFC and MCFC fuel cell types is not predictable. For example, the SOFC has the nascent ability to oxidise natural gas directly, and the MCFC is fuel omnivorous as a result of its mature 600 °C isothermal anode reform capability. Those latter attributes are in contrast to the confinement of the PFFC to hydrogen of minimal CO content, from hydrocarbons processed in an inefficient combustion-driven reformer (inefficient relative to anode reform). The Ballard PFFC has, however, achieved high power density with good, but not unlimited, manoeuvrability. 

The so-called E- and F-designs for stacks with planar anode substrate type cells and metallic interconnects constitute the work horses at Forschungszentrum Jiilich used for testing SOFC materials, cells and manufacturing processes in cell and stack development since its introduction in the year 2000 [1]. Ferritic interconnects were chosen since they offer a high electric conductivity and thus the potential for high power density in the stacks. On the other hand the ferritic material gives rise to chromium evaporation (which can poison the cathodes) and is prone to massive corrosion at temperatures above approximately 900°C [2],... 

FZJ has adopted the design with stainless steel interconnect plates due to the steel s high electrical conductivity und the ensuing high power densities and compact stack designs. At the same time this material has a promising potential for low cost production. Still, the problems of chromium species evaporation from the steel and the corrosion behaviour of steel in SOFC relevant atmospheres need to be carefully addressed in order to achieve an... 

The PEMFC (see Table 17.2 for identification) has the greatest potential to reach high power densities. DMFCs suffer from the high activation potential of the cathodic reduction of oxygen and anodic oxidation of methanol. MCFCs operate at 650°C and SOFCs at 1000°C, their electrolytes being, respectively, molten carbonates and solid metal oxides. Their activation overpotentials are small, but ohmic overpotentials at the... 

There are two types of SOFC planar type and tubular type. An SOFC operates at 800 °C or higher temperatures. Although it can operate with high power density due to its high temperature, the stability of the component materials should be checked for a longtime operation. 

Working temperature of solid oxide fuel cells (SOFC) varies in the range of 600-900 °C. A unique feature of these cells is their ability to utilize methane or other hydrocarbons as fuels. In combination with high power density (about 1 W cm ), this makes SOFCs a very attractive power source for residential applications. 

There are various types of fuel cells that are under development. The most noticeable ones are polymer electrolyte membrane (PEM) fuel cells, phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). PEM fuel cells are mainly being targeted toward transportation needs due to their ability to provide high power densities at reasonable operating temperatures ( 100°C). PAFCs and MCFCs are being developed primarily for stationary applications since their power densities are lower than PEM. SOFCs are currently being developed for both stationary applications and transportation applications but high-temperature material development is needed before they become commercially viable. 

Vora SD (2007) Development of high power density seal-less SOFCs. In Eguchi K, Singhal SC, Yokokawa H, Mizusaki J (eds) Solid oxide fuel ceUs-X. Electrochem Soc, New Jersey, pp 149-154... 

As constructive alternatives, SOFCs can be used as planar or tubular SOFCs, respectively. In the past period, the planar SOFCs become more attractive for the commercialization because of their high power density and low production costs [2]. The planar SOFCs may also be divided into (i) electrolyte-supported and (ii) anode-supported solid oxide fuel cells. Also, more and more attention was focused on solid oxide fuel cells operating at low and/or intermediate temperatures. The decrease of temperature demands an electrolyte with higher ionic conductivity than, for example, the conventional YSZ. 

Integrated planar SOFC and flat-tube high-power density designs... 

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