Fuel cell applications pdf

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Advantages of this class of fuel cells include high efficiency, long-term stability, fuel cell applications pdf flexibility, low emissions, and relatively low cost. SOFCs use a solid oxide electrolyte to conduct negative oxygen ions from the cathode to the anode. Solid oxide fuel cells have a wide variety of applications, from use as auxiliary power units in vehicles to stationary power generation with outputs from 100 W to 2 MW. Because of these high temperatures, light hydrocarbon fuels, such as methane, propane, and butane can be internally reformed within the anode.

Whether your business is local or global, and storage into account. Δ as an Electrolyte for Low, as their performance is not degraded by lower temperatures. The Japanese ENE FARM project will pass 100, on the anode side, coated side of the catalyst faces the membrane in the fuel cell. The fuel cell was a stack design that allowed the fuel cell to be integrated with the plane’s aerodynamic surfaces.

Such reformates are mixtures of hydrogen, carbon monoxide, carbon dioxide, steam and methane, formed by reacting the hydrocarbon fuels with air or steam in a device upstream of the SOFC anode. SOFC power systems can increase efficiency by using the heat given off by the exothermic electrochemical oxidation within the fuel cell for endothermic steam reforming process. SOFC stacks with planar geometry require on the order of an hour to be heated to light-off temperature. SOFCs can have multiple geometries. SOFCs can also be made in tubular geometries where either air or fuel is passed through the inside of the tube and the other gas is passed along the outside of the tube. The tubular design is advantageous because it is much easier to seal air from the fuel.

The performance of the planar design is currently better than the performance of the tubular design, however, because the planar design has a lower resistance comparatively. Cross section of three ceramic layers of a tubular SOFC. A single cell consisting of these four layers stacked together is typically only a few millimeters thick. Hundreds of these cells are then connected in series to form what most people refer to as an “SOFC stack”. Reduction of oxygen into oxygen ions occurs at the cathode. These ions can then diffuse through the solid oxide electrolyte to the anode where they can electrochemically oxidize the fuel.

In this reaction, a water byproduct is given off as well as two electrons. These electrons then flow through an external circuit where they can do work. The cycle then repeats as those electrons enter the cathode material again. Consequently, granular matter is often selected for anode fabrication procedures. Like the cathode, it must conduct electrons, with ionic conductivity a definite asset. YSZ part helps stop the grain growth of nickel.

Larger grains of nickel would reduce the contact area that ions can be conducted through, which would lower the cells efficiency. The anode is commonly the thickest and strongest layer in each individual cell, because it has the smallest polarization losses, and is often the layer that provides the mechanical support. If the fuel is a light hydrocarbon, for example, methane, another function of the anode is to act as a catalyst for steam reforming the fuel into hydrogen. This provides another operational benefit to the fuel cell stack because the reforming reaction is endothermic, which cools the stack internally. C which is possible because they have the ability to overcome a larger activation energy.

The electrolyte is a dense layer of ceramic that conducts oxygen ions. Its electronic conductivity must be kept as low as possible to prevent losses from leakage currents. The high operating temperatures of SOFCs allow the kinetics of oxygen ion transport to be sufficient for good performance. The electrolyte material has crucial influence on the cell performances.

SOFC will broaden and many existing problems can potentially be solved. Cathode materials must be, at a minimum, electronically conductive. Mechanically, it has a similar coefficient of thermal expansion to YSZ and thus limits stress buildup because of CTE mismatch. Also, LSM has low levels of chemical reactivity with YSZ which extends the lifetime of the materials. In order to increase the reaction zone beyond the TPB, a potential cathode material must be able to conduct both electrons and oxygen ions.

Composite cathodes consisting of LSM YSZ have been used to increase this triple phase boundary length. SOFCs as they are more active and can make up for the increase in the activation energy of the reaction. The interconnect can be either a metallic or ceramic layer that sits between each individual cell. Its purpose is to connect each cell in series, so that the electricity each cell generates can be combined.

Because the interconnect is exposed to both the oxidizing and reducing side of the cell at high temperatures, it must be extremely stable. For this reason, ceramics have been more successful in the long term than metals as interconnect materials. However, these ceramic interconnect materials are very expensive as compared to metals. The material of choice for an interconnect in contact with Y8SZ is a metallic 95Cr-5Fe alloy. Ceramic-metal composites called ‘cermet’ are also under consideration, as they have demonstrated thermal stability at high temperatures and excellent electrical conductivity.