EML4930L13

EML4930L13 - S ustainable E nergy S cience and E ngineering...

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Unformatted text preview: S ustainable E nergy S cience and E ngineering C enter Fuel Cell Technology 1. Technology overview 2. Fuel cell performance 3. Fuel cell systems 4. Sample calculations 5. Experiment using PEM cell Reference: Fuel Cell Handbook, 5 th Edition, US DOE, October 2000. Goal: To provide a better understanding of the fuel cell technology, its benefits and systems issues that influence its application. S ustainable E nergy S cience and E ngineering C enter Fuel cell: A device for directly converting the chemical energy of a fuel into electrical energy in a constant temperature process. Besides offering high theoretical efficiency, especially at low temperatures, fuel cells emit low or zero levels of pollutants. They can run on wide variety of fuels ranging from gaseous fuels such as hydrogen and natural gas to liquid fuels such as methanol and gasoline. Main applications: Stationary power generation Transportation Battery replacement. Fuel Cell Technology Overview S ustainable E nergy S cience and E ngineering C enter Ballard 250 kW PEMFC power system S ustainable E nergy S cience and E ngineering C enter Vehicle Fuel Cell System S ustainable E nergy S cience and E ngineering C enter Solar Hydrogen System S ustainable E nergy S cience and E ngineering C enter Operation of a Solid Polymer Fuel Cell (SPFC) Under load a single cell produces about 0.7 volts. S ustainable E nergy S cience and E ngineering C enter In order to achieve a useful output power individual cells are connected together in a ‘stack’ using an interconnect called bipolar plate. MEA: Membrane Electrode Assembly: A combination of electrolyte and electrodes Fuel Cell Stack S ustainable E nergy S cience and E ngineering C enter Carnot efficiency: The maximum efficiency of a heat engine is subject to the Carnot efficiency limitation, which defines the maximum efficiency that any heat engine can have if its temperature extremes are known. Where T H and T L are the absolute high and low temperatures respectively. Fuel cell efficiency: The theoretical efficiency of a fuel cell is related to the ratio of two thermodynamic properties, namely the chemical energy, represented by Gibbs Free Energy ( ∆ G o ) and the total heat energy, represented by the Enthalpy ( ∆ H o ) of the fuel. η C = 1 − T L T H η FC = Δ G o Δ H o Fuel Cell Efficiency S ustainable E nergy S cience and E ngineering C enter Comparison of theoretical efficiency of a fuel cell running on hydrogen as a function of temperature with that of the Carnot efficiency at the same temperature, assuming T L = 25 o C Efficiency vs Temperature Fuel cell operating at low temperatures emit low levels of pollutants such as SO x and NO x when using methanol and natural gas....
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This note was uploaded on 10/22/2011 for the course ESC 2005 taught by Professor Staff during the Spring '11 term at FSU.

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EML4930L13 - S ustainable E nergy S cience and E ngineering...

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