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First and second law analyses of a biomass fulled solid oxide fuel ceel-micro turbine hybrid system

Arabacı, Selin
Fuel cells are direct energy conversion devices to generate electricity. They have the lowest emission level of all forms of electricity generation. Fuel cells require no combustion of the fuel. The thermal energy gained from fuel cells may be utilized in micro turbines (gas turbines). In this work, first and second law analyses are performed on a hybrid system consisting of a solid oxide fuel cell (SOFC) combined with a micro turbine to be able to find an optimum point of pressure and corresponding mass ratio to gain maximum work output. Also another system with same equipments only without a gas turbine is investigated to see the effects of gas turbine. The analyses are performed utilizing a code written in MATLAB for each of the equipments. Fuel used is biomass with a certain concentration. To be able to use biomass in a fuel cell-micro turbine hybrid cycle, it is gasified and converted into a certain calorific value gas, with the use of gasifiers. In this study fluidized bed gasifier is utilized since it has the advantage of good mixing and high heat transfer leading to a uniform bed condition. Desulphuration and gas filter units will be implemented in order to clean the producer gas before being used in hybrid system. For a certain percentage of the fuel that may pass through the fuel cell without being used, a combustor is utilized. Optimum point mass and pressure ratios for system are MR = 0.6411 and Pr = 8. Gas turbine supplies more power and higher efficiency to the system. There are different choices for fuel selection in hybrid systems. The reason why biomass is examined among these is that it decreases the depletion of energy carriers and reduces the environmental impact.