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.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12610152/index.pdf |
| Date | 01 November 2008 |
| Creators | Arabaci, Selin |
| Contributors | Yuncu, Hafit |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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