Exergoeconomic analysis and optimization of organic Rankine cycles
Heat sources such as biomass, industrial waste heat and solar thermal provide the potential to produce renewable environmentally low impact electricity. Using these resources efficiently within economic constraints is important for viability of these systems. This thesis explores a regenerative orga...
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| Language: | en |
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2012
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| Online Access: | http://hdl.handle.net/10155/231 |
| Summary: | Heat sources such as biomass, industrial waste heat and solar thermal provide the
potential to produce renewable environmentally low impact electricity. Using these
resources efficiently within economic constraints is important for viability of these
systems. This thesis explores a regenerative organic Rankine cycle for use in low
temperature heat sources. A Bitzer model scroll expander is used for the prime mover for
the system. This expander has a reliable model in which thermodynamic analysis can be
done. Various working fluids are explored to investigate which one will provide the most
power output and efficiency within system constraints. Using optimization, each fluid is
tested within physical constraints for optimal operating conditions using system exergy
efficiency as the objective function. An exergoeconomic analysis is performed to predict the
cost rate of electricity of the system and is compared to current contract rates from the
Ontario Power Authority. Dimethyl ether shows promising results with a system exergy
efficiency of 11.76% and system energy efficiency of 2.84% at a source temperature of
120℃. The degree of superheat and pressure ratio are used as the independent variables in
the optimization. Highest isentropic efficiency for the expander is 29.22%, showing large
potential for improvement. Electricity cost rates for the system assuming 20 year life are
0.132 $/kWh to 0.197 $/kWh depending on the fuel input cost for dimethyl ether. At the
current state the system shows merit with large potential for improvement in the
expander. === UOIT |
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