ME 267 Mechanical Engineering Fundamentalsteacher.buet.ac.bd/ronin/ME 267-gaspowercycle.pdf ·...
Transcript of ME 267 Mechanical Engineering Fundamentalsteacher.buet.ac.bd/ronin/ME 267-gaspowercycle.pdf ·...
Gas Power Cycle
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ME 267
Mechanical Engineering Fundamentals
Gas Power Cycle
Gas Power Cycle
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Gas Turbine
• A turbine that uses hot gases as its working fluid
• It uses generally liquid fuels, although gaseous fuels and even
in some cases solid fuels may also be used
• A simplest type of gas turbine consists of a compressor, a
combustion chamber and a turbine
Gas Power Cycle
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Application
• Aircraft turbojet/turbofan engines
• Trains
• Tanks
• Naval/Maritime
• Power generation & auxiliary applications
Gas Power Cycle
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Basic Components
Gas Power Cycle
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Basic Components
Compressor
Supplies high pressure air for combustion process
Combustion Chamber
• Air and fuel are mixed, ignited, and burned
• Spark plugs used to ignite fuel
Turbine
• Hot gases converted to work
• Can drive compressor and external load
• Consists of one or more stages designed to develop
rotational energy
• Uses sets of nozzles and blades
Gas Power Cycle
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Gas Turbine
Single shaft
• Power coupling on same shaft as turbine
• Same shaft drives rotor of compressor and power components
Split Shaft
• Gas generator turbine drives compressor
• Power turbine separate from gas generator turbine
• Power turbine driven by exhaust from gas generator turbine
• Power turbine drives power coupling
Gas Power Cycle
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Single Shaft and Split Shaft
Gas Power Cycle
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Air-standard assumptions
• The working fluid is air, which continuously circulates in a closed
loop and always behaves as an ideal gas.
• All the processes that make up the cycle are internally reversible.
• The combustion process is replaced by a heat-addition process
from an external source.
• The exhaust process is replaced by a heat-rejection process that
restores the working fluid to its initial state.
Gas Power Cycle
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Brayton Cycle
A closed-cycle gas-turbine engine. An open-cycle gas-turbine engine.
Gas Power Cycle
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Brayton Cycle
Gas Power Cycle
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Brayton Cycle
Gas Power Cycle
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Brayton Cycle: Regeneration
Gas Power Cycle
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Brayton Cycle: Regeneration
Gas Power Cycle
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Brayton Cycle: Intercooling, Reheating and Regeneration
Gas Power Cycle
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Brayton Cycle: Intercooling, Reheating and Regeneration
Gas Power Cycle
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Brayton Cycle: Intercooling and Reheating and Regenaration
Consider an ideal gas-turbine cycle with two stages of compression and
two stages of expansion. The pressure ratio across each stage of the
compressor and turbine is 3. The air enters each stage of the
compressor at 300 K and each stage of the turbine at 1200 K.
Determine the back work ratio and the thermal efficiency of the cycle,
assuming (a) no regenerator is used and (b) a regenerator with 75
percent effectiveness is used. Use air-standard assumptions.
Gas Power Cycle
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Brayton Cycle: Intercooling and Reheating and Regenaration
Gas Power Cycle
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COMBINED GAS–VAPOR POWER CYCLES