ME 267 Mechanical Engineering Fundamentalsteacher.buet.ac.bd/ronin/ME 267-gaspowercycle.pdf ·...

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Gas Power Cycle 25 April 2011 1 ME 267 Mechanical Engineering Fundamentals Gas Power Cycle

Transcript of ME 267 Mechanical Engineering Fundamentalsteacher.buet.ac.bd/ronin/ME 267-gaspowercycle.pdf ·...

Page 1: ME 267 Mechanical Engineering Fundamentalsteacher.buet.ac.bd/ronin/ME 267-gaspowercycle.pdf · 2015-06-01 · ME 267 Mechanical Engineering Fundamentals Gas Power Cycle . Gas Power

Gas Power Cycle

25 April 2011 1

ME 267

Mechanical Engineering Fundamentals

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

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Gas Power Cycle

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Application

• Aircraft turbojet/turbofan engines

• Trains

• Tanks

• Naval/Maritime

• Power generation & auxiliary applications

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Gas Power Cycle

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Basic Components

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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

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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

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Single Shaft and Split Shaft

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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.

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Brayton Cycle

A closed-cycle gas-turbine engine. An open-cycle gas-turbine engine.

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Brayton Cycle

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Brayton Cycle

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Brayton Cycle: Regeneration

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Brayton Cycle: Regeneration

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Gas Power Cycle

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Brayton Cycle: Intercooling, Reheating and Regeneration

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Brayton Cycle: Intercooling, Reheating and Regeneration

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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.

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Brayton Cycle: Intercooling and Reheating and Regenaration

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COMBINED GAS–VAPOR POWER CYCLES