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Gas Turbine Technology : Flying Machine to

Ground Utilities

P M V Subbarao

Professor

Mechanical Engineering Department

A White Collar Power Generation Method

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Progress in Rankine Cycle

Year 1907 1919 1938 1950 1958 1959 1966 1973 1975

MW 5 20 30 60 120 200 500 660 1300

p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 15.9 24.1

ThoC 260 316 454 482 538 566 566 565 538

TroC -- -- -- -- 538 538 566 565 538

FHW -- 2 3 4 6 6 7 8 8

Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1

h,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40

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The most Unwanted Characteristic of RankineGroup of Power Generation Systems

The amount of cooling required by any steam-cycle power plantis determined by its thermal efficiency.

It has nothing essentially to do with whether it is fuelled by

coal, gas or uranium. Where availability of cooling water is limited, cooling does not

need to be a constraint on new generating capacity.

Alternative cooling options are available at slightly higher cost.

Nuclear power plants have greater flexibility in location thancoal-fired plants due to fuel logistics, giving them more

potential for their siting to be determined by coolingconsiderations.

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Cooling Problems !!!!

The bigger the temperature difference between the internalheat source and the external environment where the surplusheat is dumped, the more efficient is the process inachieving mechanical work.

The desirability of having a high temperature internallyand a low temperature environmentally.

In a coal-fired or conventionally gas-fired plant it ispossible to run the internal boilers at higher temperaturesthan those with finely-engineered nuclear fuel assemblies

which must avoid damage. The external consideration gives rise to desirably siting

power plants alongside very cold water.

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Steam Cycle Heat Transfer

For the heat transfer function the water is circulated

continuously in a closed loop steam cycle and hardly any islost.

The water needs to be clean and fairly pure.

This function is much the same whether the power plant is

nuclear, coal-fired, or conventionally gas-fired. Cooling to condense the steam and surplus heat discharge.

The second function for water in such a power plant is to coolthe system so as to condense the low-pressure steam and

recycle it. This is a major consideration in siting power plants, and in the

UK siting study in 2009 all recommendations were for siteswithin 2 km of abundant water - sea or estuary.

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Water, Water & Water .!!!!!

A nuclear or coal plant running at 33% thermal efficiencywill need to dump about 14% more heat than one at 36%efficiency.

Nuclear plants currently being built have about 34-36%thermal efficiency, depending on site (especially watertemperature).

Older ones are often only 32-33% efficient.

The relatively new Stanwell coal-fired plant in Queenslandruns at 36%, but some new coal-fired plants approach 40%and one of the new nuclear reactors claims 39%.

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History & Repetition 1791: A patent was given to John Barber, an Englishman,

for the first true gas turbine. His invention had most of the elements present in the

modern day gas turbines. The turbine was designed to power a horseless carriage. 1872: The first true gas turbine engine was designed by Dr

Franz Stikze, but the engine never ran under its ownpower.

1903: A Norwegian, gidius Elling, was able to build thefirst gas turbine that was able to produce more power thanneeded to run its own components, which was consideredan achievement in a time when knowledge aboutaerodynamics was limited.

Using rotary compressors and turbines it produced 11 hp(massive for those days).

He further developed the concept, and by 1912 he haddeveloped a gas turbine system with separate turbine unitand compressor in series, a combination that is nowcommon.

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1914: Application for a gas turbine engine filed by

Charles Curtis. 1918: One of the leading gas turbine manufacturers oftoday, General Electric, started their gas turbinedivision.

1920: The practical theory of gas flow throughpassages was developed into the more formal (andapplicable to turbines) theory of gas flow past airfoils

by Dr A. A. Griffith. 1930: Sir Frank Whittle patented the design for a gas

turbine for jet propulsion.

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THE WORLDS FIRST INDUSTRIAL GAS TURBINE

SETGT NEUCHTEL

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4 MW GT for Power Generation

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First turbojet-powered aircraftOhains engine on He 178

The worlds first aircraft to fly purely on turbojet power, the

Heinkel He 178.

Its first true flight was on 27 August, 1939.

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Steam Turbine Vs Gas Turbine : Power Generation Experience gained from a large number of exhaust-gas turbines for

diesel engines, a temp. of 538C was considered absolutely safe for

uncooled heat resisting steel turbine blades. This would result in obtainable outputs of 2000-8000 KW withcompressor turbine efficiencies of 73-75%, and an overall cycleefficiency of 17-18%.

First Gas turbine electro locomotive 2500 HP ordered from BBC by

Swiss Federal Railways The advent of high pressure and temperature steam turbine withregenerative heating of the condensate and air pre-heating, resulted incoupling efficiencies of approx. 25%.

The gas turbine having been considered competitive with steam

turbine plant of 18% which was considered not quite satisfactory. The Gas turbine was unable to compete with modern base loadsteam turbines of 25% efficiency.

There was a continuous development in steam power plant which ledto increase of Power Generation Efficiencies of 35%+

This hard reality required consideration of a different application forthe as turbine.

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Anatomy of A Jet Engine

1 2 34 5 6

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Variation of Jet Technologies

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Ideal Jet Cycles

T0

2

3

4

5

Direction

1

6jTurboJet

6f 7f

6p 7p

Turbofan

Turboprop

~1970sAero Rejected Engines & Aero Derivative Engines

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Brayton Cycle

1-2 Isentropic compression (in a compressor)

2-3 Constant pressure heat addition

3-4 Isentropic expansion (in a turbine)

4-1 Constant pressure heat rejection

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pv & Ts diagrams

SSSF Analysis of Control Volumes Making a Brayton Cycle:

CV

outin

CV WgzV

hmgzV

hmQ

22

22

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CV

outin

wgzV

hgzV

hqCV

22

22

Specific Energy equation of SSSF :

No Change in potential energy across any CV

CVoutin whhqCV ,0,0

Calorically perfect and Ideal Gas as working fluid.

CVoutpinp wTCTCqCV ,0,0

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)( 010212 TTchhw pcomp 12 : Specific work input :

23 : Specific heat input :

34 : Specific work output :

41 : Specific heat rejection :

)( 020323 TTchhq pin

)( 040343 TTchhw ptur

)( 010414 TTchhq pout

Isentropic Processes:

1

01

02

01

02

T

T

p

p 1

04

03

04

03

T

T

p

p

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01040203

& pppp

Constant Stagnation Pressure Processes:

1

04

031

01

02

04

03

01

020

T

T

T

T

p

p

p

prp

011

00102

TrTT p

0

03

1

0

0304

T

r

TT

p

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)()(01020403

01020403

TTTTc

hhhhwww

p

compturnet

)1(1

)()(

001

0

003

010103

03

TTc

TTT

Tcw

p

pnet

)( 0103

0103

T

TTTcw pnet

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)( 010030203 TTchhq pin

)(

0103

01

0

0301003

TTc

TT

TTc

q

w

p

p

in

net

th

h

11111

0

0

h

p

in

netth

rqw

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11

10

0

h

p

th

r

010030

001

0

030

001

0

003

1)1(

)1(1

TTcTT

c

TTcw

pp

pnet

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00.1

0.2

0.3

0.4

0.5

0.6

0.7

0 10 20 30

thh

pr0

Pressure Ratio Vs Efficiency

P R ti V S ifi W k t t

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ne t

pr0

Pressure Ratio Vs Specific Workoutput

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0

0.2

0.4

0.6

0.8

0 10 20 30Pressure ratio

hth

wneth%

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0

0.2

0.4

0.6

0.8

0 10 20 30Pressure ratio

1872, Dr Franz Stikzes Paradox