prof. r. shanthini nov 12, 2012 1 an engineering example for unsustainable development

Prof. R. Shanthini Nov 12, 2012

1

An engineering example for unsustainable development


2

How is electricity generated from

non-renewable energy sources (oil, coal or

natural gas)?

Diesel Generator

Gas Turbine (GT) Steam Turbine

(ST)

Combined Power Plant

(GT & ST)


3

Electric Generator


4

http://electron9.phys.utk.edu/phys136d/modules/m8/images/gen.gif

Magnet

Rotating wire loop

Electrical output

S

N

How to rotate the wire loop?

Electric Generator

We need a rotating shaft?


5

http://www.electricityforum.com/images/motor-eout.gif

Wind turbine gives a rotating shaft


6

Water turbine could also give a rotating shaft


7

Diesel generator

It is a diesel engine coupled to a electric generator.

Diesel engine provides the rotating shaft.

http://www.rkm.com.au/animations/animation-diesel-engine.html


8

Diesel generator

It is a diesel engine coupled to a electric generator.

Diesel engine provides the rotating shaft.

http://www.rkm.com.au/animations/animation-diesel-engine.html


9

Diesel generator

http://www.myrctoys.com/engines/ottomotor_e.swf


10

Comp-ressor

fresh air

Combustion Chamber

fuel

GasTurbine

gasesto the stack

Gen

compressed air

hot gases

Gas Turbine Power Plant


11

Gas turbine to produce electricity


12

Gas turbine driving a jet engine


13



14

Comp-ressor

fresh air

Combustion Chamber

fuel

GasTurbine

gasesto the stack

Gen

compressed air

hot gases


(WGT)out

(WC)in

(QCC)in


15

Comp-ressor

fresh air

Combustion Chamber

fuel

GasTurbine

gasesto the stack

Gen

compressed air

hot gases


(WGT)out

(WC)in

(QCC)in

Useful work output = ?

Total heat input = ?

Total energy loss = ?


16


Useful work output =

Total heat input =

Thermal efficiency of the GT power plant

(WGT)out

(WC)in

(QCC)in

-

(QCC)in

(WGT)out

(WC)in

-ηthermal =

goes to electricity generation

comes with the fuel


17

= = 22 – 28%

Energy wasted:

- [ ]=

=

72 – 78% of heat released by the fuel

for 50 to 100 MW plant

(QCC)in

(WGT)out

(WC)in

-

(QCC)in

(WGT)out

(WC)in

-

ηthermal



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= TC

1 - TH

Hot reservoir at TH K

Heat engine converts heat into work

Cold reservoir at TC K

ηthermal = Wout

Qin

Wout

Qin

Qout

< ηthermal

ηCarnot

ηCarnot


19

ηCarnot =

Carnot efficiency of the GT power plant


TC

TH

1 -Lowest temperature(exhaust gas temperature)

Highest temperature(combustion chamber temperature)

ηCarnot =

= (QCC)in

Maximum possible work output

Total heat input

Maximum possible work output ηCarnot


20


Second-law efficiency of GT power plant

(QCC)in

ηCarnot

= Maximum possible work output

Useful work output

= (QCC)

inηthermal

ηCarnot

= ηthermal

< 1


21

Steam turbine

http://www.bizaims.com/files/generator.JPG


22

SteamTurbine

Gen

Steam Turbine Power Plant


23

C

saturated water

hot gases

SteamTurbine

Gen

compressed water

superheated steam

Condenser

Pump

cooling watersaturatedsteam

Steam Generator



24

R. Shanthini 15 Aug 2010

Steam turbine to produce electricity

Oil could be used instead of coal.

Steam engines are also used to power the train.


25


C

saturated water

Gen

compressed water

superheated steam

cooling water

(WST)out

Pump

SteamTurbine

Condenser

Steam Generator

saturatedsteam

(QSG)in

hot gases

WPin


26

ηthermal = (WST)

out (WP)

in

(QSG)in

-= 30 – 40%

Energy wasted:

(QSG)in

- [ (WST)out

- (WP)in]

=

=

60 – 70% of heat released by the fuel




27

atmosphericair

fuel

GT

gasesto the stack

C

hot gases

ST

cooling water



28

atmosphericair

fuel

GT

gasesto the Stack ST

C

hot gases

ST

cooling water



29



30



31

ηthermal = Heat released by fuel

Useful work output at GT & ST

= 36 – 50%

Energy wasted:

= 50 – 64% of heat released by the fuel




32

Nuclear Power Plant

C

Pressurized water

ST

cooling water

CORE Control rods

Containment

PWR


33

R. Shanthini 15 Aug 2010

Nuclear power plant to produce electricity


34

= 31 – 34%

Energy wasted:

= 66 – 69% of heat released by the fuel


Nuclear Power Plant

ηthermal = Heat released by fuel

Useful work output at ST


35

According to the 2nd Law of Thermodynamics

when heat is converted into work, part of the heat energy must be wasted

Power generation

type

Unit size (MW)

Energy Wasted (MW)

Diesel engine 10 - 30 7 – 22

Gas Turbine 50 - 100 36 – 78

Steam Turbine 200 - 800 120 – 560

Combined (ST & GT) 300 - 600 150 – 380

Nuclear (BWR & PWR) 500 - 1100 330 – 760


36

50% - 70% lost in producing

electricity

2% - 20% lost in transmitting

electricity

Generation, transmission and end-use losses


37

Electric power sector 70% energy losses

Transportationsector

Industrialsector

Residential & Commercial

sector

80% energy losses

25% energy losses

20% energy losses

Typical energy losses in an industrialised country


38

A user of a car always asks for some minimum requirements while using a car.

- The drive should be smooth and easy

- The car should maintain a good speed so as to cope up with other cars in traffic

- Easy and fast refuelling of cars

- A good mileage

- Less pollution


39

EffCarnot =

TC 1 -

TH

TC

TH = Flame temperature (800oC)

= Exhaust Temperature (40oC)

EffCarnot =

313 K1 -

1073 K

71%≈

Vehicles mostly uses Internal Combustion Engines


40

A Typical Car:

100 kJ

63 kJ

18 kJ

17 kJ

2 kJ

Engine losses in fuel energy conversion, In engine cooling and with exhaust gases

Energy for accessories

Standby Idle

Fuel Energy

6 kJ

12 kJ

Driveline losses

2.5 kJ

4 kJ

5.5 kJ

Aerodynamic drags

Rolling resistance

Braking

Source: http://www.fueleconomy.gov/feg/atv.shtml

Urban Driving


41

A Typical Car:

100 kJ

69 kJ

25 kJ

4 kJ

2 kJ

Engine losses in fuel energy conversion, In engine cooling and with exhaust gases

Energy for accessories

Standby Idle

Fuel Energy

5 kJ

20 kJ

Driveline losses

11 kJ

7 kJ

2 kJ

Aerodynamic drags

Rolling resistance

Braking

Source: http://www.fueleconomy.gov/feg/atv.shtml

Highway Driving


42

Take 10 mins.

Discussion Point 4:

Is there a problem in burning oil and coal to make electricity and to drive automobiles in such an inefficient manner?


43

Carbon dioxideCarbon dioxide

Global warmingGlobal warming

Climate changeClimate change

Kyoto protocolKyoto protocoletc.etc.

Fossil fuel use Fossil fuel use

March of the Penguins March of the Penguins

Erin BrockovichErin Brockovich

The Big Ask The Big Ask

The Story of StuffThe Story of Stuff

and more…. and more….

should be watched under parental care

should be watched under parental care

prof. r. shanthini nov 12, 2012 1 an engineering example for unsustainable development

Documents

thermalgas turbine power

electricity gas turbine

steam turbine http

rotating shaftwater

diesel engine

fueluseful work output

electricity oil

natural gas