2001 Yusuf-SIMSEK Solar Chimney Www-physics.metu

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Solar Energy I

2001-02-1

Instructor : Prof. Dr. AHMET ECEVIT

Presented by: Yusuf SIMSEK


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TABLE OF CONTENT PAGE

1. Introduction 4

2. The Collector 7

2. Structure of the Collector 8

.

4. The Energy Storage in the Collector 11

. mney

6. Solar Chimney Prototype at Manzanares (Spain) 14

7. Turbines 16

8. How Does Collector Work? 17


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9. Collector Efficiency 21

11. The Chimne 25

12. The Turbine 32

.

14. Typical Dymensions for Solar Chimneys 38

5. Termodynamics

16. Operation 41

17. Technical Data Quantities 42

18. Energy Production Costs 44

19. Conclusion47


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.

Solar chimney converts the solar radiation into electricity. Itconsists of three simple parts:

Glass roof collector

Chimney

Turbine

Basicall air is heated b solar radiation under the lass roof

and it starts to move toward to the chimney. Turbines which are

placed at the base of the chimney converts this mechanical power

. . .


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and a high chimney can be designed to generate 100 to 200 MW

continously 24 h a day. Thus even a small number of solar chimneys

can rep ace a arge nuc ear power s a on. o ar c mneys opera e

simply and have a number of other advantages:

,

Due to the heat storage system the soalr chimney will operate.

Solar chimneys are particularly reliable and not liable to break

down, in com arision with other solar eneratin lants.

Unlike conventional power stations (and also other solar

thermal power station types), solar chimneys do not need cooling

water.


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Unlike conventional power stations (and also other solarthermal power station types), solar chimneys do not cooling

.

The building materials needed for solar chimney, mainly

concrete and lass are available ever where in sufficient

quantities.

Even in poor countries it is possible to build a large plant

without high foreign currency expenditure by using their ownresources and work forces [1].


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2. The Collector

Collector is the part of the chimney that

produce hot air by the green house effect. It

plastic film. The roof material is stretchedhorizontally two or six meter above theChimneygroun . e e g o e roo ncreases

adjacent to the chimney base, so that the air is

diverted to the chimney base with minimumr c on oss. s cover ng a m s e s or

wave solar radiation component and retains

long-wave radiation from the heated ground.

o ec or

us t e groun un er t e roo eats up an

transfers its heat to the air flowing radially

above it from the outside to the chimney [2].Turbine

. .


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3. Structure of the Collector

The structure of the collector changes to the coveringmaterial we used. If we use plastic film we can construct the

s e e on y a us ng e space e ween e ro s as me er.

In this type skeleton attaching plastic film is easy and it is

particularly suitable for very large collector surface in remoteplaces because of the small quantites of the materials needed

and low transportation cost. The 45 000 m2 of the prototype

the optimum and cheapest material in the long life term [3].


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4. Glazed CollectorA flate glazed roof must have much more durable skeleton.

Besause glazing increases the mass of the roof. Its rods are more

stronger and they are attached like in the picture below (Fig. 2.). A

collector roof of this kind has a very long lifespan. With proper

maintanence this can easill be 60 ears or more 4 .

Fig. 2. Collector Glass Roof of Solar ChimneyPrototype at Manzanares from Inside


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A flate glazed collector can convert up to 70% of

irratiated solar energy into heat, dependent on air

throughput, a typical annual average is 50%. Also the

ground under the roof provides natural energy storage

. ,

temperature increases towards tothe tower and energy loss increases

near the chimney. We can increase

the ability of the collector roof by

double lazin about the tower

(Fig. 3).

Fig. 3. Aerial View of Solar

Chimney Prototype at Dusk.


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5. The Energy Storage in the CollectorWater filled black tubes are laid down side by side on

the black sheeted or sprayed soil under the glass roofcollector (Fig. 4). They are filled with water once and remainclosed thereafter, so that no evaporation can take place. Thevolume of water in the tubes is selected to corres ond to awater layer with a depth of 5 to 20 cm depending on the

desired power output.nce e ea rans er e ween ac u es an wa er

is much larger than that between the black sheet and thesoil, even at low water flow speed in the tubes, and since

the heat capacity of water (4.2 kJ/kg) is much higher thanthat of soil (0.75 - 0.85 kJ/kg) the water inside the tubes

night, when the air in the collector cools down [6].


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Fig. 4:Principle of heat storage underneath the roof usingwater-filled black tubes.


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6. Chimney

The chimney is the plants actual

thermal engine (Fig. 5). Its optimal surface-

volume ratio decreases friction loss and makes

it like a pressure tube. The upthrust of the air

proportional to the air temperature rise T in

the collector and the volume of the cchimney.

temperature of the air by about T= 35oC. This

produce an updraught velocity in the chimney

of about V=15m/s [7].

Fig. 5. Chimney


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7. Solar Chimney Prototype at Manzanares

pa n (F g. 6)

only 1.5mm thick

10m diameter

e e o ea ng

was 150mm

vertically at intervals

of 8.6m and shiftened

every 4m y exter or

trussrirelers [8].Fig. 6. Solar Chimney Prototype

at Manzanares


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c mney 195 m g

and 10 m in diameter

surrounded by a collector

240 m in diameter.

Fig. 7. Prototype of the solar chimney at Manzanares.


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8.Turbines

The turbines, the air current is converted into mechanical

energy. The turbines are always placed at a height of 9 meter at the

base of the chimney. According to the size of the turbine, they

placed horizontally (Fig. 8) or verticaly (Fig. 9) and also the number

of the turbines can var .

Fig. 8. Horizontal Fig. 9. Vertical


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9.How Does A Collector

When solar radiation pass

throu h the trans arent roof it is

absorbed by the ground elements andit converts into heat energy. When air

,

to move toward the chimney and

gains a velocity (Fig. 10).Fig. 10. Solar Chimney

Power Plants

so ar c mney co ec or conver s ava a e so ar radiation G onto the collector surface Acoll into heat output.

Collector efficiency ncoll can be expressed as ratio of the

heatoutput of the collector as heated air Q and the solar radiation

G (measured in W/m2) times Acoll[9].


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Collector Efficiency Heat Output

Collector Area


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Spesific heat capacity of the air

The temperature differences

e ween e co ec or an ou ow


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Air speed at collector

outflow/chimney inflowChimne cross-section area

Spesific dendsity of air at temperature To +T at

collector outflow/chimney inflow


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10. Collector Efficiency


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Additionaly valid for heat balance collector:

ective absor tion coefficient of Loss correction value in W/m2K , allowin

the collector for emission and convection loss

Thus collector efficiency can

also be expressed like this:


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ses and ground storage in the collector area neglected.

Typical Values:

= 0.75-0.8

= - 2 =

G=1000 W/m2

T=300C


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11.The Chimney

The efficiency of the chimney (i.e. The conversion of heat

kinetic energy) is particularly independent of the rise of air

perature in the collector; it is essentially determined by the

o .

s solar chimneys can make particularly good use of the low

in air temperature produced by heat emitted by the ground

ng e n g an even e meager so ar ra a on o a co

. Comparing with the collector and turbine, the chimney

ciency is relativelly low, hence the importance of size in its

ciency curve. For example, at a height of 1000 meters,ney efficiency is somewhat greater than 3% [10].


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er air is

lative to

r inside

himney

different from the inside the

chimney.

HC

P(pressure) under the

gravity changes with

res ect to hg. 11 Chimney Height

feratial form g : acceleration due to gravity

nd

HC : Chimney height


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HC

r ens y n e c mney

g. 11 Chimney Height

t of the chimney


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Ptot increases with chimney height.

is consist of two components(dynamic and static)

Ptot =PS+Pd

he static pressure difference drops at the turbine, the dynamic

component describes the kinetic energy of the air flow.

soPS= O Ptot=Pd

Ptot=ptotVC,max AC Efficiency of the chimney can

be establishedvolume


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Actual division of the pressure difference into a static

the turbine. If the turbine is left out, a maximum flow speed

of VC,max is achieved and the whole pressure difference is

use o acce era e e a r.

elli E uation:

0

T Temperature rises between collector inflow and


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his basic simplified explanation one of the basic charesteristic

so ar c mney,w c s t at t e c mney e c ency smentaly dependent only on chimney height. Flow speed and

rature rise in the collector do not come into it.

Thus the power contained in the flow


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12.The Turbine

Turbine in a solar chimney do not work with staged

locity like a free-running wind energy converter, but as a

sed pressure-staged wind turbogenerator, in which, similarly

a hydroelectric power station, static pressure is converted totational ener usin a cased turbine- in this a lication

stalled in a pipe. The energy yield of a cased pressure-staged

rbine of this kind is about eight times greater than that of a

- - .

Air speed before and after the turbine is about the same. The

r unit time and the fall in pressure at the turbine. With a viewmaximum energy yield the aim of the turbine regulation

s em s o max m ze s ro uc un er a o era n


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Blade pitch is adjusted during operation to regulate

.As soon as the wind speed in the chimney exceed 2.5 m/s the

ine is started automaticaly and cut into the public grid. The

ut power of the turbine is adjusted by limiting the rotation

uency of the turbine. This can be adjusted by changing thee an le automaticall Fi . 12 .


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he pressure drop

wt

Powerwt =VC ACPS

ctrical Power W = V I

ume Flow

finally we get the equation


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3. The A ro riate Charesteristic Curve

wt

between these extreme at:

PP=V

PS

.

2/3PtotPs

. 13. Characteristic Curve


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Thus mechanical power taken up by the

owerwt,max = coll c coll

Powerwt,max = (2/3)ncoll(g/CpTo)HoAcollG


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ollector Diameter Dcoll: 2200m

o ar rra a on : m

echanical Efficiency nwt : 0.8

ollector Efficiency ncoll : 0.6

eat Capacity of the Air CP : 1005j/kgKmbient Temperature T0 : 20

0C

ravit Acceleration : 9.81m/s2

ic: (2/3)(0.8x0.6)[9.81/(1005x293)]x750x3751000x1000


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. Typical Dymensions for Solar Chimneys

With Different Power

Power BlockMW 5 30 100 200

With 2300 kWh/m y global radiationymens ons

Collector

Diameter Dcoll

m 1110 2200 3600 4000

Chimney Height

HCm 445 750 950 1500

Chimney

Diameter DC

Annual Energy

ProductionGWh/y 13.9 87.4 305.2 600


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15. Thermodynamics2

Block Size MW 5 30 100

erature rise

ollector

oK 25.6 31.0 35.7

ft Velocity in

mney

ul load)

m/s 9.1 12.6 15.8

l PressurePa 388.3 767.1 1100.5erence

ure Loss by

riction Pa28.6 62.9 80.6

ector n

imney)

ure Drop at Pa314.3 629.1 902.4


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Pressure Loss atPa 40.4 75.1 117.5

verage Annual Efficiency

Collector % 56.24% 54.72%

Chimne % 1.45% 2.33%

52.65%

3.10%

Turbines % 77.00% 78.30% 80.10%

Whole System % 0.63% 1.00% 1.31%


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Power Block Size MW 5 30 100

.

Annual Energy Production

Total GWh/y 13.9 87.4 305.2

Per m2 kWh/m2y 14.4 23.0 30.0

Annual Operating

h/y 8423 8506 8723ours

Full Load Hours h/y 2780 2913 3052

. . .

Night Energy

ProductionGWh/y 1.5 8.7 32.0


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17. Technical Data Quantities

ower Block Size MW 5 30 100

ollector Diameter m 1110 2200 3600

ss Collector Roof-m 162 252 346

tal Covered Area m 76 118 159

Glass Roof Area

Totalm2 967700 3801000 10180000

2x4mmm2 328880 1318000 3570000

Single Glazedm2 61900 2433000 6510000


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lass Roof Area m2 947700 3801000 10080000

Chimney Area m2 4500 11000 20000

lass Roof Height

(external)m 2.0 4.5 6.5

lass Roof Height

(internal )m 10.0 15.5 20.5

Raw Glasskm2 1.3 5.1 13.7

a e. : o ec or a a uan es


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18. Energy Production Costs

With the support of construction companies,he glass industry and turbine manufacturers a rather

ould be compiled. We asked a big utility "Energie in

Baden-Wrttemberg" to determine the energyproduction costs compared to coal- and combinedycle power plants based on equal and common


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Fig. 14. Energy production costs from solar chimneys, coal and


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No ecological harm and no consumption ofsources not even for the construction. Solar chimne s

redominantly consist of concrete and glass which areade from sand and stone plus self-generated energy.

-nd stone solar chimneys can reproduce themselves. Auly sustainable source of energy! [13].


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REFERENCES:

The Solar Chimney. The use of three oldtechnologies. Retrieved 1 December 2001 from;ttp: w re . ses.org w re u cat ons esearc .ns e

aultview/0DED34BF3EB9A985C12569840055F09E/$File/SolarChimne _short_version. df

Schlaich, J. (1995). Solar Chimney: Electricity from the

Sun. Stuttgart; Edition Axel Menges, p.16.Schlaich, J. (1995). Solar Chimney: Electricity from theSun. Stuttgart; Edition Axel Menges, p.28.

Schlaich, J. (1995). Solar Chimney: Electricity from theSun. Stuttgart; Edition Axel Menges, p.17.


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Schlaich, J. 1995 . Solar Chimne : Electricit from the

Sun. Stuttgart; Edition Axel Menges, p.16.

The Solar Chimney. The energy storage. Retrieved 1December 2001 from;

http://wire0.ises.org/wire/Publications/Research.nsf/def

File/SolarChimney_short_version.pdf

Schlaich, J. 1995 . Solar Chimne : Electricit from theSun. Stuttgart; Edition Axel Menges, p.18.

Internet sayfasini bul

Schlaich, J. (1995). Solar Chimney: Electricity from theSun. Stuttgart; Edition Axel Menges, p.52.


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Schlaich, J. 1995 . Solar Chimne : Electricit from the


Schlaich, J. (1995). Solar Chimney: Electricity from the


The Solar Chimney. Energy Production Costs. Retrieved 1

Decem er 2001 rom;

http://wire0.ises.org/wire/Publications/Research.nsf/defau

ltview/0DED34BF3EB9A985C12569840055F09E/$File/SolarChimney_short_version.pdf

The Solar Chimney. Energy Production Costs. Retrieved 1

December 2001 from;

http://wire0.ises.org/wire/Publications/Research.nsf/defau

ltview/0DED34BF3EB9A985C12569840055F09E/ File/


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2. Collector glass roof of solar chimney prototype at

Manzanares from inside. Retrieved 30 November 2001 from

ttp://wire0.ises.org/wire/independents/imagelibrary.nsf/25bcb728e30a3e

$File/glass_roof_from_inside.jpg

3. Aerial View of Solar Chimney Prototype at Dusk. Retrieved

30 November 2001 from;

ttp://wire0.ises.org/wire/independents/ImageLibrary.nsf/H/O?

4. The energy storage; Principle of heat storage underneath the

roof using water-filled black tubes. Retrieved 1 December

2001 from;ttp://wire0.ises.org/wire/Publications/Research.nsf/defaultview


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5. Solar Chimney prototype during construction. Retrieved 30November 2001 from;

http://wire0.ises.org/wire/independents/imagelibrary.nsf/396e92819880db7dc125680f00443688/1982AF4545393096C1256984004F7395/

$File/SolarChimneyManzanaresChimneyConstruction.jpg

6. Solar Chimney Prototype at Manzanares. Retrieved 30November 2001 from;

p: w re . ses.org w re n epen en s mage rary.ns e

80db7dc125680f00443688/1162284EE820787FC1256984004CF03F/

$File/manzanares_air.jpg

10. Solar Chimney Power Plants. Retrieved 30 November 2001

from; http://www.argonet.co.uk/users/bobsier/sola6.html

. e o ar mney. nergy ro uc on os s. e r eve

December 2001 from;http://wire0.ises.org/wire/Publications/Research.nsf/defaultview


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