Mahakal Institute Of Technology, Ujjain: Project:-design Of Prototype Solar Chimney Power

MAHAKAL INSTITUTE OF TECHNOLOGY, UJJAIN PROJECT :- DESIGN OF PROTOTYPE SOLAR CHIMNEY POWER GENERATOR GUIDED BY:- DR. SANTOSH VYAS

NAME AND ROLL NO. OF TEAM MEMBERS :PRADEEP RATHORE (0704ME151062) PRAFFUL JAISWAL (0704ME151063) PRANAV GAUR (0704ME151067) RAJESH ANJANA (0704ME151076)

YOGENDRA SINGH PANWAR (0704ME151116)

CONTENT • OBJECTIVE • THE SOLAR CHIMNEY

• PARTS OF THE SOLAR CHIMNEY

• THEORETICAL FORMULATION FOR POWER OUTPUT & EFFICIENCY

• DESIGN AND FABRICATION DETAILS

COLLECTOR

• ADVANTAGES

TURBINES

• LIMITATIONS

CHIMNEY

• CONCLUSION

• WORKING PRINCIPLES OF SOLAR CHIMNEY

OBJECTIVE • IN MANY PARTS OF THE WORLD, THERE IS A GROWING AWARENESS THAT SOME ALTERNATIVE ENERGY SOURCES COULD HAVE AN IMPORTANT ROLE TO PLAY IN THE PRODUCTION OF ELECTRICITY. • HOWEVER, ONLY THE SOLAR ENERGY REPRESENTS TOTALLY NONPOLLUTING INEXHAUSTIBLE ENERGY RESOURCE THAT CAN BE UTILIZED ECONOMICALLY TO SUPPLY MANS ENERGY NEEDS FOR ALL TIME .

THE SOLAR CHIMNEY • THE SOLAR CHIMNEY IS BASICALLY HYDRAULIC POWER PLANT, BUT INSTEAD OF WATER IT USES HOT AIR. BENEATH A LARGE GLASS ROOF AIR IS HEATED. IT ENTERS A VERTICAL TUBE PLACED AT THE CENTER OF THE ROOF AND CREATES AN UP DRAUGHT THERE INSIDE THE TUBE KAPLAN – TYPE WIND TURBINE WITH ELECTRICAL GENERATOR AND PRODUCING ELECTRICITY.

• CONTINUOUS OPERATION IS GUARANTEED BY PLACING TIGHT WATER – FILLED TUBES UNDER THE ROOF. THE WATER HEATS UP DURING THE DAYTIME AND EMITS ITS HEAT AT NIGHT. THESE TUBES ARE FILLED ONLY ONCE, NO FURTHER WATER IS NEEDED. • THE SOLAR CHIMNEY SYSTEM CONSISTS OF THREE PARTS THE COLLECTOR, TURBINES AND THE CHIMNEY.

PARTS OF THE SOLAR CHIMNEY THE COLLECTOR • COLLECTOR IS THE PART, WHICH IS USED TO PRODUCE HOT AIR BY GREEN-HOUSE EFFECT. IT IS USUALLY 5-6 METERS HIGH AND COVERS A VERY LARGE AREA ABOUT THOUSANDS OF M² AS SEEN IN FIGURE 2. • THERE IS NO LIMITATION FOR THE SURFACE AREA. THE LARGER THE AREA, THE MORE ENERGY GENERATED FROM THE CHIMNEY. • THERE SHOULD BE SLIGHTLY INCREASING HEIGHT TOWARDS TO THE CHIMNEY IN ORDER TO OBTAIN MINIMUM FRICTION LOSS

TURBINES • TURBINES, SEEN IN FIGURE , ARE USED TO CONVERT AIR CURRENT TO THE MECHANICAL ENERGY. • TURBINES ARE PLACED HORIZONTALLY IN CHIMNEY, VERTICALLY IN THE COLLECTOR. IN ORDER TO OBTAIN MAXIMUM ENERGY FROM THE WARMED AIR, TURBINES BLADES SHOULD COVER ALL THE CROSS-SECTIONAL AREA OF THE CHIMNEY. • TO DO THIS, ONE BIG TURBINE OR A FEW SMALL TURBINES SHOULD BE USED IN CHIMNEY.

THE CHIMNEY • THE MOST IMPORTANT PART OF THE PLANT IS THE CHIMNEY, SEEN IN FIGURE . IT ACTS AS A THERMAL ENGINE. SINCE THE FRICTION LOSS IS MINIMUM IN THE CHIMNEY IT LIKES A PRESSURE TUBE. • LONGER THE CHIMNEYS HEIGHT, THE MORE THE ENERGY PRODUCED FROM THE CHIMNEY. • THE EFFICIENCY OF THE CHIMNEY IS NOT DEPEND ON THE AMOUNT OF THE TEMPERATURE RISING, BUT DEPENDS ON THE OUTSIDE TEMPERATURE. • THUS, EFFICIENCY DIRECTLY PROPORTIONAL TO THE RATIO BETWEEN THE HEIGHT OF THE CHIMNEY AND THE OUTSIDE TEMPERATURE.

WORKING PRINCIPLE OF SOLAR CHIMNEY • TRANSPARENT ROOF, WHICH IS SEEN İN FIGURE 10, ADMİTS THE SHORT WAVE SOLAR RADİATİON COMPONENT AND RETAİNS LONGWAVE RADİATİON FROM THE HEATED GROUND. THUS, WHEN SOLAR RADİATİON PASS THROUGH THE TRANSPARENT ROOF İT İS ABSORBED BY THE GROUND ELEMENTS AND İT CONVERTS İNTO HEAT ENERGY.

Fig. 10 Transparent roof

WORKING PRINCIPLE OF SOLAR CHIMNEY • SINCE AIR IS HEATED, IT STARTS TO RISE UP AND MOVE TOWARDS TO CHIMNEY,SEEN İN FIGURE 11. ALSO, IT GAINS VELOCITY. • HEATED AIR ENTERS THE CHIMNEY PLACED AT THE CENTER OF THE ROOF AND CREATES AN UP DRAUGHT THERE.

• INSIDE THE CHIMNEY, TURBINES WITH ELECTRIC GENERATOR, PRODUCE ELECTRICITY.

Fig. 11 Schematic seen of the solar chimney

Tower

Chimney Height (m)

Tower Diameter (m)

Apron Area Apron (sq.m) height (m)

OUTPUT INDEX INDEX (Power Ch.Ht/ Apron Area generation) Apron Area / Ch.Ht

MANZANAR 195 ES, Spain (Built 2002)

10

45000

2

50 KW

0.004333

230.769

Gaboronte Botswanna (Built 2005)

22

1

160

NO DATA

NO DATA

0.1375

7.2727

Australian Govt (Planned 2002)

1000

130

38.5×105

NO DATA

200 MW

2.59×10-5

38484

Greentower, 1500 Nambia (planned 2008)

280

37×106

NO DATA

400 MW

4.05×10-5

24667

THEORETICAL FORMULATION FOR POWER OUTPUT AND EFFICIENCY OF SUT • IN OUR CONSIDERATION, WE IDENTIFIED THREE VARIABLES THAT WOULD INFLUENCE THE POWER OUTPUT OF THE SUT: 𝐴APRON, AREA OF APRON, ΗTOWER, HEIGHT OF TOWER AND 𝐷TOWER, DIAMETER OF TOWER. • POWER IS GENERATED FROM THE WIND TURNING THE TURBINE. FOR NOW WE SET ASIDE THE BASE EFFICIENCY OF THE TURBINE AND ASSUME IT HAS 100% EFFICIENCY, HENCE THE POWER OUTPUT IS SIMPLY DEPENDENT OF THE WIND VELOCITY AND THE AREA COVERED BY THE TURBINE. 𝑃=(1/ 2)𝜌𝑐P𝐴TURBINE𝜈3

• THE AREA, 𝐴, IS SIMPLY THE DIAMETER OF THE TOWER AT THE POINT WHERE THE TURBINE IS PLACED. FOR OUR SETUP, WE USE THE MOST GENERAL CASE FOR THE TOWER AND ASSUME IT HAS UNIFORM DIAMETER THROUGHOUT. 𝐴TURBINE= (1/ 4)𝜋𝐷2TOWER • THE VELOCITY OF THE AIR, 𝑣, IS CAUSED BY THE CONVECTION FLOW OF THE AIR DUE TO HEATING FROM THE SUN. ADDITIONALLY THE AIR EXITS AT THE TOP OF THE TOWER WHERE THE TEMPERATURE IS COOLER. HENCE, THE VELOCITY OF THE AIR IS GIVEN BY THE FOLLOWING: 𝑣 = (2𝑔𝐻TOWER(Δ𝑇/TA))1/2 WHERE Δ𝑇 REPRESENTS THE DIFFERENCE IN TEMPERATURE BETWEEN THE HEATED GAS AT THE BOTTOM OF THE TOWER AND THE TOP OF THE TOWER AND 𝑇 REPRESENTS THE AMBIENT TEMPERATURE OF THE AIR AT THE TOP.

METHODOLOGY ADOPTED:-

Parameters

values

Chimney height (Hch)

7 feet

Chimney diameter (Dch)

90 mm

Collector diameter (Dcoll)

5 feet

Distance from ground to the cover Solar irradiance (G)

(Hcoll)

2 feet 198.32 W/m2

Collector efficiency factor (F’) Ambient temperature (Tamb.)

27 C

DESIGN AND FABRICATION DETAILS: • 1. FABRICATION OF CHIMNEY • A METALLIC CONE STAND IS USED AS THE BASE OF OUR PROTOTYPE SOLAR CHIMNEY. HOLES WERE DRILLED AT EQUAL SPACING FOR SECURING OF SUPPORT WIRES. • RECTANGULAR SECTIONS OF THE CONE WERE CUT OFF TO ALLOW FOR AIR FLOW FROM UNDER THE APRON TO THE CHIMNEY. • A LONG PVC PIPE WAS USED AS OUR CHIMNEY. THESE ARE JOINED TOGETHER AND AIRSEALED USING DUCT TAPE.

FABRICATION DETAILS: • 2. FABRICATION OF GROUND • ROOF CONCRETE ACT AS THE “GROUND” OF THE ENTIRE SETUP. THEY ARE SELECTED TO BE GREY SO AS TO PREVENT THE GROUND FROM ABSORBING ALL THE LIGHT (AND THUS, HEAT) AS WELL AS ABSORB SUFFICIENT AMOUNT OF IRRADIATION, ALLOWING THE AIR INSIDE THE APRON TO ABSORB MORE HEAT TO CREATE A LARGER TEMPERATURE DIFFERENTIAL. • TO HELP IDENTIFY THE MIDDLE OF THE SETUP, A CROSS WAS MADE FROM FOUR CORNERS OF THE GROUND. AFTER POSITIONING THE CHIMNEY, THE POINT WAS MARKED FOR FUTURE REFERENCE.

FABRICATION DETAILS: • 3. FABRICATION OF TURBINE • THE TURBINE WAS MADE OF A DC MOTOR AND AN APPROPRIATELY SIZED FAN BLADE. AFTER ATTACHING THE BLADES TO OUR MOTOR, THE ENTIRE SETUP WAS ATTACHED TO A FRAME SUPPORT WHICH IS THEN HOT GLUED TO THE INSIDES OF OUR CHIMNEY. THE SEVEN FAN BLADE SELECTED WERE 2.5” AND 3” AND WERE INTENDED TO FIT OUR CHIMNEYS WITH INNER DIAMETER OF 3” AND 3.5” RESPECTIVELY.

FABRICATION DETAILS • 4. FABRICATION OF SOLAR PLATE COLLECTOR • FOR OUR COLLECTOR, FIVE PIECES OF TRANSPARENT PLASTIC COVER WAS BOUGHT. WE THEN CUT OUT A SHEET OF PLASTIC, WITH AN OPENING IN THE CENTRE TO FIT OVER THE CHIMNEY. FISHING LINES WERE TIED FROM THE CHIMNEY BASE TO SURROUNDING STAND TO SUSPEND THE GLASSES, LETTING IT ACT AS OUR COLLECTORS. • 5. ELECTRICAL SETUP • WITH DATA THAT STATES THE 7MW OUTPUT OF SOLAR TOWER, THE CIRCUIT WAS SCALED SMALL AS OUR POWER OUTPUT IS PREDICTED TO BE IN THE MILLIWATTS RANGE. RESISTORS OF 0.25W RATING WERE PURCHASED AS WE DO NOT NEED THE HIGHER POWER RATINGS FOR THIS EXPERIMENT.

ILLUSTRATIVE IMAGES:

ADVANTAGES • SOLAR CHIMNEY POWER STATIONS ARE PARTICULARLY SUITABLE FOR GENERATING ELECTRICITY IN DESERTS AND SUN-RICH WASTELAND.

• IT PROVIDES ELECTRICITY 24 HOUR A DAY FROM SOLAR ENERGY ALONE. • NO FUEL IS NEEDED. IT NEEDS NO COOLING WATER AND IS SUITABLE IN EXTREME DRYING REGIONS. • IT IS PARTICULARLY RELIABLE AND A LITTLE TROUBLE-PRONE COMPARED WITH OTHER POWER PLANTS.

• THE MATERIALS CONCRETE, GLASS AND STEEL NECESSARY FOR THE BUILDING OF SOLAR CHIMNEY POWER STATIONS ARE EVERYWHERE IN SUFFICIENT QUANTITIES. • NO ECOLOGICAL HARM AND NO CONSUMPTION OF RESOURCES.

LIMITATIONS • SOME ESTIMATES SAY THAT THE COST OF GENERATING ELECTRICITY FROM A SOLAR CHIMNEY IS 5X MORE THAN FROM A GAS TURBINE. ALTHOUGH FUEL IS NOT REQUIRED, SOLAR CHIMNEYS HAVE A VERY HIGH CAPITAL COST . • THE STRUCTURE ITSELF IS MASSIVE AND REQUIRES A LOT OF ENGINEERING EXPERTISE AND MATERIALS TO CONSTRUCT .

CONCLUSION • SOLAR CHIMNEY POWER PLANTS ARE AN INTERESTING ALTERNATIVE TO CENTRALIZED ELECTRICITY GENERATION POWER PLANTS. IT IS AN IDEALLY ADAPTED TECHNOLOGY FOR COUNTRIES THAT LACK A SOPHISTICATED TECHNICAL INFRASTRUCTURE, WHERE SIMPLICITY AND UNCRITICAL OPERATION OF THE INSTALLATION IS OF CRUCIAL IMPORTANCE. A DETAILED LITERATURE SURVEY OF THIS SYSTEM WAS PERFORMED. THE REVIEW DISCUSSES THE PRINCIPLES AND CHARACTERISTICS OF SUCH A SYSTEM, ITS REQUIREMENTS, ITS CONSTRUCTION AND ITS OPERATION. IT GIVES ALSO A BRIEF OVERVIEW OF THE PRESENT STATE OF RESEARCH AT THE SOLAR CHIMNEY POWER PLANT AND FUTURE PROSPECTS FOR LARGE-SCALE PLANTS. THIS PAPER SHOWED THAT FEW PROTOTYPES HAVE BEEN TESTED IN THE WORLD. IT CAN BE CONCLUDED THAT SUCH SYSTEMS NEED TO BE VERY LARGE IF THEY ARE TO GENERATE SIGNIFICANT QUANTITIES OF POWER. BECAUSE OF HIGH CONSTRUCTION COST OF SOLAR CHIMNEY, MANY RESEARCHERS HAVE CHOSEN THE NUMERICAL WAY IN THEIR STUDIES ESPECIALLY CFD METHODS.

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