PARABOLIC TROUGH COLLECTOR

AKSHAY CHANDEL (601)MITHIL PANDEY(627)KUSUMA SUJAN(644)ANKIT SINGH(606)

Parabolic Trough CollectorA parabolic trough is a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror. 

The energy of sunlight which enters the mirror parallel to its plane of symmetry is focused along the focal line, where objects are positioned that are intended to be heated. For example, food may be placed at the focal line of a trough, which causes the food to be cooked when the trough is aimed so the Sun is in its plane of symmetry

Types of solar collectorsMotion Collector type Absorber

typeConcentration

ratio

Indicative temperature range (°C)

Stationary

Flat plate collector (FPC) Flat 1 30-80

Evacuated tube collector (ETC) Flat 1 50-200

parabolic collector (PC) Tubular1-5 60-240

Single-axis tracking

5-15 60-300Linear Fresnel reflector (LFR) Tubular 10-40 60-250

Parabolic trough collector (PTC) Tubular 13-45 60-300

Cylindrical trough collector (CTC) Tubular 10-50 60-300

Two-axes tracking

Parabolic dish reflector (PDR) Point 100-1000 100-500

Heliostat field collector (HFC) Point 100-1500 150-2000Note: Concentration ratio is defined as the aperture area divided by the receiver/absorber area of the collector.

TEI Patra: 3-18 July 2006

Modified view of PTC with Glass and without Glass

Design ParametersParameters Parabolic Trough Collector

Rim Angle (Degrees) 90

Focal Length (mm) 200

Mirror Length(mm) 914.4

Aperture Width(mm) 647.7

Depth of Parabola(mm) 250

SS Sheet Thickness(mm) 0.5

Concentration Ratio 13.6

Thermocouple  

Thermal Conductivity of SS (w/m/k)  16.3

Thermal Conductivity of Copper (w/m/k)  385

DATA ANALYSIS OF PTC

Hourly temperature data of Shirpur

Date/Time 9am-10am 10am-11am

11am-12pm

12pm-1pm

1pm-2pm 2PM-3PM

21st april 32 °C 34°C 36°C 37°C 38°C 38°C

22nd april 32°C 34°C 35°C 36°C 36°C 37°C

23rd april 32°C 34°C 35°C 36°C 37°C 37°C

24th april 34°C 35°C 37°C 37°C 38°C 39°C

25th april 36°C 36°C 38°C 39°C 40°C 40°C

26th april 34°C 36°C 38°C 39°C 39°C 40°C

27th april 35°C 37°C 39°C 40°C 41°C 42°C

                                                             Hourly temperature data for 1 week

Three Days Analysis of Water Temperature without Glass Cover

Date/Time 9am-10am

10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

21st april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           Date/Time 9am-10am

10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

22nd april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           Date/Time 9am-10am

10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

23rd april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           

Three Days Analysis of Water Temperature with Glass Cover

Date/Time 9am-10am

10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

24th april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           Date/Time 9am-

10am10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

25th april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           Date/Time 9am-10am

10am-11am

11am-12pm

12pm-1pm

1pm-2pm

2pm-3pm

26th april            HTF inlet temp. Tin [oC]

           

HTF outlet temp. Tout [oC]

           

iirradiance G [W/m2]

           

For the condition of  F = D , the rim angle becomes equal to 90° and the receiver makes minimum intercept angle with radiation reflected from Parabolic Trough

Design of PTC

where θm is the half acceptance angle limited by the size of the sun’s disk, small scale errors and irregularities of the reflector surface and tracking errors. 

)sin(1

maxm

C

Concentration Ratio of PTC.• The concentration ratio (C) is defined as the ratio of the aperture area to the receiver/absorber area, i.e.:

• For flat-plate collectors with no reflectors, C=1. For concentrators C is always greater than 1. For a single axis collector the maximum possible concentration is given by:

     

and for two-axes tracking collector:

TEI Patra: 3-18 July 2006 Intensive program: ICT tools in PV-systems Engineering

r

a

AA

C

)sin(1

maxm

C

)(sin1

2maxm

C

where θm is the half acceptance angle limited by the size of the sun’s disk, small scale errors and irregularities of the reflector surface and tracking errors.

THERMAL ANALYSIS OF PTC.

Convection and Conduction of PTC

 Convection heat exchange between the receiver and    the fluid =Qcrf = hcrf Ari (Tri − Tf )Andhcrf = Nurfλf /driWhere,Hcrf  = Heat Transfer Coefficient Between Receiver And Fluid.Ari =∏.d.L (Internal Surface of Receiver).Tri = Inner temperature of receiver.Tf = Average temperature of fluid.Dri = inner diameter of receiver. λ = Thermal Conductivity of fluid.

CONTD..

Conduction through ReceiverConduction heat transfer through the receiver Qkr is : Qkr =  (Tre – Tri)/RkrAnd       Rkr = (ln(dre/dri))/2∏ λrLWhere , Tre = outer temperature of the receiver, ◦C Tri = inner temperature of the receiver, ◦Cdre = outer diameter of the receiver, mm dri = inner diameter of the receiver, mmλr =  thermal conductivity of the receiver W/mm/◦C

COLLECTOR’S EFFICIENCY

Collector’s Efficiency EquationHow efficient is the collector in capturing the sun’s energy:Collector efficiency = heat capturing capability -heat loss

Heat loss of a collector =  Fr UL * (Tm-Ta)/G

Where, 

Fr UL = the collector’s thermal losses. The smaller, the better.∆ T =Collector fluid T minus air TG = Solar Insolation. (w/ m2 )

Contd…

Heat Capturing Capability = Fr(τα)Where,

Fr(τα) = The amount of solar energy that can be absorbed by the collector is characterized by Fr (taualpha), its optical efficiency. The higher, the better.

Linear efficiency equationHow efficient is the collector in capturing the sun’s energy :

η= Fr(τα) -Fr UL * (Tm-Ta)/G.Where , η =  Collector’s Efficiency

PTC Project ConsiderationsFactors for successful project:1. Large demand for hot water to reduce importance of fixed costs2. High energy costs (e.g. natural gas not available)3. No reliable conventional energy supply4. Strong environmental interest by building owner/operator 5. Daytime hot water loads require less storage Daytime hot water

loads require less storage 6. Lower cost, seasonal systems can be financially preferable to

Lower cost, seasonal systems can be financially preferable to higher higher- -cost year cost year- -round systems round systems.

7. Maintenance similar to any plumbing system, but operator must Maintenance similar to any plumbing system, but operator must be committed to timely maintenance and repairs

Advantages of PTC1. Solar  Water  Heaters  are  the  most  cost  effective  and 

environmentally  friendly  way  to  harness  solar  energy  for domestic and commercial applications. They can be used in any climate and the only fuel they need is SUNLIGHT.

2. Save  Energy:40%  of  an  advantages  over  conventional  water heating systems as they:

3. Save  Interior  Space:  These  systems  are  usually  located  on rooftops.

4. Safer:  These  systems  eliminate  the  risk  of  accidents  in bathrooms due to electrical water heating equipment.

5. They require little or no maintenance, while providing hot water all day, everyday.

APPLICATIONS1. Restaurants, Clubs & Resorts2. Hospitals, Hostels, Institutions3. Canteens and Laundries4. For Swimming pool water heating5. Process Industries6. Green buildings to earn renewable energy points7. For Can washing at Dairy collection centres8. General washing & cleaning purposes9. Agricultural sector10. As Infer to the boiler ( Closed Loop / open loop) Or we can say to fed pre 

heated water to the boiler.11. Can be used to provide direct Hot water to VAM based Air conditioning 

systems

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