Indigenous Development of Parabolic TroughCollector Technology

Lead Industry Partner: MILMAN

Association: National Chemical Laboratory

Raja Ramanna Center for Advanced Technology

Indian Institute of Technology, Madras

MILMAN®

In Brief …..

PIONEERS IN LARGE VOLUME INDUSTRIAL PVD EQUIPMENT IN INDIA

• 3 MILLION PARTS PER MONTH

AlSnSi TOP COATING

Ni DIFFUSION

BARRIER

COPPER LEAD

BEARING

AlSnSi

Ni

CuPb

• NEW GENERATION OF TURBO

DIESEL ENGINES HAS HIGH

MOMENTUM

• ABRASIVE WEAR

• ADHESIVE WEAR

• MATERIAL AlSnSi ALLOY WITH

Ni DIFFUSION BARRIER

• HIGH FATIGUE LIFE/HIGH

EMBEDDIBILITY

PROJECT COST 12 CRORES

LEADING INDUSTRIAL EQUIPMENT

SUPPLIER IN INDIA

PIONEERS IN PLASMA NITRIDING

OF TITANIUM TURBINE RODS

BODYCOTE, BHEL, INDO-

GERMAN TOOL ROOM, NML, BIT,

UNITHERM

80 MILLION PER MONTH

SOLAR PARABOLIC COLLECTOR

SOLAR TRACKER

Milman

GLASS TO METAL

SEAL - RRCATPHOTORECIEVER

TUBE - Milman

SOLAR SELECTIVE

COATING – NCL, NAL

MILMAN®

• Coatings optimized on Milman PVD system

• CERMET/OTHER MULTIAYER coatings by Magnetron Sputtering have shown promising properties

• Absorption Coefficient ≈ 90-96% and emissivity ≈ 8-10%

• Emissivity measurements carried out at 450⁰C

• Cross-check of best samples at PTB, Germany in future

GM SEAL

GM SEAL (70mm) JOINED TO BOROSILICATE GLASS BY GRADED SEAL

Most important Component from Reliabilitypoint of view

Tested for leak rates at 10**-9 torr lit. / s

Passed shear tests at 9 MPa

Good quality oxide formation optimized in ambient air conditions

Thermal Shock Test at 190 C

Process understanding complete. Mass Production technique development underway

Thermal Modeling of Parabolic Trough Collector Receiver

The Receiver

• Parabolic trough receiver, also called heat collecting element

(HCE), is the key component in the parabolic trough solar

thermal power system

• It comprises of central metal pipe sputtered solar selective

coating , a glass tube surrounding the central metal pipe

• Metal bellows allows to release the stress between the outer glass tube and inner stainless steel tube caused

by different coefficients of thermal expansion

• The vacuum-tight enclosure between metal pipe and glass tube significantly reduce

heat losses at high operating temperatures and protect the solar-selective coating from

oxidation

• Suitable vacuum levels must be maintained in the receivers so as to ensure

performances during its projected lifetime

• The glass envelope usually has an antireflective coating to improve transmissivity

• The working temperature is currently limited by the cracking temperature of the

synthetic oil working fluid

Heat Collection Element Model

Qsol,abs : The concentrated solar radiation absorbed by the absorber tube

(W/m)

Qconv,HTF : The heat transferred to the HTF from the inner absorber surface

through convection (W/m)

Qcond,abs : The heat transferred through the absorber from the outer absorber

surface to the inner absorber surface by conduction (W/m)

Qrad,ann : The heat transferred across the evacuated annulus from the outer

absorber surface,to the inner glass surface through radiation

(W/m)

Qcond,gl : The heat transferred through the glass envelope from the inner

glass surface to the outer glass surface by conduction (W/m)

Qrad,sky : The heat transferred from the glass envelope to the sky through

radiation (W/m)

Q : The heat transferred to ambient from the outer glass surface

Receiver Specification

Outer diameter of the receiver (do) : 70mm

Inner diameter of the receiver (di) : 65.6mm

Outer diameter of the glass cover(dco): 120mm

Inner diameter of the glass cove (dci) : 115mm

Length of the receiver (L) : 4.06m

(Burkholder, 2009)

• A study of trough thermal analysis is necessary to evaluate the performance of a parabolic trough collector

• MATLAB coding was developed to evaluate the thermal performance of parabolic trough collector

• Receiver considering both parametric and fixed inputs

• The absorber tube is divided into 500 uniform segments, heat loss and thermal performance was evaluated

Parameter LS3

collector

ENEA

collector

Absorptivity(α) 0.9 0.96

Reflectivity(ρ) 0.93 0.94

Transmissivity(

τ)

0.95 0.97

Shading loss 0.97 0.99

Structural loss 0.95 0.98

Optical

efficiency %

73.27 84.82

Parametric Considerations for the

Optical Efficiency of the Receiver

• Design and Construction Complete

• Important Considerations

–Efficiency Analysis– Weight of structure

– Manufacturability

– Simplicity and Precision achieved in assembly

– Installation at Customers

The support structure of the commercial parabolic trough collectors are classified as:

(a) torque tube with mirror supporting arms (b) space frame,

(c) bed type or a combination of torque tube and space frame (torque box), pylon etc

An analysis of structural prospects of various commercial collector designs has be made, and an

optimal support structure is proposed.

Supporting Structure

WP-1.2 Design of support structure: torque box, mirror

supporting frames, and receiver support.

(a

)

(c)

(b

)

1. Torque tube 2. Mirror arm

3. Rectangular

pylon4. A section

pylon

5. Bearing support

holding hydraulics

6. Bearing support

7. Receiver adjustment 8. Receiver support 9. Receiver plate 10. Receiver base

Components of support structure

Support structure

Torque tube

(LS-2, ENEA)

Space frame

(Solargenix, LS-3)

Modified torque

tube

Torque box

(Eurotrough)

T-flaps

(Albias trough)

Rhombus

(Proposed design)

Supporting Structure

Configuration 1 Configuration 2 Configuration 3

Free body diagram for torque tube

Fixed end

Collector position

Torque tube

Torsion due to its

weight

Center of gravity

• Torque tube is subjected to basically two kinds loads - bending and torsion.

• Bending load due to wind at 14.3m/s and torsion load due to its own weight.

• Analysis is made on the torque tube for under combined bending and torsion for three different

configurations shown below.

• Analysis is also made by giving torsional load alone so as to find the Torsional rigidity.

Analysis of Torque Tube

Configuration 1:

Configuration 2:

Configuration 3:

Boundary conditions

Load due to wind drag : 5494.4N(14.3m/s)

Load due to weight of the setup : 17767 N

Results

Max. stress intensity : 31.43 N/mm2

Max. twist : 0.55 mrad

Results

Max. stress intensity : 90 N/mm2

Max. twist : 0.6 mrad

Results

Max. stress intensity : 115.6 N/mm2

Max. twist : 0.6 mrad

WP-1.3 Structural analysis of the trough under static and wind load

conditions

Boundary conditions

Load due to wind drag : 5494 N (14m/s)

Load due to weight of the setup : 17761.7 N

Results:

Maximum stress intensity : 97.8N/mm2

Maximum deflection : 1.432mm

Results:

Maximum stress intensity : 97.8N/mm2

Maximum deflection : 1.432mm

• Pylon is subjected to two kinds of loads (a) load due to wind (b) weight of the collector acting at

the bearings.

• Analysis is made for the same boundary condition for the selected A-section pylon and for the

rectangular pylon to find their optimum sizes.

A-section pylon

Rectangular pylon

Erection of Parabolic Trough Collector

Erection and Installation of Parabolic Trough Collector

Erection and Installation of Parabolic Trough Collector - Fixing of Mirror Arms

Erection and Installation of PTC - Fixing of Mirror

Erection and Installation of PTC – Tracking and Focusing

TWO COMPLETE TRACKING SYSTEMS ALONG WITH HYDRAULICS INSTALLED AT IIT MADRAS

• Hydraulic System coupled with Advance Controller

• Inclinometer for absolute measurement of position

• Drives 6 modules of three Troughs on each side

• Accuracy 1.7 mrad

• Validation at DLR, Germany

WEATHER STATION, PYRHELIOMETER, FLOW METERS, ‘SUNPERFECT’

TRACKER, TEPERATURE AND PRESSURE SENSORS ARE BEING

INSTALLED TO BE INTEGRATED WITH THE AUTOMATION SYSTEM

Erection and Installation of Parabolic Trough Collector

Ongoing Activities

Parabolic Trough Collector Testing:

- Standard Operating Procedure (SOP) for PTC Testing : Performance Evaluation by Experimental Validation

- Optical Performance : Mirror contour & collector alignment; Mirror reflectivity and durability

- Thermal efficiency test procedure : Concentrator thermal efficiency, Receiver Thermal Loss Tests

PREPARATION OF INDUSTRIAL SIZE PVD SYSTEM FOR DEPOSITION OF SELECTIVE COATING

SCALING UP OF LABORATORY PROCESS [AT NCL/NAL] INTO INDUSTRIAL SCALE

SETTING UP OF MULSTAGE ULTRASONIC CLEANING FACILITY WITH FIXTURES FOR CLEANING LONG STEEL

AUGUMENTATION OF AUXILLARY EQUIPMENT AND UTILITIES:◦ SOFT WATER PLANT◦ WATER CHILLER◦ DIESEL GENERATOR

AUTOMATION OF THE TEST SET UP AT IIT MADRAS

Optical Efficiency of Parabolic Structure

Thermal efficiency of Trough together with Receiver

tube

Thermal loss analysis of receiver tube

Temperature stability of operation

Performance assessment at DLR, Germany

Assessment of accuracy of Tracking mechanism

Thermal cycling degradation studies

Thermal Shock Degradation

–Parabolic Trough 5.77 M [MILMAN/IITMADRAS]

–Mirrors [SAINT GOBAIN/THERMO GLASS]

–Tracking System [MILMAN]

–Photoreceiver Tube [MILMAN]

–HTF [INDIANOIL]

– Piping, Joints, Pumps etc.[MILMAN]

FIELD TRIALS AT MILMAN AND IIT MADRAS

QUALIFICATION AT DLR, KOLN, GERMANY

TRIAL SYSTEMS FOR SOLAR DEVELOPERS IN JNNSUM PHASE I◦ Megha Engineering : 50 Mwatt

◦ Cargo Power: 25 Mwatt

EXPLORE GLOBAL MARKETS: 1000 MWatt

PREPARE FOR JNNSUM PHASE II [ MNRE ANNNOUNCEMENT AWAITED]