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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]