A Concentrated Solar Thermal Energy System

178 Pages·6.392 MB·English

by  Newton C.C.

THE FLORIDA STATE UNIVERSITY

FAMU-FSU COLLEGE OF ENGINEERING

A CONCENTRATED SOLAR THERMAL ENERGY SYSTEM

By

C. CHRISTOPHER NEWTON

A Thesis submitted to the
Department of Mechanical Engineering
in partial fulfillment of the
requirements for the degree of
Master of Science

Degree Awarded:
Spring Semester, 2007

Copyright 2007
C. Christopher Newton
All Rights Reserved
The members of the Committee approve the Thesis of C. Christopher Newton
defended on December 14, 2006.

______________________________
Anjaneyulu Krothapalli
Professor Directing Thesis

______________________________
Patrick Hollis
Outside Committee Member

______________________________
Brenton Greska
Committee Member

The Office of Graduate Studies has verified and approved the above named committee members.

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This thesis is dedicated to my family and friends for their love and support.

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ACKNOWLEDGEMENTS

I would like to thank Professor Anjaneyulu Krothapalli and Dr. Brenton Greska
for their advisement and support of this work. Through their teachings, my view on life
and the world has changed.
I would also like to give special thanks to Robert Avant and Bobby DePriest for
their help with the design and fabrication of the apparatus used for this work. Also, I
would like to thank them for teaching myself, the author, the basics of machining.
Mike Sheehan and Ryan Whitney also deserve mention for their help with setting
up and assembling the apparatus used in this work.
The help and support from each of these individuals mentioned was, and will
always be greatly appreciated.

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TABLE OF CONTENTS

List of Tables ................................................................................................ Page viii

List of Figures ................................................................................................ Page ix

Abstract ...................................................................................................... Page xiv

1. Background ................................................................................................ Page 1

1.1 Introduction........................................................................................... Page 1
1.2 Historical Perspective of Solar Thermal Power and Process Heat....... Page 2
1.2.1 Known Parabolic Dish Systems.......................................... Page 3
1.3 Solar Thermal Conversion.................................................................... Page 5
1.4 Solar Geometry (Fundamentals of Solar Radiation)............................. Page 6
1.4.1 Sun-Earth Geometric Relationship..................................... Page 6
1.4.2 Angle of Declination........................................................... Page 7
1.4.3 Solar Time and Angles........................................................ Page 10
1.5 Solar Radiation..................................................................................... Page 13
1.5.1 Extraterrestrial Solar Radiation.......................................... Page 13
1.5.2 Terrestrial Solar Radiation.................................................. Page 14
1.6 Radiative Properties.............................................................................. Page 17
1.7 Solar Collector/Concentrator................................................................ Page 18
1.7.1 Acceptance Angle............................................................... Page 21
1.7.2 Thermodynamic Limits of Concentration........................... Page 22
1.8 The Receiver/Absorber......................................................................... Page 23
1.8.1 Cavity Receiver................................................................... Page 24
1.8.2 External Receiver................................................................ Page 25
1.9 Heat Storage.......................................................................................... Page 25
1.9.1 Sensible Heat Storage......................................................... Page 25
1.9.2 Latent Heat Storage............................................................ Page 26
1.10 Rankine Cycle..................................................................................... Page 26
1.10.1 Working Fluid................................................................... Page 29
1.10.2 Deviation of Actual Cycle from Ideal............................... Page 29
1.11 Steam Turbine..................................................................................... Page 30
1.11.1 Impulse Turbine................................................................ Page 31
1.11.2 Reaction Turbine............................................................... Page 31
1.11.3 Turbine Efficiency............................................................ Page 32
1.12 Overview............................................................................................. Page 33

2. Experimental Apparatus and Procedures........................................................ Page 34

2.1 Introduction........................................................................................... Page 34
2.2 Solar Collector...................................................................................... Page 34
2.3 The Receiver......................................................................................... Page 36
2.4 Steam Turbine....................................................................................... Page 39

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2.5 Gear-Train............................................................................................. Page 41
2.6 Working Fluid of Solar Thermal System.............................................. Page 43
2.7 Feed-Water Pump................................................................................. Page 44
2.8 Tracking ............................................................................................... Page 45
2.9 Data Acquisition................................................................................... Page 49
2.9.1 Instrumentation................................................................... Page 50
2.10 Power Supply...................................................................................... Page 50
2.11 Generator/Alternator........................................................................... Page 53

3. Analysis/Results and Discussion.................................................................... Page 55

3.1 Introduction........................................................................................... Page 55
3.2 Solar Calculations................................................................................. Page 55
3.3 Analysis of the Dish.............................................................................. Page 57
3.3.1 Efficiency of Collector........................................................ Page 61
3.4 Receiver ............................................................................................... Page 66
3.4.1 Boiler Efficiency................................................................. Page 76
3.5 Turbine Efficiency................................................................................ Page 77
3.6 Turbine/Gear-Train Analysis................................................................ Page 78
3.7 Analysis of the Rankine Cycle.............................................................. Page 79
3.8 Generator and Energy Conversion Efficiency...................................... Page 81

4. Conclusions …................................................................................................ Page 83

4.1 Introduction........................................................................................... Page 83
4.2 Solar Calculations................................................................................. Page 83
4.3 Trackers ............................................................................................... Page 83
4.4 Solar Concentrator................................................................................ Page 84
4.5 Receiver/Boiler..................................................................................... Page 84
4.6 Steam Turbine....................................................................................... Page 85
4.7 Generator.............................................................................................. Page 85
4.8 Cycle Conclusions ............................................................................... Page 85
4.9 Future Work ......................................................................................... Page 86

APPENDICES ................................................................................................ Page 88

A Rabl’s Theorem..................................................................................... Page 88
B Solar Angle and Insolation Calculations.............................................. Page 91
C Solar Calculations for October 12th ..................................................... Page 100
D Collector Efficiency for Varied Wind Speeds...................................... Page 105
E Calculations for Collector Efficiency on Oct. 12th for Beam Insolation Page 111
F Collector Efficiency as Receiver Temperature Increases..................... Page 118
G Geometric Concentration Ration and Maximum Theoretical Temperature Page 121
H Geometric Concentration Ratio as Function of Receiver Temperature Page 125
I Receiver/Boiler Efficiency Calculations.............................................. Page 128
J Mass Flow Rate Calculations for Steam into Turbine.......................... Page 129
K Steam Turbine Efficiency Calculations................................................ Page 131

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L Rankine Cycle Calculations.................................................................. Page 134
M Drawings/Dimensions of T-500 Impulse Steam Turbine and Gear-Train Page 142
N Receiver Detailed Drawings and Images.............................................. Page 147
O Solar Charger Controller Electrical Diagram....................................... Page 157
P Windstream Power Low RPM Permanent Magnet DC Generator....... Page 159

REFERENCES ................................................................................................ Page 161

BIOGRAPHICAL SKETCH .............................................................................. Page 164

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LIST OF TABLES

Table 1.1: Average values of atmospheric optical depth (k) and sky diffuse factor
(C) for average atmospheric conditions at sea level for the United States Page 16

Table 1.2: Specular Reflectance Values for Different Reflector Materials......... Page 18

Table 2.1: Design Conditions of the T-500 Impulse Turbine.............................. Page 39

Table 2.2: Correlation of Pump Speed to Flow Rate........................................... Page 45

Table 3.1: Test results for mechanical power determination of steam turbine/
gear-train output shaft........................................................................ Page 79

Table 3.2: Inlet and outlet temperature, pressure, and entropy values for the
various components of the system. .................................................... Page 80

Table 3.3: Sample of loads tested on generator and the resulting voltage and power Page 45

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LIST OF FIGURES

Figure 1.1: Solar Furnace used by Lavoisier ...................................................... Page 2

Figure 1.2: Parabolic collector powered printing press ...................................... Page 3

Figure 1.3: Photographs of Vanguard and McDonell Douglas concentrator systems Page 5

Figure 1.4: Motion of the earth about the sun ..................................................... Page 7

Figure 1.5: Declination Angle as a Function of the Date ................................... Page 8

Figure 1.6: The Declination Angle ..................................................................... Page 8

Figure 1.7: Equation of Time as a function of the time of year .......................... Page 11

Figure 1.8: Length of Day as a function of the time of year ............................... Page 12

Figure 1.9: The Variation of Extraterrestrial Radiation with time of year ......... Page 14

Figure 1.10: Variance of the Total Insolation compared to Beam Insolation...... Page 17

Figure 1.11: Concentration by parabolic concentrating reflector for a beam parallel
to the axis of symmetry, and at an angle to the axis ...................... Page 19

Figure 1.12: Cavity Type Receiver ..................................................................... Page 24

Figure 1.13: Basic Rankine Power Cycle ........................................................... Page 26

Figure 1.14: T-s Diagram of Ideal and Actual Rankine Cycle............................ Page 27

Figure 1.15: T-s Diagram showing effect of losses between the boiler and turbine Page 30

Figure 1.16: Diagram showing difference between an impulse and a reaction turbine Page 31

Figure 2.1: Image of dish sections and assembled dish ...................................... Page 35

Figure 2.2: Image of applying aluminized mylar to surface of dish ................... Page 35

Figure 2.3: Exploded 3-D layout of receiver ...................................................... Page 36

Figure 2.4: Image of Draw-salt mixture in receiver ........................................... Page 37

Figure 2.5: Diagram of instrumentation of receiver ........................................... Page 38

Figure 2.6: Image of receiver assembled at focal region of concentrator ........... Page 38

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Figure 2.7: Images of T-500 Impulse Turbine Rotor .......................................... Page 39

Figure 2.8: Images of T-500 Steam Turbine housing ......................................... Page 40

Figure 2.9: Images of T-500 Steam Turbine Assembled .................................... Page 40

Figure 2.10: Images of Gear-Train Assembly .................................................... Page 42

Figure 2.11: Images of Steam Turbine and Gear-Train Assembled ................... Page 42

Figure 2.12: Image of water tank ........................................................................ Page 43

Figure 2.13: Image of pump and controller ........................................................ Page 44

Figure 2.14: Images of the frame with actuators ................................................ Page 46

Figure 2.15: Image of LED3 Solar Tracker Module .......................................... Page 47

Figure 2.16: Image of LED3 module in plexi-glass housing .............................. Page 47

Figure 2.17: Image of LED3 module sealed in plexi-glass housing ................... Page 48

Figure 2.18: Image of tracking module attached to concentrator ....................... Page 48

Figure 2.19: Image of the data acquisition program used (SURYA) ................. Page 49

Figure 2.20: Two 12-volt deep cycle batteries wired in series............................ Page 51

Figure 2.21: Thin-filmed flexible photovoltaics.................................................. Page 51

Figure 2.22: Image of Solar Charger Controller.................................................. Page 52

Figure 2.23: Image of 400 Watt DC to AC Power Inverter................................. Page 53

Figure 2.24: Image of Windstream Power 10 AMP Permanent Magnet Generator Page 53

Figure 2.25: Performance Curves for the Generator............................................ Page 54

Figure 2.26: Image Generator, Gear-train, and Steam Turbine Assembled........ Page 54

Figure 3.1: Solar Altitude and Azimuth Angles for October 12th ...................... Page 56

Figure 3.2: Plot showing comparison between available Total Insolation and
available Beam Insolation ............................................................... Page 57

Figure 3.3: Relationship between the concentration ratio and the receiver
operation temperature....................................................................... Page 61

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