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Solar Energy Engineering Processes And Systems

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Solar Energy Engineering Processes And Systems

Preface

The origin and continuation of humankind is based on solar energy. The
most basic processes supporting life on earth, such as photosynthesis and the
rain cycle, are driven by solar energy. From the very beginning of its history
humankind realized that a good use of solar energy is in humankind’s benefit.
Despite this, only recently, during the last 40 years, has solar energy been harnessed
with specialized equipment and used as an alternative source of energy,
mainly because it is free and does not harm the environment.
The original idea for writing this book came after a number of my review
papers were published in the journal Progress in Energy and Combustion
Science. The purpose of this book is to give undergraduate and postgraduate
students and engineers a resource on the basic principles and applications of
solar energy systems and processes. The book can be used as part of a complete
two-semester junior or senior engineering course on solar thermal systems. In
the first semester, the general chapters can be taught in courses such as introduction
to solar energy or introduction to renewable sources of energy. This
can be done by selecting only the descriptive parts of the various chapters and
omitting most of the mathematical details, which can be included in the course
for more advanced students. The prerequisites for the second part are, at least,
introductory courses in thermodynamics and heat transfer. The book can also
be used as a reference guide to practicing engineers who want to understand
how solar systems operate and how to design the systems. Because the book
includes a number of solved examples, it can also be used for self-study. The
international system of units (SI) is used exclusively in the book.
The material presented in this book covers a large variety of technologies
for the conversion of solar energy to provide hot water, heating, cooling, drying,
desalination, and electricity. In the introductory chapter, the book provides
a review of energy-related environmental problems and the state of the climate.
It also gives a short historical introduction to solar energy, giving some details
of the early applications. It concludes with a review of renewable energy technologies
not covered in the book.
Chapter 2 gives an analysis of solar geometry, the way to calculate shading
effects, and the basic principles of solar radiation heat transfer. It concludes
with a review of the solar radiation measuring instruments and the way to construct
a typical meteorological year.
Solar collectors are the main components of any solar system, so in Chapter 3,
after a review of the various types of collectors, the optical and thermal analyses
of both flat-plate and concentrating collectors are given. The analysis for
flat-plate collectors includes both water- and air-type systems, whereas the
Preface
xiv Preface
analysis for concentrating collectors includes the compound parabolic and the
parabolic trough collectors. The chapter also the second-law analysis
of solar thermal systems.
Chapter 4 deals with the experimental  the performance
of solar collectors. The chapter outlines the various tests required to
determine the thermal efficiency of solar collectors. It also includes the methods
required to determine the collector incidence angle modifier, the collector
time constant, and the acceptance angle for concentrating collectors. The
dynamic test method is also presented. A review of European standards used
for this purpose is given, as well as quality test methods and details of the solar
keymark certification scheme. Finally, the chapter describes the characteristics
of data acquisition systems.
Chapter 5 discusses solar water heating systems. Both passive and active
systems are described, as well as the characteristics and thermal analysis of heat
storage systems for both water and air systems. The module and array design
methods and the characteristics of differential thermostats are then described.
Finally, methods to calculate the hot water demand are given, as are international
standards used to evaluate the solar water heater performance. The chapter also
includes simple system models and practical considerations for the setup of solar
water heating systems.
Chapter 6 deals with solar space heating and cooling systems. Initially,
methods to estimate the thermal load of buildings are given. Then, some general
features of passive space design are presented, followed by the active system
design. Active systems include both water-based and air-based systems.
The solar cooling systems described include both adsorption and absorption
systems. The latter include the lithium bromide–water and ammonia-water systems.
Finally, the characteristics for solar cooling with absorption refrigeration
systems are given.
Industrial process heat systems are described in Chapter 7. First, the general
design considerations are given, in which solar industrial air and water
systems are examined. Subsequently, the characteristics of solar steam generation
methods are presented, followed by solar chemistry applications, which
include reforming of fuels and solar cells. The chapter also includes a description
of active and passive solar dryers and greenhouses.
Solar desalination systems are examined in Chapter 8. The chapter initially
analyzes the relation of water and energy as well as water demand and consumption
and the relation of energy and desalination. Subsequently, the exergy analysis
of the desalination processes is presented, followed by a review of the direct
and indirect desalination systems. The chapter also includes a review of the
renewable energy desalination systems and parameters to consider in the selection
of a desalination process.
Although the book deals mainly with solar thermal systems, photovoltaics
are also examined in Chapter 9. First the general characteristics of semiconductors
are given, followed by photovoltaic panels and related equipment. Then, a
review of possible applications and methods to design photovoltaic (PV) systems
are presented. Finally, the chapter examines the concentrating PV and the hybrid
photovoltaic/thermal (PV/T) systems.
Chapter 10 deals with solar thermal power systems. First, the general
design considerations are given, followed by the presentation of the three basic
technologies: the parabolic trough, the power tower, and the dish systems. This
is followed by the thermal analysis of the basic cycles of solar thermal power
plants. Finally, solar ponds, which are a form of large solar collector and storage
system that can be used for solar power generation, are examined.
In Chapter 11, methods for designing and modeling solar energy systems
are presented. These include the f-chart method and program, the utilizability
method, the Φ, f-chart method, and the unutilizability method. The chapter
also includes a description of the various programs that can be used for the
modeling and simulation of solar energy systems and a short description of the
artificial intelligence techniques used in renewable energy systems modeling,
performance prediction, and control. The chapter concludes with an analysis of
the limitations of simulations.
No design of a solar system is complete unless it includes an economic analysis.
This is the subject of the final chapter of the book. It includes a description
of life cycle analysis and the time value of money. Life cycle analysis is then
presented through a series of examples, which include system optimization and
payback time estimation. Subsequently, the P1, P2 method is presented, and the
chapter concludes with an analysis of the uncertainties in economic analysis.
The appendices include nomenclature, a list of definitions, various sun
diagrams, data for terrestrial spectral irradiation, thermophysical properties of
materials, curve fits for saturated water and steam, equations for the CPC curves,
meteorological data for various locations, and tables of present worth factors.
The material presented in this book is based on more than 25 years of experience
in the field and well-established sources of information. The main sources
are first-class journals of the field, such as Solar Energy and Renewable Energy;
the proceedings of major biannual conferences in the field, such as ISES,
Eurosun, and World Renewable Energy Congress; and reports from various societies.
A number of international (ISO) standards were also used, especially with
respect to collector performance evaluation (Chapter 4) and complete system
testing (Chapter 5).
In many examples presented in this book, the use of a spreadsheet program
is suggested. This is beneficial because variations in the input parameters of
the examples can be tried quickly. It is, therefore, recommended that students
try to construct the necessary spreadsheet files required for this purpose.
Finally, I would like to thank my family—my wife Rena, my son Andreas,
and my daughter Anna—for the patience they have shown during the lengthy
period required to write this book.