prepared by safiullah shirzad, senior student of Renewable Energy, Kandahar university,Afghanistan

2. 4/23/20192
Kandahar University
Engineering Faculty
Energy Department
issue
Solar Thermal Power Systems
Prepared by: group third
Group leader: Safiullah Shirzad

3. One of the greatest, gift that Allah
glorious bestowed to us.
4/23/20193

4. Contents
4
 Introduction
 Parabolic trough collector systems
 Power tower systems
 Dish systems
 Thermal analysis of solar power plants
 Solar updraft towers

5. Introduction
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solar thermal power systems were among the very
first applications of solar energy, application utilized
a concentrating collector to supply steam to a heat
engine. The main challenge in designing these
systems is to select the correct
operating temperature.

6. Contin
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 Electricity can also be produced with geothermal
energy and wind power. However, with concentrating
solar power systems, there are no complicated
siliconmanufacturing processes, as in the case of PVs;
no deep holes to drill, as in the case of geothermal
systems; and no turbine housings that need to be kept
greased at high elevations from the ground, as in wind-
power systems.

7. Types Of Solar Collector
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 Parabolic trough system
parabolic trough collectors are the most developed solar
technology to generate heat at temperatures up to 400 C for
solar thermal electricity generation, Parabolic solar collectors
focus sunlight onto a receiver pipe through which a synthetic
oil circulates.The current synthetic oil is an aromatic
hydrocarbon, biphenyl-diphenyl oxide,VP-1. The synthetic
oil is then piped through a heat exchanger to produce steam
that drives a conventional electricity-generating turbine. As
with other renewable technologies, no pollutants are emitted
in the process of generating electricity.

8. Types Of Solar……….
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The most critical time for power generation and delivery,
and the time in which the selling price of the power per
kWh is highest, is between noon and 6 pm in the summer
months of June to September. The operating strategy is
designed to maximize solar energy use. The turbine-
generator efficiency is best at a full load; therefore, the
natural gas extra is also used to allow full load operation,
which maximizes plant output. The tracking system
includes the drive, sensors, and controller.

9. Contin
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The major components of the systems are the:
o collectors,
o the fluid transfer pumps
o the power generation system
o the natural gas auxiliary subsystem,
o and the controls.
 The biggest application of this type of system is
the nine southern California power plants known
as solar electric generating systems (SEGS),
which have a total installed capacity of 354 MWe
(Kearney and Price, 1992).

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11. Contin…
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Aims to reduce the cost in half in the coming years,
includes:
Higher-reflectivity mirrors.
• More advanced sun-tracking systems.
• Better receiver selective glazes, with higher absorptance
and lower emittance.
• Better mirror-cleaning techniques
• Development of trough system designs that provide the
best combination of low initial cost and low maintenance.

12. Contin
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 parabolic trough collector systems produce heat at
about 400 C ,This heat can be stored in an
insulated container and used during nighttime.

13. Power Tower System
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power towers or central receiver systems use
thousands of individual sun-tracking mirrors, called
heliostats, to reflect solar energy onto a receiver
located atop a tall tower. The receiver collects the
sun’s heat in a heat transfer fluid , that flows
through the receiver. This is then passed optionally
to storage and finally to a power conversion
system, which converts the thermal energy into
electricity and supplies it to the consummers.

14. Contin
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 a central receiver system of power tower system
is composed of five main components:
1- heliostats, including their tracking system;
2-receiver;
3-heat transport
4- thermal storage;
5-controls.

15. Cont.…..
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Power towers could generate electricity at around
US$0.04/kWh by 2020.

16. Contin
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 The general requirements to install a solar tower
plant are a site with high direct normal
irridiation,and the site needs to be level and have
available water.

17. Conti….
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Advantages :
o the ability to include a thermal storage,
o the low thermal capacity (quick start-up),
o and a high efficiency potential due to high
achievable temperatures.
A thermal storage , through which the operation of
the power plant can be held for a certain time at
constant power, depending on the storage
dimensions.

18. Contin
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 Generally, this thermal storage can be designed
with an unlimited capacity, securing a continuous
power plant operation. It is used as a safeguard,
storing energy in times of high irradiation, and
enables operation of the plant after sunset or
during periods of cloudy weather.

19. Cont….
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they can achieve temperatures from 800 to over 1000
C. The solar energy is absorbed by a working fluid,
which is subsequently used to generate steam to power
a typical turbine. The heat transfer fluid may either be
water-steam, liquid sodium, or molten nitrate salt
(sodium nitrate–potassium nitrate).

20. Dish systems
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A dish-engine system is composed primarily of a
collector, a receiver, and an engine, Dish-engine
systems use a dual-axis tracking system to follow
the sun and so are the most efficient collector
systems because they are always pointing at the
sun. The thermal energy can be either transported
to a central generator for conversion or converted
directly into electricity at a local generator coupled
to the receiver.

21. Contin
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 Each dish produces 5–25 kW of electricity and
can be used independently or linked together to
increase generating capacity. A 650 kW plant
composed of twenty-five 25-kW dish-engine
systems requires about a hectare of land.

22. Cont….
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23. Cont.….
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The engine generators include basically the
following components:
• A receiver to absorb the concentrated sunlight to
heat the working fluid of the engine, which then
converts the thermal energy into mechanical work.
• A generator attached to the engine to convert the
work into electricity.
• A waste-heat exhaust system to vent excess heat
to the atmosphere.

24. Thermal analysis of solar power
plants
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Heat input
Generally, the efficiency of a Rankin cycle can be improved by
increasing the pressure in the boiler.

25. Contin
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 the actual pumping process is 1–20 and the
actual turbine expansion process is 3–40.

26. Contin
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27. Contin
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28. Continued
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To avoid the increase of moisture in the steam
coming out from the turbine, steam is expanded to
an intermediate pressure and reheated in the boiler.

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32. Continued…..
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 Regenerative cycle
Is a cycle which its efficiency be approximately same as
Carnot cycle efficiency.
The regenerative cycle efficiency
is given by:

33. Continued…
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 Note

34. Example
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35. Soluotion
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37. Solar Updraft Power
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The solar updraft tower is a renewable-energy power plant for
generating electricity from solar power. The principle of operation
of a solar chimney or updraft power plant is that because of its
lower density hot air rises and creates a flow. The system consists
of a chimney, a solar energy collector and wind turbines. In the
collector, which is a large area of covered land, air is heated by
solar radiation under a transparent (glass) or translucent (plastic)
roof. This heat is forced upward through the chimney thereby
creating a wind force as the joint between the roof and the tower
base is airtight. Force from the tower then draws in more hot air
from the collector, and cold air comes in from the outer perimeter.
By placing wind turbines at the base of the tower the wind force
can be used to produce electricity.

38. Conti……
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39. Cont.…..
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The energy efficiency of the solar updraft tower is low.
Therefore, a relatively large area is required for
collecting the heated air in combination with a tall
chimney. It is estimated that for a 200 MW capacity
plant, the solar collector should have an area of 38 km2
and the chimney height is 1000 m.The conversion
efficiency of such a plant would be about 0.5%.

40. Instance
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Photograph of the Manzanares solar updra
tower plant in Spain

41. Contin…..
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 Completion of the construction phase in 1982 was
followed by an experimental phase, the purpose of
which was to demonstrate the operating principle of a
solar tower. The goals of this phase of the project were
to:
 1. Obtain data on the efficiency of the technology
developed;
 2. Demonstrate fully automatic, power plant-like
operation with a high degree of reliability; and
 3. Record and analyze operational behavior and
physical relationships on the basis of long-term
measurements.

42. Result of Research
Table 10.4 Main Dimensions and Technical Specifications of the Manzanares
Prototype Item Value
Nominal output 50 kW
Tower height 194.6 m
Tower radius 5.08 m
Mean collector radius 122.0 m
Mean roof height 1.85 m
Number of turbine blades 4
Typical collector air temperature increase 20 K
Collector covered with plastic membrane 40,000 m2
Collector covered with glass 6000 m2
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43. Continued
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 Advantages
 The collector uses both direct and diffuse
radiation.
 No cooling water is necessary for its operation in
arid areas.
 Simple materials and known technologies are
used for its construction.
 Efficiency
where, g is the acceleration due to gravity (m2/s),
Ht is the tower height (m), cp is the air heat
capacity
(J/kg K) and To is the ambient temperature (K).

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