PARABOLIC TROUGH SOLAR CONCENTRATOR

DESIGN AND FABRICATION OF
“PARABOLIC SOLAR
CONCENTRATOR”
with sole objective to define future projects to
save natural gas
29-Jul-08 2RIZWAN MASOOD.

RESEARCH TEAM
Rizwan Masood, Student of Chemical
Engineering Department, UET Lahore.
Dr. A.R. Saleemi, Chairman, Department of
Chemical Engineering, UET Lahore.
Dr. A.H. Dilawari, Professor at SNGPL Chair on
Gas Engineering.
29-Jul-08 RIZWAN MASOOD. 3

.
SYNOPSIS
This presentation includes following topics.
1. Solar energy and it's importance in present era.
2. Potential for solar energy in Pakistan.
3. Introduction to “Solar Concentrating Collectors”.
4. Design of “Parabolic Trough Concentrator”.
5. Basic Parts and Structure.
6. Performance and efficiency calculations.
7. Applications in modern processes.

.
 The sun has a surface temperature of 6000°C, maintained by
continuous nuclear fusion reactions between hydrogen atoms
within its interior. These nuclear reactions will gradually convert
all of the hydrogen into heavier elements, but this is a relatively
slow process and the sun should continue to supply power for
another 5 billion years.
 The sun radiates huge quantities of energy into the surrounding
space, and the tiny fraction intercepted by the Earth's
atmosphere, 150 million km away, is however equivalent to about
15,000 times humanity's present rate of use of fossil and nuclear
fuels.
1. SOLAR ENERGY.

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 Even though approximately
one-third of the intercepted
energy is reflected away by the
atmosphere before reaching
the earth's surface, this still
means that a continuous and
virtually inexhaustible flow of
power amounting to 10,000
times our current rate of
consumption of conventional
fuels is available in principle to
human civilization.
1. SOLAR ENERGY.

.
 In this figure the places in
dark orange color are
high solar insolation
regions.

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Solar energy technologies have great potential
to benefit our nation. They can diversify our
energy supply, reduce our dependence on
natural gas and imported fuels, improve the
quality of the air we breathe, offset greenhouse
gas emissions, and stimulate our economy by
creating jobs in the manufacturing and
installation of solar energy systems.

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MONTHLY AVG DAILY TOTAL RADIATION ON HORIZONTAL SURFACE FOR LAHORE.
Month Day length(hr) Rad (cal/cm2) Rad (cal/m2) Rad (J/cm2) Rad(j/m2) flux(W/m2)
JAN 10.2 256 2560000 1075.2 10752000 292.81046
FEB 10.9 333 3330000 1398.6 13986000 356.42202
MAR 11.8 435 4350000 1827 18270000 430.08475
APR 12.8 499 4990000 2095.8 20958000 454.81771
MAY 13.6 545 5450000 2289 22890000 467.52451
JUN 14 533 5330000 2238.6 22386000 444.16667
JUL 13.8 491 4910000 2062.2 20622000 415.09662
AUG 13.1 448 4480000 1881.6 18816000 398.98219
SEP 12.2 436 4360000 1831.2 18312000 416.93989
OCT 11.2 361 3610000 1516.2 15162000 376.04167
NOV 10.4 297 2970000 1247.4 12474000 333.17308
DEC 10 244 2440000 1024.8 10248000 284.66667

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3. INTRODUCTION.
 Concentrator: Concentrator are oriented
to track the sun so that the beam
radiation will be directed onto the
absorbing surface. Collector that directs
radiation onto the receiver.
 Collector: The aperture of the
concentrator is the opening through
which the solar radiation enters the
concentrator
 Receiver: Radiation is absorbed and
converted to some other energy form
(e.g. heat).

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3. INTRODUCTION.
Concentration Types
a) Parabolic trough collector
b) Linear Fresnel collector
c) Central receiver system
with dish collector and
d) Central receiver system
with distributed reflectors

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a) Parabolic Trough Collector
It is a principle of geometry that a
parabolic reflector pointed at the
sun will reflect parallel rays of light
to the focal point of the parabola.
 A parabolic trough is a one-
dimensional parabola that focuses
solar energy onto a line. Physically,
this line is a pipe with a flowing
liquid inside that absorbs the heat
transmitted through the pipe wall
and delivers it to the thermal load.
3. INTRODUCTION.

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Parabolic Trough Collector (con)
A trough captures sunlight over a large aperture area and
concentrates this energy onto a much small receiver area,
multiplying the intensity of the sun by a concentration
ratio in the range of 10-80. It is the process of
concentration that allows troughs to delivery high
temperature thermal energy.
 However, to achieve such concentration, a trough tracks
the sun in one axis continually throughout the day. The
required tracking accuracy is within a fraction of a degree.
3. INTRODUCTION.

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 Parabolic Geometry (CON)
A parabola is the locus of a point that moves so that its
distances from a fixed line and a fixed point are equal.
The equation of a parabola is as follow.
X2 = 4a Y
where, 4a = lattice rectum
a = Focus point

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This may be found for a particular
parabola from Equation by
integrating a differential segment
of this curve and applying the
limits x = h and y = d/2 as
pictured in Figure. where d is the
distance across the aperture of
the parabola as shown in figure
and h is the distance from the
vertex to the aperture.

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From the Figure the result is
where S= length of parabolic arc.
 The cross sectional area of the space enclosed between a
parabola and a line across its aperture and normal to the axis is
given by
 Reflecting surface area of a parabolic trough can be calculated
as follow.
As = S . L where , L = length of through.
4. Design of “Parabolic Trough Concentrator”. (CON)

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There are basically five major part of a parabolic trough
concentrator system, which are as follow;
a) Reflecting surface.
b) Absorber.
c) Support structure.
d) Tracking system.
e) Pumping system.
5. Basic Parts and Structure.

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5. Basic Parts and Structure (CON)
a) Reflecting surface.

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b) Absorber.

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c) Support structure.

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d) Tracking system.

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e) Pumping system.

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PERFORMANCE
There are basically two types of performances which are to be
considered during design .
a. Optical performance.
b. Thermal performance.
a) Optical performance
optical performance of a solar concentrator depends on the
optical characteristics of reflecting surface, glass envelope,
absorber and also on geometry of parabola
6. Performance and Efficiency Calculations.

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PERFORMANCE
a) Optical performance
absorbed radiation per unit area of unshaded aperture is
given by:
S=Ibρ(γτα) Kγτα
Where Ib is effective incident beam radiation on the
plane of aperture, ρ is the reflectance of the concentrator, γ is
intercept factor, τ is transmittance, and α is absorptance. Kγτα
is an incidence angle modifier that can be used to account for
deviations from the normal of the angle of incidence of the
radiation on the aperture

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 PERFORMANCE
b. Thermal performance
The actual useful energy gain:
Where Aa is the unshaded area of the concentrator aperture
and Ar is the area of the receiver, S is the absorbed solar
radiation per unit of aperture area, Ti and Ta are inlet fluid
temperature and ambient temperature FR is the collector heat
removal factor.

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 OVER ALL EFFICIENCY
Over all efficiency of a solar collector is based on the optical
and thermal performances.
the over all efficiency can be calculated as;
η = (Qu / Ib) × 100

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Solar Concentrating Collector are currently
used for
Cooling and air-conditioning
Steam generation (for electricity power-plants)
Desalination of sea water
Production of hot water for domestic and
industrial use
Production of hydrogen gas
7. Applications

THANK YOU

PARABOLIC TROUGH SOLAR CONCENTRATOR

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