1. HEAT ENERGY COLLECTION VIA PARABOLIC SOLAR REFLECTOR
Ritesh Toppo¹, Rahul Tripathi², Rahul Mahamalla³, Er.Dileshwar Kumar Sahu*
¹Undergraduate Bachelor of Engg. Student, Department of Mechanical Engineering, BIT-Raipur, CG India-492001
¹Info.Ritesh2035@Gmail.Com
+91-7587438297
²Undergraduate Bachelor of Engg. Student, Department of Mechanical Engineering, BIT-Raipur, CG India-492001
²Rahul10Tripathi@Gmail.Com
³Undergraduate Bachelor of Engg. Student, Department of Mechanical Engineering, BIT-Raipur, CG India-492001
³Rahul.Mahamalla5520@Gmail.Com
*Assistant Professor, Department of Mechanical Engineering, BIT-Raipur, CG India-492001
Abstract
This paper presents the development of a solar parabolic dish collector prototype for rural areas with high solar resource availability
in India, which have no access to electricity service or budget resources to purchase a stove (electric or gas). The solar co llector
prototype proposesa solution to solve these kindsof issues and use sunlight to work it. Through a polished Aluminum parabolic dish,
solar radiation is concentrated into a specific area called focus, where thermal energy is generated and is used for cooking or
fulfilling a necessity without high investment and helping the environment. To finish, it describes the decisive stages of the prototype
implementation, which provides the solar resource analyzed in India, the theoretical analysis, the structural design, the study, and
manufacturing materials.
.
Key words: Focus, Heat losses, solarconcentrator,Thermal efficiency, Temperature
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1. INTRODUCTION
Most of the power generated nowadays is produced utilizing
fossil fuels, which releases tons of carbon dioxide and other
pollutants every second. More importantly, fossil fuel will
eventually exhaust. In order to make the development of our
civilization sustainable and cause less harm to our
environment, people are looking for new source of substitute
clean and green energy. Because of the increasing demands in
clean energy, the solar energy industry is one of the fastest
growing forces in the world. Nowadays there are several
major directions for solar technology development. For
example, photovoltaic (cells) systems directly convert the
solar energy into electrical energy while concentrated solar
power systems first convert the solar energy into thermal
energy and then further convert it into electrical energy
through a thermal engine; it’s a conversion of low grade
energy to high grade energy. After a systemhas been installed,
it will be tough task to upgrade the systems or change the
operation methods. In order to choose the right solar system
for a specific geographic location, we want to understand and
compare the basic mechanisms and general operation
functions of several solar technologies that are widely studied.
This paper not only gives technologies a brief introduction
about the fast developing solar technologies industry, but also
may help us avoid long term switching cost in the future and
make the solar systems performance more efficient,
economical and stable.
1.1 Why Solar Energy is one of the forestanding
Solution to World Energy Crisis
The sun is the most plentiful and celestial energy source for
the earth. All wind, fossil fuel, hydro and biomass energy have
their origins in sunlight. Solar energy falls on the surface of
the earth at a rate of 120 petawatts, (1 petawatt = 1015 watt).
This means all the solar energy received from the sun in one
days can fulfill the whole world’s energy demand for more
than 20 years.
We are able to calculate the potential for each renewable
energy source based on today’s technology. Future advances
in technology will lead to higher potential for each energy
source. However, the worldwide demand for energy is
expected to keep increasing at 5 percent each year. Solar
energy is the only choice that can satisfy such a colossal and
steadily increasing energy impositions.
There are several applications for solar energy, for instance:
electricity generation, solar propulsion, photochemical, solar
desalination, and room temperature control. The collection of
solar energy and its transfer to electricity energy will have
wide application and deep impact on our society, so it has
attracted the attention of the researchers and scientists.

2. 1.2 Basics of solar thermal collection/solar
concentrating power
The basic principle of solar thermal accumulation is that when
solar radiation is incident on a surface (such as that of a black
– body) part of this radiation is absorbed, thus increasing the
temperature of the surface.
As the temperature of the body increases, the surface loses
heat at an increasing rate to the surroundings. Steady state is
reached when the rate of the solar heat gain is balanced by the
rate of heat loss to the ambient surroundings. Solar
concentrators increase the amount of incident energy on the
absorber surface as compared to that on the concentrator
aperture. The increase is achieved by the use of reflecting
surfaces or other optical means which concentrate the incident
radiation onto a suitable absorber / receiver.
Electricity is high grade energy. This means it can be easily
transferred into other forms like mechanical or heat energy. If
we are able to generate economic and plentiful electricity
energy, together with the easy transportation electricity energy
transmission, the electric power will increase it shares in
demand sectors dramatically.
Fig 2: Heliostats Tower
1.3 ENVIROMENTAL CONDITIONS IN RAIPUR
CHHATTISGARH
The north westerly hot winds coming from Rajasthan and
Madhya Pradesh have led to increase in maximum
temperatures in several parts of Chhattisgarh, crossing 46
degrees Celsius.
Raipur, Bilaspur and Champa remain hottest in state with heat
waves accompanied by dry weather and humidity across state
.people prefers remaining indoors as maximum temp.
Recorded in morning around 11 am crossed 39 degree Celsius
and fluctuates at 45.5 degree Celsius and 35 degree till 10 am.
Some data’s are given below :- ( 3 March 2016)
CONDITIONS COMFORT
TIME TEMP WEATHER WIND HUMIDITY
11.30 33ºC Partly
sunny
6Km/h 38%
14.30 35ºC Scattered
clouds
7Km/h 33%
17.30 34ºC Partly
sunny
4Km/h 35%
20:30 30ºC Passing
clouds
No
Wind
48%
23:30 27ºC Passing
clouds
No
Wind
56%
Table 1: Local weather report
Fig 1: Parabolic Solar Reflector

3. 2. DESIGN OF PARABOLIC REFLECTOR
2.1 Prototype design:
The prototype design was carried out contemplates the
parabola and focus characteristics, as well as the dimensions
adjusted to the estimated budget.
Fig 3: Solar Parabolic Dish
Fig 4: Solar Parabolic Dish
Fig 5: Basic structural Nomenclature of parabolic dish
Fig 6: Real time image of prototype model of solar reflector
designed and constructed by authors.

4. 2.2 DESIGN OF PARABOLIC REFLECTOR
USING CAD MAX5 SOFTWARE
Fig 7: Wire frame view
Fig 8: Solid 3D view
Fig 9: 3D Back view
Fig 10: Perspective 3D Front view

5. 3. SELECTION OF MATERIAL REQUIRED TO
CONSTRUCT SOLAR COLLECTOR
To select the materials, the most relevant aspects were
evaluated so they would permit good performance, bearing in
mind optical, physical, and thermal factors. The collector’s
useful life, optical efficiency, and thermal efficiency depend
on these factors to guarantee its operation. Initially, we
defined the optical, thermal, and other factors that must be
considered to select the materials and, thereafter, we selected
the material based on these criteria.
3.1 BASIC DISH MATERIAL AND
MANUFACTURING
The basic reflector design consists of the following
materials:-
• A parabolic reflector profile built of fiberglass or other
suitable metal, mostly aluminum (Al) with a extended steel
feed horn and amplifier in its middle.
• A steel actuator device that allow the dish to receive solar
energy from sun.
The Manufacturing Process:-
A. To make fiberglass suitable for dish manufacture. A sheet
molding compound mixture that includes reflective metallic
material and ultraviolet deflecting compositions is mixed with
resin of calcium carbonate and a stimulus cure. The mixture
forms a paste that is skunked onto a sheet of polyethylene film
that has fiberglass added in chopped form. The result is a sheet
stratum with the compound paste, fiberglass, and the
polyethylene film
B. The sheet is then pressed at 88 degrees Fahrenheit (30
degree Celsius to mature). To shape the sheet into the desired
parabolic shape it is pressed at high pressure .The dish is then
trimmed cooled and polished and then after it is usable.
C. For metallic dishes that common medium choice is
aluminum it can be used by following properties:-
i) Weight
ii) Strength
iii) Linear expansion
iv) Machining Formability
v) Conductivity
Material comparison
The material comparison table values given below are
commercially pure metals
Table 2: Material comparison & its properties
Properties Al Fe Cu Zn
Density, g/cm³ 2.7 7.9 8.9 7.1
Melting point, ºC 658 154
0
1083 419
Thermal capacity,
j/kg, ºC
900 450 390 390
Thermal
conductivity, W/m,
ºC
230 75 390 110
Coeff. Of linear
expansion x10^-6/ºC
24 12 16 26
EI Conductivity,
I.A.C.S
60 16 100 30
EI, resistance x10^
-9 Ωm
70 105 17 58
Modulus of
elasticity, GPa
70 220 120 93

6. 3.2 DIAMOND SHAPED GLASSES
In this reflector generally diamond shaped simple glasses are
used which have a specific property which are given below on
table:-
Chemical Composition:-
Composition Percentage
Sio₂ 80.6%
B₂o₃ 13%
Na₂o₃ 4%
Al₂o₃ 2.3%
Miscellaneous
Traces
0.1%
Table 3: Chemical properties of mirror
Physical Properties:-
Coefficient of
expansion
32.5*10^-7 cm/cm ºC
Strain Point 505 ºC
Anneal Point 575 ºC
Soften Point 858 ºC
Density 3.23 g/cm
Young’s Mod. 6.4*10000 kg/mm²
Refractive
Index
1.474
Temperature
Limits
490 ºC -230 ºC
Max Thermal
Shock
160 ºC
Table 4: Physical properties of mirror
4. THEORITICAL ANALYSIS OF SOLAR
CONCENTRATOR
4.1. Prototype Geometry
The collector’s parabola geometry is fundamental to guarantee
proper functioning of the prototype; an error during the
geometric calculation would represent deviation of the solar
rays; consequently, the absence of temperature at the focal
point, which would give way to obtaining low thermal
efficiency.
To calculate the parabola, a mathematical analysis was
performed to find the values that satisfy the design criteria,
like: diameter, aperture angle, and concentration ratio.
Fig 11: Reflector prototype geometry
4.2 Dimensions of the solar collector parabolic dish
Nomenclature Value Description
Da 1.5 Diameter of aperture (m)
F 0.42 Focus (m)
A 0.015 Radius of the cylinder
receptor
Table 5: Dimensions of the solar collector parabolic dish
4.3 The diameter ofaperture and the maximum angle
that defines it are related by equation (1)
∅ = 2𝑎𝑟𝑐𝑡𝑔𝐷𝑎4𝑓 = 83.521°………. (1)
Another important parameter to adequately define the
geometry of the solar collector parabolic dish is the edge
radius or maximum distance value existing between the focal
point and the paraboloid extreme. Equation (2) defines said
value as the following:
𝑟𝑟 = 2𝑓1+𝑐𝑜𝑠∅ = 0.7548 mts………… (2)
An indicator to bear in mind in solar collector systems is the
concentration index or concentration ratio; the higher the
concentration ratio, the higher the temperature to be reached
with the solar concentrator system. Parabolic dish collectors
are characterized for having a higher concentration ratio than
the rest of the solar collector system. The concentration index
is defined as the ratio between the aperture area and receiver
area.
𝐶 = 𝐴𝑎*𝐴𝑟……….. (3)

7. The aperture area can be calculated through the following
ratio:
𝐴𝑎 = 𝜋𝐷𝑎24 = 1.7671 𝑚²…………….. (4)
To find the area of the receiver, it is necessary to consider the
aperture angle, the radius of the receiver, the radius of the
edge, and the angle supported by the sun seen fromthe earth.
This last constant is because the rays from the sun are not
parallel to each other, given that the sun has a finite radius.
From the earth, the sun is seen as a circular dish that subtends
a 32' or 0.53° α angle. It is known that a=0.015 m, c is the
hypotenuse formed between the focus and point B and
Ø=83.521°. According to the aforementioned, we have:
𝑐 = 𝑎𝑠i𝑛∅ = 0.015096429 m…………… (5)
Now, point B would be equal to:
𝑏 = 𝑟𝑟−𝑐 = 0.739725………………….. (6)
Where Rr is the receptor radius. According to the previous
equation, we obtain:
𝑅𝑟 = 𝑏𝑠in (𝛼2) = 1.72131x10 ³‫־‬ m……………. (7)
Upon observing Figure 10, the following geometric ratio is
noted among points BCE: Where h/2 is ha lf the contact
surface of the receiver cylinder. With the equation, we obtain
the angle formed between h/2 and Rr.
Θ = 90+α2……………….. (8)
We also find half the contact surface of the receiver cylinder,
as noted in equation (9):
ℎ² = 𝑅𝑟cos (𝜃−∅) = 0.00206 m…… (9)
Calculated area of receiver is, h = 387.92mm²
With values Aa, Rr and applying equation (3), we proceed to
calculate the concentration ratio of the solar collector
parabolic dish:
C=1.7671 m², 0.0003879 m²=4555.671……………… (11)
The calculated concentration ratio corresponds to the
maximum concentration obtained within a parabolic
concentratorwith a flat receptor; however, equation 11 does
not consider the angular dispersion in the receptor. The main
causes of said dispersion are: inappropriate solar monitoring,
poor quality in the polish of the reflector surface, and
inadequate curvature on the concentratorsurface.
Bearing in mind the angular dispersion and considering that all
the specularradiation reflected is on an angular cone with
(0.53 ° + δ).
Where: δ is the specular deviation, which has a theoretical
value of 3 degrees.Finding the value of h1, the actual
maximum concentration ratio is 35
4.4 Necessary values to calculate temperature in the
receiver
Parameter Nomenclature Value(unit)
Environmental
Temperature
T-amb 20 ºC or 291016
K
Approximate
temp.of the sun
T-asol 5726.84 ºC or
6000 K
Emissivity del
receiver
e 0.5
Maximum
efficiency range
of solar collector
(40%-60%)
n 0.4
Table 6: Necessary values to calculate temperature in the
receiver

8. 5. FINAL DESIGN OF MODEL WITH
DIMENSIONS
Fig 12: Model with design and dimensions
6. REAL TIME OBSERVATIONS
Sr.No Noticed
Time
Ambient
temperature
Output
temperat
ure
01 8:00 am 23 ºC 90 ºC
02 9:00 am 28 ºC 140 ºC
03 10:00 am 33 ºC 190 ºC
04 11:00 am 38 ºC 240 ºC
05 1:00 pm 45 ºC 295 ºC
7. CONCLUSION
The work presented in the paper is an attempt of designing a
solar reflector of selected dimensional parameters. Extensive
literature review was carried out to elucubrate the various
perspective and application of solar reflectors. A suitable
designing procedure and software was chosen from the
available method to design different parts of solar reflector.
3D max cad software is used extensively for making parts.
Solar reflector technology is non conventional system and
attracting wide attention due to their varied applications.
Development of a sophisticated engineering product like solar
reflector smooth surface is a continuous process.
A lot of work is yet to be done on the design aspects before
the solar reflectors readied for market consumption. The
design algorithm has to take into various other parameters to
make to suitable for practical applications. Also,
manufacturing of such complex shapes of parabola profile is
another ongoing investigation work.
Further research work is needed to carry so the design and
manufacture process would result in development of even
better and more efficient solar reflector panels.
8. ABBREVIATIONS
Symbol Description Unit
Aa Aperture area m²
Ar Receiver area m³
D Distance
between
Sun and earth
Km
ET Equation of
Time
Minute
hͭͭͭͭ
Radiation heat
transfer
coefficient
W/m² K
I Beam solar
radiation
W/m²
K Thermal
Conductivity
W/m K
Table 8: Symbols and their usual meanings
Table 7: Experimental observations

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