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1. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
337
CFD Analysis of Solar Flat Plate Collector
Prof. P.W.Ingle1
, Dr. A. A. Pawar2
, Prof. B. D. Deshmukh3
, Prof. K. C. Bhosale4
1
Assistant Professor Mechanical Engineering Department, S.R.E.S. College of Engineering, Kopargaon, Maharashtra,
2
Professor Mechanical Engineering Department, RSCOE, Thathwade, Pune,
3,4
Assistant Professor Mechanical Engineering Department, S.R.E.S. College of Engineering, Kopargaon, Maharashtra
Abstract - This thesis attempts to present numerical
simulation of solar collector developed exclusively for grape
drying. Solar drying of grapes is much feasible technically and
economically. There has been a remarkable achievement in
solar drying of grapes due to sustained research and
development associated with the adoption of advanced
technologies.
Simulation is an important tool for design and operation
control. For the designer of a drying system, simulation makes
it possible to find the optimum design and operating
parameters. For the designer of the control system, simulation
provides a means to device control strategies and to analyze
the effects of disturbances.
In the present thesis the computational fluid dynamics
(CFD) tool has been used to simulate the solar collector for
better understanding the heat transfer capability. 3D model of
the collector involving air inlet, wavy structured absorber
plate,glass cover plate, and pebble block is modeled by
ANSYS Workbench and the unstructured grid was created in
ANSYS ICEM. The results were obtained by using ANSYS
FLUENT software.
The objective of this work is to compare theoretically and
experimentally work done with the work done by using
computational fluid dynamics (CFD) tool with respect to flow
and temperature distribution inside the solar collector. The
outlet temperature of air is compared with experimental
results and there is a good agreement in between them
Keywords—Solar Collector, Drying, Temperature ANSYS,
CFD
I. INTRODUCTION
Solar energy is the most considerable energy source in
the world. Sun, which is 1.495x1011
(m) far from the earth
and has a diameter of 1.39x109
(m), would emit
approximately 1353 (W/m2
) on to a surface perpendicular
to rays, if there was no atmospheric layer. The world
receives 170 trillion (KW) solar energy and 30% of this
energy is reflected back to the space, 47% is transformed to
low temperature heat energy, 23% is used for
evaporation/rainfall cycle in the Biosphere and less than
0.5% is used in the kinetic energy of the wind, waves and
photosynthesis of plants.
Solar energy systems consist of many parts. The most
important part of these systems is the solar collector where
the heat transfer from sun to absorber and absorber to fluid
occurs. In order to affect the performance of these systems,
generally modifications on solar collectors are performed.
With the rapid development in civilization, man has
increasingly become dependent on natural resources to
satisfy his needs. Drying fruits and vegetables such as
grapes, pepper, pawpaw, etc is one of those indispensable
processes that require natural resources in the form of fuels.
Solar dryer is fast becoming a preferred method of drying
fruits, food grains considering the potential of saving
significant amounts of conventional fuel. The major factor
that limits the solar energy for drying application is that it
is a cyclic time dependent energy source. Therefore, solar
systems require energy storage to provide energy during
the night and overcast periods. In addition, one of the major
requirements in using solar energy for drying application is
the development of a suitable drying unit, which should be
fast and energy efficient[1].
Solar energy collectors are special kind of heat
exchangers that transform solar radiation energy to internal
energy of the transport medium. The major component of
any solar system is the solar collector. Of all the solar
thermal collectors, the flat plate collectors though produce
lower temperatures, have the advantage of being simpler in
design, having lower maintenance and lower cost. To
obtain maximum amount of solar energy of minimum cost
the flat plate solar air heaters with thermal storage have
been developed. Solar air heater is type of solar collector
which is extensively used in many applications such as
residential, industrial and agricultural fields.[2]
Solar collectors are the key component of active solar-
heating systems. They gather the sun's energy, transform its
radiation into heat, then transfer that heat to a fluid (usually
water or air). The solar thermal energy can be used in solar
water-heating systems, solar pool heaters, and solar space-
heating systems.

2. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
338
A. Flat-plate collectors
Flat-plate collectors are the most common solar collector
for solar water-heating systems in homes and solar space
heating. A typical flat-plate collector is an insulated metal
box with a glass or plastic cover (called the glazing) and a
dark-colored absorber plate. These collectors heat liquid or
air at temperatures less than 80°C.
The objective of present study is to perform CFD
simulation of flat plate collector with air flow. The CFD
model was validated with experimental results. Based on
the results of the experiments CFD analysis of air on solar
flat plate collector is carried out. There are certain
limitations for experimental results thus data at each and
every point cannot be obtained, hence CFD is the tool
which handles complex situations where experimental is
not applicable because of limitations and cost effectiveness
problem. The overall aim of this work is to understand the
flow and temperature distribution of air through solar flat
plate collector[3].
II. PROBLEM STATEMENT
The objective of present study is to perform CFD
simulation for solar air collector. The results obtained by
CFD simulation are been validated with experimental
results.The experimental conditions taken for solar air
collector, the same has been used for CFD simulation. The
overall aim of this work is to understand the flow behavior
and temperature distribution of air inside the solar collector
and compare the outlet temperature of air with
experimental results.
The 3D model consisting of the solar air collector
involving air inlet, wavy structured absorber plate , glass
cover plate, and pebble block is model by ANSYS
Workbench and the unstructured grid was created in
ANSYS ICEM. The results were obtained by using
ANSYS FLUENT software
The overall dimension for solar air collector is
2000X1000X130 mm3
with 4 mm thick glass plate which is
placed at around 126 mm from the top side of the collector.
The wavy structured absorber plate of 2000 mm length,
1000 mm wide and 2 mm in thickness. Inlet of solar air
collector is of circular cross section with diameter of 70
mm. There are two outlets to the solar collector with
circular cross section having diameter 60 mm.
Fig.1 Isometric view of Solar flat plate collector
III. NUMERICAL SIMULATION BY SOFTWARE
Computational system dynamics is the analysis of the
systems involving fluid flow, heat transfer and associated
phenomenon such as chemical reactions by means of
computer-based simulation. The technique is very powerful
and spans a wide range of industrial and non-industrial
applications areas. Some examples are: aerodynamics of
aircrafts and vehicles, hydrodynamics of ships, combustion,
turbo machinery, electrical and electronic engineering,
chemical process engineering, external and internal
environment of buildings, marine engineering,
environmental engineering, hydrology and oceanography,
metrology, biomedical engineering etc. from the 1960s
onwards, the aerospace industry has integrated CFD
technique into design, R & D and manufacture of aircrafts
and jet engines. More recently the methods have been
applied to the design of internal combustion engines,
combustion chambers of gas turbines and furnaces.
Furthermore, motor manufacturers now routinely predict
drag forces, under bonnet airflow and the in-car
environment with CFD. Increasingly CFD is becoming a
vital component in the design of industrial products and
processes.
The ultimate aim of development in the CFD field is to
provide a capability comparable to other CAE (Computer-
Aided Engineering) tools such as stress analysis codes.

3. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
339
The main reason why CFD has lagged behind is the
tremendous complexity of the underlying behavior, which
precludes a description of the fluid flows this is at the same
time economical and sufficiently complete. The availability
of affordable high performance computing hardware and
the introduction of user friendly interference have led to a
recent upsurge of interest and CFD is poised to make an
entry into the wider industrial community in the 1990s.
Clearly the investment costs of a CFD capability are not
small, but the total expense is not normally as great as that
of a high quality experimental facility. Moreover, there are
several unique advantages of CFD over experimental-based
approaches to fluid systems design.
1. Substantial reduction of lead times and costs of new
design.
2. Ability to study systems where controlled experimental
are difficult or impossible to perform. (e.g. very large
systems)
3. Ability to study systems under hazardous conditions at
and beyond their normal performance limits. (e.g. safety
studies and accident scenarios)
4. Practically unlimited level of detail of results.
In contrast CFD codes can produce extremely large
volumes of results at virtually no added expense and it is
very cheap to perform parametric studies, for instance to
optimize equipment performance[4].
A. Basics in CFD
CFD codes are structured around the numerical
algorithms that can tackle fluid flow problems. In order to
provide easy asses to their solving power all commercial
CFD packages include sophisticated user interfaces to input
problem parameters and to examine the results. Hence all
code contains three main elements:
1. Pre-processor
2. Solver
3. Post-processor
B. Numerical Modeling of solar air collector
The procedure adopted to simulate the solar air collector
by CFD tool is as follows:
a. The 3D model is been modeled by using ANSYS
WORKBENCH software as shown in Fig.2
b. After creation of 3D model, the unstructured grid is
been created by using ANSYS ICEM software as
shown in fig 3 and fig.4
c. The unstructured grid created consist around 1.5 crore
elements.
d. The unstructured grid which is created then imported
in ANSYS FLUENT software and the experimental
conditions are used while simulating the solar air
collector.
e. The model was defined by using 3D segregated solver
with steady condition, energy equation, and K-epsilon
of viscous model.
f. The fluid chosen to simulate solar collector is air. The
air properties used in this simulation is shown in table
no.1
g. The boundary conditions used in this simulation are
shown in table no.2 and 3.
h. After setting all boundary conditions in fluent
software, to solve the numerical equations the
initialization by inlet is to be done.
i. To visualize the residuals of iterations verses
convergence limit, the residual monitor is set to be in
ON state condition.
j. To get the final results the numbers of iterations are
set around 10000. The results for these simulations
were converged at around 4000 to 6000 iterations.
k. As the number of elements are more to get the
converged results the time taken for these simulations
will be more with single processor.
l. Finally after getting the proper converged results the
air flow distribution and heat transfer inside the solar
air collector is been plotted in the form of Contour
plots.
m.The outlet temperature is been calculated from
ANSYS FLUENT after getting converged results and
been compared with the experimental results.
Fig.2. 3D model of solar air collector visualizing the absorber plate

4. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
340
Fig.3 3D mesh of Solar Flat Plate Collector
Fig. 4 Meshing by using ANSYS fLUENT
TABLE 1.
PROPERTIES OF AIR
Property Value
Mass flow rate of air 0.0105 Kg/sec
Density 1.165 kg/m3
Thermal Conductivity 100 W/m K
Specific Heat 1005 J/kg K
TABLE 2
PROPERTIES OF PEBBLE BLOCK
Property Value
Density 1350 Kg/m3
Thermal Conductivity 100 W/m K
Specific Heat 300-600 J/kg K
TABLE 3
PROPERTIES OF GLASS
Property Value
Density 1000 Kg/m3
Thermal Conductivity 1.75 W/m K
Specific Heat 910 J/kg K
C. Assumptions considered for simulation
1. Air is used as working fluid, it is compressible
fluid.
2. Problem is considered 3D and steady state.
3. Surface considered in geometry are smooth air
flow over it is frictionless.
4. Ambient temperature is considered constant.
5. Flow is assumed to be turbulent.
6. Turbulence specification method of turbulent
intensity and viscosity ratio with 5 % and 10
respectively. By default these values are can be
taken 3 % and 3 respectively or calculated as per
model. Here it is been assumed that turbulence will
be more so approximately value has been taken by
doing trial and error for convergence of model
results[5].
IV. RESULT AND DISCUSSION
The results obtained from the CFD analysis of solar flat
plate collector are presented in this section. The simulation
is carried out for different times of the day i.e.9 am to 5
pm. Then the results obtained by this simulation compared
with the experimental results as shown in fig 4. The curves
are plotted to indicate experimental and simulated outlet
temperatures versus time. From fig 4 it seems that the
difference between experimental and simulated outlet
temperature for different times is almost 5˚C.

5. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
341
TABLE 4
COMPARISON OF EXPERIMENTAL AND CFD RESULTS
Time
Hrs
Solar
Intensity
(W/m2
)
Ambient
temperature
(0
C)
Collector
temperature
obtained by
CFD(0
C)
Collector
temperature
(0
C)
9 am 621.7 32.5 60.87 55.7
10
am
750.5 34.7 73.75 60.5
11
am
879.5 37 85.34 67.4
12 909 38.9 93.38 76.5
1 pm 948 38.5 96.10 78.1
2 pm 909.5 41.1 93.40 75.2
3 pm 790 40 84.84 68.8
4 pm 597.5 35 68.14 60.3
5 pm 357 33 43.06 42
Graph 1. Comparison of CFD and experimental results for day1
Also the temperature distribution and flow distribution
are obtained by CFD simulation. The contour plots
obtained for temperature distribution and velocity
distribution in streamlines are shown in fig 5(a), 5(b), 5(c),
5(d).
Fig.5(a) Streamlines for temperature distribution
Fig.5(b) Streamlines for temperature distribution at 9 am of the day
Fig.5(c) Streamlines for velocity distribution

6. International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 4, April 2013)
342
Fig.5(d) Streamlines for velocity distribution at time 9am of day
V.CONCLUSION
There is a good agreement between the experimental and
simulated results for outlet air temperatures. Although there
are some small discrepancies due to some experimental
imperfectness matters, we still have a good confidence in
the CFD simulation program that can be used in the future
for more complex solar collector problem.
It is found from the CFD analysis that the flow of air in
the solar flat plate collector is not properly distributed. In
order to overcome this issue we can introduce baffles at the
inlet of collector which improves the efficiency of of solar
flat plate collector.
REFERENCES
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[2] Decho Thueaktphum, Kittitep Fuenkajorn,” A rock fills based solar
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[3] Mohamed Selmi, Mohammed J. Al-Khawaja and Abdulhamid
Marafia, “Validation of CFD simulation for flat plate solar energy
collector,” Renewable Energy 33 (2008) 383–387 .
[4] Kumaresan G, Iniyan S and Velraj R, “Experimental and CFD
analysis of a solar based cooking unit”, Institute for Energy Studies,
CEG Anna University, Chennai - 600025, India.
[5] Fabio Struckmann, “Analysis of a Flat-plate Solar Collector”, 2008
MVK160 Heat and Mass Transport ,May 08, 2008, Lund, Sweden
[6] . K. Vasudeva Karanth, Manjunath M. S. and N. Yagnesh Sharma,
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Proceedings of the World Congress on Engineering 2011 Vol
III,WCE 2011, July 6 - 8, 2011, London, U.K.
[7] David Luna, Yves Jannot, Jean-Pierre Nadeau, “An oriented-design
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Applied thermal engineering 30 (2010) 2808-2814
[8] G. D. Rai, “Solar Energy Utilization”, Khanna Publishers, page no.
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