International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 1, January 2015
ISSN 2319 - 4847
The effect of ambient conditions on system
efficiency of concentrated solar plants
(Parabolic trough and central tower)
Latifa SABRI1, Mohammed BENZIRAR2
1
Physics Department, Faculty of Sciences and Technology
Hassan II University, Mohammedia, Morocco
2
Physics Department, Faculty of Sciences and Technology
Hassan II University, Mohammedia, Morocco
ABSTRACT
The ambient conditions are ones of the most important factors because it affects the energy load of Concentrated Solar Power
(CSP). Among these conditions, there is ambient temperature and wind speed. There have been many studies that determine the
effect of these parameters on the energy yield of CSP plants; but there is no particular study that has discussed the influence of
these parameters on the system efficiency of CSP plants. This paper evaluates the effects of ambient conditions on the system
efficiency of CSP plants of two types of CSP systems: parabolic trough and central tower technologies. The results show that
the ambient conditions affect the system efficiency of the CSP systems. The influence of these factors should be taken into
account so as to have a deep insight in solar mirrors design.
Key words: CSP, system efficiency, ambient conditions, impact.
Corresponding Author: Latifa SABRI.
1.INTRODUCTION
Other than causing a severe environmental degradation, the use of fossil fuels also causes serious environment
problems especially the greenhouse. Nowadays, research efforts are taking place to develop alternative sources of
energy, more efficient conversion technologies and environmentally sustainable applications. The use of solar energy
technology is a viable solution to some of the environmental problems that were generated by the use of fossil fuels.
Nowadays, the world knows a great interest for developing a new technology to produce electricity without any
emission of pollution .One of these technologies is a CSP (Concentrated Solar Power) system that uses solar energy
using mirrors without emitting pollutants and requiring no fuel as shown in Figure 1[1].
Fig 1: The compenents of CSP plants.
The incident solar radiation is collected in a specific system using a mirrors, heat a thermal fluid. This fluid is then
used to drive a turbine and generate electricity. During the night, the energy can be saved in the thermal storage.
Volume 4, Issue 1, January 2015
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 1, January 2015
ISSN 2319 - 4847
The main concentrated solar power systems are: The parabolic trough system, the parabolic dish system, the central
tower system and linear Fresnel as seen in Figure 2[2].
Fig 2: The different types of CSP systems.
Certainly, the performance of these power plants depends on ambient parameters including: ambient temperature,
wind speed, direct radiation, etc. Many studies have been done like [3, 4, 5, 6], which determine the impact of the
meteorological parameters on performances of CSP plants. In this article, there will be a study of the impact of these
parameters on the system efficiency of CSP plants
There are models that give the system efficiency of CSP plants from ambient conditions such as
this equation [7]:
 system   th  ( abs
Where
 abs    Tabs 4  hconvection  (Tabs  Tamb )

 field  C  I DNI
 th is the thermal efficiency, 
is the solar field efficiency,
(1)
 abs is the radiative absorptivity of the
field
 abs is the radiative emissivity of the absorber,  is the Stefan–Boltzmann constant 5.67 * 10 8
(W/m2K4), Tabs is the absorber temperature, Tamb is the ambient temperature (°C), C the concentration factor, I DNI
is the direct irradiation (W/m2) and V is the wind speed (m/s). The convective heat exchange hconvection can be
absorber,
formulated [8]:
hconvection  5.7  3.8  V
(2)
In which V is the wind speed (m/s). Baseline values given and outlined in Table 1 are used for the receiver efficiency
calculation.
Table 1.Baseline parameter values used to calculate receiver efficiency in Eq. (1).
Volume 4, Issue 1, January 2015
 th
 abs
 field
0.38
 abs
C
0.95
0.88
0.6
100 and 1000
Page 102
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 1, January 2015
ISSN 2319 - 4847
2.MATERIALS AND METHODS
To obtain the purpose of this paper, parabolic through and central tower type of CSP technologies considered. In order
to get the results of this article, the meteorological data are taken from the site of Casablanca, Morocco the 7 August
2012 with the specific parameters mentioned in Table 2 and Figures 3, 4 and 5.
Table2. Overview of the meteorological conditions at Casablanca.
Latitude
33.37 °N
Longitude
-7.58 °E
Elevation
206 m
Time zone
GMT 0
Fig3: The direct irradiation in Casablanca on 7 August 2012.
Fig4: The ambient temperature in Casablanca on 7 August 2012.
Fig5: The wind speed in Casablanca on 7 August 2012.
From the figures, it’s seen that the ambient temperature and the direct irradiation increase until midday of the day and
then they break down. These meteorological data are used as input to performance simulation software named SAM
(System Advisor Model). System Advisor Model (Version 2014.11.4) [9] is a performance and financial model
Volume 4, Issue 1, January 2015
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 1, January 2015
ISSN 2319 - 4847
designed to facilitate decision making for people involved in the renewable energy industry. SAM PT Physical model is
used for calculating the absorber temperature. The front of view of the software SAM is seen in Figure 6.
Fig6: The front of view of System Advisor Model.
3.RESULTS
The impact of the ambient conditions such as: ambient temperature and wind speed on the system efficiency of CSP
plants is summarized in Figures 7, 8 and 9.
Fig7: The variation of system efficiency for parabolic trough and central tower with the time of the day 7 August 2012
in Casablanca.
Fig8: The variation of system efficiency for parabolic trough and central tower with the ambient temperature in
Casablanca.
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
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Fig 9: The variation of system efficiency for parabolic trough and central tower with the wind speed in Casablanca.
From two figures 8 and 9, it’s found that with an increase of ambient temperature and wind speed, the system efficiency
of the two types of CSP plants (Parabolic trough and central tower) breaks down. Fig 8 shows that system efficiency
change slightly with different ambient temperatures. At Tamb = 22 °C, system efficiency is 35% for Parabolic trough,
and when Tamb = 28 °C, system efficiency is 27% for parabolic trough. But there are no extremely changes in the case
of the system efficiency of the central tower systems. As seen from Fig 9, the system efficiency changes slightly with
different wind speeds. At V = 2.7 m/s, system efficiency is 35.2%, and when V = 6.2 m/s, system efficiency is 27% for
the parabolic trough. While the system efficiency of the central tower stand approximately stable.
Wind lifts dust and scatters in environment resulting in shading and poor performance of CSP plants.
4.CONCLUSION
Among the most popular applications of renewable energy technology is the installation of CSP systems using sunlight
to produce electricity. This paper has presented a detail overview of the ambient factors that affect the system efficiency
of the two types of CSP plants: parabolic trough and central tower. The important theme of these factors is ambient
temperature and wind speed. It has been shown that ambient conditions (Ambient temperature and wind speed) has a
negative impact on the performance of CSP plants and it is clear those designers and power plant operators should
make every effort to mitigate against these effects. In conclusion, ambient temperature and air velocity can drop the
efficiency of CSP systems so they should be studied in evaluating the system efficiency. The next steps for this work
would be to scale up the numerical models for larger sized power plants.
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org
Volume 4, Issue 1, January 2015
ISSN 2319 - 4847
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