1. MODELING AND ANALYSIS OF A SOLAR
PHOTOVOLTAIC ASSISTED ABSORPTION
REFRIGERATION SYSTEM
Presented by
Dr. Aritra Ganguly
Assistant Professor
Department of Mechanical Engineering
Bengal Engineering and Science University, Shibpur
Howrah, West Bengal-711103
IV
th
Presented at
International Conference on Advances in Energy Research

2. OVERVIEW OF PRESENTATION
 Introduction and Objective of the work
 Mathematical model of Absorption system
 Modeling of solar photovoltaic modules
 Results and Discussion
 Conclusions
 References
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3. INTRODUCTION
 Air-conditioning has now become an integral part of modern life not only
from the view point of luxurious comfort, but also as a necessity in
places, where the weather condition is hostile.
 Conventional VCR-based air-conditioning systems are most common in
domestic applications.
 Large power consumption by the compressor, in view of present trend
towards energy conservation, is a matter of serious concern.
 Harmful effects on the environment by the use of synthetic refrigerants
and lack of knowledge about the use of natural replacements are also
worrying factors.
 Use of vapor absorption based system offers an attractive alternative to
technologists.
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4. PROBLEMS OF VAPOUR COMPRESSION SYSTEM
•
•
Poor performance at part load
condition.
•
Necessity to superheat the
refrigerant leaving the evaporator
before entering compressor
•
Fig.1: Vapour Compression System
Large power consumption of
compressor especially during
start.
Harmful effects of synthetic
refrigerant on environment.

5. ADVANTAGES OF VAR SYSTEM
 Operated by low-grade thermal energy, instead of high-grade
electrical energy
 Noise free operation & less maintenance requirement.
 Absence of compressor — no problems with rotary component.
 Can operate at reduced evaporator temperature and pressure.
 The
performance is marginally influenced under part load
condition.
 The system can be built in very high capacities, even above
1000 TR.
 The system can be used where the electricity is difficult to obtain
or is expensive.
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6. OBJECTIVE OF THE PRESENT WORK
 Present work conceptualizes the use of solar photovoltaic
modules for powering a LiBr-H2O absorption system for a
cooling load of 0.5 TR.
 A mathematical model has been developed for the LiBr-H2O
absorption refrigeration system as well as its power
system.
 Performance analysis of the VAR as well as the power
system for representative days of various seasons of a
climatic cycle.
 Computation of cumulative daylong electrical energy
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supplied to and discharged from the battery.

7. SCHEMATIC REPRESENTATION OF PV POWERED VAR SYSTEM
7
Fig.2: Schematic of PV POWERED VAR System

8. MATHEMATICAL MODEL OF VAR SYSTEM
QC
QG
1
Condenser (TC )
Generator (TG )
8
7
Condenser
pressure (pC )
2
Refrigerant
side
Mixture side
Heat
Exchanger
9
6
Evaporator
pressure (pE )
3
Evaporator (TE )
QE
5
4
10
Absorber (TA )
QA
Fig.3: Schematic of VAR System
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9. MATHEMATICAL MODEL OF VAR SYSTEM

mR =QE
(h4 −h3 )
(1)


X ss mss = X ws mws



mss = m R +mws



QG = mR h1 +mws h8 −mss h7

WP = mR ( h6 −h5 )
COP =QE
(QG
+WP )
(2)
(3)
(4)
(5)
(6)
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10. MODELING OF SOLAR PHOTOVOLTAIC SYSTEM
iPV
Rs
iD
V
iL
Fig. 4: Equivalent circuit diagram of a solar photovoltaic cell.
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11. Modeling of Solar Photovoltaic (PV) system
Contd.
• The cell terminal current can be expressed as:
i PV =i L −i D
i L = i scref [1 + ∆i sc (Tmod ule −Tmod ule ref
iD
(7)
 It
)] ×
 I tref







q (V +i PV × Rs )
= i sat exp(
) −1
γKTmod ule


Ns =
Vsystem
Vmod ule
(8)
(9)
(10)
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The value of series resistance being very small, it has been neglected in the
present analysis (Paul et al. 2004).

12. RESULTS AND DISCUSSION
Fig. 5: Hourly variation of mass flow rate of strong solution, weak solution, refrigerant and
generator heat load for the month of January.
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13. RESULTS AND DISCUSSION
contd.
Fig. 6: Variation of electrical energy supplied to and discharged from the battery for a
representative day in January
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14. RESULTS AND DISCUSSION
contd.
Fig. 7: Variation of electrical energy supplied to and discharged from the battery for a
representative day in March
14

15. RESULTS AND DISCUSSION
contd.
Fig. 8: Variation of electrical energy supplied to and discharged from the battery for a
representative day in May
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16. RESULTS AND DISCUSSION
contd.
Fig. 9: Variation of electrical energy supplied to and discharged from the battery for a
representative day in September
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17. Cumulative Daylong Electrical Energy
Supplied to and Discharged from the Battery
January
Energy to
battery (Ah)
Energy
from
battery (Ah)
March
May
September
874
1246
1428
1246
138
139
231
141
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18. CONCLUSION
•
•
•
•
•
A model for a solar photovoltaic powered LiBr-H 2O absorption
refrigeration system with battery back-up has been developed for a
cooling load of 0.5 TR.
The performance of the system has been analyzed for various seasons
of a full climatic cycle considering weather data for the place as input.
The study revealed that fifty two number of modules (CEL Make PM
150) each having two modules in series along with a battery bank of
1200 Ah ( 6 x 200 Ah) can power the system in a standalone manner.
There is a considerable surplus of electrical energy in the battery
throughout the year which can meet the requirement of energy deficit
hours of the day satisfactorily. The surplus is found to be the maximum
in May.
The study thus reinforces the viability of a standalone LiBr-H 2O
absorption system which can meet its own energy needs through solar
photovoltaic modules and also cater to the energy requirements of the
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surrounding community.

19. References










Kim, D.S. and Ferreira, C.A.I. (2008) Solar refrigeration options – a state-of-the-art review, International Journal
of Refrigeration, 31, pp. 3–15.
Pongtormkulpanicha, A., Thepa, S., Amornkitbamrung and Butcher, C. (2008) Experience with fully operational
solar driven 10 ton LiBr-H2O single effect absorption cooling system in Thailand, Renewable Energy, 33, pp.
943–949.
Enibe, S.O. (1997) Solar refrigeration for rural applications, Renewable Energy, 12, pp. 157-167.
Chen, G. and Hihara, E. (1999) A new absorption refrigeration cycle using solar energy, Solar Energy, 66, pp.
479-482.
Patek, J. and Klomfar, J. (2006) A computationally effective formulation of the thermodynamic properties of LiBr–
H2O solutions from 273 to 500 K over full composition range, International Journal of Refrigeration, 29, pp. 566–
578.
Wagner, W., Cooper, J.R., Dittmann, A., Kijima, J., Kretzschmar, H-J., Kruse, A., Mareš, R., Oguchi, K., Sato, H.,
Stöcker, I., Šifner, O., Takaishi, Y., Tanishita, I., Trübenbach, J. and Willkommen Th. (2000) The IAPWS
industrial formulation 1997 for the thermodynamic properties of water and steam, Journal of Engineering Gas
Turbine and Power, 122, pp. 150-182.
Chenni, R., Makhlouf, M., Kerbache, T., Bouzid, A. (2007) A detailed modeling method for photovoltaic cells,
Energy, 32, pp. 1724-1730.
Tiwari, G.N. (2004) Solar energy-Fundamentals, design, modeling and applications, Narosa Publishing House,
New Delhi, India.
Available online at www.celindia.co.in (accessed on 1.11.2011).
Telecommunication Engineering Centre (TEC), New Delhi. Planning and maintenance guidelines for SPV (solar
photovoltaic) power supply. 2004; available online at http://www.tec.gov.in/guidelines.html (accessed on
27.05.2012).
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20. THANK YOU
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