The document discusses the development of a vapor absorption refrigeration system for automobile air conditioning that uses waste heat from engine exhaust, utilizing R-134a as the refrigerant and DMF as the absorbent. This system is shown to improve vehicle performance and reduce engine power consumption compared to conventional vapor compression systems, which require significant energy and may decrease engine life. The findings indicate a coefficient of performance (COP) of 2.41, suggesting a more economical and efficient option for vehicle air conditioning.

1. International INTERNATIONAL Journal of Mechanical JOURNAL Engineering OF and MECHANICAL Technology (IJMET), ISSN ENGINEERING
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ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
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ISSN 0976 – 6340 (Print)
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Volume 5, Issue 7, July (2014), pp. 42-50
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IJMET
© I A E M E
DEVELOPMENT OF AIR CONDITIONING SYSTEM BASED ON VAPOUR
ABSORPTION REFRIGERATION CYCLE FOR AUTOMOBILES USING
EXHAUST GASSES WITH R134a-DMF
1G. Karthik, 2K. Usha Rani, 3Sayi Likhitha S S
1Application Engineer, Heating Ventilation Air Conditioning Refrigeration, Ahmadabad,
Gujarath-382435, India
2Academic Consultant, Dept. of Mechanical Engineering, School of Engg Tech, Sri Padmavathi
Mahila University, TIrupathi, Chittor Dist, Andhra Pradesh – 517502, India
3Asst.Professor, Dept. of Mechanical Engineering, N.B.K.R.I.S.T., Vidyanagar, Nellore (Dist),
Andhra Pradesh – 524 413, India
1. ABSTRACT
The air conditioning system of automobiles in today’s world uses “Vapour Compression
Refrigerant System” (VCRS) which absorbs and removes heat from the interior of the vehicle. The
system utilizes power from engine shaft as the input power to drive the compressor of the refrigerant
system. The loss of power of the engine to run the VCR system can be neglected by utilizing another
refrigeration system i.e. a “Vapour Absorption Refrigerant System”. In a Vapour Absorption
Refrigerant System, a physicochemical process replaces the mechanical process of the Vapour
Compression Refrigerant System by using energy in the form of heat rather than mechanical work.
The experimental work to utilize the waste heat from exhaust gases from an engine for the vapour
absorption refrigerant system with R-134a as refrigerant and DMF as absorbent. The experimental
results indicated that vehicle performance enhances, noise reduces, maintenance becomes easier, and
highly reliable. The data obtained from experimentation is presented analyzed in this paper.
2. INTRODUCTION
The vapour absorption refrigeration system is one of the oldest methods of producing
refrigerating effect. The principle of vapour absorption was first discovered by Michael Faraday in
1824 while performing a set of experiments to liquefy certain gases. The first machine was based on
Vapour Absorption Refrigeration machine was developed by a French scientist, Ferdinand Carry, in
1860. This system may be used in both the domestic and large industrial refrigerating plants. The

2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
refrigerant commonly used in vapour absorption system is Ammonia. This system uses Heat energy
instead of mechanical energy as in vapour compression system, in order to change the condition of
refrigerant required for the operation of the refrigeration cycle. In automobile air conditioning load
factors are constantly and rapidly changing as the automobile moves over highways at different
speeds and through different kind of surroundings. As the car moves faster there is greater amount of
infiltration into the car and the heat transfer between the outdoor air and the car surface is increased.
The sun baking down on a black top road will raise its temperature to 350oC – 450oC approximately
and thus increases the amount of heat transmitted into car. Therefore, the car is subjected to varying
amounts of heat load when its orientation changes during the journey. An automobile engine utilizes
only about 35% of available energy and rests are lost in the form of heat and mechanical losses to
cooling and exhaust system. If one is adding conventional air conditioning system to automobile, it
further utilizes about 4-5% of the total energy. Therefore automobile becomes costlier, uneconomical
and less efficient. The conventional air conditioning system in car decreases the life of engine and
increases the fuel consumption, further for small cars compressor needs 3 to 4 bhp i.e. a significant
ratio of the power output. Keeping these problems in mind, a car air conditioning system is proposed
which is using exhaust heat. The advantages of this system over conventional air-conditioning
system are that it does not affect designed efficiency life and fuel consumption of engine. G
VICATOS, J GRYZAGORIDIS and S WANG (1) proposed a new system, Vapour Absorption
Refrigeration of System based on Exhaust gas from an Internal Combustion Engine. Here energy
from the Exhaust gas of an Internal Combustion Engine is used to power absorption Refrigeration
system to Air condition an Ordinary passenger. In this theoretical Design is verified by the unit that
is tested under both laboratory and road-test conditions, by using Refrigerant 134a and absorbent
Dimethylformamide(DMF) the cooling effect for a passenger in a vehicle is been very comfort.
Dimethylformamide is a clear liquid, miscible with water and majority organic solvents and it is used
as a solvent in the production of fibers, films, and surface coatings.
2.1. Comparison of Vapour Absorption Air Conditioning over Vapour Compression Air
Conditioning:
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2.1.1. Method of compression of the refrigerant:
One of the most important parts of any air conditioning cycle is the compression of the
refrigerant since all the further operations depend on it. In the vapour compression air conditioning
system the compression of the refrigerant is done by compressor which can be of reciprocating,
rotating or centrifugal type. In the vapour absorption air conditioning system, the compression of the
refrigerant is done by absorption of the refrigerant by the absorbent. As the refrigerant is absorbed, it
gets converted from the vapour state to liquid state so its volume reduces.
2.1.2. Power consumption devices:
In the vapour compression cycle the compressor is the major power consuming device while
in the vapour absorption cycle the pump used for pumping refrigerant-absorbent solution is the major
power consuming device.
2.1.3. The amount of power required:
The compressor of the vapour compression cycle requires large quantities of power for its
operation and it increases as the size of the system increases. In case of the vapour absorption
system, the pump requires very small amount of power and it remains almost the same (or may
increase slightly) even for higher capacities of air conditioning. Thus the power consumed by the
vapour absorption system is less than that required by the vapour compression system.

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
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2.1.4. Type of energy required:
The vapour absorption system runs mainly on the waste or the extra heat in the plant. Thus
one can utilize the extra steam from the boiler, or generate extra steam for the purpose and also use
the hot available water. Similarly the waste heat from the diesel engine, hot water from the solar
water heater, etc. can also be utilized. In case of the vapour compression system, the compressor can
be run by electric power supply only; no other types of energy can be utilized in these systems.
2.1.5. Running cost:
The vapour compression air conditioning system can run only on electric power, and they
require large amount of power. These days the electric power has become very expensive, hence the
running cost of the vapour compression air conditioning system is very high. In case of the
absorption air conditioning system only small pump requires electric power and it is quite low. In
most of the process industries, where the absorption refrigeration is used, there is some extra steam
available from the boiler, which can be used for running the system. Thus in absorption air
conditioning system no extra power in the pure electric form is required and the energy that would
have otherwise gone wasted is utilized in the plant. Thus the running cost of the absorption air
conditioning system is much lesser than the vapour compression system.
Table 1: List of Components of Vapour Absorption Air Conditioning over Vapour
Compression Air Conditioning
Vapour Absorption Air Conditioning
Vapour Compression Air Conditioning
• Generator
• Drier
• Condenser
• Capillary tube
• Evaporator
• Absorber
• Pump
• Connection Tubes
• Glass Cloth Tape
• Insulation Foam Tube
• Compressor
• Condenser
• Expansion valve
• Evaporator
3. EXPERIMENTAL SETUP

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
45
The basic components of Vapour absorption Refrigeration system for Automobile Air
conditioning are Generator, Drier, Condenser, Capillary tube, Evaporator, Absorber, Pump,
Connection Tubes, Glass Cloth Tape, Insulation Foam Tube. In this experiment Refrigerant 134a and
absorbent Dimethylformamide (DMF) are used. The properties of the refrigerant and absorbent are
listed in the table1 and table 2 respectively.
Table 2: Properties of R-134a refrigerant
No Properties R-134a
c Boiling Point -14.9°F or -26.6°C
2 Auto-Ignition Temperature 1418°F or 770°C
3 Ozone Depletion Level 0
4 Solubility In Water
0.11% by weight at 77°F or
25°C
5 Critical Temperature 252°F or 101°C
6 Cylinder Colour Code Light Blue
7 Global Warming Potential (GWP) 1200
Table 3: Properties of Di Methyl Formamide
(C3H7NO)
Properties Value
Molecular formula C3H7NO
Molecular weight 73.09g/mol
Boiling point 153°C
Freezing point -60.4°C
Density
20°C
949 kg/m³
40°C
931 kg/m³
Vapour pressure
20°C
40°C
60°C
0.38 kPa
1.3 kPa
3.9 kPa
Vapour density 2.5
Critical values
Temperature
Pressure
Volume
374 °C
4.42 Mpa
3.65 m³/kg
To generate base line data, the engine is allowed to run at different throttle position (one-fourth
and half) considering engine speed as running parameter. The mass flow rate of air, mass flow
rate of fuel and temperature of exhaust gas is measured. For measuring the required data circular
orifice, u tube manometer, burette for petrol measurement and thermocouple for exhaust temperature
measurement in installed on engine. The cooling load of a typical automobile is also considered at
steady state conditions.

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
46
4. CALCULATIONS
For design considerations we have to take assumptions which are based on the basis of
normal summer ambient weather/temperature conditions as well as the temperature to be maintained
at Evaporator Coil is also assumed to be maintained for human comfort.
Table 4: Design consideration of automobile air conditioning unit based on vapour absorption
refrigeration system (CAPACITY=1TR)
Temp
(°C)
Temp
(K)
Press
ure
(bar)
Specific
Enthalpy
(kJ/kg)
Specific Entropy
(kJ/kg K)
Enthalpy
(kJ/kg)
Liquid
(hf)
Latent
(hfg)
Liquid
(sf)
Vapour
(sg)
Liq+Vap
(hg)
Absorber
(T_A)
33
306
5.4
228 409
1.0885 1.7190
181
Generator
(T_G)#
90
363
9.2
254 418
1.1809 1.7122
164
Condenser
(T_C)
38
311
9.2
254 418
1.1809 1.7122
164
Evaporator
(T_E)
19
292
5.4
228 409
1.0885 1.7190
181
Calculations based up on Human comfort.
(For ease of calculation and compactness of the model we have made all of our calculations, taking
Capacity = 1TR)
Coefficient of Performance (COP) = [ ]= 2.41
Workdone (Winput) = [ ]= 87.02 kj/min = 1.45 kw
Mass of Refrigerant Flowing (mf) = = 0.78 kg/min
Volume of Refrigerant Flowing (vf) = ) = 0.000059 m3/sec
Power Required to Drive Suction Pump = = 26 W

6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
Amount of heat required in Generator = (Win x 1000 -Ppump) watts = 1.424 kj/sec
Amount of heat rejected by refrigerant = Mass of refrigerant flowing in cycle x
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Sp.heat of refrigerant x (Tc – Ta) kj/min
= 0.78 x 1.350 x (311-306)=0.088 kj/sec
Table 5: Calculated cop values for different generator temperatures
Tg (ok) Ta(ok) Tc(ok) Te(ok) COP
363 306.0 311.0 292.0 2.41
353 306.3 310.5 294.0 2.37
343 306.5 310.2 294.8 2.03
333 307.1 309.9 296.3 1.69
323 307.4 309.1 299.0 1.42
At certain limit of temperature as per design we reached Generator temperature at 363 ok,
Condensing temperature 311 ok, Evaporating temperature 292ok and COP is 2.41.
Based on these Temperatures we have drawn various graphs with different parameters.
5. VARIOUS GRAPHS
5.1 The variation of Evaporator temp with Generator temp.
The above graph shows that when the generator temperature increases the Evaporator
temperature is decreased.

7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
5.2 The variation of COP with Generator temperature
The above graph shows that when the generator temperature increases the COP is increased.
5.3 The variation of COP with Evaporator temperature
The above graph shows that when the Evaporator temperature decreases the COP is increased.
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8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
5.4 The variation of COP with Condenser temperature
The above graph shows that when the Condenser temperature increases the COP is increased.
5.5 The variation of COP with Absorber temperature
The above graph shows that when the Absorber temperature decreases the COP is increased.
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6. CONCLUSION
The present project is successful in designing and developing an automobile air conditioning
system using engine waste heat based on Vapour Absorption Refrigeration System. By using R-134a
and DMF as a refrigerant and absorbent combination. It saves the power of engine as it replaces the
compressor by the four components i.e. Absorber, Pump, Generator Pressure Reducing Valve out

9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 5, Issue 7, July (2014), pp. 42-50 © IAEME
of which only the pump consumes some power that too is very feeble as compared to that of the
Compressor, and thus helps in saving of fuel.
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This system can be employed to commercial heavy vehicles including those which are
involved in the transportation of refrigerated products, as this system can easily provide the
refrigeration/air-conditioning of cabin as per the requirements by using the exhaust heat of the
vehicle’s engine (which is in abundance in such vehicles) thus will not add any additional engine to
run the air-conditioning/refrigerating unit in vehicle and hence reduces the operational cost. All in
all, it can be a very well and economical asset for the automobile and can completely change the
scenario of Automobile Air-Conditioning System.
In case of vapour compression refrigeration system an amount of 15% engine work is
required to drive the refrigeration motor. The present investigation has successfully saved this work
by replacing vapour compression refrigeration system with Vapour Absorption Refrigeration
System. The COP of Vapour Absorption Refrigeration System developed by the present project is
2.41 and the lower temperature achieved is 19oC.
REFERENCES
[1] Alam Shah (2006), A Proposed Model for Utilizing Exhaust Heat to run Automobile Air-conditioner,
The 2nd Joint International Conference on “Sustainable Energy and
Environment (SEE 2006)” 21-23 Nov; 2006, Bangkok, Thailand.
[2] G Vicatos, J Gryzagoridis, S Wang, Department of Mechanical Engineering, University of
Cape Town, A car air-conditioning system based on an absorption refrigeration cycle using
energy from exhaust gas of an internal combustion engine. “Journal of Energy in Southern
Africa (Vol 19 No 4), November 2008”
[3] M. Hosoz , M. Direk, Department of Mechanical Education, Kocaeli University, Umuttepe,
41100 Kocaeli, Turkey, Performance evaluation of an integrated automotive air conditioning
and heat pump system “Received 5 November 2004; accepted 18 May 2005 Available online
14 July 2005.” Energy Conversion and Management 47 (2006) 545–559
[4] Khurmi R S, Gupta J K, Refrigeration and Air Conditioning- 2010, Vapour Absorption
Refrigeration (Pg 238-249).
[5] Ganeshan V, Internal Combustion Engine- 2010, Heat Rejection Cooling (Pg 445-467)
[6] Domkundwar Domkundwar, Refrigeration Air-Conditioning Data book.
[7] K.Ganesh Babu, K.Ravi Kumar and Dr. Md. Azizuddin, “Performance Improvement by
Reducing Compressor Work of R-134a and R22 used Refrigeration Systems by using Two-
Phase Ejector”, International Journal of Advanced Research in Engineering Technology
(IJARET), Volume 4, Issue 3, 2013, pp. 187 - 193, ISSN Print: 0976-6480, ISSN Online:
0976-6499.
[8] Dr. Ashok G. Matani and Mukesh K. Agrawal, “Performance Analysis of Vapour
Compression Refrigeration System using R134a, Hc Mixture and R401a as Working
Medium”, International Journal of Mechanical Engineering Technology (IJMET),
Volume 4, Issue 2, 2013, pp. 112 - 126, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.
[9] Anirban Sur and Dr.Randip.K.Das, “Review on Solar Adsorption Refrigeration Cycle”,
International Journal of Mechanical Engineering Technology (IJMET), Volume 1, Issue 1,
2010, pp. 190 - 226, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.