refrigerants...

2. Refrigerants
By
Engr.Hashim Hasnain

3. REFRIGERANTS
A refrigerant is a substance or a heat carrying medium which
during a refrigerant cycle absorbs heat from a low temperature
system and discades the heat absorbed to high temperature
system,
It’s a medium of heat transfer through a change in phase such as
evaporation and condensation. Refrigerant is thus are the
working substance in refrigeration system.
“ Refrigerant acts as a transportation medium to move heat
absorbed in the evaporator to the condenser where it is
rejected ”.

4. CLASSIFICATION OF REFRIGERANTS

5. BASED ON WORKING PRINCIPLE

6. Based on Working Principle :-
REFRIGERAN
TS
PRIMARY REFRIGERANTS SECONDARY REFRIGERANTS
1) Used directly as
working fluids.
2) Undergo phase
change.
Eg, R134a, R404a
1) Liquids that are used
to transport energy.
2) Not undergo any
phase change.
Eg. Water , brines.

7. • Primary refrigerants: are those fluids, which are
used directly as working fluids, for example in
vapor compression and vapor absorption
refrigeration systems
These fluids provide refrigeration by undergoing a
phase change process in the evaporator.
Secondary refrigerants: are those liquids, which
are used for transporting thermal energy from one
location to other. Secondary refrigerants are also
known under the name brines or antifreezes

8. PROPERTIES OF IDEAL REFRIGERANT:
1. The refrigerant should have low boiling point and low freezing point.
2. It must have low specific heat and high latent heat. Because high specific heat
decreases the refrigerating effect per kg of refrigerant and high latent heat at
low temperature increases the refrigerating effect per kg of refrigerant.
3. The pressures required to be maintained in the evaporator and condenser
should be low enough to reduce the material cost and must be positive to
avoid leakage of air into the system.
4. It must have high critical pressure and temperature to avoid large power
requirements.
5. It should have low specific volume to reduce the size of the compressor.
6. It must have high thermal conductivity to reduce the area of heat transfer in
evaporator and condenser.
7. It should be non-flammable, non-explosive, non-toxic and non-corrosive.
8. It should not have any bad effects on the stored material or food, when any
leak develops in the system.

9. 9) It must have high miscibility with lubricating oil and it should not have
reacting properly with lubricating oil in the temperature range of the system.
10) It should give high COP in the working temperature range. This is necessary
to reduce the running cost of the system.
11) It must be readily available and it must be cheap also.

10. TYPES OF PRIMARY REFRIGRANTS
• 1) Halocarbon refrigerants
• 2) hydrocarbon refrigerants
• 3) azetropes
• 4)Inorganic refrigerants
.

11. HALOCARBON REFRIGERANTS
• These were the most commonly used refrigerants until the ban on these
compounds due to environmental reason. Essentially these refrigerants are
compounds of chlorine,florine and carbon

12. LAMINAR AND TURBULENT BOUNDARY LAYER

13. REFRIGERANT CHEMICAL NAME APPLICATION properti
R-11 Trichloromonofluoromethan
e
Centrifugal
chillers/compressor
Non flamm
R-12 Dichlorodifluoromethane Reciprocating & rotatory
equipment
R-13 Monochlorotrifluoromethane Low stage cascade
system
R-13B1 Bromotrifluoromethane Low to medium temp.
application
R-113 Trichlorotrifluoroethane Low capacity chillers
R-114 Dichlorotetrafluoroethane High capacity chillers
R-500 Refrig. 152A/12 Reciprocating
compressor
R-502 Refrig. 22/115 Reciprocating
equipments
CFCs:

14. • Refrigerant R12: The refrigerant R12 is the most widely used refrigerant in the domestic
and large commercial establishments. Its chemical formula is CCl2F2 and its boiling
point is -300C at 1 bar. It is a non-flammable, non-explosive, non-irritating, non-toxic
and odourless refrigerant. It 62 Refrigeration and Air Conditioning remains chemically
stable up to 550 0C. Also, it does not affect the material of the refrigeration system. It is
available in abundance and is quite cheap. However, its use is being discontinued
nowadays for its contribution to ozone depletion which will be discussed later
• Refrigerant R13 :Its chemical formula is CClF3. it is a non-flammable, non-toxic and
stable refrigerant. It is very suitable for achieving low temperatures in a cascade
refrigeration system. Its specific volume is high and therefore, it is suitable for
centrifugal compressors. However, it also has a negative effect on ozone depletion.
• Refrigerant R22: Its chemical formula is CHClF2. it is also a non-toxic, non-flammable,
non-corrosive and non-irritating refrigerant. It is the most common refrigerant for use
in large refrigeration systems and is preferred to

15. Refrigerant R114 Its chemical formula is C2Cl2F4. Its boiling point corresponding to 1 bar is
about 30C. It has properties very similar to those of R12 with respect to water and oil
combination. It is not suitable for low temperature refrigeration since it has negative
evaporator pressure even at around 9 0C. It is non-toxic, non-explosive and non-
corrosive even in the presence of water.

16. HYDROCARBON REFRIGERANT
Combination of HYDROGEN+FLUORINE+CARBON.
Excellent thermodynamic properties
Flammable
This group consists of colorless fluids normally in gaseous state and made up of various
combinations of carbon and hydrogen

17. REFRIGERANT CHEMICAL NAMES APPLICATION
a. R-22 Monochlorodifluoromethane Commercial A.C
a. R-123 Dichlorotrifluoroethane chillers
R-124 Chlorotetrafluoroethane Medium chillers
R-401A R-22 + R-152a + R-124 Medium temp. system
R-401B R-22 + R-152a + R-124 Transport refrigerator
R-402A R-22 + R-125 + R-290 Ice machine
R-402B R-22 + R-125 + R-290 Super market
refrigeration

18. REFRIGERANT CHEMICAL NAMES APPLICATION
R-23 Trifluoromethane Low temp.
refrigeration
R-134A Tetrafluoroethane Automative
system &
commercial ref.
R-404A R-125 + R-143a + R-134a Medium & low
temp.
R-407C R-32 + R-125 + R-134a R 22 replacement
R-410A R-32 + R-125 Residential A.C
R-507 Refrig. 125/143a Commercial ref.

19. AZETOPES
Stable mixture of refrigerants
Vapor and liquid phases retain identical composition over a wide range of
temperature
Refrigerant
number
Mixing formula application
R-500 73.8% R-12 and
36.2% R-152
Non flammable.
R-502 48% R-22.and
51% R-115
R-504 48% R-32 and
51% R-115

20. R-500. it is non flammable non toxic non corrosive
It is used commercial industrial applications
20% grater refrigerant capacity than R-12
Boliling point -33
R-502, low temperature -50
Flammable non toxic
Boling point is -46
Low condencing temperature,increase the compressor life and improves lubrication
properties

21. R-504. non flammable non toxic
Boiling point is -57
It is used for low temperature application
INORGANIC REFRIGERANTS.
These are non hydrocarbon refrigerants mostly naturally available
R-717 Ammonia
R-718 water
R-729 air
R-744 Carbon dioxide
R-764 sulphur dioxide

22. WATER AS REFRIGERANT
Water as refrigerant is used in absorption system .New developing
technology has created space for it for use in compression cycles also.
But higher than normal working pressure in the system can be a factor in
restricted use of water as refrigerant
Carbon Dioxide
Non Flammable, Non toxic
Inexpensive and widely available
Its high operating pressure provides potential for system size and weight
reducing potential.
Drawbacks:
Operating pressure (high side) : 80 bars
Low efficiency

23. AMMONIA AS REFRIGERANT
Excellent thermodynamic characteristics: small molecular mass, large latent heat, large
vapour density and excellent heat transfer characteristics
High critical temperature (132C) : highly efficient cycles at high condensing temperatures
Its smell causes leaks to be detected and fixed before reaching dangerous concentration
Relatively Low price
Draw back of Ammonia as Refrigerant
Toxic
Flammable ( 16 – 28% concentration )
Not compatible with copper
Temperature on discharge side of compressor is higher compared
to other refrigerants

24. THERMODYNAMIC PROPERTIES
• Boiling point :- It should have low boiling point.
• Freezing point :- It should have low freezing point.
• Evaporative pressure :- It should be above atmospheric pressure.
• Condensing pressure :- It should have low condensing pressure.
• Latent heat of vaporization :- It should have high latent heat of
vaporization.
• Critical pressure and temperature :- It should be above the condensing
pressure and temperature.
• Thermal conductivity :- It should have high thermal conductivity.
• Co-efficient of performance :- COP has direct effect on running cost of
refrigeration cycle so higher the COP lower will be the running cost.

25. Thermodynamic Properties
Refrigerants R 12 R 22 R
134a
R
404a
R
407a
NH3 H2O CO2
B.P (⁰C) -28.8 -
40.81
-26.2 -46.4 -45 -33 100 -57
F.P (⁰C)
Latent heat
of
vaporization
(KJ/kg)
166.9
5
233.7
5
215.9 143.6
8
235.5
7
1371.
2
2.257 571.
3
Critical temp.
(⁰C)
112 96.15 100.9
5
72.07 82.2 132.4 374 30.9
8
Critical
pressure
(bar)
41.15 49.9 40.6 37.32 45.15 8.88 217.7 77.7
7
Specific heat
at const.
pressure
(KJ/mol.K)
.074 .057 1.03 1.520 .037
4
Refrigerants R 12 R 22 R
134a
R
404a
R
407a
NH3 H2O CO2
B.P (⁰C) -28.8 -40.81 -26.2 -46.4 -45 -33 100 -78.3
F.P (⁰C) -157.7 -160 -96.66 ------ ------- -77.7 0 -56.6
Latent heat
of
vaporization
(KJ/kg)
166.9
5
233.7
5
215.9 143.6
8
235.5
7
1371.2 2.25
7
571.3
Critical temp.
(⁰C)
112 96.15 100.95 72.07 82.2 132.4 374 30.98
Critical
pressure
(bar)
41.15 49.9 40.6 37.32 45.15 8.88 217.
7
77.77
Specific heat
(KJ/mol.K)
.074 .057 .08754 1.03 1.520 6.91 4.18 .0374
COP(@ 35’C) 3.677 3.701 3.586 3.603

26. CHEMICAL PROPERTIES
• Toxicity :- It should be non toxic. It should not be harmful for humans.
• Corrosiveness :- It should not be corrosive and should not have any
effect on materials used in equipments.
• Flammability :- It should be inert and should not catch fire when
subjected to high temperature.
• Miscibility with oil :- It should not react with lubrication oil.
• Chemical stability & inertness :- It should be chemically stable for
operating ranges of temperature.

27. PHYSICAL PROPERTIES
• Specific volume :- It should be low in vapour state.
• Viscosity :- It should have low viscosity.
• Leakage Detection :- It should have less tendency to leak & if it leaking
it should have a pungent smell so that the leakage can be detected
easily.