Refrigeration & hvac system

1. Refrigeration & HVAC
System
akila prasad 1

2. WHAT HAPPENED WHEN PUT ICE INTO THE
GLASS?
akila prasad 2

3. THERE ARE
SOME SMALL
WATER BUBBLES
OUT SIDE OF THE
GLASS….!
akila prasad 3

4. WHAT IS
HAPPENED?
• The water vaper was solidification from the
environment and gather in outside the beaker.
So;
We can cooled the separated environment and,
the water vaper also get out from the separated
environment.
When the air touch the out side of beaker and in
cause of it the dust in the air also gather on the
out side beaker wall.
Therefor the three conditions are prove before
we discuss in the air condition system.
akila prasad 4

5. Where 4th condition?
If the air is circulate using the blower fan, the cold air will produce.
The all points are cover and the air condition process is happening. Modern air condition
systems are develop by this method. akila prasad 5

6. Refrigeration
cycle
akila prasad 6

7. Each cycle of operation consists of the four
fundamental changes of state or processes;
Compression
Condensation
Expansion
Evaporation
akila prasad 7

8. Compression :
• The low pressure vapour refrigerant in
dry state is drawn from the evaporator
during the suction stroke of the
compressor. During compression stroke
pressure and temperature of the
refrigerant increases.
akila prasad 8

9. Condensation
• The high pressure and high temperature
vapor refrigerant enters in to the
condenser through the discharge line .
Heat will be rejected in to the cooling
medium and the refrigerant change its
state from vapor to liquid
akila prasad 9

10. Expansion
• After condenser, the liquid refrigerant
is stored in the liquid receiver until it
passes through expansion valve. The
function of the expansion is to allow the
liquid refrigerant under controlled
pressure in to the low pressure path of
the system.
akila prasad 10

11. Evaporation
The low pressure liquid refrigerant after
expansion in the expansion device enters the
Evaporator or Refrigerated space and absorbs
its heat. Due to this heat, the refrigerant
changes its state from liquid to vapors and then
sucked back by the compressor during its
suction stroke .
The cycle is repeated till the required
temperature gets inside the refrigerator.
akila prasad 11

12. Reversed
Carnot Cycle
• Reversing the Carnot cycle does reverse
the directions of
heat and work interactions.
• A refrigerator or heat pump that
operates on the reversed Carnot cycle is
called a Carnot refrigerator or a
Carnot heat pump.
• The reversed Carnot cycle is the most
efficient refrigeration cycle operating
between two specified
temperature levels.
• It sets the highest theoretical COP.
akila prasad 12

13. Schematic of a Carnot Refrigerator
• (1-2) refrigerant absorbs heat isothermally from a low
temperature
source at TL in the amount of QL.
• (2-3) refrigerant compressed to
state 3 (temperature rises to TH)
• (3-4) refrigerant reject heat to high
temperature at TH in the amount QH.
Refrigerant changes from saturated
vapor state to a saturated liquid state in
the condenser .
• (4-1) refrigerant expands adiabatically
to state 1(temperature drops to TL)
akila prasad 13

14. Schematic of
a Carnot
Refrigerator
and T-S
diagram of
Reversed
Carnot Cycle
akila prasad 14

15. Consists of 4
processes
of Reversed
Carnot
Cycle
Adiabatic Compression
Isothermal Compression
Adiabatic Expansion
Isothermal Expansion
akila prasad 15

16. Reversed Carnot Cycle
(1-2) Adiabatic compression of
the working fluid with the aid of T1
external work.The temperature
of the fluid rises fromT2 toT1.
Q1
Isothermal
Comp
(2-3) Isothermal compression of
the working fluid during which
heat is rejected at constant high
temperatureT1.
(3-4) Adiabatic expansion of the
working fluid.The temperature of
the working fluid falls fromT2 to
T1.
Adiabatic
Exp
Q2
T2
Adiabatic
Comp
Isothermal
Exp
(4-1) Isothermal expansion of air
Q1
where heat is absorbed at low
temperatureT2 from the space
being cooled.
Q2
akila prasad 16

17. Carnot cycle.
The results is a cycle that
operates in the
counterclockwise
direction no T-S diagram,
which is called the
reversed Carnot cycle.
akila prasad 17

18. COP of Refrigerator
Heat absorbed Q2 =T2ds
Heat rejected Q1 =T1ds
Work input = Heat Rejected - Heat Absorbed
= Q1- Q2 =T1ds - T2ds =(T1-T2)ds
COPR = cooling effect = QL = Q2 = T2ds
work input Wnet.in Q1- Q2 (T1-T2)ds
akila prasad 18

19. Point to
remember…!
• Practically, the reversed Carnot cycle cannot
be used for refrigeration purpose as the
adiabatic process requires very high speed
operation, whereas the isothermal process
requires very low speed operation.
akila prasad 19

20. WHAT IS AIR
CONDITIONING?
• Air is cooled or Heated.
• Cleaned or filtered.
• Circulated or recirculated.
• Control the quality & quantity.
THIS MEANS BY AIR CONDITIONING SYSTEM
TEMPERATURE,HUMIDITY & VOLUME OF AIR
CAN CONTROOLLED AT ANY TIME IN ANY
SITUATION
akila prasad 20

21. HISTORY
• The first electrical air conditioning was invented by Willis
Haviland carrier in the year 1902 he was also known as the
‘father of mode
Rn air conditioning’.
• The carrier air conditioning company of America was
established by him .Today carrier corporation is the biggest
air conditioner manufacturer and marketing corporation in
the world.
akila prasad 21

22. HOW AN AIR
CONDITIONER
WORKS
• Air conditioning includes the cooling and heating of
air ,cleaning and controlling its moisture level as well
as conditioning it to provide maximum indoor
comfort.
• An air conditioner transfer heat from the inside of a
building to the outside.
• Refrigerant in the system absorbs the excess heat
and is then pumped through a closed system of
piping to an outside coil.
• A fan blows outside air over the hot coil ,
transferring heat from the refrigerant to the outdoor
air.
• Because the heat is removed from the indoor air
,the indoor area is cooled.
akila prasad 22

23. AIR
CONDITIONING
SYSTEM
COMPONENTS
1. Compressor.
2. Condenser coil.
3. Evaporators.
4. Blowing unit.
5. Thermostat.
akila prasad 23

24. 1.Compressor.
*It is recognized as the engine of the air conditioning
system. The compressor function together with a
substance called working fluid that can easily
transform from gas into a liquid. The main task of the
compressor is to convert low pressure gas into a high
pressure gas .
TYPES OF COMPRESSOR
I. Open type compressor.
II. Semi-hermetically sealed.
III. Hermetically type compressor.
akila prasad 24

25. 2.Condensor coil.
• There is a fan fitted into the condenser coil
which cools down the high pressure gas and
converts it back into a liquid this part can be
see the outside of house.
akila prasad 25

26. 3.evaporator.
• Evaporator was located inside the house the
evaporator is usually found near the
furnace . the high pressure gas which is now
transformed into the low pressure liquid
reaches this section of the air conditioning
system.
akila prasad 26

27. 4.BLOWING UNIT.
• These are the two parts of the system
which work together to draw room air to
the evapovator and disseminate cool air all
over house.
akila prasad 27

28. 5.thermostat.
• This component helps maintain the
temperature in air conditioning system by
regulating the heat energy flowing inside
and outside of it.
akila prasad 28

29. TYPE OF AIR –
CONDITIONING
SYSTEM
1. Window air- conditioning
system
2. Split air-conditioning system
3. Central air-conditioning
system
4. Package air-conditioning
system
akila prasad 29

30. WINDOW AIR-
CONDITIONING SYSTEM
• Window air conditioners are
one of the most commonly
used and cheapest type of
air conditioners.
• Window air conditioners
units are reliable and simple
to install solution to keep a
room cool while avoiding the
costly construction of central
air system.
akila prasad 30

31. SPLIT AIR-CONDITIONING
SYSTEM
• The split air conditioner
comprises of two parts,
indoor unit and outdoor
unit.
• The outdoor unit fitted
outside the room.
akila prasad 31

32. CENTRAL AIR-
CONDITIONING SYSTEM
• The central air conditioning
plants or the systems are
used when large buildings ,
hotels , theaters , airports ,
shopping malls and etc.
• The window and split air
conditioner are used for
small rooms or small office
spaces . these small units
cannot satisfactorily cool the
large halls , auditoriums ,
reception areas and etc.
akila prasad 32

33. PACKAGED AIR
CONDITIONING SYSTEM
• The window and split air
conditioners are usually used
for the small air conditioning
capacities up to 5 tons.
• The packaged air
conditioners are used for the
cooling capacities in
between these two extreme.
akila prasad 33

34. APPLICATIONS
HOMES
RESTURANTS
INDUSTRY
OFFICE
COLLEGES OR UNIVERSITY
TELEPHONE EXCHANGE
AUDITORIUMS
RECEPTIONS AREAS
akila prasad 34

35. ADVANTAGES
OF AIR
CONDITION
SIMPLE CONTROL
EASY MAINTENANCE
EASY INSTALLATION
GIVES CONSTANT TEMPERATURE
INCRESED COMFORT LEVEL
MOST AIR CONDITIONERS ALSO REDUCE HUMIDITY LEVEL,WHICH
HELPS BOTH COMFORT AND REDUCES MOLD GROWTH
akila prasad 35

36. DISADVANTAGES
OF AIR
CONDITION
HIGH COST MONEY
EFFECTS THE ENVIROMENT BY
REALEASING THE CFC
CONTRIBUTION TO POLLUTION
FROM POWER PLANTS
akila prasad 36

37. HEATING VENTILATION
AND AIR-CONDITIONING
akila prasad 37

38. HEATING VENTILATION AIR CONDITIONING
akila prasad 38

39. HVAC brief
description
HVAC stands for Heating,
Ventilation, and Air
Conditioning.
HVAC systems control the indoor
environment(temperature,
humidity, air flow, and air filtering)
Mechanical intervention to
condition the air to a
preferred temperature and relative
humidity.
akila prasad 39

40. Human
Comfort
• Conditions at which most people are
likely to feel comfortable most of the
time.
• Also called as Thermal Comfort.
• Temperature:
Summer - 78⁰F (25⁰C)
Winter - 68⁰F (20⁰C)
• Relative Humidity: 30 %- 60%.
akila prasad 40

41. By Using HVAC
System :
Temperature can be Raised or Lowered.
Humidity can be Raised or Lowered.
Maintain Proper Filtration of Air.
Proper Air Movement.
Outside Air can be Added and Removed.
To hold the air contamination within acceptable limits.
akila prasad 41

42. Application of HVAC
System :
• Residential
• Commercial
• Industrial
• Educational
• Pharmaceuticals
• Hospitals
• Malls/Offices
• And many more….
akila prasad 42

43. Heat Transfer :
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44. Conduction, Convection & Radiation
• Conduction : Is transfer of heat
through solid matters.
• Convection : Is transfer of heat
through liquid.
• Radiation : Is transfer of heat
through gas/air.
akila prasad 44

45. • Degree Centigrade - °C
Metric : Standard International (SI Unit)
• Degree Fahrenheit - °F
English : Inch Per Pound (IP Unit)
Degree Temperature
akila prasad 45

46. Roof
Partition
Infiltration
Glass solar
Exterior Wall
Lights
People
Equipment
Floor
Wall
akila prasad 46

47. Factors Affecting
human comfort
• Dry-bulb temperature
• Humidity
• Air movement
• Fresh air
• Clean air
• Noise level
• Adequate lighting
• Proper furniture and
work
surfaces
akila prasad 47

48. Unit of
Refrigeration :
• TR: 1 TR is amount of heat to be extracted
from the atmosphere for Melting one metric
ton of ice in 24 Hrs.
• 1TR: 12000 BTU/HR
• 1TR: 3000 KCAL/HR
=50 KCAL/MIN
akila prasad 48

49. System selection
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50. Steps of
Selecting the
System :
Calculation of cooling load requirement.
Selection of techno-economical system.
Equipment selection.
Designing Air distribution system.
Designing Water distribution system.
Designing Refrigerant distribution system.
Evaluation of system to be used.
akila prasad 50

51. Factors to considering
during Cooling load
requirement
• Building detailed layout.
• Use of Space.
• Physical dimension of space.
• Inside room design condition.
• Filtration level required.
• Ambient condition.
• Glass area exposed to sun.
• Occupancy.
• Lighting load.
• Equipment load.
• Fresh air requirement.
• Infiltration of outside air
akila prasad 51

52. Factors
affecting
System
Selection :
Budget of Client.
Need/Requirement of client.
Use of Space.
Outside condition.
Floor layout.
Location and dimension of beam/Column.
Power availability.
Space availability.
And many more…
akila prasad 52

53. akila prasad 53

54. What is Psychometric Chart...??
• A psychrometric chart is a graphical representation of
the processes of air. Psychrometric processes
include physical and thermodynamic properties if Air.
• Provides a graphical representation of air and its
properties.
• Knowing any two conditions of air allows the other
conditions of the air to be found
akila prasad 54

55. Properties of Air -
Psychometric
• Dry bulb temp.
• Wet bulb temp.
• Humidity.
• Dew point.
• Moisture content.
• Heating.
• Cooling.
• Humidity.
• De-Humidify.
akila prasad 55

56. Types of Air Conditioning System
DX-SYSTEM - Direct Expansion
• A direct expansion air conditioning (DX) system uses a refrigerant
vapour expansion/compression (RVEC) cycle to
directly cool the supply air to an occupied space.
• DX systems (both packaged and split) directly cools the air
supplied to the building because the evaporator is in
direct contact with the supply air.
akila prasad 56

57. Dx-System -
Direct
Expansion
akila prasad 57

58. CHILLED
WATER SYSTEM
• Chilled water air conditioning systems are commonly
used in applications that need large cooling capacity
such as hypermarket, industrial process and commercial
air conditioning such as offices and factories
• This system makes use of water as its secondary
refrigerant. Chiller is used to remove heat from the
water which is then circulated through other
components to absorb heat from the space.
akila prasad 58

59. CHILLED WATER SYSTEM
akila prasad 59

60. Refrigerant
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61. What is a
Refrigerant?
"Refrigerant is the fluid used for heat transfer in a
refrigerating system that absorbs heat during
evaporation from the region of low temperature
and pressure, and releases heat during
condensation at a region of higher temperature
and pressure.”
akila prasad 61

62. Classification of Refrigerants
• Primary refrigerants
• Secondary refrigerants
Primary refrigerants
• These are the refrigerants which cool the substance or space
directly by absorbing latent heat .
• It absorbs heat during evaporation in the evaporator and
releases heat energy during condensation in condenser It is
also known as direct expansion system.
• Ammonia, Freon, SO2, Co2 etc.
• These fluids provide refrigeration by undergoing a phase
change process in the evaporator.
akila prasad 62

63. Secondary
Refrigerants
In refrigeration plant a secondary coolant
is used as cooling medium which absorb
heat from refrigerated space and transfer
to primary refrigerant in evaporator.
Secondary refrigerants are also known
under the name brines or antifreezes.
akila prasad 63

64. Classification
Of Primary
Refrigerant
Halo-
carbon
Refrigerant.
Azeotrope
Refrigerant
.
Inorganic
Refrigerant.
Hydro-
carbon
Refrigerant.
akila prasad 64

65. Halocarbon Refrigerants
Halocarbon Refrigerant are
all synthetically produced
and were developed as the
Freon family of refrigerants.
They are fluorocarbons of
methane and ethane series.
They contain I or more of
these halogens. (chlorine,
bromine, fluorine)
Non toxic, non-flammable,
non-explosive, non-
corrosive, non-irritant to
human body and cyes.
Odourless, colourless.
Will not react with food
product stored in the
refrigerated space Will not
react with lubricating oil.
Has excellent
thermodynamic properties.
Only disadvantage is ozone
layer is damaged
akila prasad 65

66. Examples ÷
✓ CFC's - RI1, R12, RI13, RI14, R115
✓ HCFC's- R22, R123
✓ HFC's - R134a, R404a, R407C, R410a P
akila prasad 66

67. FREON 12 (Dichloro-difluro methane-cel2F2)
o Mostly used in domestic and commercial refrigerants (in ice cream cabinets, display
cabinets, deep freezer)
o It is very widely used, colourless gas with mild odour
o Heavier than air
o Does not dissolve in water, moisture content should not exceed 0.0025% by weigh
o Refrigerating effect per unit volume of ammonia is about 1.5 times that of Freon-12
o It does not react with ferrous metals, aluminium phosphor bronze
o It attacks copper, copper alloys, zinc and bronze and dissolves in water It does not react
with lubricating oils in the absence of moisture, but Oxidizes them in the presence of
water vapour
akila prasad 67

68. Inorganic Refrigerants
▪ Inorganic refrigerant were exclusively used before the introduction of halocarbon. These
refrigerant are still in use due to there inherent thermodynamic and physical properties.
• Carbon dioxide
• Water
• Ammonia
• Air
• Sulphur dioxide
akila prasad 68

69. Azeotrope Refrigerants
• This type of refrigerants consist of mixture of different refrigerants which can
not separated under pressure and temperature and have fixed thermodynamic
properties.
• A stable mixture of two or several refrigerants whose vapour and liquid phases
retain identical compositions over a wide range of temperatures.
• Azetropic mixtures are designated by 500 series.
Examples ÷
✓ R-500 : (73.8% R and 26.2% R152)
✓ R-502 : (8.8% R and 51.2% R 115)
✓ R-503 : (40.1%R and 59.9% R13)
akila prasad 69

70. Zeotropic Refrigerant
• A zeotropic mixture is one whose composition in liquid phase differs to that in
vapour phase. Zeotropic refrigerants therefore do not boil at constant
temperatures unlike azeotropic refrigerants.
• Zeotropic refrigerants are designated by 400 series.
Examples ÷
✓ R-404a: R125/R143a/R134a ( 44% ,52% ,4% )
✓ R-407c: R32/125/R134a ( 23% ,25% ,52% )
✓ R-410a: R32/125 ( 50% ,50% )
akila prasad 70

71. Hydrocarbons
• Most of the hydrocarbons refrigerant are
successfully used in industrial and commercial
installation. They possess satisfactory
thermodynamic properties but are highly
flammable and explosive.
• Growing using very small commercial systems
like car air-conditioning system.
Examples ÷
✓ R170 , Ethane , C2H6
✓ R290 , Propane , C3H3
✓ R600 , Butane , C4H10
✓ R600a , Isobutane , C4H10
akila prasad 71

72. Secondary
Refrigerant
▪ The refrigerants are brine which is used as
intermediate fluid between evaporator and the
substance or space to be cooled.
▪ They cool the substance by absorbing their
sensible heat. Also called indirect expansion
system.
akila prasad 72

73. Designation of
Refrigerants
▪ Since a large number of refrigerants have been
developed over the years for a wide variety of
applications, a numbering system has been
adopted to designate variety of refrigerants.
From the number one can get some useful
information about the type of refrigerant, its
chemical composition, molecular weight etc.
akila prasad 73

74. Physical
characteristics
of
Refrigerants
o Boiling and condensing temperature and
pressures.
o Freezing temperature.
o Critical temperature.
o Discharge temperature.
o Latent heat of vaporisation.
o Specific heat.
o Density.
o Viscosity.
akila prasad 74

75. Thermodynamic
Properties Of
Refrigerant
▪ Boiling and condensing temperature and pressures.
The boiling temperature of refrigerant at atmospheric
pressure should be low.
• The evaporator and condensing temperatures
determine the pressures.
• The maximum condensing temperature is largely
affected by climatic condition.
• It is desirable to select a refrigerant whose saturation
pressure is a few pounds above atmospheric pressure.
• If the boiling temperature of the refrigerant is high at
atmospheric pressure then compressor has to operate
at high vacuums.
• Both evaporator and condenser pressure should be
positive and it should be near to atmospheric pressure.
akila prasad 75

76. ▪ Freezing temperature.
• Should have low freezing temperature. Since the
freezing temperature of most of refrigerant is below
-35 °C.
▪ Critical temperature.
• Should be well above the maximum condensing
temperature.
▪ Discharge temperature.
• High discharge temperatures from the compressor
should be avoided.
• It causes some refrigerant breakdowns as well as
poor lubrication effectiveness.
akila prasad 76

77. ▪ Evaporator and condenser pressure.
▪ Latent heat of vaporization.
• Heat which converts the refrigerant from the liquid state to vapour.
• It should have a higher value.
▪ Density.
• Low vapour density refrigerants are preferred.
▪ Viscosity.
• Low viscosity of the liquid refrigerant is desired to reduce the pressure drop in the lines.
akila prasad 77

78. Chemical
properties of
refrigerants
▪ Toxicity.
• Rated based on its effect on human beings over
specified periods.
• Should be non toxic and non irritation.
▪ Flammability and explosion Hazard.
• Should be non-flammable and non-explosive.
▪ Refrigerant Odours.
• Can be both an asset and a hazard.
• Makes it easy to detect the leaks but at the same
time may contaminate foodstuffs in storage.
akila prasad 78

79. Should be non - flammable.
Should be non - explosive.
Should be non - toxic.
Should not react with lubricating oil.
Should not react with moisture.
Should not contaminate the food materials kept inside the refrigerating system.
akila prasad 79

80. Environmental
and safety
properties
▪ At present the environment friendliness of the
refrigerant is a major factor in deciding the
usefulness of a particular refrigerant. The
environmental and safety properties are:
• Ozone Depletion Potential
• Global Warming Potential
• Total Equivalent Warming Index
• Toxicity
• Flammability
• Chemical stability
• Compatibility
• Miscibility with lubricating oils
akila prasad 80

81. THANK YOU
akila prasad 81

82. Group member
• Ff
• Kk
• Ll
• M
• K
• h
akila prasad 82