REFRIGERATION CYCLE - BASICS OF HVAC

BASICS OF HVAC
HEATING VENTILATION
AND
AIR-CONDITIONING
Prepared by,
Mohammed Abdul Mujeeb Khan
B.Tech – Mechanical Engineer
P.G.D – Business Administration

Prepared By : MOHAMMED ABDUL MUJEEB KHAN - B.TECH MECHANICAL ENGINEER
BASICS OF HVAC

BASICS OF HVAC

BASICS OF HVAC
A refrigerant is a substance or mixture, usually a fluid.
It is used in a refrigeration cycle. In most cycles it undergoes phase
transitions from a liquid to a gas and back again. Many working
fluids have been used for such purposes.
Depending on their included chemical elements.
Refrigerant Chemical Composition.
Hydrogen (H)
Carbon (C)
Chlorine (Cl)
Florien (F)

BASICS OF HVAC
Freon Refrigerants.
Depending on their included chemical elements :
Hydrogen (H),
Carbon (C),
Chlorine (Cl)
Florien (F)
They are named after as follows:
CFCs (Chlorofluorocarbons): R11, R12, R113, R114, R115
HCFCs (Hydrochlorofluorocarbons): R22, R123
HFCs (Hydrofluorocarbons): R134a, R404a, R407C, R410a

BASICS OF HVAC
The most common types of refrigerants are:
Azeotropic Refrigerants.
Zeotropic Refrigerants.

BASICS OF HVAC
Azeotropic Refrigerants.
Azeotropic mixtures are mixtures of two or more refrigerants whose
vapour and liquid phases retain identical compositions over a wide
range of temperatures.
Azeotropic refrigerants boil at constant temperatures.
Typical examples of azeotropic mixtures can be seen below:
R-502 : 8.8% R22 and 51.2% R115
R-503 : 40.1% R23 and 59.9% R13

BASICS OF HVAC
Zeotropic Refrigerants.
Zeotropic mixture is one whose composition in liquid phase differs to
that in vapour phase.
Zeotropic refrigerants do not boil at constant temperatures.
Typical examples of Zeotropic mixtures can be seen below:
R404a : R125/143a/134a (44%,52%,4%)
R407c : R32/125/134a (23%, 25%,
R410a : R32/125 (50%, 50%)

BASICS OF HVAC
CFC, HCFC & HFC...?
Refrigerants are generally classified into one of the above three
substances.
Brief explanation of each, to help you understand the differences...

BASICS OF HVAC
CFC – Refrigerants
These are substances containing CARBON, FLORINE and CHLORINE
chemicals. The CFC refrigerant is now totally banned from use or
production within all countries.
The CFC refrigerants such as the once popular R12 has the highest
ozone depleting. It is unlikely that many systems exist in operation with
this refrigerant...

BASICS OF HVAC
HCFC – Refrigerants
These are substances containing HYDROGEN, CARBON, FLORINE and
CHLORINE chemicals.
The HCFC refrigerants such as the popular R22 has a potential to
damage ozone (rating 0.05) and is also a green house gas. There are
still many systems utilizing these refrigerants...

BASICS OF HVAC
HFC – Refrigerants
These are substances containing HYDROGEN, FLORINE and CARBON
chemicals. The HFC gases are used extensively in every day systems.
There is no current ban upon these gases but responsible use and
equipment inspections is mandatory.
•The HFC refrigerants have no ozone depletion potential, including
R410A and R134.
With no chlorine in the mix, this is safer for the environment and is
now being used in place of R22.

BASICS OF HVAC
Ozone Depletion
Ozone depletion is the decay of the protecting ozone layer that filters
out harmful UV light.
An ozone depleting substance can remain in the stratosphere for long
periods, causing holes in the layer and allowing harmful UV rays to
reach the earths surface.

CondenserEquipment's:
1
2
3
4
Compressor
Expansion
valve
Evaporator
BASICS OF HVAC

BASICS OF HVAC
Two different pressures exist in the refrigeration cycle.
The evaporator
or low pressure,
in the "low side.
The condenser, or high pressure,
in the "high side".

BASICS OF HVAC
• Refrigeration is the removal of heat from a material or space, so that it’s temperature
is lower than that of it’s surroundings.
• This cycle is based on the physical principle, that a liquid extracts heat from the
surrounding area as it expands (boils) into a gas.
• To accomplish this, the refrigerant is pumped through a closed looped pipe system.
• The closed looped pipe system stops the refrigerant from becoming contaminated and
controls its stream. The refrigerant will be both a vapor and a liquid in the loop.

BASICS OF HVAC
• Two different pressures exist in the refrigeration cycle. The evaporator or low
pressure, in the "low side" and the condenser, or high pressure, in the "high side".

BASICS OF HVAC
• Low Boiling Point
• Low Freezing Point
• High Latent Heat
• Chemically Inert & stable
• Non Flammable
• Non toxic
• Should not react with lubrication oil of comp
• Should not be corrosive

BASICS OF HVAC
Defined: Any substance capable of absorbing heat from another
required substance can be used as refrigerant i.e. ice ,water, brine, air
etc.
Primary Refrigerants
Refrigerants:
Secondary Refrigerants

BASICS OF HVAC
They take part directly in refrigeration system.
Example: Freon Ammonia.
First they are cooled by primary refrigerants and then they are circulated to cool the system.
Example: Chilled Water.

BASICS OF HVAC
End of Part 2.1

REFRIGERATION CYCLE - BASICS OF HVAC

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