Ammonia refrigeration plant

Introduction- The basic purpose of a
refrigeration plant is to produce cooling
effect. Refrigeration systems use basic
physics to move heat energy out of one
area into another, leaving the first area
cooler than it was before. The
refrigerator in your kitchen does the
same work, it prevents your milk from
going bad. Massive Industrial facilities
like dairy processing plants and food
processing plants rely on large-scale
refrigeration systems for their day-to-day
operations.

Insulated pipe
Compressed vapour
Water coming from tank
Liquid refrigerant
Uninsulated pipe
Indications
1) Compressor 5)Receiver
2)LPHP Cut-Off 6)Condenser
3) Temperature control 7)Evaporator
4) Expantion valve
Water going to tank
Fig-1.2 “Layout of Ammonia Refrigerant plant”
1
4
5
7
3
2
6

Type of refrigerant used:- Refrigerant used
in this plant is Ammonia (NH3) and it is a
natural refrigerant. It is a colourless gas
with a characteristic pungent smell and it is
also known as R-717. It has been used in
industrial applications since the 1930s and
is generally acknowledged as being the
most efficient refrigerant. It has a low
boiling point and is favoured because it is a
highly energy efficient refrigerant which
also has minimal environmental impact,
having zero ODP (Ozone Depletion
Potential) and zero GWP (Global Warming
Potential). It is lighter than air and NH3
boils at −33.34 °C (−28.012 °F) at a pressure
of one atmosphere.

COMPRESSO
R
CONDENSO
R
EXP. VALVE EVAPORATO
R
COMPRESSION
EXPANSION
CONDENSATIO
N
EVAPORATION
PROCESSES INVOLVED IN
REFRIGERATION CYCLE

COMPRESSO
R
CONDENSO
R
R
COMPRESSION
REFRIGERATION CYCLE
CONDENSATION
EXPANSION EVAPORATION

COMPRESSO
R
CONDENSO
R
R
COMPRESSION
REFRIGERATION CYCLE
CONDENSATIO
N
EXPANSION EVAPORATION

COMPRESSOR
A
A compressor is a mechanical device
used to raise pressure [Fig-1.3] There
are 4 compressors in this refrigerant
plant – 2 of them are used for Ice Bank
tank and 2 of them are used for Cold
water tank. All of them are
reciprocating type compressor.
Flywheel of compressor is connected
with motor with the help of 4 V-belts.
Motor used is of 50 hp and is started
with the help of Star Delta starter.
Motor transfers power to flywheel with
the help of belts and then flywheel
rotates the crank shaft and then
connecting rod transfer rotatory
motion from crank shaft into
reciprocating motion to piston. Motor
specifications in Table -1.2.
B
of Motor
37
LCW200L
68
8PDP
1450
301
2800705-10
63A3
Table-1.2
C
is 12 TR and one of
The low-pressure
m evaporator drawn
valve. The refrigerant
e and then delivered
lve. The temp of
ng compression
g at very high RPM
to friction, which
de compressor.
ket inside compressor
being flow to keep the
lubricating oil below
ween piston and body.
essor which
g oil so that no
th it. For more
r to Table-1.1 and of
D
4
3

CONDENSER
Main function of condenser is to condense the vaporize ammonia
refrigerant that is coming from the compressor discharge valve by
loss of heat to the surrounding. Condenser has no. of tubes
through which ammonia refrigerant is flowing as in Fig-1.4. Due to
multiple tube surface area is increased followed by increase in
heat transfer rate. There is water circulating system by which
there is raining of water of the condenser tubes to condense the
refrigerant. There is a sink of water below this condenser, water
that is raining over tubes of condenser fall in sink by taking away
refrigerant latent heat converting the refrigerant into liquid,
duration of falling down the water get cold by flowing air and from
the sink this water gets circulated continuously with help of
centrifugal pump. We generally use water having potassium
permanganate (KMnO4) in it to prevent growth of fungus, bacteria
etc [Only if we use stored water for a while]. If we are using fresh
water we need not to mix potassium permanganate in water.
Fig- 1.4 Condenser

• Used for holding extra amount of ammonia refrigerant.
• Used where evaporator volume is large compared to condenser
volume.
• Placed between condenser and filter .
• Filled partly with vapour and partly with liquid ammonia during
working.
• A plastic pipe of normal water having number holes installed over
it.
All specifications in Table-1.3
Specifications of pressure
vessel (ammonia receiver)
Thickness of walls 6 mm
Max. permissible working
pressure
150 Psi
Design pressure 275 Psi
Length 5.689 m
Installation date 2002
Table – 1.3
Cold water line
Ammonia outlet pipe
Ammonia inlet pipe
Water
Water circulating
pipe
Ammonia Receiver

EXPANSION VALVE
 Produce cooling effect by throttling mechanism.
 Control flow of refrigerant by use of filler bulb
filled with similar gas as in system.
 The valve open against spring pressure in the
valve body .
 As load increase filler bulb sense increase in
temperature and gas will expand cause the
expansion valve to open.
 Installed near evaporator.
 Require special design considerations due to the
erosive effects of ammonia vapours.
Fig-1.6 Expansion Valve

EVAPORATOR
Main cooling part of ammonia refrigeration system.
A. Ammonia enter in evaporator coil in liquid form
after expansion from expansion valve.
B. Ammonia refrigerant is flowing through
evaporator coil which take latent heat from
products kept inside and convert into vapours.
C. Evaporator coil made up of copper mainly.
D. Ammonia refrigerant is in vapour form upon
leaving evaporator coil.

OIL SEPARATOR
 Oil separator function is to separate the oil from
ammonia refrigerant gas.
 Oil separator is mounted in the high-pressure pipe
between the compressor and condenser.
 Oil that is used in compressor for lubricating
purpose in piston or in other parts, small amount
of oil is mixed with refrigerant gas and come out
from discharge valve during discharging. To
separate this oil use of oil separator is necessary. Fig-1.8 Oil Separator

FILTER DRIER
1. Filter-drier in a refrigeration or air conditioning system has
two essential functions:
a) To adsorb system contaminants, such as water, which can
create acids
b) To provide physical filtration. The ability to remove water
from a refrigeration system is the most important function of
a drier. Water can come from many sources such as leakage
in pipes, trapped air, to name a few.
2. The three most common type of desiccants used are
molecular sieve, activated alumina and silica gel.

LOG BOOK OF AMMONIA REFRIGERANT PLANT AT
EXPERIMENTAL DAIRY-
There is a log book which has to be maintained by
operators working in ammonia refrigerant plant. They
have to fill in the desired information in log book
which is used to keep record of the information. [As in
Table-1.4] From seeing log book one can see that
there are many columns having relevant information
like temperature of water, suction pressure of
refrigerant, discharge pressure of refrigerant, which
pumps are working etc. There is also a column of
comment in which the operator can write something if
there is something unusual in working of refrigeration
plant like if there is shut down of plant due to leakage,
shut down of plant due to maintenance etc.

Table-1.4 Log table of
ammonia refrigerant plant

Dairy processing handbook
By Tetrapak
Refrigeration and air conditioning
By C.P. Arora
Refrigeration and air conditioning
By Eurasia Publishing house
www.wikipedia.org
Class Lectures
REFERENCE

Ammonia refrigeration plant

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