APPLICATION OF REFRIGERATION AND AIR CONDITIONING

1. Application of Refrigeration
and Air Conditioning
Prof.P.W.INGLE
Sanjivani College of Engineering Kopargaon

2. Domestic Refrigerator
• Domestic Refrigerator
• Domestic Air Conditioners
• Automotive Air Conditioners
• water coolers
• Commercial Refrigeration-Ice plant
• Commercial Refrigeration- Dairy , cold storage
• Commercial Air Conditioning-Multiplex,
• Hospitals.

3. Domestic Refrigerator

5. Domestic refrigerator is used for preserving food and other
essential items and also for formation of ice
They are usually specified by internal gross volume and deep
freezer volume. Refrigerators are becoming the common item
for household use, vendors shop, hotels, motels, offices,
laboratories, hospitals, chemist and druggist shops, studios
etc. the freezer space is meant to preserve perishable products
at a temperature below 0 degree Celsius such as fish, meat
chicken etc and to produce ice and ice-cream as well. The
refrigerators in India are available in different sizes i.e
90,100,140,200,250, 380 liters of gross volume.

6. The freezers are usually provided at the top portion of the
refrigerator space occupying around one-tenth to one third of
the refrigerant volume.
Working: The low temperature low pressure refrigerant vapor
is drawn through the suction line to the compressor.
The accumulator provided between the suction line and the
evaporator collects liquid refrigerant coming out of evaporator
due to incomplete evaporation, if any prevent it entering the
compressor.
The compressor then compresses the refrigerant vapor to a
high pressure and high temperature. The compressed vapor
flows through the discharge line into the condenser. In the
condenser the vapor refrigerant at high pressure and high
temperature is condensed to liquid refrigerant at high pressure
and low temperature.

7. The high pressure liquid refrigerant then flows through the filter
(Filter driers are devices used in a HVAC system that are a combination
of filter and dryer (or drier). A filter is used to remove any particle such as
dirt, metal or chips from entering the refrigerant flow control. The
refrigerant flow control device could be thermostatic expansion valve or
simply a capillary tube. These suction line filter-driers include protection
from moisture and organic or inorganic acids, resulting from burnouts, or
chemical changes in the system refrigerant or oil. They're especially suited
for system cleanup after a burnout, or when major work has been performed
on the system
After filter refrigerant is then flows to the capillary tube attached to the
suction line. The warm refrigerant passing through the capillary tube give
some of its heat to cold suction line vapor. This increases the heat absorbing
quality of the liquid refrigerant and superheat of vapor entering in the
compressor

8. The capillary tube expands the liquid refrigerant at
high pressure to the liquid refrigerant at low pressure
so that liquid refrigerant is passed into the evaporator.
In the evaporator the liquid refrigerant gets
evaporated by absorbing heat from container or food
items or other things placed In the refrigerator and is
sucked back into the compressor and cycle is repeated.
Thermostat switch maintains a requisite temperature in
the refrigerator and freezer between -7 0C to -50C and
in remaining part temperature remains between 7 0C to
150C

9. Defrosting in refrigerators:- Since evaporator operates at the
temperature below freezing point of water it is subjected to
accumulation of frost or ice acts as an insulation to the heat
transfer to the evaporator, which lead to further thickening
ultimately lead to the reduction in evaporator capacity and
system efficiency.
Thus the removal of frost or defrosting of refrigerator is
essential at regular interval, done by manually putting off the
refrigerator, and restarting only after complete defrosting of
evaporator.
While most refrigerators, freezers, and refrigerator-freezers on the
market today have automatic defrost controls, some
models are available with manual defrost. Automatic defrost
refrigerators work by heating the interior refrigerator coils at regular
intervals.

10. Domestic Air Conditioners

11. The window air conditioner works on the vapor compression
refrigeration cycle. The basic components of the system are
compressor, condenser, a capillary tube and an evaporator, in addition,
filters, accumulators, motors, fan and electrical controls from the rest
of components.
• The high pressure gas (refrigerant), which comes out of the
compressor, is condensed in the condenser using ambient air as a
coolant.
• The liquid refrigerant is expanded in a capillary tube and then enters
the evaporator. Here, it evaporates and causes the refrigerating effect.
• Then fan blows the fresh air over the evaporator coil, which cools the
air. The cool air is supplied the room. Meanwhile, refrigerant from
the evaporator enters the compressor to be compressed and the cycle is
repeated itself.

12. Automotive Air Conditioners

13. Air conditioning facilitates the removal of heat from
inside the vehicle. The principle applied is that heat
is removed by conduction and convection. An
evaporator which is cold absorbs the heat from the
air that is passed through it and then cold air is
forced out through the vents inside the car by the
blower motor. This is done by pressurizing
refrigerant (134a) with a compressor and then
releasing refrigerant (134a) inside the air conditioner
evaporator

14. Water Cooler
Water cooler are of two types Instantaneous type and storage type
Instantaneous type water cooler have again classified as bottle type,
pressure type and self contained or remote type cooler
In case of instantaneous type cooler consist of two separate cylindrically
wound coils made of copper or stainless tube. The evaporating
refrigerant is in one of the coil and water to be cooled is in the other coil.
1. Bottle type cooler:- In this type of water to be cooled is stored in thein
the bottle or reservoir. The dripping water from the faucet is collected in
the waste water basin or water drip. Its usual size is 25 litres and is
suitable for places where plumbing installation is expensive and drains
are available

15. Bottle type water cooler

16. Pressure Type Cooler
Here water is supplied under pressure. For filling glass
tumblers or container faucets or similar means are
provided. A valve is employed to control an
appropriate flow of water or projected stream of water
from a bubbler. The city main water enters the cooler
through the inlet connection at the rear of cooler. It
then passes through a precooler. The precooler is
cooled by the waste water of the cooler. As the waste
water temperature is low, it is made use of cooling the
supply water by passing through a pipe coil wrapped
around the drainage line ( a counter flow heat
exchanger ). The amount of cooling is depends upon

17. The precooled water then enters the storage chamber and loses its heat to
the refrigerant. The outlet water pipe is connected at the bottom of the
storage tank, which is fitted with a self closing valve or bubbler. A
thermostat controls the temperature of the water in a pipe to a set point

18. Self contained remote type cooler
This type cooler employs a mechanical refrigeration system. The water
cooled from the remote cooler is supplied to desired drinking place ,
away from the system

19. Storage type of cooler
Such type of cooler are used where continuous
supply of water is not available. Water is filled in the
storage tank and the level of water is kept same by
use of float valve. The storage tank is surrounded by
an evaporator coil through which flows a low
pressure liquid refrigerant which takes away the heat
of water and thus make it cold. When the water
attains desired temperature the thermostat operates
and disconnects the power supply to motor.

20. Storage type of water cooler

21. Desert cooler
It is suitable for place where the humidity is quite
low and temperature is quite high. These
conditions are in conformity with desert areas.
Hence cooler are called as desert coolers. The
principle on which a desert cooler works is
evaporative cooling. Evaporative cooling is the
process in which sensible heat is removed and
moisture is added to the air. When air passes
through a spray of water it gives up heat to water,
some of the water evaporates and pick up heat
from air equivalent to its latent heat. The vapor

23. Working:- The water is filled in the sump of the cooler from
water supply main, the level of which is controlled by a float
valve. A water pump lifts the water and supplies it at the
top of cooler to the water distribution system which consist
small branches of copper pipe or so equipped with orifices
which delivers equal amount of water to the troughs which
in turns supply water to the wetted pads. The water which
drops back from the pad is recirculated. The pump may be
made up of brass, stainless steel or even plastic. The blower
pulls the air through the wetted pads and deliver it to space
to be cooled through an opening in the fourth side of the
cabinet of desert cooler the air which is sucked through the
wetted pads is cooled by evaporative cooling.

24. Ice Plant

25. The commercial ice is produced by freezing potable (drinking)
water in standard cans placed in rectangular tanks. The tanks are
filled with chilled brine. For increasing the heat transfer from the
water in the can to the chilled brine, the brine solution is kept in
constant motion by agitators. The agitators can be vertical or
horizontal by means of electric motors. The brine temperature is
maintained by the refrigeration plant at -7 to -10 degree celcius.
The ammonia gas is used as the refrigerant because of its excellent
thermal properties.
The high temperature high pressure ammonia is condensed in
condenser may be shell and tube or evaporative type. The
condensed liquid is collected in the receiver and then expanded in
expansion valve. Due to expansion pressure of liquid ammonia is
reduced.

26. It then passes through the evaporative coil surrounding a brine
tank in which brine solution is filled. The low pressure liquid
ammonia absorbs the heat from the brine solution equivalent to its
latent heat of evaporation , gets converted into vapor state and
again fed to compressor to complete the cycle. The depth of tank
is such that the brine level is around 25 mm higher than the water
level in the cans.
Cooling in tank is achieved by brine circulation. This brine
solution is usually prepared from commercial calcium chloride
having appropriate concentration. If tank is small cooling coil is
inserted in it and for large plant brine is cooled in the chiller
before being pumped by the brine pump into the ice tank. The cold
brine circulates around the cans causing ice formation.

27. Cold Storage

28. The cold storage is a building designed to store certain
goods like food stuffs, fruits, vegetables and dairy products
within well defined temperature range and relative humidity.
The cold storage is also an application of air conditioning in
a way that the air is cooled by passing it over a cooling coil
of refrigeration plant and supplied back to the room.
The temperature and humidity conditions maintained inside
a cold storage depends upon the type of product stored
inside e.g. vegetables require temp between 273k to 278k
with RH 80 to 90 %, milk require 277k to 278 k etc.
cold storages have two types 1. cold storages for products
which are to be maintained at temp of 0 degree Celsius and
above 2. below 0 degree Celsius

29. Dairy Refrigeration
Milk of buffaloes and cows procured from rural areas , milk societies animal farms is
transported by the insulated milk tank truck ,cans, to the dairy farm which performs
blending, processing and packaging of milk for distribution to customers for safe
human consumption. The raw milk should be cooled to 2.2 degree celcius as quickly
as possible in order to suppress the growth of bacteria causing milk spoilage.
The raw milk procured from various sources at about 25 to 35 degree celcius is
passed through a regenerative heat exchanger and then to homogenizer. Milk is
homogenized in order to disperse the butter fat content uniformly through the
entire volume of the milk. The homogenized milk is then allowed to pass through a
heat exchanger meant to pasteurization of milk.
Pasteurization is done as a batch and high temperature short time continuous. In
batch type milk is filled in vat almost full of raw milk holding it to a temperature of
not less than 62 degree celcius for 30 minute. The heating is done by hot water or
steam with indirect contact heat exchanger. In the continuous type milk is heated to
a temp not less than 72 degree celcius and is kept for 16 second

30. Milk from pasteurization passes through the flow
diversion valve to the regenerative heat exchanger if milk
is at a temperature much lower than 38 degree celcius,
otherwise it should go directly to cooler. The pasteurized
milk is finally passed through a milk chiller.
The milk chilling is done by using water being chilled by
an evaporator of the refrigeration system. The milk
chilling is done up to 5-10 degree is sent to the bottle
filler, polythene pack using an automatic machine which
provide metered amount of milk. Thereafter milk is
distributed using suitable transportation system

31. MILK PROCESSING

32. Air Conditioning system
Two type of air conditioning system are used in practice
depending on particular application 1. Central air conditioning 2.
Unitary system
1. The central air conditioning:- a cooling plant is located at the
central place and the chilled water is supplied to various
buildings. In general it is quite economical for large tonnage if
buildings are scattered all over in a limited distance, easy
maintenance, absence of sound and vibration, easy control, less
power consumption and centralized cooling pond. It has a main
chilling plant room and a cooling pond for the condenser water,
sometime huge air cooled condenser is used.

33. Central air conditioning system of an academic institution

34. The air is cooled over cooling coil in the main duct either
being sucked or forced through the main duct. The return air
together with make up (fresh air) enters the duct through the
air filter. The preheater is used to heat air before it is cooled.
The moisture addition if any is accomplished by a water
sprayer. Larger water droplets are separated by the
eliminator.
A preheater coil is provided to maintain the desired
temperature before the fan or blower. The central air
conditioning system supply either conditioned air or chilled
water to various buildings.

35. Main duct- cooling and dc humidification coil

36. 2. Unitary air conditioning system
The unitary system contains the cooling plant and
supply the conditioned air directly to buildings.
Whole system is mounted on a frame is also called
self contained or packaged unit. The packaged
units are available up to around 20 ton capacity or
more. Condenser may be water cooled or air
cooled. Some condensers are located away from
the packaged units. To provide condenser water,
spray towers are used depending upon the design

37. Air cooled and water cooled Unitary AC system

38. Split air Conditioner
Split air conditioner implies the bifurcation of conventional window air conditioner
into two parts 1. cooling coil having a motor and a fan mounted in a cabinet and is
kept inside the room, 2. compressor, condenser and motor with fan mounted in a
cabinet and is kept outside the room.
The cooling coil may be floor mounted where cooling coil is kept on the floor on a
suitable frame or ceiling mounted in which the cooling coil is hung from the
ceiling or it is mounted to the wall near the ceiling or wall mounted at a particular
height as per convenience.
On the other hand compressor and condenser with a separate fan are kept outside
the room in a suitable casing.
The distance between evaporator and condenser should not be more than 5 to 15
m . The head difference between the condenser and evaporator should not be
more than 5 m.

39. Split Air Conditioner