Refrigeration and air conditioning

Refrigeration & Air Refrigeration & Air ConditionCondition

Prepare by:- Shivkumar Panjabi1

Prepare by:-Shivkumar PanjabiPrepare by:-Shivkumar Panjabi

It is defined as the process of providing and maintaining a temperature well below that of surrounding atmosphere.

In other words refrigeration is the process of cooling substance.


If the main purpose of the machine is to cool some object the machine is named as refrigerator

If the main purpose of machine to heat a medium warmer than the surroundings, the machine is termed as heat pump.


Food Preservation . Poultry Forms . Development of certain Scientific

Instruments . Weaving in textile Industry . Improvement in production in shop

floor. Medical Science , Surgery. Customer delight in theaters & shops.

Prepare by:- Shivkumar Panjabi 5

Refrigerants:-It is a heat carrying medium which absorbs heat from space and rejects heat to outside the refrigerator.Properties of Refrigerants •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 Prepare by:- Shivkumar Panjabi

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Important refrigerants •Refrigerant is the working fluid used in refrigerators . Commonly used refrigerants are:

1.Ammonia : used in ice plants, large cold storages, skating rings etc. 2.Carbon dioxide : used in marine refrigerators, dry ice making etc. 3.Methyl chloride: used in domestic & industrial refrigerators (now obsolate) 4.Fluorocarbons : Freon -11,12,13,22,113,114, etc. These are used in domestic & industrial applications.These chemicals damage the ozone layer and hence they are being replaced. Prepare by:- Shivkumar Panjabi

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Capacity of a Refrigeration Unit : • Capacity of a refrigerating machines are

expressed by their cooling capacity.• The standard unit used for expressing the

capacity of refrigerating machine is ton of refrigeration.

• One ton of refrigeration is defined as, “the quantity of heat abstracted (refrigerating effect) to freeze (into ice) one ton of water in a duration of 24 hours at 0o c”.

Heat extracted from at oo c = latent heat of ice Latent heat of ice = 336 kJ/kgi.e., 336 kJ of heat should be extracted one kg of

water at 0o C to convert it into ice.


One ton of refrigeration= 336x1000 kJ/24 hrs.

= 336x1000 kJ/min

24x60One ton of refrigeration = 233.333 kJ/min

= 3.8889 kJ/sec

For calculation purpose,One ton of refrigeration = 12600 kJ/hr = 210 kJ/min

Ton of refrigeration = 3.5 kJ/sPrepare by:- Shivkumar Panjabi

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C.O.P is a measure of efficiency of a refrigeration cycle/ system.

It is the measure of the effectiveness of the refrigeration system. It is the ratio of refrigerating effect (Q) to the input work required to produce the effect(w) .

COP =refrigerating effect/work input = Q/W



IntroductionIntroduction

How does it work? Refrigeration and air conditioning is used to cool products or a building environment.

Ref ri gerat ion &

AC

High Temperature Reservoir

Low Temperature Reservoir

R Work Input

Heat Absorbed

Heat Rejected

Types of RefrigerationTypes of Refrigeration

• Vapour Compression Refrigeration (VCR): uses mechanical energy

• Vapour Absorption Refrigeration (VAR): uses thermal energy

Refrigeration systems


Type of RefrigerationType of Refrigeration

Vapour Compression Refrigeration

Refrigeration cycle

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side

CompressorExpansion Device

1 2

3

4




Refrigeration cycle

Low pressure liquid refrigerant in evaporator absorbs heat and changes to a gas

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4




©© UNEP 2006 UNEP 2006

Refrigeration cycle

The superheated vapour enters the compressor where its pressure is raised

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4




©© UNEP 2006 UNEP 2006

Refrigeration cycle

The high pressure superheated gas is cooled in several stages in the condenser

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4




Refrigeration cycle

Liquid passes through expansion device, which reduces its pressure and controls the flow into the evaporator

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4


Function of main Parts

•Compressor -The function of the compressor is to continuously draw the refrigerant vapour from the evaporator and compress it to a high pressure. •Condenser -Condensor is used to condense the refrigerant from vapour to liquid. •Expansion valve –The function of expansion valve is to meter the proper amount of liquid refrigerant and reduce the pressure of liquid refrigerant entering the evaporator. •Evaporator -In evaporator the lower temperature refrigerant absorbs the heat from the space to be cooled and the refrigerant gets evaporated.



Vapour Absorption Refrigeration

Condenser Generator

Evaporator

AbsorberCold Side

Hot Side


Air conditioning is the simultaneous control of temperature ,air humidity ,air movement and air cleanliness.

Principle:- The device or unit which provides air

conditioning is called air conditioner. Continuous cyclic process of

drawing ,cooling and recirculation of the cooled air maintains indoor space cool at required lower temperature which is required for comfort cooling.



• The basic elements of air conditioning system:--• Fans : For circulation of air• Filters : For cleaning air• Heating Elements : Heating of air(It may be

electric heater , steam , hot water.)• Control System : It regulates automatically the

amount of cooling or heating.• Grill : It adjust the direction of the conditioned air

to the room.• Tray : It collects condensed water.• Refrigerating Plant : provide cooling . It consist of

compressor/generator and asorber,eveporator,condensor,expansion device(capallary tube).

Air Conditioning System


Window Air Conditioner

1) Blower: This is the small blower that is fitted behind the evaporator or cooling coil inside the assembly of the window air conditioner system. The blower sucks the air from the room which first passes over the air filter and gets filtered. The air then passes over the cooling coil and gets chilled. The blower then blows this filtered and chilled air, which passes through the supply air compartment inside the window air conditioner assembly. This air is then delivered into the room from the supply air grill of the front panel.

2) Propeller fan or the condenser fan: The condenser fan is the forced draft type of propeller fan that sucks the atmospheric air and blows it over the condenser. The hot refrigerant inside the condenser gives up the heat to the atmospheric air and its temperature reduces.

3) Fan motor: The motor inside the window air conditioner assembly is located between the condenser and the evaporator coil. It has double shaft on one side of which the blower is fitted and on the other side the condenser fan is fitted. This makes the whole assembly of the blower, the condenser fan and the motor highly compact.


Window Air Conditioner


Split Air Conditioner

[email protected]@indusuni.ac.in

The Split Air Conditioner divided in two parts:--

(1)First part:-Include the evaporator,filter,evaporator fan and grill. They placed inside the room.

(2)Second part:-Include Condensor ,fan,compressor.This placed out side the room.diameter tubes.therefore,small hole rquired in wall of installation of split air condition.The split air conditioning units are available in capacity range of 1 to 3 tons.



Refrigeration & Air Refrigeration & Air Conditioning SystemsConditioning Systems

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