Refrigeration System

Components

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Faculty Name: Prof. Ajaypalsinh G. BaradBranch: MechanicalSemester: 6th

Name of Subject: Refrigeration and Air Conditioning

Outline

• Introduction

• Compressor

• Condenser

• Expansion Device

• Evaporators

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Compressors:

• It removes low temperature and low pressure

refrigerant vapours from the cooling coil through the

suction line.

• It compresses these refrigerant vapours by increasing

the pressure and temperature resulting in an increase

of boiling point of the refrigerant,

• It discharges the refrigerant vapours of high

temperature and pressure to condenser through

discharge line.

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Compressors:

There are mainly three types of compressors in use:

Reciprocating compressor,

Rotary compressor,

Centrifugal compressor

• Reciprocating and rotary compressors are more commonlyused for small capacities but for lower evaporatortemperatures.

• Centrifugal compressors are essentially large dischargecapacity compressors. These are preferred for higherevaporator temperatures applications like, water chillersand air conditioners. They offer high efficiency but areexpensive.

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Reciprocating Compressor:

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Reciprocating Compressor:

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Rotary Compressor:

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Rotary Compressor:

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Rotary Compressor:

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Rotary Compressor:

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Rotary Compressor:

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Centrifugal Compressor:

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Screw Compressor:

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Scroll Compressor:

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Scroll Compressor:

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Hermitecally Sealed Compressor:

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Condensers:

• A condenser is a heat exchanger which removes heat

of the hot vapor refrigerant discharged from the

compressor.

• The condenser are classified into the following three

groups:

(1) Air-cooled condensers

(2) Water-cooled condensers, and

(3) Evaporative condensers.

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Air-cooled condensers

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Water-cooled condensers

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Water-cooled condensers

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Water-cooled condensers

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Evaporative condensers

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Expansion devices:

• Following are the main types of expansion devices

used in industrial and commercial refrigeration and air

conditioning system.

1.Capillary tube

2.Hand-operated expansion valve

3.Automatic or constant pressure expansion valve

4.Thermostatic expansion valve

5.Float valve

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Expansion devices:

• Capillary tube

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Expansion devices:

• Capillary tube

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Expansion devices:

• Capillary tube

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Expansion devices:

• Capillary tube

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Expansion devices:

Capillary tube

• The pressure drops due to the frictional resistance

• For a given state of the refrigerant, the pressure drop is directly

proportional to the length and inversely proportional to the bore

diameter of the tube

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Expansion devices:

• Hand operated expansion valve

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Expansion devices:

• Automatic Expansion Valve

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Expansion devices:

• Thermostatic Expansion Valve

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Evaporators:

• The function of an evaporator is to absorb heat from

the surrounding location or medium which is to be

cooled by means of a refrigerant.

• The evaporators may be classified as follows:

According to operating conditions:

(i) Flooded type evaporators;

(ii) Dry or direct expansion type evaporators.

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Evaporators:

According to type of construction:

• Bare tube coil evaporator,

• Finned tube evaporator,

• Plate evaporator,

• Shell and tube evaporator,

• Shell and coil evaporator,

• Tube-in-tube evaporator,

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Evaporators:

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Evaporators:

• Capillary tube

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Evaporators:

• Bare tube coil evaporator

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Evaporators:

• Finned tube evaporator

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Evaporators:

• Plate Evaporator

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Evaporators:

• Shell and tube evaporator

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Evaporators:

• Shell and Coil

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Evaporators:

• Tube in Tube

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Refrigeration piping:

Selection of piping and fittings on the basis of

• Frictional resistance offered by pipe wall to flow of fluid,

• Velocity of flow.,

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Refrigeration piping:The design and operation of refrigerant piping system are as

follows:

• Ensure proper feed of refrigerant to the evaporators.

• Refrigerant line be so designed that pressure drop is not

excessive.

• Excessive amounts of lubricating oil may not be trapped in

any part of the system.

• It should protect the compressor from the loss of refrigerant

and lubricating oil.

• It should prevent liquid refrigerant from entering the

compressor during operating and idle time.

• It should maintain dry and clean system.44

Refrigeration Accessories :

Oil separator:

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Refrigeration Accessories :

Sight glass:

The sight glass is used as for,

• Moisture indicator.

• Liquid indicator.

• Liquid level indicator.

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Refrigeration Accessories :

Driers :

• Moisture in refrigeration systems is factor in the formation

of acids, sludge and corrosion.

• Drier is used to remove moisture from the system.

• It is placed in liquid line just before a strainer.

• It has silica gel in it to absorb the moisture either left over

in the system after charging or developed over a period due

to chemical action on oil.

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Refrigeration Accessories :

Filters :

• The filters act to strain out any particles that may be in

the system.

• Any particles can plug capillary tubes and thermostatic

expansion valve screens.

• The filter is placed at the inlet to the expansion device.

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Refrigeration Accessories :

Receiver :

• A receiver is a storage area for refrigerant.

• The liquid from condenser goes by gravity to a receiver.

• It is used to take care of load variation.

• It also help the condenser to drain refrigerant freely.

• The outlet tube of the receiver ensures that only liquid

goes to expansion device.

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Refrigeration Controls :

The controls used to cycle the refrigerating system on or

off are of two principle type,

• Temperature actuated,

• Pressure actuated.

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Refrigeration Controls :

Temperature actuated control:

• A temperature actuated control is also known as

thermostats.

• The temperature actuated controls are:

– Bulb type temperature sensing element,

– Bimetal type temperature sensing element.

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Refrigeration Controls :

Pressure actuated controls:

• They are used to control the pressure of the refrigerant in

the system. It is used as safety controls.

• Low pressure cutout

• High pressure cutout

• Oil failure cutout

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Thermal insulation:

• The materials having extremely low thermal conductivities

are called insulating materials.

• Desired properties of an ideal insulating material

– Thermal conductivity

– Permanence

– Strength

– Water-repellent

– Fire-proof

– Light weight

– Odorless

– Low-cost

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Classification of insulating materials:

• Flake insulation

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Classification of insulating materials:

• Fibrous insulation

– Organic or inorganic and may or may not be bonded.

– Glass or Rockwool are the most common materials

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Classification of insulating materials:

• Granular insulation

– Composed of small nodules that contain voids

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Classification of insulating materials:

• Cellular insulation

– Composed of small individual cells produced from glass,

rubber or plastic

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Classification of insulating materials:

• Reflective insulation

– Composed of parallel thin sheets of foil having high thermal

reflectance

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