Expansion devices in refrigeration systems serve two purposes: expanding refrigerant from high to low pressure and controlling the flow of liquid refrigerant to the evaporator. There are two main types of expansion devices - variable restriction devices like automatic expansion valves and thermostatic expansion valves, and constant restriction devices like capillary tubes. Capillary tubes are fixed restriction devices that are simple and inexpensive but only provide constant pressure drop via friction and acceleration. Automatic and thermostatic expansion valves can vary the flow of refrigerant in response to temperature. Compressors increase the pressure of vaporized refrigerant and come in positive displacement varieties like reciprocating and scroll compressors or non-positive displacement centrifugal compressors.

1. REFRIGERATION AND AIR
CONDITIONING
EXPANSION DEVICES
Presented by: Tarun Chauhan

2. Expansion devices:
An expansion device in a refrigeration system normally serves two
purposes :
•The thermodynamic fuction of expanding the liquid refrigerantfrom
condenser pressure to evaporator pressure.
•The control functions which may involve the supply of liquid to the
evaporator at the rate at which it is evaporated. This determines the
efficiency with which evaporator surface is utilized.
REFRIGERATION AND AIR CONDITIONING

3. An expansion device is essentially a restriction offering
resistance to flow so that pressure drops, resulting in throttling
process.
TYPES:
•Variable restriction type
1. Automatic expansion valve
2. Thermostatic expansion valve
3. Float valves
•Constant restriction types
1. Capillary tubes
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4. CAPILLARY TUBES
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•Fixed restriction type device.
•Simple and no moving part.
•Low cost
•Pressure drop developed due to:
1. Friction
2. Acceleration

5. AUTOMATIC EXPANSION VALVE
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6. THERMOSTATIC EXPASION VALVE
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7. COMPRESSORS:
The basic function is to compress the suction vapour from evaporator
To condenser pressure.
Mechanical compressors are basically of two types:
•Positive displacement machines:
Reciprocating, rotary, scroll ad screw compressors
•Non positive displacement machines:
Centrifugal compressors
On the basis of their enclosing pattern they are classified as :
•Hermetically sealed
Motor, cylinder and crank case Re fully enclosed inside a dome
•Semi sealed
Partially enclosed motor
•Open type
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8. ROTARY COMPRESSORS:
•Rolling piston type
•Rotating vane type
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9. SCREW COMPRESSORS:
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10. CENTRIFUGAL COMPRESSOR:
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11. THANK YOU!!!
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