Types of compressors

COMPRESSORTYPES

MERITS AND DEMERITSAPPLICATIONS

Saloni Sharma 114126 Sumer Naryal 114154 Tushar kaushik 114160Vandana kaushal 114163Vikas Yadav 114166Yash Gajwani 114172

Group members

Compressors are mechanical devices that compress fluids.

A compressor is a machine used to compress the refrigerant from the evaporator and to raise its pressure so that the corresponding temperature is higher than that of the cooling medium.

INTRODUCTION

COMPRESSOR

Positive displacement

typeDynamic

type

Reciprocating Rotary Screw

Centrifugal

Scroll

Positive displacement typeReciprocating compressor Uses pistons driven by a crankshaft to deliver 

gases at high pressure.

The intake gas enters the suction 

manifold, 

flows into the compression 

cylinder where 

Compressed by a piston driven in a reciprocating motion via a crankshaft, 

and is then discharged. 

High pressure and high power compressed gas can e produced.

Initial cost is less.

Continuous discharge

Pros• Low reliability.

• Plot area.

• Large volume capacity.

Cons

Positive displacement type compressors In rotary compressors, the vapour refrigerant

from the evaporator is compressed due to the movement of the blades

Refrigerants : R-12, R-22, R-144 and ammonia

THERE ARE TWO TYPES OF ROTORY COMPRESSORS: single stationary blade type rotary compressor rotating blade type rotary compressor

ROTARY COMPRESSORS

Consist of: Single stationary cylinder A roller(or impeller) shaft Sealing Blade set into the slot of a cylinder

Functioning Blade moves in and out of the slot to follow the rotor when it rotatesWhen the shaft rotates, the roller also rotates so that it always touches the cylinder wallRefrigerant is compressed and discharged to the condenserIn this way, the low pressure and temperature vapour refrigerant is compressed gradually to high pressure and temperature

SINGLE STATIONARY BLADE TYPE COMPRESSOR

Consist of : Cylinder Slotted rotor containing number of blades Centre of rotor is eccentric with the centre of cylinder Functioning: Blades are forced against the rotation of the motor Low pressure and temperature vapour refrigerant from

the evaporator is drawn through suction port As rotor turns, the suction vapour refrigerant entrapped

between the two adjacent blades is compressed The compressed refrigerant at high pressure and

temperature is discharged through the discharge port to the condenser

ROTATING BLADE TYPE ROTARY COMPRESSOR

Low maintenance due to low rotating speed and fewer moving parts.

Suitable for unclean environment.

Pros Cons•Not suitable for high pressure.

•Oil carry over problem is present.

SCREW COMPRESSOR•Rotary screw compressors also belong to the category of positive displacement compressors machine a rotary compressor essentially consists of two helically-grooved rotors•The male rotor consists of lobes and is normally the driving rotor. The female rotor has gullies and is normally the driven rotor.

Vibrations are less.

Small size compressor can produce high flow rate.

Pros Cons •Oil carryover problem

•Life expectancy is short

•Not suitable for unclean environment

Scroll Compressor

A scroll compressor (also called spiral compressor, scroll pump and scroll vacuum pump) is a device for compressing air or refrigerant. It is used in air conditioning equipment, as an automobile supercharger (where it is known as a scroll-type supercharger) and as a vacuum pump.

A scroll compressor operating in reverse is known as a scroll expander, and can be used to generate mechanical work from the expansion of a fluid, compressed air or gas. Many residential central heat pump and air conditioning systems and a few automotive air conditioning systems employ a scroll compressor instead of the more traditional rotary, reciprocating, and wobble-plate compressors.

Scroll compresor

Pros Cons Efficient because do not

have dynamic discharge valve that introduces additional throttling losses

Smaller space requirement

Have fewer moving parts so long life of compressor

No noise and less vibrations

Scroll compressors are more vulnerable to introduced debris.

A reciprocating compressor run in any direction and still function, whereas a scroll compressor must rotate in one direction

Accumulation issues are high.

Not suitable for very high refrigeration

A single-stage centrifugal compressor mainly consists of the following four components as ◦ (a) An inlet casing to accelerate the fluid to the

impeller inlet. ◦ (b) An impeller to transfer energy to the fluid in the

form of increase in static pressure and kinetic energy. ◦ (c) A diffuser to convert the kinetic energy at the

impeller outlet into pressure energy (static enthalpy). ◦ (d) A volute casing to collect the fluid and to further

convert the kinetic energy into pressure energy (static enthalpy).

CENTRIFUGAL COMPRESSOR

Suitable for continuous compression.

High power and high compressibility is possible.

Oil free output.

Pro Cons•Costly equipment

•Maintenance is sophisticated

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