Many people misunderstood and used to call a condensing unit as a compressor. A condensing unit is a container that contain cooling system, there are many important devices in cooling system and one of the devices is a compressor.
This article will help one understand a vital tool in a refrigeration system since compressor is a heart of the cooling system.
Principles of Compressors
Compressor is extremely important in cooling system that increases pressure to gas refrigerant. A compressor absorbs gas refrigerant from low pressure side of an evaporator through the pipes and compresses the refrigerant, this increase both temperature and pressure of refrigerant before passing the fluid to condenser. A process of compression to gas refrigerant is a process that converts gas refrigerant into liquid. Refrigerant needs to pass through the whole refrigeration system and transforms back into a ready-to-use matter.
Divide Compressor according to Compression Methods
1. Reciprocation Type Compressor
Reciprocating compressor uses a basis of Crank Shaft so that the reciprocation compresses where by the reciprocation moves in a horizon within air cylinder that uses power from an engine or a motor. When the reciprocation moves downward, it absorbs gas refrigerant through suction valve. After that, refrigerant is contained in the cylinder. When the cylinder moves upward, it creates high pressure and opens valve, therefore, refrigerant moves onto the next process.
2. Rotary Type Compressor
Rotary compressor is similar to reciprocating compressor. It uses bearings to compress refrigerant into its process. It is commonly used in small air conditioning because it has low vibration and quiet. There are 2 types of rotary compressors.
1. Rotary Compressor, Rotary Propeller
Comprises of roller piston made from iron circular around camshaft which is installed inside Cylinder block of a compressor. Once the refrigerant is absorbed from pipes in between gaps of roller onto Cylinder block, refrigerant is absorbed by those gaps before passing on to the next process.
2. Rotary Compressor Composes of Rotating Blade
Inside the channel of camshaft, propeller rotates refrigerant between the rotor then refrigerant will be compressed. No return valve is used to make sure that fluid only flow in one direction.
3. Scroll Type Compressor
Mostly used in large water chiller since this type of compressor can operate large amount of refrigerant. It also creates by mixing pros of both Rotary and Reciprocation type making this type of compressor very efficient.
Mechanism behind scroll compressor is 2 set of propellers, where one set creates motion and the other set stays stationary. Pressure inside this type of compressor depends on rotating speed of the propeller.
4. Screw Type Compressor
Contains 2 screws, female rotor and male rotor. Female rotor uses spiral slot to hold on to refrigerant while male rotor uses spiral to rolled refrigerant out of both side of screws. Screws work when the gear rotates. It will force refrigerant to enter Interlube space, refrigerant that enters Interlube space will be trap until it reaches the end of spiral groove then fluid will be sent to the dispenser.
5. Centrifugal Type Compressor
Centrifugal type compressor is mostly used in air conditioner or large cooling system. Structure of Centrifugal type compressor contain large propeller, suction system is used to suck refrigerant to the centre of the compressor then the propeller will hurl the refrigerant, this will create centrifugal force.
Compressor is the only component in cooling system that requires lubrication, to lubricate rings and cylinder. However, during the operation some of the lubricant will be mixed with refrigerant. It is needed to make sure that refrigerant will not react with lubricant. This is one of the reason why choosing suitable lubricant is important.
Good lubricant should have these following qualities:
1. Produce strong oil film to perfect lubrication
2. Highly stable and obstruct turning into soot easily
3. Very unreactive, lubricant must not react with refrigerant and must be hard to degenerate in order to prevent stain
4. Low Pour Point – lubricant must not mix with refrigerant since it can cause clotting in an area with extreme temperature
5. Low Floc Point to prevent grafting in an area with extreme temperature
Compressor is divided into several categories however most compressor follow the same principles which is pressurise gaseous refrigerant. Choice of compressor need to be analysed according to cooling system to obtain the most suitable type of compressor for cooling system.
If you need any advice about type of compressor for cooling system, please feel free to contact us here or comment under this article, we are more than happy to give you advice.
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