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What is difference between Hermetic Rotary Compressor?
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Descride two methods for cooling and overheated compressor?
1) Most hermetic compressors are cooled by the suction gas. If there is an undercharge, there will be an undercooling (or overheating) of the motor. 2) Ambient air is used to cool the air in the fan department.
What is an hermetic compressor?
a fully welded or serviceableIn hermetically sealed compressor, the compressor and the motor are enclosed in the welded steel casing and the two are connected by a common shaft. This makes the whole compressor and the motor a single compact and portable unit that can be handled easily. The hermetically sealed compressor is very different from the traditional open type of compressors in which the compressor and the motor are different entities and the compressor is connected to the motor by coupling or belt.Construction of the Hermetically Sealed Reciprocating CompressorIn hermetically sealed compressor, in one side of the enclosed casing the various parts of the compressor like cylinder, piston, connecting rod and the crankshaft are located. If it is a multi-cylinder compressor, there are more than two cylinders inside the casing. On the other side of the casing is the electric winding inside which the shaft of the motor rotates. This motor can be single speed or multi-speed motor. In hermetically sealed compressors the crankshaft of the reciprocating compressor and the rotating shaft of the motor are common. The rotating shaft of the motor extends beyond the motor and forms the crankshaft of the hermetically sealed reciprocating compressor.All these parts of the hermetically sealed compressor are assembled and enclosed in a strong and rigid casing made up of welded steel shell. The steel shell comprises of two half rounded steel bodies that are welded together to form the casing for the hermetically sealed compressor. In some cases the two halves of the shell can be bolted together instead of welding, which permits easy opening of the casing in case of compressor burnout.The hermetically sealed compressors have inbuilt lubrication system for the lubrication of the piston and cylinder and crankshaft. The lubricant also acts the coolant for the piston and cylinder. Additionally, the cool suction refrigerant also offers cooling effect. Externally, the casing has refrigerant suction and discharge connections that are connected to the evaporator and condenser respectively. There is also socket for the electrical connection.The typical condenser unit with the hermetically sealed compressor is shown in above fig. Such condenser units are called as hermetic condenser units. In the other image various parts of hermetically sealed multi-cylinder reciprocating compressor are shown.Types of Hermetic CompressorsOne of the most popular types of the hermetically sealed compressors are the reciprocating compressors. They were the first to be used as the hermetically sealed compressors are still being used widely. These days the vane type of rotary compressor has become more popular. It is considered that the rotary type of hermetically sealed compressor consumes less electricity, makes lesser noise, requires lesser maintenance, and is cheaper than the reciprocating type of hermetically sealed compressor. This is because the rotary compressors has less frictional parts and have only a rotor. The centrifugal types of hermetically sealed compressor are used for the large units.
Which is best Rotary compressor or reciprocating compressor?
Receip or Piston type compressor are used for large duty cycle work (A/c or other equipments), energy hungry but last longer (Heavy Duty). Where as rotary compressor are energy efficient with higher ( Energy Efficiency Ratio) but lower duty cycle and shorter life. Selection of compressor are based on the nature of application. Normally, for room A/Cs with capacity less than 3 ton, most companies offer rotary compressor due to it's EER and less duty cycle. For heavy duty A/Cs, recip or piston compressor best suited.
Is poor compressor can cause high head pressure in an air cooled condenser?
Poor compressor performance should result in low head pressure as the system cools better than the compressor can pump.
Why Hermetic compressor motor manufactured from special material?
Hermetic manufactured from special materials because Hermetic compressor motor materials must be compatible with the refrigerant and oil circulating in the system.
Why you cant have a centrifugal switch in a hermetic motor?
The hermetic compressor cannot use a centrifugal switch like an open motor because it will disrupt the start winding. Hermetic compressors work through insulated motor terminals, and not in the open.
Why is the hermetic compressor motor manufactured from special material?
because the hermatic compressor motor must be compatible with the refrigerant and oil circulating in the system.
Servicing a stuck hermetic compressor?
To service a stuck Hermetic compressor,repair the start components of the air conditioning compressors.
How can a hermetic compressor be tested for efficiency?
There are a few ways to test a hermetic compressor for efficiency.Compressor Vacuum TestClosed-Loop Compressor Running Bench TestClosed-Loop Compressor Running Field TestCompressor Running Test in the System
What is the hermetic motor?
Hermetic motors are motors used in hermetic compressors. Hermetic motor use wound stators and squirrel cage rotors, without shaft bearings and have a relatively tight design.
What is difference between Hermetic Rotary Compressor?
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What are the parts of refrigeration compressor?
The parts of a hermetic (sealed) reciprocating compressor is as follows; motor, crankshaft, bearings, valves, and pressure relief valve and piston(s). there are other smaller parts that can be named but these are the main players. The hermetic scroll compressor is a little different than the reciprocating compressor because it uses an orbiting scroll and a stationary scroll to compress the refrigerant instead of pistons. This is why a scroll compressor cannot run "backwards". The scroll compressor also has an oil pick up tube which differs from a reciprocating compressor. Now a "semi-hermetic" compressor is build like a small engine. It has an oil pump, reed valve plate, unloaders, pistons, bearings, etc. A screw compressor is in a class all to itself.
Why can't you have a centrifugal switch inside a hermetic compressor motor?
The centrifugal switch is likely to wear out and require replacement. It could also create a spark which could cause fumes from the oil inside the motor
What could happen if a semi hermetic compressor is operated with the suction service valve backseated and the discharge valve frontseated?
the compressor capacity will increase
Why hermetic compressor color black?
because black body absorbs/emit maximum heat
How can a compressor be tested for efficiency?
There are a few ways to test a hermetic compressor for efficiency.Compressor Vacuum TestClosed-Loop Compressor Running Bench TestClosed-Loop Compressor Running Field TestCompressor Running Test in the System
