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The workhorse of the refrigeration industry is the reciprocating compressor, built in sizes ranging from fractional-kilowatt to hundreds of kilowatts refrigeration capacity. Modern compressors are single-acting and may be single-cylinder or multi-cylinder. In multi-cylinder compressors, the cylinders are in V, W, radial or in-line arrangements.
During the suction stroke of the piston, low-pressure gas is drawn in through the suction valve, which may be located in the piston or in the head. During the discharge stroke, the piston compresses the refrigerant and then pushes it out through the discharge valve, which is usually located in the cylinder head. Compressors today operate at speeds as high as 60 r/s.
A compressor whose crankshaft extends through the compressor housing so that the motor can be externally coupled to a shaft is called an open-type compressor. A seal must be used where the shaft comes through the compressor housing to prevent refrigerant gas from leaking out or air from leaking in if the crankcase pressure is lower than atmospheric.To avoid leakage, the motor and compressor are often enclosed in the same housing.
Improved techniques for insulating the motor electrically have allowed motors to operate even though they are in contact with the refrigerant. In many designs the cold suction gas is drawn across the motor to keep it cool. Almost all small motor-compressor combinations are used in refrigerators, freezers and residential air-conditioners are of the hermetic type. The only connections to the compressor housing are the suction and discharge fittings and electric terminals. Moisture in the system can be damaging to the motor; therefore, dehydration of hermetic units before charging is essential.
| Reciprocating compressor | поршневий компресор |
| Fractional-kilowatt | однокіловатний |
| Suction | всмоктування |
| Suction stroke | всмоктуючий цикл |
| Low-pressure gas | повітря низького тиску |
| Piston | поршень |
| Valve | клапан |
| Radial or in-line arrangement | радіальне або рядне розташування |
| Discharge stroke | виштовхувальний цикл |
| Refrigerant | хладогент |
| Crankshaft | колінчатий вал |
| Seal | сальник |
| Leakage | витікання |
| Crankcase | картер |
| Housing | корпус |
| Insulating | ізолювання |
| Motor-compressor combinations | компресорні комбінації |
| Electric terminals | електричні клеми |
| Fittings | фітінги |
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| Comprehension check. | | | Use the verbs given in brackets in the past perfect cont., past simple, present perfect, past perfect, present perfect cont., past perfect cont. |