The purpose of the compressor in the vapour compression cycle of compression of low-pressure from dry gas evaporator and raise its pressure, which is capacitor. Compressors can be divided into two types, volume and dynamic, as shown in Fig. 4.1. Volumetric compression types of discrete volumes of low-pressure gas physically reduction of volumes of causing an increase of the pressure and dynamic types for increasing the rate of low pressure gas and then reduce it to increase pressure.
On Fig. 4.2 shows the approximate range of cooling capacity, covered by various types. The most easily recognizable gearbox type or reciprocating piston compressor and , being easily visualized, it will be used as reference material for the description of the compressor and features before moving on to other types.
The first piston refrigeration compressors were built in the mid-19th century, and have evolved from steam engines, which provided the tractor (see Fig.
4.3). The construction was first double action, but there was difficulty in maintaining gas-tightness of the rod, so the design turned to one-acting machine sump suction inlet pressure, leaving only a rotating shaft, as a possible source of the leak, and it was hermetically Packed gland. Today, the majority of compressors are completely closed, with motor the prisoner.
Types of Refrigeration and Air Conditioning equipment, Compressors
There are different types of compressors used in refrigeration and air conditioning machines, namely: reciprocating, rotary, screw, centrifugal, and scrolling. All this was briefly described below:
Piston compressors are one of the most widely used types of refrigeration compressors. They piston and cylinder as the location of the car engine. Reciprocating motion of the piston due to external forces compresses the refrigerant inside the cylinder. There are three types of piston compressors: hermetic, semi-hermetically closed and open-ended. Open piston compressors can be of the same type cylinder or multi-cylinder type.
Screw compressors consist of a pair of mesh screws, between which the refrigerant is compressed. They can produce a high pressure for a small amount of gas. They consume less energy, than for a piston compressors and used widely. It can be used as refrigerants R12, R22, and others.
Rotary compressors have two rotating elements, like gears, between which the refrigerant is compressed. These compressors can pump refrigerant below or moderate the pressure of condensation. Because they can handle small amounts of gas, and produce less pressure, they are used in fewer applications.
The centrifugal compressor impeller or blower, which can handle large volumes of gas, but at a relatively low pressure of condensation. It is suitable for work with refrigerants such as R-11, R-113 and other
Scroll compressor consists of two interleaved scrolls, one of which is fixed and the other to the eccentricity of the orbit without rotation. During its motion with small gaps are created between the scrolls, where the refrigerant is compressed. Scrolls can have different shape, as involute, Archimedean spiral, or hybrid curve. In other arrangement scrolls can turn its beating to recompress.