This piston machine that provides a compression method that is different from reciprocating or screw compressors. The process of compression is achieved couple of scrolls as shown in Fig. 12.12. Referring to the figure, scroll to having an open end on the left side of the sub-figure b is fixed and cannot move. Another roll her right end is fixed, but the rest of the drive from the electric motor to orbit around a Central line Fixed scrolling. Suction gas comes in two open slots, educated fixed ends of each of the scrolls (sub-figure b) and, as orbit begins, steam trap volumes of gas is formed (sub-figure c).
As the orbit of the revenues of these two trapped volume of movement in the radial direction to the center of the scrolls and compressed. Meanwhile, the open ends of the scroll again can recognize another pair of volume of the pumped environment. For clarity, the illustration, Fig. 12.12 shows only radial stroke one pair of trapped gas suction on external slots for compression in the middle and unloading at one end of the centre of the scrolls.
This can be seen on the figure that, in the middle of the scrolls at the end of the fixed scrolling not move, but in the end orbit scroll to the effect of the compression. As orbit continues a series of pulses hot gas is released in the centre of the scrolls, almost as a continuous stream high-pressure gas.
There are no valves and fewer moving parts than reciprocating compressors. Frictional and other losses are reduced due to the closure of production tolerances, and isentropic efficiency (equation)is improved. The compressor has a high volumetric efficiency (see Fig. 12.11) and best performance factor. It is quieter and less vibration.
Spiral compressors available in a range from 3 to 50 kW, with air-cooled condensers. The application was in the world, especially in household and industrial air-conditioners. Capacity control is usually through an inverter, giving compressor with variable speed from 15 to 50 Hz with a corresponding variable refrigerant mass flow. The advantage of this scheme is the smooth start of electric drive engines.
In comparison with air cooling, piston machine, scroll condensing set has a flatter response curve of the efficiency of cooling capacity than the outside temperature. Most are tight and there is virtually no maintenance. Almost all split-systems now use the scroll compressors with variable refrigerant flow through the inverter control of the vehicle motor...