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For an adiabatic compression process, there is no heat exchange with the surroundings. If the adiabatic process is reversible (frictionless), then the process is called isentropic process in which the entropy of the system does not change. However, in an actual compressor, during adiabatic compression, there are losses due to friction in air and blade…

The velocities of air encountered in centrifugal compressors are very high as compared to that in reciprocating compressors. Therefore, total head quantities should be taken into account in the analysis of centrifugal compressors. The total head quantities account for the kinetic energy of the air passing through the compressor. Consider a horizontal passage of varying…

The comparison of centrifugal and rotary compressors is given in Table 14.2.   Table 14.2 Comparison of centrifugal and rotary compressors

The comparison of centrifugal and reciprocating compressors is given in Table 14.1.   Table 14.1 Comparison of centrifugal and reciprocating compressors

Impellers are of two types—single-eye type and double-eyed type as shown in Fig. 14.3 (a) and (b), respectively. In a single-eye type, air enters into the compressor from one side only, whereas in a double-eyed type, air enters from both sides. A double-eyed type impeller sucks in more air and has the advantage of self-balancing over a single-eye…

As the air flows through the impeller and diffuser, there is a variation of both velocity and pressure as shown in Fig. 14.2. Nearly half of the total pressure rise takes place in the impeller and the remaining half occurs in the diffuser. A pressure ratio of 4 can be achieved in single-stage compressors. For higher…

The air enters the eye of the compressor at atmospheric pressure and low velocity. The inlet buckets guide the air to the impeller where it moves radially outward and is guided by the impeller blades. The impeller increases the momentum of the air flowing through it, causing a rise in pressure and temperature of the…

Essentially, a centrifugal compressor consists of four elements namely, inlet buckets, impeller, diffuser, and casing as shown in Fig. 14.1. The inlet buckets are attached to the shaft and rotate with it, which guide air on the impeller. The impeller consists of a disc on which radial blades are attached. The diffuser surrounds the impeller and…

A centrifugal compressor is of rotodynamic type in which air flows continuously and steadily through various parts and the rise in pressure is primarily due to the centrifugal action. It is used to supply large quantities of air but at a lower pressure ratio.