Power Plant Engineering

8.12.1 TYPES OF SUPERCHARGER
Supercharging is done by means of compressor; there are two types of compressors that may be
used as super chargers. They are as follows:
1. Positive displacement type super chargers.
(a) Piston Cylinder type
(b) Roots blowers
(c) Vane blower
2. Centrifugal type super chargers or turbo type.
3. Turbo type super chargers.
Root blowers
Vane blower
Impeller
Diffuser
Centrifugal types
Fig. 8.12
Fig. 8.13

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DIESEL POWER PLANT
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The blowers are usually driven from the engine cranks shaft by mean of Spur, helical or herring-
bone gears, silent chains or V-belts at a speed 2-3 times the engine speed. In the case of turbo-super-
charger, the super charger is coupled to a gas turbine in which the exhaust of the engine is expanded.
The positive displacement types are used for low and medium speed engines with speeds not
over 4000 rev/min. Positive displacement type used with many reciprocating engines in stationary plants,
vehicles and marine installations.
The piston cylinder type is used on large and slow speed stationary engines, but their use is
limited since they are bulkier, more expensive and less dependable than the rotary type blowers.
Centrifugal blowers are used both on low speed and high-speed engines. Centrifugal blowers
driven by exhaust gas turbine are small and light and are used for stationary, locomotive, and marine and
aircraft engine. The speed of the centrifugal type of blowers is high about 10000 to 15000 rev/min for
low speed engines and 15000 to 30000 rev/min for high-speed engines such as aircraft engines.
Centrifugal type widely used as the supercharger for reciprocating engines, as well as compres-
sor for gas turbines. It is almost exclusively used as the supercharger with reciprocating power plants for
aircraft because it is relatively light and compact, and produces continuous flow rather than pulsating
flow as in some positive displacement types.