Turbochargers and superchargers

SUPERCHARGERS AND TURBOCHARGERS

DEFINITION

The process of increasing the density of inlet air in internal combustion engines. This increases the power output of the engine. It  is called supercharging.

 Methods of supercharging 

  1. Engine driven superchargers
  2. Rotary blowers
  3. Centrifugal compressors
  4. Turbochargers driven by exhaust gases of the engine

Advantages of supercharging

  1. Increase in power output
  2. Reduction in weight to power ratio
  3. Overcomes over loss of power in high altitudes
  4. Reduction in the size of the locomotive engine
  5. Reduction in the size of the marine engine

Disadvantages of supercharging

  1. Increase in Detonation in Spark ignition engines
  2. Increase in friction loss
  3. Increases load on the bearing
  4. Increased weight of the entire assembly
  5. Melting possibility of piston top
  6. Possibility of pre-ignition increases
  7. Possibility of overheating of exhaust valves

DEFINITION OF A TURBOCHARGER

A turbocharger is a high speed turbine which is run by the exhaust gases of the IC engine. This turbine runs the supercharger to increase overall power output of the IC engine.

Advantages of Turbochargers

  1. It is very suitable for high speed engines.
  2. No gearing is required between the gas turbine and the supercharger (high speed compressor).
  3. Energy of exhaust gases can be used for some useful purpose. This heat is almost  one third of the total heat produced.
  4. Increase power input of the engine at a cheaper rate and hence is economical.
  5. Noise pollution of exhaust gases decreases.
  6. Overall maintenance reduces
  7. Turbochargers occupy less space and hence are compact.

Disadvantages of Turbochargers

  1. Total initial cost increases.
  2. It increases fuel consumption at lower speeds.
  3. In the turbocharger, the temperature of air increases during compression.  Which in turn reduces the density of the air. It reduces the mass of air entering the cylinder. In order to increase the mass of air into the cylinder, compressed air is cooled before it enters the cylinder of the internal combustion engine.