16 April 2017

Actual cycles and their analysis

The actual cycle for IC engines differs from the fuel-air cycles and air-standard cycles in many respects. The actual cycle efficiency is much lower than the air-standard efficiency due to various losses occurring in the actual engine operation.

The major losses are due to :

  • Progressive combustion 
  • Variation of specific heats with temperature
  • Dissociation of the combustion products
  • Incomplete combustion of fuel
  • Heat transfer into the walls of the combustion chamber
  • Blowdown at the end of the exhaust process
  • Gas exchange process
These all losses are made from previous experience and some simple tests on the engines and these estimates can be used in evaluating the performance of an engine.