If the Ignition in Internal Combustion Engines takes place at the end of Compression Stroke then the engine runs without knocks,with good efficiency.
The Compression Ignition Engines are so design that the temperature at the end of the Compression is above the self-Ignition Temperature of Fuel. In this case,no spark plug as like in Spark Ignition required for Ignition.
Basically Four methods are used for Ignition.Out of that,Hot Tube Ignition Method and,Spark Ignition method are covered in last post.Remaining two will be covered in this post.That are as follows
03)Hot Combustion Chamber Ignition:-
The another name of this method is "Surface Ignition or Hot Surface Ignition".This method is used in Engines working on "Dual Combustion Cycle".The fuel is Ignited by being injected into a Hot Tube or Combustion Chamber containing Compressed Air.
The bulb which is located at the compression end of the Engine Cylinder and connected by a narrow space or throat to the combustion space of the cylinder is unjacketed and initially heated from an external source,like Lamp.At the end of Compression Stroke the Fuel is injected comes in contact with the red hot bulb and thus the ignition commences.
Once the Engine starts the heat retained from the previous explosion is sufficient to ignite the fuel in the next cycle.
This method is used in heavy oil engines working on Constant Pressure Cycle (Diesel Cycle).The Air is Compressed to such a high Pressure that its Temperature is higher than that at which the fuel burns.The Fuel is then injected into this hot compressed air where its ignition start spontaneously.
In Hot Tube Ignition and Hot Combustion Chamber Ignition,the exact point of the cycle at which ignition commences is quite uncertain.This problem does not occurs in Compression Ignition.