Question

Would you advocate incorporating an Atkinson-like step (isobaric compression after the completion of the power stroke) in a diesel engine? Explain.

 

 

Answer 1

Diesel cycle (compression ignition) engines — In this, mixture of fuel and air gets compressed isentropically then combustion occurs at top dead centre (TDC) and expands isobarically after that, there is isentropic expansion and finally cools at constant volume (isochoric).

 

1 - 2: - Isentropic compression.

2 - 3: - Reversible constant pressure

3 - 4: - Isentropic expansion

4 - 1: - Reversible constant volume cooling.

 

Atkinson cycle: -

Ideal Atkinson cycle consists of isentropic compression, isochoric heating, isobaric heating isentropic expansion, isochoric cooling and isobaric cooling.

 

1 - 2: Isentropic compression

2 - 3: Combustion

3 - 4: Isobaric heating

4 - 5: Adiabatic Expansion

5 – 6 - 1: Exhaust

 

After the completion of the power stroke, if isobaric compression is incorporated in a diesel engine, then compression ratio will increase which leads to high temperature and results to premature combustion.

 

If there is incorporation of Atkinson like step in diesel engine, premature combustion occurs.

Diesel cycle (compression ignition) engines — In this, mixture of fuel and air gets compressed isentropically then