Basic Ideal Cycles for Marine Diesel Engines

First and foremost you should understand these cycles are basically ideal cycles. Internal Combustion engines work mostly on one of the three cycles namely Otto cycle, Diesel cycle or Dual cycle. 

Otto Cycle

 Otto cycle is considered as the ideal cycle for petrol or spark ignition engines. In this cycle heat addition is at constant volume

1 – 2 isentropic compression from V1 to V2

2 – 3 addition of heat Qin at constant volume

3 – 4 isentropic expansion to the original volume

4 – 1 rejection of heat Qout at constant volume

Diesel Cycle

 Diesel cycle is considered as the ideal cycle for diesel engines or compression ignition engine.In this cycle heat addition is at constant pressure

The cycle consists of four processes,

1 – 2 isentropic compression from V1 to V2

2 – 3 addition of heat Qin at constant pressure

3 – 4 isentropic expansion to the original volume

4 – 1 rejection of heat Qout at constant volume

Dual Cycle

> It is the combination of both otto and diesel cycle. Combustion occurs partly at constant volume and partly at constant pressure. Most of the diesel engine including Marine Diesel Engines are working under duel cycle

1 – 2 isentropic compression from V1 to V2

2 – 3 addition of heat Qin at constant volume

3–4 addition of heat Qin at constant pressure

4– 5 isentropic expansion to the original volume

5 – 1 rejection of heat Qout at constant volume

Note: An isentropic process is a thermodynamic process, in which the entropy of the fluid or gas remains constant.

You Can Answer Following Questions

> Draw and Explain Otto Cycle

> Draw and Explain Diesel Cycle

> Draw and Explain Dual Cycle

> Marine diesel engines work on which cycle? (V.Imp)