Dual Combustion Cycle

Dual Combustion Cycle is a combination of Otto cycle and Diesel cycle. It is sometimes called semi-diesel cycle, because semi-diesel engines work on this cycle. In this cycle, heat is absorbed partly at a constant volume and partly at a constant pressure.

The ideal dual combustion cycle consists of two reversible adiabatic or isentropic, two constant volume and a constant pressure processes. These processes are represented on p-v and T-s diagrams as shown in Fig 5.13 (a) and (b) respectively.

The air standard efficiency of this cycle is given by,

Notes:

1. For Otto cycle, p = 1; and for Diesel cycle, α = 1.

2. The efficiency of dual combustion cycle is greater than Diesel cycle and less than Otto cycle, for the same compression ratio.