Comparison of Otto, Diesel & Dual Cycles

For same compression ratio and heat rejection (Figures 30.2 (a) and (b))

1-6-4-5: Otto cycle

1-7-4-5: Diesel cycle

1-2-3-45 Dual cycle

For the same Q₂ , the higher the Q₁ , the higher is the cycle efficiency

For the same maximum pressure and temperature (Figures 30.3 (a) and (b))

1-6-4-5: Otto cycle

1-7-4-5: Diesel cycle

1-2-3-45 Dual cycle

Q₁ is represented by:

area under 6-4 for Otto cycle
area under 7-4 for Diesel cycle and
area under 2-3-4 for Dual cycle and Q₂ is same for all the cycles

The actual cycles are modifications on the Air Standard cycles in the following manner: