Compare the efficiency of Otto cycle and diesel cycle for same maximum pressure with neat sketch.
Comparison of efficiency of Otto Cycle and Diesel cycle for same pressure ration and same conditions
The air-standard Otto and Diesel cycles are drawn on common p-v and T-s diagrams for the same pressure ratio and maximum temperature, for the purpose of comparison.
Otto Cycle 1-2-3-4-1 And Diesel Cycle 1-2”-3-4-1
The construction of cycles on T-s diagram proves that for the given conditions the heat rejected is same for all the Otto and Diesel cycles (area under process line 4-1).
Since, by definition, the cycle, with greater heat addition will be more efficient. From the T-s diagram,
Qs(diesel)= area under 2”-3
Qs(otto) =area under 2-3
Therefore for the same pressure ratio
Qs(diesel) > Qs(otto)
Thus ,
diesel > otto