Question 44Motor Plants - Assistant Engineer

The correct answer is B. The pressure-volume diagram in option B represents the theoretical diesel cycle, which is characterized by constant-pressure combustion. This is in contrast to the constant-volume combustion of the Otto cycle (gasoline engines), which is represented by the diagrams in options A, C, and D. The diesel cycle is the ideal thermodynamic cycle for compression-ignition, internal combustion engines, which is the operating principle of diesel engines. The constant-pressure combustion during the power stroke is a key feature that distinguishes the diesel cycle from other engine cycles.