🔍 Key Concepts
• Review the theoretical diesel cycle P–V diagram and what each numbered point represents (intake, compression, combustion, expansion, exhaust).
• Recall that in the ideal diesel cycle, fuel is added so that heat is supplied at constant pressure, and then the gases do work on the piston.
• Look at how volume and pressure change between points "3" and "4" on the curve in the illustration.
💭 Think About
• From point "3" to point "4", is the piston moving toward or away from top dead center (is cylinder volume increasing or decreasing)?
• If volume is changing but pressure is mostly falling, which process in a diesel engine stroke does that best represent: compression, combustion at constant something, or power/expansion?
• In the ideal diesel cycle, which segment (1–2, 2–3, 3–4, or 4–1) is associated with the power stroke where the hot gases push the piston down?
✅ Before You Answer
• Check whether volume increases or decreases between points "3" and "4" on the P–V diagram.
• Confirm whether pressure is roughly constant or clearly changing along the 3–4 curve.
• Match that P–V behavior to the textbook description of compression, constant-pressure combustion, constant-volume combustion, or expansion in the ideal diesel cycle.