Question:easy
Which of the following processes is/are used for heat addition in an air-standard dual cycle?
Which of the following processes is/are used for heat addition in an air-standard dual cycle?
Show Hint
Think about the two-stage heat addition in a dual cycle, one part at fixed volume and one at fixed pressure.
Updated On: Jul 28, 2026
- Isochoric
- Isobaric
- Isentropic
- Isothermal
Show Solution
The Correct Option is A, B
Solution and Explanation
Step 1: Trace the dual cycle stages.
Start from state 1 with isentropic compression to state 2, no heat transfer here.
From state 2 to state 3 the gas is heated at constant volume, this is the isochoric leg.
Step 2: Check the second heat addition leg.
From state 3 to state 4 the gas keeps absorbing heat, but now at constant pressure, this is the isobaric leg.
After state 4 the gas expands isentropically to state 5 and then rejects heat at constant volume back to state 1, and neither of these two legs adds heat.
Step 3: Match against the options.
Isentropic and isothermal processes do not appear as heat addition steps anywhere in this cycle, so C and D drop out.
Final Answer:
Heat is added first at constant volume, then at constant pressure.
Options A (isochoric) and B (isobaric) are the correct choices.
Start from state 1 with isentropic compression to state 2, no heat transfer here.
From state 2 to state 3 the gas is heated at constant volume, this is the isochoric leg.
Step 2: Check the second heat addition leg.
From state 3 to state 4 the gas keeps absorbing heat, but now at constant pressure, this is the isobaric leg.
After state 4 the gas expands isentropically to state 5 and then rejects heat at constant volume back to state 1, and neither of these two legs adds heat.
Step 3: Match against the options.
Isentropic and isothermal processes do not appear as heat addition steps anywhere in this cycle, so C and D drop out.
Final Answer:
Heat is added first at constant volume, then at constant pressure.
Options A (isochoric) and B (isobaric) are the correct choices.
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