Could someone help me study this cyclic process of an ideal gas?

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Philip Koeck said:
I have a follow-up question (also to @Chestermiller):

W1-2 has to be the same as -Qh so that ΔU becomes zero for a complete cycle.
Philip Koeck said:
I have a follow-up question (also to @Chestermiller):

W1-2 has to be the same as -Qh so that ΔU becomes zero for a complete cycle.

If, however, I insist on calculating W1-2 as Pext ΔV I'm a bit stuck.
With Pext equal to P2, the internal pressure in state 2 (which seemed the obvious choice to me), I get only about half of -890 J.
Surely Pext can't be higher than P2.
Philip Koeck said:
If, however, I insist on calculating W1-2 as Pext ΔV I'm a bit stuck.
With Pext equal to P2, the internal pressure in state 2 (which seemed the obvious choice to me), I get only about half of -890 J.
Surely Pext can't be higher than P2.
Unless you know ##P_{ext}## explicitly for an irreversible expansion or compression, you can not determine the work (without solving the internal Navier Stokes equation, the continuity equation, and the differential thermal energy balances equation simultaneously).
 
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