[melaniejs (OP)]

Joseph asks:

Is the online Omni calculator correct as a combined gas law calculator?

I saw that adiabatic expansion work was greater than corresponding compression to bring it back to its initial volume.
But this observation for nitrogen and some non ideal gases indicates a work output. If we introduce a hot reservoir and run it in cycles it makes a perpetual motion machine of 2nd kind without a cold reservoir.

Can anyone help Joseph out?