How Can You Design an Adiabatic and Reversible Thermodynamic System?

[decerto]

Homework Statement

Design an explicit system which does the following: It goes adiabatically and reversibly from state A to B. Then it returns from state B to state A probably irreversibly and receiving some heat from the outside world on the way. It can't give out heat.

Homework Equations

$PV^{\gamma}=c$ for an adiabatic process
$PV=c$ for an isothermal process

The Attempt at a Solution

[/B]
I attempted to draw various 3 step PV diagrams using isobaric and isochoric steps but they all gave out heat. The only way I can think of doing this is if the adiabatic process is the same as an isothermal process i.e
$PV^{\gamma}=PV$
$\gamma=1$
$C_p=C_v$

But this can't be true for an ideal gas so I have no idea.

 

[DrClaude]

I attempted to draw various 3 step PV diagrams using isobaric and isochoric steps but they all gave out heat.

Doesn't that depend on the direction of the process?

 

[decerto]

Doesn't that depend on the direction of the process?

Yes but amn't I forced into a direction that gives out heat after an adiabatic process then a process which takes in heat if I want to get back to the start?

 

[DrClaude]

Yes but amn't I forced into a direction that gives out heat after an adiabatic process then a process which takes in heat if I want to get back to the start?

I haven't worked out the details, but if your adiabatic process is an expansion, can't you go back to state A without any heat leaving the system?