- #1
goran d
- 32
- 0
Lets say we got a larger cylinder-piston combo and a smaller one.
First we move the larger cylinder, filling in with vacuum. Then we pump in air, using the smaller cylinder, isothermally, with variable expansion ratio.
Here, we clearly have exp ratio > P_atm/P_final
We then compress the larger cylinder isothermally, this time
we have exp ratio = P_atm/P_final
Thus we have gained energy from the air, or so it seems?
This is because work of isothermal expansion is proportional to ln(exp ratio)
First we move the larger cylinder, filling in with vacuum. Then we pump in air, using the smaller cylinder, isothermally, with variable expansion ratio.
Here, we clearly have exp ratio > P_atm/P_final
We then compress the larger cylinder isothermally, this time
we have exp ratio = P_atm/P_final
Thus we have gained energy from the air, or so it seems?
This is because work of isothermal expansion is proportional to ln(exp ratio)
Last edited by a moderator: