Hi,
Smoluchowski's trap door was proven to fail to obtaining work in a system without heat difference. The problem turns is random movement of trap door due to random particle movements. However I could not find any discussions of such system where the "trap door" did not involve moving parts...
Hi,
I independently had a similar thought today and after a bit of google-ing found your post. I think your idea is good, at least when we view gas as a bunch of molecules that have a position in space, some energy and inertia.
The Ideal reed valve you propose is trying to achieve 100%...