In article ,
says...

Air is driven through the aperture of a valve by a force which is the
product of the pressure differential existing across the aperture times
the area of the aperture. A small aperture will necessarily have less
force pushing air through it, and will push less air in a given time. But
that doesn't affect the amount of work the air can do on the load side.

Work isn't a time function. Work is force times distance. How long it
takes is irrelevant. Less work is done pushing air through a small
aperture than through a large one of the same length. In other words,
open the valve fully, no regulation, and more work is required to move
air through the length of the valve than would be required if the valve
were nearly closed.

Of course you move more air per unit time in the former case, but
work isn't a time function, so that's not relevant when calculating
dissipation.


This is a proud day indeed for RCM. Gary has just abolished
both the second law of thermodynamics and entropy with a
rhetorical flourish. All the more miraculous is this was
all done without resorting to pesky physics, mathematics or
experimental evidence, and in the face of numerous
counterexamples.

All that's left is construction of a device to move air
from a low pressure to high pressure vessel without doing
any work, beyond those annoying "parasitic losses."

If you listen carefully you can hear Messrs. Rumford,
Joule, Carnot, Boltzmann and Helmholtz applauding from
beyond the grave.

Ned Simmons