Hydro Differential pressure exchange over unity system.

[wildew]

From TK
There must be a reason for this, otherwise the simplification you have shown would have been used in the real device. I don't know what difference it makes but there must be one, and if we keep ignoring the bags in our sims and sketches we might never understand what the bags are actually for.

One good reason for this is a continually over looked principle of the system.
It's frequently stated that once the riser of one ZED has lifted, the cycle is reversed by pressing down on the riser - This is incorrect
It was also discussed just a few pages ago.....
Once the free-flow ends, the process of transferring water from the POD of one ZED to the POD of the other is assisted. VERY important point.
Are there other ways? Sure, but I can't think of an easier one.

[TinselKoala]

@Webby: I'm really not sure of the importance of the timespan of lifting; I just thought that "instant" would be simpler from a calculation point of view but from a work standpoint it shouldn't make any difference. Until we get into power issues, that is, which is the rate at which work is done, distinct from the quantity of work.
But it sounds like you've got the procedure down, and the skill to do the repeatable measurements.

Running your numbers:

25 g water, 26 inches from rest to lift: input
600 g removable mass, 15/16 inch lift: output

converting to metric,
26 inches x 2.54 cm/inch = 66 cm
and
15/16 inch x 2.54 cm/inch = (15 x 2.54)/16 = 2.4 cm

So input work is proportional to 25 g x 66 cm = 1650 g-cm
and output work is proportional to 600 g x 2.4 cm = 1440 g-cm
for an efficiency of 1440/1650 = 0.87 or 87 percent, a perfectly reasonable figure.


Please check my work, and if I've made any wrong assumptions or errors let me know so I can correct them. And thanks for the clear reporting!

[TinselKoala]

@Wildew.... you are right mostly I think, but we have been told that there is no water transferred between the Zeds, just force, apparently, between the bags: as one fills the other is squashed, but there isn't any interchange of the actual water.
I think. It would be nice to be clear on this point, especially in the sketches, sims and thought experiments. Sometimes oversimplification can lead one astray.

[wildew]

From MT
It would be indeed interesting, it is also not clear to me how adding layers helps here.

I was going over one of Larry's spreadsheets for the umpteenth time and finally let something sink in that's been mentioned many many times.....
Guess I'm just as guilty as many for not seeing something the first, or second, or third time.
The pressure and lift values for the innermost riser are the highest of the five, WT?
Oh yeah, DUH, being so accustomed to standard hydraulics I just wanted to "see" that the riser with the greatest area would have the greatest lift, CRAP!
What to the other risers accomplish? They provide resistance against the incoming fluid ( frictionless hydraulic cylinder ) so the pressure in that inner-most riser will be the highest. Two forces there too, hydraulic lift from pressure and buoyant lift from displacement.
The other risers DO also contribute to lift from both pressure and buoyancy so all parts are contributing in multiple ways.
No wonder the math guys are having trouble......

[wildew]

TK I think. It would be nice to be clear on this point, especially in the sketches, sims and thought experiments. Sometimes oversimplification can lead one astray.

Wholeheartedly agreed!
Maybe sketches should show a different colored separation between masses of water there. From thought experiments, a mostly frictionless cylinder of sorts. Energy calcs should also take into account the force required there to stroke. I believe roughly 30 percent of the stroke output from one ZED is applied there to cause the opposite one to stroke.