But for good or for ill?I just had the thought that the volume of the steam pipes going to your turbine might be big enough to give you some cushioning from the steam itself acting as a spring.
But for good or for ill?I just had the thought that the volume of the steam pipes going to your turbine might be big enough to give you some cushioning from the steam itself acting as a spring.
The graph does not represent what will happen. For instance to calculate the pressure with the base hypothesis of four active cylinders you would have each area times the force total force of the pistons to yield one pressure output. This should be a constant. The pressure will dip when one cylinder is removed and increase when its replaced by another. So the pulse frequency will be when the pistons unload and load. The more active cylinders the less the pulse will be, but still depends on the volume each cylinder produces.Question for the pump experts:
Below is a graph of what I believe the Pressure out over time (or shaft rotation) of a 9 piston swash plate pump would look like. The GREEN lines show the pressure & flow rate of the 4 pistons which are actively supplying pressure and flow at any given time in the pumps rotation. Because there are 4 pistons pushing fluid out at all times, pressure at the output should never drop below the "Average" line.
Am I right or wrong ??
View attachment 156716
View attachment 156717
That makes sense to me, especially the difference between the axial and double acting pump.
The reason both triplex and axial pumps have 3 pistons is the pressure wave overlap. If those double acting pumps of yours are holding up to the heat, what about driving 3 off of jack shafts from a common motor. Then you'd have 6 pulses that you could overlap?
I tried to find a chart showing actual piston velocities in a fixed swash plate system, but all I could find was papers on variable flow swash plate units, where the piston travel is not fixed.
Seeing the actual actuation behavior of the pistons on a graph would have been nice.
In terms of resonance between the pump output and coils, I personally think it would be obvious. The license plate on my bike has a couple points where it resonates with the little bike engine and it causes a very audible racket. your system should act in kind, with resonance... well... resonating.
It seems to me that if you added a couple of accelerometers to your unit, in places they won't get cooked, an arduino should give you the pressure spike induced system vibrations as a simple to graph read out. Any sudden spikes in the vibration would let you know if you hit resonance.
To be clear it wouldn't likely show the pump graph but the overall system "noise" as I assume that the tubes generate lots of vibration as they vaporize the water.
The units are cheap so it wouldn't break the bank, if you are concerned about resonance.
Does that make sense?
Oh boy I can't wait for this move to be over. Then you guys can dog pile my projects
Since, as I recall correct me if I am wrong, you're boiler is intended to operate above the critical point, you might have more cushioning then you think as you will have the water phase changes to absorb the pulses?
Edit: I was staring right at the forest but missed it because a bunch of trees were in the way
check out fig 6
https://tud.qucosa.de/api/qucosa:71101/attachment/ATT-0/
It shows the behavior of a single piston on a fixed plate.
Actually most of the paper is useful because while it is about variable plates, it is comparing them to fixed plates.
Hope this helps.
Yes, adding accelerometers to sense & measure vibration is a good idea, especially during the development phase.
And you're right about the boiler making a fair bit of vibrations as the water first begins to boil, but it quiets down once the boiler is putting out a steady flow of steam.
Move ?? What move ??
I can only get to the critical point with R123, or some other Organic working fluid. The critical point of water is 374 C
and 3,200 psi,...my copper tube boiler would most certainly rupture long before I reached those numbers. The critical point for R123 is 184 C at 533 psi, which is well within the capabilities of my boiler.
That's a interesting paper you linked,... the primary focus is on how pump pulses cause a sort of feedback problem, where the pump pulses induce small changes in the angle of the swash plate in a variable plate system, which then causes more pump pulses. This all occurs because the swash plate angle controls use the hydraulic output from the pump.
Yes, adding accelerometers to sense & measure vibration is a good idea, especially during the development phase.
And you're right about the boiler making a fair bit of vibrations as the water first begins to boil, but it quiets down once the boiler is putting out a steady flow of steam.
Move ?? What move ??
I can only get to the critical point with R123, or some other Organic working fluid. The critical point of water is 374 C
and 3,200 psi,...my copper tube boiler would most certainly rupture long before I reached those numbers. The critical point for R123 is 184 C at 533 psi, which is well within the capabilities of my boiler.
That's a interesting paper you linked,... the primary focus is on how pump pulses cause a sort of feedback problem, where the pump pulses induce small changes in the angle of the swash plate in a variable plate system, which then causes more pump pulses. This all occurs because the swash plate angle controls use the hydraulic output from the pump.
I can relate,....when I moved from San Francisco to Thailand I waited for 3 long months for all my household goods, including all my hand tools and benchtop CNC mill, to arrive, then several more weeks for my crates to make it through Thai customs.I'm in the middle of a move and thus between houses with no functioning work shop, so I can't start anything. Only dream lol.
Sorry I got the criticality mixed up.
Well happily it's not that rough, but the new place had a lot of hidden work. I was supposed to be happily nesting in a pile of swarf months ago!I can relate,....when I moved from San Francisco to Thailand I waited for 3 long months for all my household goods, including all my hand tools and benchtop CNC mill, to arrive, then several more weeks for my crates to make it through Thai customs.
Out of curiosity, any updates?
Yup, it's the rainy seasonMore test parts arrived and I'm ready to connect them to the boiler,....now, if it would just stop raining :-(
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My boiler test stand,... under the very wet, black rain cover.
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