Big problems getting my first stirling to work..Help

[larsinist]

I have done Coke Can Stirling Engine but i can get it to work, so i have been thinking it have to be the cranck shaft,i have build the diaphragm of a bottle neck, i just cutted the top of, and turn it upside down and i use a grommet to make a good seal for the hose. the piston is just of roockwool/steelwool

I need som help here, i am can do everything you ask me to do, just please help me

[larsinist]

Here is the 90 degres offset,or is the hose to long?..
the crank is uinstalled cause i think there is something wrong there

[tomostre]

check seal: press lightly against the walls of pressure vessel. Does membrane react? if so, good. Check that it is not too tight - if the membrane is too tight, the pressure is insufficient to stretch it to make a 12x2mm stroke - heat the pressure vessel and move displacer by hand, does the membrane react? If it doesnt react enough, see if your displacer volume proportions are good. If it inflates but deflates without moving displacer, you got an air leak. A good membrane will spring up when you pull up on the displacer, and go down as quickly when you drop the displacer. Also, keep in mind your membrane stroke should be more then your crankthrow, i.e if your crank is 12 mm, your membrane should be at least 25mm between the lowest and the highest position.

Is there dead air under the membrane?

[larsinist]

i have checked the seal,the membrane react when i press the walls!i dont thing the membrane is thight, but i will dubble check it..my membrane moved 5mm så if i understand you right, i need my crank to be 2.5mm?

[tomostre]

the stroke (up and down movement of the membrane) should be sufficient for the crank to make a full turn, so yes. A consideration though, is that smaller crank throw will give less leverage - to lift up the displacer, once the whole thing is connected.

[larsinist]

its running, it was the membran to thight, i will take a video of it

[larsinist]

[youtube]https://www.youtube.com/watch?v=OtRJ2o6 ... e=youtu.be[/youtube]
https://www.youtube.com/watch?v=OtRJ2o6 ... e=youtu.be

[larsinist]

It stopped when it became warm, and i think i got an air leak in between piston section and the topp section,so now i have glued it with epoxy,i think that will solve my problems,i will also build a cooling system,but first i need it to run again!
Are there any other ways to lift the rockwool piston then the nylon wire,cause i think its leaking alot there,so are there other ways i could build the piston to crankshaft,instead of the nylon wire?

It was really fun when it started,so i hope i can do it again!,one more question,can i use a straight rod from the membran to the crank shaft?,the one i use now are in zig zag

Thanks for all the help i have got so far,and sorry my bad English

[tomostre]

generally, nylon fishing wire going through a piece of inner tube will leak less then other heavier metal shafts. I would think of different gland designs, i guess the fun is testing one design vs another. Friction is the biggest enemy there, more then the leaks.
As far as your pushrod - yes it can be straight, but be sure to measure it to the right length (i think they suggest a zig-zag so you could adjust the length)

[larsinist]

i have read alot of the brass rod,they say the sterling can make more rps with the brass rod,what if i purchase a brass rod in 0.2mm and a brass tube with a innerdiameter on 0,2mm,and polish the rod so there will be minimal friction,what you think of that?

[tomostre]

Great, go in the direction your gut takes you. Your first stirling is running, right? As a reference point, there are many variables that can make it more efficient, from density / weight /size of displacer, to length of tube (volume of dead air), bearings, flywheel design, crank throw, membrane material, etc. Pushrod becomes an issue when downward acceleration of the crank exceeds g (roughly 9.7 m/s /s) and you see your fishing line slack. That will happen at (correct me someone) say, the order of 200 rotations per minute?
the shelf that your power membrane is sitting on seems to flex somewhat; if the energy required to bend your engine like that at every rotation, went to turning of your flywheel instead, results could surprise you. Cheers!

[larsinist]

its my first yea, but its in small pieces, the membrane mount flex alot, so i shall build a new one,i just need to deside what parts i shall order.i am thinking of using ballbearings to the flywheel shaft.
so what about a 2mm flywheel shaft/crank shaft?,with 2 ballbearings with a inner dim at 2mm.and i am also thinking of using the 3/4" brass tube with epoxy piston as membran,will that give me more rpm?

And that dead air, can you please explain it???