Design/Build One HP Alpha Stirling Engine

[blairmc]

Where can I find more information on how to build a one horsepower alpha stirling engine? Are detailed design plans available? How does one evaluate using air or helium as a heat transfer medium? How or can one create a sealed bushing sufficient enough to keep the helium within the pressurized chamber?

Thanks, Michael

[Ian S C]

To solve the problrm of crankshaft seals; don't use them. Build the motor with a generator built in with no shaft coming out of the motor, all you need is the wires sealed, the flywheel is inside as well. Ian S C

[blairmc]

If you used helium as a working fluid, what pressures are common?

[Ian S C]

Pressures up to 200 atmopheres, or near to 3000psi have been used with Hydrogen, and Helium. THE Phillips engines used air at up to 20 atmospheres, or 300psi, these are the pressures that us lesser mortals might aim for, the higher pressures require some serious engineering, this is where the real power comes from. Ian S C

[Ferraccio]

Engine close in a shell, needs inside also a start motor (or the generator that supply starting action). In fact the motor have to be started...., as all thermical engines
The use Hydrogen or helium, instead of air nitrogen impacts on dimension of tube/clearances, for eat exchanges (hot side-cols side-recuperator).
Hydrogen and Helium are quite similar (the first is a bit better, and less expensive than Helium, but have to be treated with more attention), are both very small molecules, and runs very easily on VERY small piped and holes (0.2 mm).
Air is quite similar to Nitrogen, air have no cost but is oxidant, for the use of air in a pressurized body is bettere try a thecn. solution without oil lubricant (no risk of explosion). Nitrogen is not many expensive and is neutral. Air (mix of oxigen and nitrogen) and nitrogen have large molecules, that have equal larger viscosity in passages through holes and clearances.
For hi-tech engine (very small pipes, and very small clearances) the enormous increase of the exchanging surfaces overpas the main problem of this type of engine: the change of the heat of the outside; this largerly overpass (as advantage) the fact that being small molecules (small mass) carry, at the same pression less heat.
For medium level engine air or nitrogen may be are sufficient.
Is really important (and possible) do NOT use liquid lubrication, using coating in Molybdenum, graphite, teflon, and compound materials in the bearing/friction points , and overall with a good architecture of the engine, that carry the friction points in colder sites.
The use of intrinsecally lubricant materials simplify many problems.

[blairmc]

Engine close in a shell, needs inside also a start motor (or the generator that supply starting action). In fact the motor have to be started...., as all thermical engines
The use Hydrogen or helium, instead of air nitrogen impacts on dimension of tube/clearances, for eat exchanges (hot side-cols side-recuperator).
Hydrogen and Helium are quite similar (the first is a bit better, and less expensive than Helium, but have to be treated with more attention), are both very small molecules, and runs very easily on VERY small piped and holes (0.2 mm).
Air is quite similar to Nitrogen, air have no cost but is oxidant, for the use of air in a pressurized body is bettere try a thecn. solution without oil lubricant (no risk of explosion). Nitrogen is not many expensive and is neutral. Air (mix of oxigen and nitrogen) and nitrogen have large molecules, that have equal larger viscosity in passages through holes and clearances.
For hi-tech engine (very small pipes, and very small clearances) the enormous increase of the exchanging surfaces overpas the main problem of this type of engine: the change of the heat of the outside; this largerly overpass (as advantage) the fact that being small molecules (small mass) carry, at the same pression less heat.
For medium level engine air or nitrogen may be are sufficient.
Is really important (and possible) do NOT use liquid lubrication, using coating in Molybdenum, graphite, teflon, and compound materials in the bearing/friction points , and overall with a good architecture of the engine, that carry the friction points in colder sites.
The use of intrinsecally lubricant materials simplify many problems.

What do you mean when you say that "runs very easily on VERY small piped and holes (0.2mm)"? Small piped what?

Thanks

[blairmc]

Engine close in a shell, needs inside also a start motor (or the generator that supply starting action). In fact the motor have to be started...., as all thermical engines
The use Hydrogen or helium, instead of air nitrogen impacts on dimension of tube/clearances, for eat exchanges (hot side-cols side-recuperator).
Hydrogen and Helium are quite similar (the first is a bit better, and less expensive than Helium, but have to be treated with more attention), are both very small molecules, and runs very easily on VERY small piped and holes (0.2 mm).
Air is quite similar to Nitrogen, air have no cost but is oxidant, for the use of air in a pressurized body is bettere try a thecn. solution without oil lubricant (no risk of explosion). Nitrogen is not many expensive and is neutral. Air (mix of oxigen and nitrogen) and nitrogen have large molecules, that have equal larger viscosity in passages through holes and clearances.
For hi-tech engine (very small pipes, and very small clearances) the enormous increase of the exchanging surfaces overpas the main problem of this type of engine: the change of the heat of the outside; this largerly overpass (as advantage) the fact that being small molecules (small mass) carry, at the same pression less heat.
For medium level engine air or nitrogen may be are sufficient.
Is really important (and possible) do NOT use liquid lubrication, using coating in Molybdenum, graphite, teflon, and compound materials in the bearing/friction points , and overall with a good architecture of the engine, that carry the friction points in colder sites.
The use of intrinsecally lubricant materials simplify many problems.

I would assume that if you have an enclosed generator you could use it as a starter motor also?

[Aviator168]

What do you mean when you say that "runs very easily on VERY small piped and holes (0.2mm)"? Small piped what?

In order to get more heat into the system. The larger the contact surface the heat exchanger, the better. However, you have to do it with the least amount of dead space. So designer has been using small tubes for the gas to go through to pick up the heat. The smaller the ID, the more tubes you can use without increasing dead space and at the same time increase contact surface. Since Hydrogen and Helium have molecules, it is much easier for them go through those small heating tubes than, say nitrogen.

[vile_fly]

For anyone interested, you can use a GM alternator as a motor without anything more than soldering 3 wires in place and hooking them up to an electric brushless (3 phase) R/C motor speed controller. They are the new standard, now. Brushed motors are out. A cheap 30 amp unit will drive a 100amp GM alternator up to 768 rpm. There is your starter-generator in a nutshell.

Here's a link to the cheapest supplier of 3 phase R/C brushless motor speed controllers. Be sure to get the Turnigy servo tester so you can eliminate having to use a receiver-transmitter combo with a simple knob instead.

http://www.hobbyking.com/hobbyking/stor ... entCat=182

[Ian S C]

One gas thats easy to obtain these days, is Argon, the motor used it at 1100psi.
The Phillips motor used oil, and was pressurised with air, they did'nt seem to have problems. The Phillips motor could be started by motoring the generator. It had a little compressor built in to maintain pressure, and extra air was stored in the tubular frame that surrounds the motor. Ian S C

[speedless]

Hi 'Michael
Look at this for idees.
http://www.stirling.dk/page_content.php ... pe=submenu
Jan

[blairmc]

Stirling_Engine_Design.jpg (185.2 KiB) Viewed 15254 times

In reading the design spreadsheet from SESUSA, it talks about the length of the regenerator, the diameter of the regenerator housing, the free-flow area of the regenerator, the diameter of the regenerator wire, the mesh number of the wire mesh, and the number of gauzes in the regenerator stack.

Can someone explain these based on the above image?

Thanks, Michael

[Aviator168]

Can someone explain these based on the above image?

Thanks, Michael

Don't know exactly what you mean. Both the left and right engines are of double acting alpha type. As for the regenerator, it should be designed to be able to absorb/release the amount of heat injected into the engine in one cycle within half cycle time.

[blairmc]

Can someone explain these based on the above image?

Thanks, Michael

Don't know exactly what you mean. Both the left and right engines are of double acting alpha type. As for the regenerator, it should be designed to be able to absorb/release the amount of heat injected into the engine in one cycle within half cycle time.

I was reviewing the "Gas Circuit Scaling Spreadsheet" from SESUSA (http://www.sesusa.org/SEDGCS2.htm) and do not understand the section on the number of tubes for the expansion and compression areas? Nor do I understand what they mean by the diameter of these tubes, internal or external?

Thanks

[Ferraccio]

Was well indicated the importance in small clearances for hydrogen and helium, clearances are of course the passages of the gas, and so the internal diameter of pipes.
Using the air the "viscosity" of the gas do not admit flow through so small pipes/clearances without huge losses for friction in the flow.
In fact the large generators (up to hundreds of MW) for large electrical power plants are hydrogen cooled; the small diameters with a lot of tubes produce enormous increase of surfaces exchange.