a possible diamond in the rough: a powerful engine(almost)

[onecycleDan1990]

I have posted in a prior thread about a gamma engine design from 1904 with a very high torque for its displacement, and mentioned Bill Gross' Sunflower solar engine as a good starting point for developing a simple useful engine.

I believe I have found an example of just such an engine, or at least something with the potential to be a 200 or more watt engine with minor changes.

It is a mostly conventional unpressurized gamma engine mistakenly described as having a martini displacer; it has a conventional crank drive for its displacer and the same for the power piston. perhaps it has a regenerator built into its displacer in a manner similar to that of the old Robinson engines and an incorrect? name was used.

It would appear to put out a great deal of power; it was featured in an old youtube video where its bearings and pistons are screeching and smoke is emanating from the base of the power cylinder and possibly one or more bearings. Despite these enormous unintentional loads it still spins at a reasonable speed.

Its flaws appear to reside in execution, not in concept. there is clear potential for this gas circuit, but the engine was crudely built and had far too much friction to realize its full potential. My main guess is that there was a deadline to meet, and precision work would take too long.

I think It would be an interesting experiment to get the gas path dimensions and build it in a manner that would allow it to better realize its potential.

here is a link to the video: http://www.youtube.com/watch?v=NTpQKc3RPTU

[Ferraccio]

it is difficult to argue with "it seems that it seems.
For an engine not-pressurized, with the size that may be is imagined from the video, (piston engine of about 45-50 mm in diameter, stroke of 40 mm) for the resulting displ. of about 60-70 cc, I believe that it can not give more than 12-14 watt.
I rely this on the hypothesis of a line that combines the results of "well designed and built engines", as given by the formula of Beale.
see: http://www.sesusa.org/SEDAF2.htm
The excel sheet can be considered by setting
1) the power to be obtained,
2) the frequency (number of revolutions per second) and
3) the pressurization in MPa (atmosferic = 0.1).
- when 1 Mpa is equal to 145 Psi - the output is the displacement needed.
For have 200W (atmosferic) should realize a 1058 cc (good) engine.
Because I know not very well the English language I ask that this formula should be examined to see if I understood well.
Power of 200W can be achieved (with good design, and excellent contruction) with more than 100 cc, and pressurized to 145 psi (1 Mpa).

[Ferraccio]

By a simple control of MP1002CA Philips characteristics,
(beta type)
http://home-and-garden.webshots.com/alb ... 6922iLEEFG
and wikipedia:
http://en.wikipedia.org/wiki/Stirling_engine
"twentieth century revival" paragraph.
manometer pressure 1.36 Mpa, (200 psi) ; 1.46 Mpa absolute .
bore 55, stroke 27 = 64 cc,
is declared 180 up to 200 W
Extracting the number of Beale, it is not so away to 1 up to 1.11; and that is a good datum, considering that some energy (I think about 15-18%) is lost for a self beared compressor to maintain the internal pressure, for counteract the escape of air from the shaft seals.
The lost energy was not considered, at that stage, important, having the advantage of the external flyweel, that admit manual start.
However this advantage is counterbalanced by the need to store compressed air in a reservoir, with a complex start procedure.

[Ferraccio]

I correct myself: Beale number not away 0,11

[onecycleDan1990]

I thought it looked larger than 50 mm bore in the video
Also: there is something wrong with a 70 cc engine that only produces 12 to 14 watts; a properly designed flame heated engine will produce over a watt per cc of power piston displacement.

The phillips 62.3 cc generator produced 180 to 200 watts electrical output as a continuous rating. according to Making Stirling Engines by Andy Ross the actual output of the engine itself was between 450 watts and 688 watts. The type 10, from which the 102c and mp1002ca were derived produced fully a horsepower and at (if i recall correctly) less pressure than the mp1002ca.

In a book I no longer have (stirling engines by G Walker), it is stated that a water cooled, higher compression ratio engine using the Phillips generator block produced 2.7 horsepower (2025 watts) and powered a boat with four people aboard at 9 knots on the nearby canals.

My earlier mention of the Idealabs Sunflower engine was a high power likely unpressurized alpha with a plain hot cap. It produced 250 watts electric, and presumably more mechanically than the Phillips genset due to a solar thermal generator needing a more intensive turn down ratio than a kerosene fired engine. A video describing its development and showing the engine and a cad drawing of some of its internals can be seen at: http://www.ted.com/talks/bill_gross_on_new_energy.html. admittedly it is a larger engine than the one in the youtube video, but it is still putting out alot more than .15 w per cc.

What heat source were you assuming I would use. I would heat my engine's hot cap to bright red temperature with a wood gas in a cyclonic burner (the kind used to melt aluminum by the pound in crucibles)

[Ferraccio]

Onecycle,
My estimate is about a movie, without other information, but this movie shows that the technology is not at an advanced Philips study which lasted ten years.
If the displacement is greater than 50, my assessment must be updated accordingly, the stroke on the other hand it seems to me less, reviewing the movie.

However, I must note that it is strange that all build engines, but few actually tell how much energy they produce, all are content that they are running, and this is a bit 'wonderful little to define them, (as engine) mechanical jewelry. Unless there are levers plated in gold, and diamonds into the pins.

For the Philips engine, seems strange that the mechanical output is more than three times the electrical, (180-up to 230 W), where does all the energy? The transformation mech.-electr. absorbs very little power, and the bearings of the electric generator and a belt should not absorb more than 8-10%, and is a lot. Are we confident that we speak the same engine? Philips has made ​​many experiments under extreme conditions, and with different engines with external compressors, and pressures.

I am not a supporter of the Beale formula (for mid-level engine amateur) I would however like to have (as I asked ) data returned, and this data I'm looking for them too.
So I proposed to put the test: if it is always acceptable, or in what conditions, if it is incorrect, and to be amended.

[Ferraccio]

In forums are often acts of faith,
but it is strange to find so frequent acts of faith in a forum that deals with mechanics and thermodynamics.

[Soeren]

...
However, I must note that it is strange that all build engines, but few actually tell how much energy they produce, all are content that they are running, and this is a bit 'wonderful little to define them, (as engine) mechanical jewelry. Unless there are levers plated in gold, and diamonds into the pins.
...

I did :-) even it is a LTD and 2mW is not really powerful.
But I agree with you. Without exact measurements and figures it is hard to compare all the different design approaches, what we find in the internet. In my opinion with more figures we would better and faster learn, what are the important things, that differentiates a good from a not so good engine. Without figures we have to do it the hard way: Smith analysis, isothermal analysis and all this theoretical stuff....

MfG
Soeren

[Ferraccio]

I think You're right,
I note again the possibility kindly done by jimlarsen to download the book of Andy Ross,
"Making Stirling Engines, by Andy Ross"
http://StirlingBuilder.com.
Quote/// Andy Ross is one of the leading Stirling engine designers of our time, and he loves to share his work so others can build and enjoy his well designed engines.///Unquote

Stirling engine is adapt to be designed by experience, and Andy speak about this; and speak also about the approach, (or better the poor utility...), to the high theory, and the importance of other elements....
Personally I think that having test data, the Beale formula, that is only a simple empirical formula established by the averages of many medium-level engines built and tested, tells us whether we have built a jewel ...(or something a bit less).

So Andy's book to see what he has built (and the mistakes he made​​, thanks to him if he says them!), and a simple formula on excel sheet, where by placing the data of our engine (displacement, speed, ...) we may know at what level we are.

[Ferraccio]

One more point: the Beale formula, does not affect the engines big or powerful, but only the quality of the engines, if the engine is reputed good, with data what we put on, the power should be ....; if the engine was excellent ... power should be...
Simply to have a goal to be achieved, and not just "see if it turns. "