88 minute run of the Microstirling on 8ml of meths

Reid · 88 minute run of the Microstirling on 8ml of meths

My Hog engine is well run-in. The Hog is perhaps the most sensitive, easy-running
of all the micro stirling engines out there.

I think this owes to the superb engineering: self-lubricating plastic pistons
working frictionlessly in perfectly round, smooth, glass cylinder bores.

There is no metallic rubbing, and no oil on the sliding surfaces.

It is a fine, fine design and as precise as a Swiss watch.

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This video demonstrates
http://www.youtube.com/watch?v=5ytXbeAfqK8

the longest run I've gotten from the engine to date.
Of course, it is done by running a minimal flame.
Yet, the engine still does work, spinning the Wilesco color wheel for almost 1.5 hours.

Moreover, it points me in a direction for high efficiency meths burner design
which I will be putting on trial when I get a toy steam engine here some (happy) day.

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I am interested in borosilicate ("Pyrex") glass tubes and recessed glass fiber wick:

Deeply recesssed for a minimal flame. It can also run flush for a fatter flame.
Of course, increasing diameter of the glass tubing (it comes in all diameters)
will make proportionately larger flame.

The aim: to vaporize alcohol without degrading the wick.

Glass is a poor conductor of heat.
However, at the tip of the font the glass grows HOT enough to vaporize the fuel.

So, how is this any better than, say, a metallic tube?
=The metal tube may tend to rob heat from the top of itself by useless, and sometimes runaway, thermal conduction.

The other aim and result: I find that a recessed wick does not char, blacken or gunk-up.
It is protected from degradation

British meths is dyed purple.
I suspect that such dye would degrade the operation of this system in a short while,
because the dye will not burn, and may well clog the fine capillarity of the thousand-strand wick.

On my side, USA denatured alcohol is clean and residue-free.

So, for myself, I am optimistic that I can make a burner for a horizontal boiler, on this line of thought, of glass up-tubes, fitted by compression o-rings,
or simply potted in silicon RTV, into a horizontal reservoir tube,
with multiple, soft blue flames, smallish-ones (better carburation)
playing directly on the boiler bottom--perhaps four or five or six such burner tubes, larger in diameter
than the tiny tube I use for the Hog's font.

When we smell alcohol fumes, what we are smelling are the products of incomplete, poor combustion.
No sort of huge pyre-of-a-flame can burn all the fuel
because there is not enough oxygen mixed into such a raw conflagration, ie: an Esbit fire in the firebox throws smoke and tarry matter--
and a rough meths flame is only better in degree that it does not have Esbit's chemically noxious and carbonaceous matter in it.

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This dream plan may or may not work. But I think I have interest now in working this out because...

...I have recently met Esbit for the first time, and it sucks so badly,
I will not fire my next new engine, ever, with Esbit.

$7US for the very finest floss of glass fiber:
far thinner strands than the OEM wick that came in the Hog's lamp,
enough to make hundreds of custom wicks for any lamp.

James

That's great Reid!

I really want a stirling

IndianaRog

Reid,

Thanks for such a great dissertation, video and even the parts source for the glass. 88 min of run time is amazing on your HOG...but your principles of fiberglass threads inside a pyrex glass tube set your burner ideas apart from the rest of us which are for the most part replicating Mamod or Bowman burner designs to one extent or another.

I was going to fabricate a proper meths burner for my D455 soon, but I think I will let your creative juices run for a bit and learn from your experiences. I was otherwise going to replicate the burner design on my meths fired Jensen 25 conversion which is really a Mamod style burner with upright ammo casings fed off a common fuel tube at the bottom. Maybe glass tube and fiberglass would lend itself to a larger burner design like your HOG but firing a D455.

As for disliking the stink of Esbit...you join a long line of folks who have gagged their way thru a steam up like you. Meths is a far better option vs. esbit, if you want a flame.

cheers,
Rog

johnreid

88 minute run of the Microstirling on 8ml of meths! I could run one of those forever!
Those are the most fascinating machines.

Reid

Thank you, gents!

You can tell when I get excited about a brainstorm.

I didn't invent the glass font, of course.
The suggestion came from the Hog's standard, very short glass font.

That technique of theirs is a genius stroke, for what it does,
is to keep their meths pot stone-cold. It is a very safe design.

When I put this Hog to the trophy base, and thought to employ one of the two pre-drilled badge pin-holes for mounting the lamp,

the lamp was too far below the engine's hot bulb.

SO, I bought some tubing from SPI and the tubing cutter,
and there I had a longer font.

Recently I experimented with flame placement and found that,
with this tiny and very sensitive engine, it was easy to see
that the best results come from direct play of a clean blue flame
right on the bulb;
in this way I could reduce the flame size without losing power,
relatively speaking.
So I made another, even longer, font.

And by putting the wick flush, or below the font tip:
no more wick blackening.

So there it is, uber-simple, and one step beyond the Hog's font's design.

Am -sure- in my intuitive mind that this idea of glass fonting and flush-wicking
can afford to us all a new generation of superior meths burners.

As noted, due to the desirability of complete combustion,
a mulitiplicity of moderate-sized flames will trump one or two fat flames (in theory)

It is still necessary to put the same heat to the boiler as with conflagration burners.

What I proposition is, that we can do this, all the while putting fewer BTUs to the flue, so to say;
and spew fewer odors into the living room.

Needing now expert advice on how best to graft glass up-tubes to
a reservoir base.

I wish I were a machinist.

Roger, take a look at your Hog's burner cap?
inside, there is a threaded ring that mushes down on an o-ring,
which thereby grips the glass tube to a secure mechanical bond,
liquid-tight.
It's just a very good, simple, safe design they made there.

I write too much. Pardon my yakking here?

PS: An Esbit tab, burned in an ashtray for a trial,
is more nearly odorless than when burned in the oxygen-
starved confines of a firebox.

Why? In an open burn it more nearly, fully combusts;
less of the unburned vapours get away.

Thanks all,

Reid

Mister Occlusion

Interesting observations on esbit combustion at the end.

Even more interesting are your chosen wick tubes.

I hadn't thought of fiberglass mat for wicks. I've tried 0000 fine steel wool for a non-degrading wick and wadding material. Works okay, but I think I packed it too tight, so my burner gets starved for fuel.

A compression fitting to hold the tube in is a grand idea. For an alternative, is there a high temp epoxy putty type product out there that would do?

You probably still won't go far wrong with thin brass tube either. I can see your point in not heating up the fuel cell, by using the pyrex, but inside a firebox your whole burner is going to get roasting hot in short order anyway. (out of interest I clocked the outside surface of the model 75 Jensen and it was about 250-280c, as I recall [if the thermo sensor was accurate])

Best method, I think, for not overheating your fuel has to be the age old design paradigm of having your wick or vap burner element inside the firebox and the fuel cell as far removed outside as possible.

And remember: everything in the firebox gets brazed

...well, at least with high temp vap burners like I seem to have been making..

My own order from small parts arrived the other day. They were supposed to let me know the shipping charges first. So here I have this big triangular FedEx box that came via air, and I am blissfully ignorant of both shipping charge and FedEx's undoubtablty extortionate fee for doing the customs work that I did not ask them to do.

I expect to be utterly brassed off within 4 to 6 weeks...

In the meantime I have my 5/8" square brass tube that I needed, and a selection of telescoping copper tubing in 36" lengths of the 4 smallest sizes. Hopefully that is easier to work with than brass (which means it ought to look better when I'm done with it).

Reid

Hi Mark, right. I too think it best to put the main fuel supply outside of the engine, sure.

NB: there are a number of possible pitfalls in this very rough design by me: a guy with zero practical experience.

Thinking out loud again,

First: I don't know how to use MS Paint, lol.

The black line denotes the approximate position of the tops of the glass tubes
(this would put the controlled blue flames in soft play right on the boiler bottom)

= in this scenario, the firebox opening would require cutting away,
something few would like to do. But I'd do it to my (new) engine!

=you can appreciate that by the relative great distance from flame-start, to fuel manifold, the heat problem will be no problem,

=especially since the horizontal manifold is liable to be a four or five inch long piece of 1/8th inch iron water pipe,
drilled and tapped for small, brass compression fittings,
which would grip the glass tubes by neoprene o-rings, and not by copper collars.

I would hope to NOT use epoxy instead of machine parts, at least in a permanent design.

By feeding the air supply from the bottom of the base (by ventilating as necessary,) there should be a cold floor to that firebox, anyway.

And, too, we can make a heat-reflecting card of fireproof, white fiber sheet (I forget the name of the stuff, used in industry; I once had some of it)

At any rate, I don't see any trouble with heat boiling the alcohol in the tubing manifold (the iron pipe).

An external tank can be safely connected to the manifold either in the Mamod sort of way,

or remotely located via copper of by fuel line hose.

A sight glass on the tank can tell the fuel level.

The relatively tall glass up-tubes operate the same, whether the manifold is near empty,
or if the fuel liquid level actually were allowed to rise'way up into the tubes' height. The vaporization will be the same.

HOWEVER in the unlikely event of a mechanical breakage or leak,
a stand-glass of fuel with a hydrostatic head on it = fire in the hole!
not good!

So we won't aim to have a high fuel level. A wet manifold pipe will suffice.

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Many little possible pitfalls. A new way to burn down the house.
Or possibly, this will "engineer" (ha ha) very easily. Aside from the need to butcher a nice engine's firebox opening,
which I could only avoid here by installing the entire burner from -underneath the engine's baseplate-, I see no problem yet

except to learn by practice whether this proposition is workable in practice.

idea pictures to follow, using the D455 as an example:

Reid

Here are two shots of the Montagsmodell D445 that I posted back to Matthias Brenner the other day.

Products of incomplete Esbit combustion

Result of the burn of just one box of Esbit in that new engine. That sort of coking-up must reduce thermal transfer to some degree.

Re: in possible conversion to a tall-tube meths burner, note the Esbit burner tray guide. I think I would discard that tray guide:

The brass cone appears to be an extension of, and stand for, the boiler.

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Rounded brass tabs: boiler mounts
Silver tabs: Esbit tray retainer
Copper tabs: the coppered brickwork.

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IF one really wanted to, the manifold could be put below the engine base....how much cooler could it get there?

redryder

Hey you got me going over here with that video.
I don't have a colr wheel but I sure do have a little Hog motor and I had forgotten how much
fun they are. I will go and dig it out now.

Gil

tmuir

Thanks Reid, finally got around to reading this thread.
One of my biggest problems is finding suitable wick of correct diameter for all the different sized burners I have, Never though of pulling apart a sheet of woven fibre glass. I'll be taking a trip down to my hardware store in the near future to get some now.

That's what I love about this forum. The wick idea is so obvious it was slapping us all in the face but none of us saw it until now and now there will probably be collectors all round the world with smiles at the thought of a new source of cheap and easily available wick.

Reid

IndianaRog

Jeez Reid,

Some very creative thinking there. I'm thinking however you could remove the Esbit tray holder tin thing and perhaps be able to insert your burner design in the firebox opening WITHOUT needing to cut into that opening...possibly just slanting the burner towards the upper corners of the opening to get it in with a little jockeying.

Your other thought for a burner that inserted from beneath has already been invented about 70 years ago...Mersey engines of England used that exact approach and the upright burner tubes were inserted thru a wood base no less. Using your D455 as a test bed for the concept, you "could" make a shallow meths tank that fit squarely UNDER the D455's light blue metal floor. Upright glass tubes could then fit up thru the very holes already present in the center bottom of the light blue part. Only tough part would be fitting the whole D455 down precisely so as to center those glass tubes into the holes, but I'm sure the burner tank could be made to fit the underside exactly or centered with outriggers that touch the corners underneath.

I'm gonna give this idea some further thought...I have wanted to make a permanent meths burner for my D455 vs. using a Bowman burner...this is the perfect excuse to dabble!!

thanks,
Rog

Reid

Thank you Rog, I think you must be exactly right.
Yes, if we put the burner manifold below the base,
it could be the entire reservoir then.

And that would obviate any compulsive want of mine to butcher a firebox opening taller.

And yeah! All this has been done before; it's hard to get a really new idea, but you have more equipment
in terms of experience and in tooling to do more than "dabble".

So, Roger, do it!

Meanwhile I'll look, listen and learn by you guys.
Mein spiel has been sung. Or sprung,
whatever!

Mister Occlusion

Geez....That's a great idea.

You could also do up a burner like some of the old German engines had: round tin with a couple wick tubes in the top.

But yes, the essential problems to overcome are how to mount such that it is secure and also easy to refill.

Of course you could always set it up like a car fuel cell: semi permanent hidden mount underneath and a bit of copper pipe coming up and out to fill it through... probably with one of those syringes with the tapered tip or a squeeze bottle with a luer lock needle on it. You'd naturally have to know exactly how much it holds, and light it with one of those BBQ or candle lighters....

I'm still going to pursue my chicken feed approach. I like the design I've got for the model 75 now. It's a proper and stable mount. I just need a better burner element. Might try shallow wick tubes next time.

Rog? Didn't you say that you used old Jensen asbestos insulation sheets for wicks once?

IndianaRog

Mark, I did indeed use old asbesto strips for wicks...I rolled them up and inserted inside ammo casings as can be seen below:

They work beautifully and I see no risk in using them with care...made them up OUTDOORS with wind at my back and a surgical mask on. I don't touch them now they are made up...I adjust the flame height with the moveable sliding collars of aluminum tubing that I can move up and down the casings...works a treat!!

Rog

Reid

Reid

Mister Occlusion

Ah, thanks for the dandy photo, Rog; I've not seen that angle of it before.

So it functions more like a vap burner than a wick burner. I had wondered about that.

Reid: remember there's nothing new under the sun. Just new ways of implementing the old ways.

It works for me, because I know that any type of element I try has been tried before and works (because I've seen them). It's just up to me to see if I can make it work better for the application that I need it for.

So far I've had mixed success, but have learned a few things.

The school is Trial & Error U, and the teacher is Pain (well....mostly for those lessons where something goes horribly wrong..)

IndianaRog