Daft idea? Flash steam engine..

[John Hill]

So many daft ideas I cant get started on any of them!

So here is another one...

A simple 'steam' engine, single cylinder with water jacket.

A simple (if there is such a thing) injector pump would inject hot water into a hole drilled into a block of copper which would be kept really hot by a flame. As soon as the water entered the block it would flash to steam and be passed to the cylinder to do the work of pushing the piston down.

Now for the vague bits, I know the cylinder must be kept hot otherwise the flashed steam would immediately condense and nothing useful would happen.  I wonder if a water jacket would be hot enough, but if I used a jacket filled with oil how hot could I have it?  The oil would be heated by passing through the same copper block as generates the steam.

Any opinions?

Thanks

[PTsideshow]

I don't know about your version as it seems to be more complicated than the original flash steam boilers and boats that were used for the speed test and trials in the 20's and 30's.
http://madmodder.net/index.php/topic,413.0.html
http://madmodder.net/index.php/topic,408.0.html

Are two of the better books on the subject. If you haven't seen or read them.
 

[vtsteam]

John, the copper block isn't a bad idea, but lets morph that:

If you lengthened the block of copper to get more flame area on it, and more water contact surface in the hole, you might carry that on until you reduced the width dimension so that you essentially had a long square tube. Trimming the corners off of that and making it round would make it easier to manufacture and further reduce the cost of the copper while increasing further the rate of heat transfer. Of course you'd need a very long flame for something like that. So you would coil it up to make it more compact. And so we've arrived at the coiled monotube.

But i have no doubt that for a very small engine, a fairly large block of copper would produce some steam. It doesn't have to be a single hole, but could be a gallery of holes, looking on end like a bee's honeycomb. Header blocks at the end could connect the tubes in series or parallel, however desired, and in fact you could alternate water tubes with hot gas tubes. It's a heat exchanger.

It is expensive and difficult to make however. A block of copper is dear, and you'd have to drill a lot of that expensive material away. And that's a lot of drilling work and header fabrication, too.

Still, maybe it has some advantages for some purpose. Seems robust and compact, and those are good things. 

[John Hill]

The idea of the hot copper block is to have semi-internal steam generation. The block would be fixed to the cylinder head and steam only produced at the point in time where it is required (piston near TDC).  There would be no inlet valve as timing would be controlled by the stroke of the injector pump and speed controlled by the stroke of the injector pump.

A chunk of copper is not hard to find, just look for an old style wooden handled soldering iron.

The copper block is to store heat from the heat source (flame) until it is needed as steam production would be a very intermittent process, not continuous.

[vtsteam]

I guess one question you will have to answer then is whether you can get enough heat into the water via the block in that interval,

[fcheslop]

Not that well up on this.If you had a chamber and pumped the water in and restricted the outlet via a jet would that work?
Its the way an espresso machine works.The boiler is at 1.8 to 2.1bar water is pumped in at 8.5bar to a heat exchanger it then goes through a 0.8mm jet to the brew head and gives an outlet temp of 86 to 90 degrees celsius as the jets block the temp goes up eventually on some machines you end up blowing steam out of the brew head
Guess who plays with coffee machines
I worked in the plastic industry for a while the oil you need is HTO heat transfer oil if I remember correctly we ran up to 210 deg C

[John Hill]

I don't expect this to be a high speed or high power engine, if I can get enough torque to overcome the friction of the engine that will suit me fine!

Getting a quick heat transfer would be an advantage and I assume surface area is the key.  One idea is to drill a 'big' hole, say 10mm, through the block and jam the hole tight with random jumbled very fine copper wire.

My concern is that the cold cylinder will condense the steam before it does anything useful hence the need to keep the cylinder how with a hot oil jacket or maybe just flame heat it.

[RussellT]

Hi Hohn

I must be missing something here.  I don't understand why your copper block has to be separate from the cylinder.  If they were combined it'd be easy to keep the cylinder hot and you'd inject water directly into the cylinder.  You'd still need some sort of exhaust though.

Russell

[vtsteam]

fcheslop:

wonderful stuff to see and read about! 

John:

The injection into your block is momentary not continuous? Timed?


Well you know this works actually sort of, but with a diaphragm, in putt putt boats. They use a natural oscillation frequency to do the injecting, and the steam reaction to provide force and the outlets to enforce direction for outflow vs intake (which is less directional)

But of course it's only by ignoring the differences between things that you can say they are the same.

And you are thinking of a "real" engine with a piston.

I think you should build one!

[John Hill]

I am thinking that the steam generator block would be the cylinder head.

Yes, I would use my 'nutating piston' scheme to have an exhaust port open for most of the up stroke.

Nutating engine project... http://madmodder.net/index.php/topic,1389.0.html 
.... as you can see the stationery displacer is an ideal candidate for the steam generator block.

[vtsteam]

Hey, very cool engine John! 

I have no doubt that if you set your mind to build whatever the heck is in it, it will be built! 

[John Hill]

I have no doubt that if you set your mind to build whatever the heck is in it, it will be built! 

Thanks, however the various daft ideas tend to get overtaken by others before they see the light of day.

[Weston Bye]

I recall seeing an article on just such an engine in an old issue of ....Model Engineer, I believe.  'Twas exactly as you describe.  I will see if I can find it in my archives.

[picclock]

Hi John
Just my two penneth. I think the problem you have to overcome is the interface between the copper and the water. Under normal circumstances as soon as the water is changed to steam, that forms an insulating layer which prevents the rest of the water from flashing into steam. Probably the simplest way to get around this is to use a spray bar such that when the water is injected only small droplets get to touch the copper, however the problems of jet blockage due to scale would likely become an issue. Also the volume into which they are being sprayed would have to be quite small to ensure good droplet contact.

An alternative, which may make it more novel, would be to spin the heated cylinder and allow the forces of rotation to throw the higher density liquid part onto the walls promoting rapid flashing into steam. If the flash chamber was rotating it would mean that timing of the water injection could be linked to a cutout in the flash chamber. Just a thought ..

Best Regards

picclock

[John Hill]

Hi Picclock, I am hoping that by injecting the water into a large diameter passage stuffed with random packed fine wires I can get a large surface area and somewhat break up the effect of the insulating layer of steam you mentioned.

Descaling if required would be a simple matter of picking out the wire and replacing it with new.

Right now I am busy making towbars for the aircraft in our aviation museum.

[John Hill]

I recall seeing an article on just such an engine in an old issue of ....Model Engineer, I believe.  'Twas exactly as you describe.  I will see if I can find it in my archives.

Hi Weston, that could be interesting!

John (a.k.a. The Artful Bodger)

[Weston Bye]

I found the article in Model Engineer, vol 132, Number 3304, 2 September 1966.  The article is "Steam Power Without Boilers" by Clifford Hall.  Seem that he took out a patent on the method, according to the article, patent #923235.

The gist of the engine is an extension of the cylinder that contains a region of a narrow slot or space in a material of high thermal conductivity for maximum heat transfer where the water is injected.  A poppet valve serves to exhaust the expanded steam during the return stroke.  A spurt of water is injected at15 degrees before TDC while the exhaust valve is still open, the valve closing at about 5 degrees before TDC.  Expansion occurs until the valve is opened again around 30 degrees before BDC.  This timing varies with RPM.

The inventor saw fit to use a carbon piston to retard heat transfer.  The only illustrations in the article were simple sketches of a couple of cylinder head arrangements that the author was experimenting with, and some photos of heavily shrouded experimental engines that showed little detail.

[John Hill]

Thanks Weston.

My idea at this time is to build a beam engine (so that I can have a vertical cylinder).  The cylinder head will be over the fire which may be some sort of stove or even a real fire.

The cylinder will be mounted in a vertical outer cylinder with enough room for the heat from the stove to circulate around the cylinder and exhaust through a chimney or funnel.

The exhaust valve will be a poppet valve in the cylinder head with a two position latch to keep it either open or closed, as the piston comes down the valve will be pushed closed by the cylinder head and as it reaches top of stroke the valve stem will contact a fixed stop which will push it open for the down stroke.

The cylinder head will be two aluminium (I can not think of a cheap source of copper to do this) disks with a small clearance machined on the face(s) so that when they come together there will be a small clearance for the steam producing space.  Steam will pass into the cylinder through holes drilled in the top disk.  Water will enter the steam generator through a copper pipe screwed into the lower disk.  I am hoping that this configuration will give scope for easily changing the size and clearances in the steam generator and also being easy to dismantle if de scaling is required.

Water will be injected when the valve closes, or a bit before.

John

[pgp001]

I found the article in Model Engineer, vol 132, Number 3304, 2 September 1966.  The article is "Steam Power Without Boilers" by Clifford Hall.  Seem that he took out a patent on the method, according to the article, patent #923235.

The gist of the engine is an extension of the cylinder that contains a region of a narrow slot or space in a material of high thermal conductivity for maximum heat transfer where the water is injected.  A poppet valve serves to exhaust the expanded steam during the return stroke.  A spurt of water is injected at15 degrees before TDC while the exhaust valve is still open, the valve closing at about 5 degrees before TDC.  Expansion occurs until the valve is opened again around 30 degrees before BDC.  This timing varies with RPM.

The inventor saw fit to use a carbon piston to retard heat transfer.  The only illustrations in the article were simple sketches of a couple of cylinder head arrangements that the author was experimenting with, and some photos of heavily shrouded experimental engines that showed little detail.

I remember that chap came to our house when I was just a boy, he had invented the "boiler-less" steam engine and wanted someone to join forces with him to further the design and take it to market. He approached my late father about this and I remember him setting it up on our kitchen table and running it.
The engine form memory would be similar in size to a Stuart 10V, and it ran very sweetly, the reasons why my dad never got involved are lost in the mists of time now.

Phil

[Manxmodder]

Just had a read of this and it is an interesting concept.

 Just a quick thought on the potential problems caused by scale build up in the heat exchanger or injector,if water out of the tank of a dehumidifier is used then surely the scaling up problems would be completely overcome.
Anyone?

[John Hill]

Hi Manxmodder...

My ideas keep changing but my favourite at this time is to make two thick metal disks.  Each disk would have shallow passages machined in one surface and and the disks clamped together by a spring clamp and water injected into the small space between them.  De scaling would be a matter of separating the disks and giving them a brisk scrub.

[spuddevans]

Just had a read of this and it is an interesting concept.

 Just a quick thought on the potential problems caused by scale build up in the heat exchanger or injector,if water out of the tank of a dehumidifier is used then surely the scaling up problems would be completely overcome.
Anyone?

or alternatively, if your window cleaner uses the pure-water method ( brush on a stick with water spurting out the end ) have a friendly word with him and ask if he'll fill a container from his R.O. (Reverse Osmosis) filter for you. That should give you water with virtually no impurities in it.

But don't get water that is de-ionised (what comes out of his brush onto your windows) as this will tend to leach certain metals out of your boiler, continuous use of de-ionised water through copper pipe will eventually give you pin-holes .


If you explain what you want to your window cleaner I'm sure he'll help you out (assuming that he uses that system)


Tim