# experimental steam engine



## dave-in-england (Aug 31, 2013)

Hi all,

Over the last year in my spare time I have put together my design of a twin cylinder sleeve valve steam engine.

This is my first attempt at a steam engine, engines of which I know little about.

Maybe some wise old hands here on HMEM could look over the design and see if it has any chance of working in real life !


The working principal is as flash steam.

A coal burner heats up two strong stainless steel cylinders positioned in the top half of the burner.

A small piston pump built inside the base of the engine, driven by the crankshaft, forces about 10cc of water through a fine spray injector that is bolted on to one end of each stainless steel cylinder.

The water spray turns into steam inside the red hot cylinder, creating pressure in the cylinder and all along the pipework to the inlet valve.

This pressure is contained and held in the pipework momentarily until the slide valve on the side of the cylinder head opens, letting the pressure into the cylinder and forcing the piston down the bore.

The piston on the return stroke forces the spent steam out through the exhaust valve, and eventually through a tube pointing vertically in the top of the coal burner chimney, creating an incoming air draft through the hot coal fire.


I don't have any machinery or equipment, or I would have had a go at building it, but I wondered if anyone at HMEM would be interested in actually making the engine as a experimental project to see if it works. ! ! ! !

I know that this model will cost a lot in time and money and patience, but this will be something different !

There needs to be a couple of one-way valves and a water inlet control valve in the pipe circuit but I have not included them in the model.

I have made two separate videos on Youtube to show the model working as a simulation.


[ame]http://www.youtube.com/watch?v=8612QD8pCFA[/ame]

This video is of the actual engine unit, which dissolves away to show the parts working,


and this video shows the full model arrangement.

[ame]http://www.youtube.com/watch?v=2IrVKuIsJVo[/ame] 








For the size of the model reference, the base board is 1500 mm x 700 mm

The flywheels are 150 mm diameter, the boiler unit is about 200 mm square

The cylinders and pistons diameter = 40 mm x 60 mm stroke.


Every single part has been drawn and dimensioned, all drawings are in .pdf format for easy download and printing.

These drawing files are all at  www.davyarcher.com/steam 

under pdf, and all 3D screen pictures of the parts are in the pictures directory.



Comments and criticisms welcome   Ha Ha !  

2013 AUG 31 Saturday


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## wackyvorlon (Sep 1, 2013)

A thought: replace the stainless steel cylinder with a dense copper coil. Rate of heat exchange is dependant upon temperature differential, surface area, and conductivity. Copper is more conductive than stainless. Look up "pancake coils". I'd suggest having a check valve close to the boiler. The idea is to keep the steam away from the pump, this helps keep it from being cooled.


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## dave-in-england (Sep 2, 2013)

Thanks for your comment.

I was not happy with putting a copper coil directly into a 900C firebox,
the water supply to the cylinder is intermittent, having an almost dry copper coil sitting in red heat then quenched down to 100C repeatedly will probably degrade the copper coil.


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## compspecial (Sep 2, 2013)

The stainless cylinders could be heavily finned to increase their surface area for transfer of heat..also the two pistons and other reciprocating parts moving in the same direction will create a lot of  inertia forces at the end of the stroke, probably would be better set up as a boxer engine (horizontally opposed) could have potential though Dave!
    Cheers Stew.


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## wackyvorlon (Sep 4, 2013)

I just remembered something I have to mention. Red heat may be too hot. You'll have to experiment. Above a certain temperature, the steam creates a thin insulating layer. This has the effect of actually slowing down the rate of boiling. You can see this in person. Heat a metal plate, and drip water on it. Too high, and the drop will skitter around for quite some time. Once the temperature drops, however, it boils away very quickly.


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## dave-in-england (Sep 4, 2013)

The injectors would insert a very fine spray directly into the hot cylinders,
just like a diesel engine injector.

I don't think that any liquid water will sit in the bottom of the cylinder, I would have hoped that the spray turns into steam and pressure immediately.

thanks.. dave


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## AussieJimG (Sep 4, 2013)

I don't know much about steam engines but I do like your computer modelling. Particularly the dissolving model.

Jim


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## dave-in-england (Sep 4, 2013)

Thanks Jim 

I suppose that it is hard to show how a model works without hiding some parts that get in the way.

With the next model engine that I am working on, I will try to improve the visuals, I am having a hard time learning my way around this Sony Vegas 
video software, seems to be some compatibility issues, or it could just be me.
  :wall:


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## aonemarine (Sep 5, 2013)

Scratching head.... man Im going to have to think about this one a little bit.....Direct injection.?  yep need to think about it some more...


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## KBC (Sep 6, 2013)

dave-in-england said:


> Hi all,
> 
> Over the last year in my spare time I have put together my design of a twin cylinder sleeve valve steam engine.
> 
> ...


Dave,
There are some areas in your idea that is going into uncharted waters.

Firstly as you are making 2- pressure vessels in St/St fired by a coal fire of 900c if you wish to fire this up in a public place under the auspices of a club you will have to get the vessels certificated which will entail sample welds and welding done by a certified Coded welder and full calculations to prove your design.
O.K. if you are to fire it in private but you will not be covered by insurance.

Secondly with this type of heat if the spray idea works the flash steam produced will destroy a slide valve engine.

Over the past years people have made Mono tube boilers using copper tube and saying that it's a flash steam generator working at say 80 P.S.I.  where as it's only highly superheated steam.
Copper tube under high heat flakes, you can see this if you Silver solder copper  tube, it flakes on the outside and also on the inside which carries the flake into the engine and can soon destroy it and the pressures generated can very easily blow the copper tube. 
Stainless steel for a flash steam boiler of the temps that you are quoting is the prefered material.

I say these things as I have experimented with flash steam over the past 10 years using 32ft of 316 stainless tube x 1/4" o/d with 3- paraffin fueled burners and an engine of 1.125" bore x 3/4 " stroke which drives the fuel pump and the water pump to feed the coil.
These are designed around the flash steam Hydroplane of R.Kirtley who is a past world record holder of round the pole racing boats.
My boat was never intended for the 120 + mph that his boat achieves but mine at 42" long can achieve 45 mph by R/C control with rudder and stop.

When you are up in the temps of 900c special materials are required to hold the engine together and get a reasonable life out of the engine, my engine is a Poppet valve engine with the cylinder head from a lump of mild steel, the cylinder is Mehanite grade cast iron of 75Ton, the poppet valve which is operated from a cam on the main shaft after many tries to prevent it from constantly annealin is now machined from the exhaust valve of a Cummins diesel engine.

I don't mean to put you off but there is a lot of experimentation required for the project that you have in mind, trials and tribulations come to mind but I would dearly like to see somebody taking up the challenge to make your idea work.

Here are some pics of my flashsteam set up, these are all nice and shiny, the burners are now black as is the mild steel cylinder head in the last pic.
Pic No 5 shows the fuel pump and the water pump mounted in the same Ali block with the drive to the main shaft.
Brass water tank on Starboard side and fuel tank on Portside, the engine does 15.000 rpm free on the bench and I would think about 25% less ,maybe more, in the water, pumps are gear 6/1 from main shaft.

George.


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