Flash Steam Engine and Steam Coil

[edmund]

Hi Lohring,
I understand that data loggers will work perfectly for rpm measurement but if you don't have one..
An -on board- sound recorder might do the trick as well.
You clearly accomplished your goals by setting records, you already earned my respect for doing that.
My goal is or at least I am aiming to make a engine which is as fuel efficient as a a modern IC engine and is not too big or too expensive for mobile applications.
So I have a lot to think about. I might have seen something like that cyclone power thing in the past but I haven't seen any figures about efficiency. I did not yet read the whole  part in detail because it is not my first priority.
My biggest problem now is how to make a speed/power control. Electronic control can help a lot but I have no knowledge to build that, pure mechanical isn't so easy either. At least I haven't found
a simple solution for that.
I am truly impressed by the amount of power your and other flash engines produce and although the poppet valve system works obviously very well for high power output and small dimensions,  I am looking for another solution because I am afraid of problems if I want to scale up such an engine.
That is one reason why I want to “flash” into the cylinder and not before.
The dimensions wow that is something else, even one HP is not the same as “our” or general accepted -pk- which means hp  too :-). ( I am not saying -pk- is a good dimension, it should  be Watt)
It doesn't make life easier, and when I am looking at a English steam table, all I see is a bunch of numbers that doesn't mean anything to me. I have to recalculate to know what it actually means.
I am looking forward to your new records. ( and speed control )

Edmund

[edmund]

Edmond,
If I can refer you back to my post No 53 you will note that I say that I try to get as much heat from the fuel as possible
which also means that I am looking for max efficiency so you can disagree as much as you like but these burners are very efficient and to compare these engines and generators to F1 cars is quite ridiculous in the amount of money involved and is thrown into F1 engines to a guy working in a small workshop but can still get a Hydro to do 127 M.P.H.

Lohring.

Having had some words with the current record holder he like me doesn't know the pressure on the engine when it's at full bore other than to say that the steam pipe to the engine burns red, this I can confirm as mine also burns red from the generator to the engine, and as a guesstimate near 1000 p.s.i. is not far off
I shall refrain from printing his comments on your statement that 100p.s.i. will achieve 100 m.p.h.+ other than if 100 p.s.i is your goal, best of luck and we look forward to your efforts.

Dave.

The timing cycle of my engine and others is that the cam engages  4Deg before T.D.C and closes 50 deg after T.D.C.
and the valve head is 5/16" dia with a 1/32" lift.

There will be a very marginal pressure drop but don't forget that when the valve is closed for the remaining 306 deg the fuel and water pumps are still pumping and the engine awaits the next slug of flashsteam to hit the C/Head.
The burners are designed to take in air as the boat moves forward so the faster it goes it takes in more air and fuel creating a hotter burn, more pressure and more steam.

Now I have no wish to down cry anybody's thoughts but I feel that until you have built and tried a flashsteam plant you will realise the pressures and heat involved to get in excess of 120 m.p.h.

George.   

 

Hi George,

Sorry you are absolutely right, it was my own bias what made me read it wrong.
As I said before I did not yet calculate much in terms of efficiency but just by looking at the design
of the heater : cold air is used for oxygen, that alone made me wonder if you couldn't get more
heat in using waste heat to pre heat the “fresh” air/oxygen.
Variating the amount of air what I will do in my engine isn't necessarily because you only operate at full speed. However if too much is air sucked in then heat is wasted. If not enough oxygen is available the the highest possible temperature won't be reached either.
Again I don't know if it is worth the trouble but these kind of things come to my mind looking at those beautiful toys.
I am not comparing these engines with formula 1 cars, all I said that AFAIK commentators use the
sound of the engines to determine the rpm, something which can be done with these models too I think.
As I said to Lohring, I am very impressed by the performances of these engines, (and the people who makes them) don't get me wrong about that.

Edmund

[steamer]

Yes It is amazing the amount of variables conspiring to prevent any of this to work....but it is evident that George has certainly figured it out!

Thanks for sharing all this George!....it's a lot of work to post all this and answer questions...please proceed!

Dave

[lohring]

George, I think you misunderstood my 100 psi statement.  That was for brake MEAN effective pressure and can be calculated for a two stroke from BHP = BMEP x Displ. x RPM / 396,000 where displacement is in cubic inches.  For a 30 cc engine (1.8cubic inches) the power with a BMEP of 100 psi would be 100 x 1.8 x 10000/ 396000 = 4.5 hp, so the needed BMEP will be a little more, maybe 130 psi. See many on line references or derive it from the equation posted below.

The reason the mean pressure is so much lower is that the steam expands from its peak pressure of maybe 1000 psi down to atmospheric pressure at the exhaust.  If you have a late cutoff the mean pressure will be closer to the peak pressure but the efficiency will be very poor.  A very short admission gives high cycle efficiency.  There are also pressure and temperature losses in the flow through the valve so the cylinder pressure won't equal the boiler pressure.  The compression work in a uniflow engine deducts a lot of work from the expansion work as shown on the
PV graph.  (http://www.flickr.com/photos/9511023@N03/6782131921/)  That doesn't make it less efficient, it just lowers the work per cycle.

Model data loggers are very affordable, but using them takes practice.  We used the Eagle Tree (http://www.eagletreesystems.com/} on both models and full size boats.  It would take special instrumentation to read steam pressures, but speed, temperature (with the thermocouple attachment) , and rpm are straightforward.

Lohring Miller


Power
BHP = PLAN/33,000
P is brake mean effective pressure, in PSI
L is piston stroke, in feet
A is the area of one piston, in square inches
N is the number of power strokes per minute

[K.B.C]

Hi Lohring,
Yes you are quite correct I misunderstand your 100 psi statement, I also for some reason in my calcs divided N x 2 why I don't know., but now that you have pointed out my mistake it makes it even more frightening as at 15000 rpm on the bench gives a theoretical 28 H.P.  and a possible 11000 rpm in the water gives 20.6 H.P.
The 11000 rpm was recorded in a water tank so it's nearer the mark.

You have so very much more experience than I have with your I.C. and full size engines and friends with a common goal around you, where as I have ploughed a lonely road with nobody in Scotland working with flashsteam, which is why I have copied R.Kirtley and P.Windross steam plants but not wanting to go so fast and the deep "V" boat with submerged prop is quite a bit slower and as I was not concerned with weight it also helped, my boat all up without water or fuel is 25 lbs, the record breaker are restricted to 14 lbs dry weight.

I have never felt such exhilaration when after the years taken to build the plant when on the first pull of the starting cord it fired into life, you think that your I.C. engines are noisy, just wait until you fire a flashsteam Uniflow poppet valve engine ( AWESOME ) make sure that you have a silencer fitted.

Do you scratch build your own engines ?

George.

     

[lohring]

George, don't apologize.  As you said above there's no substitute for actually building a flash steam plant, and I'm still in the BS stage.  I'm planning to copy as much as I can from everyone who has preceded me in flash steam.  The more I read on the Cyclone site, the more I learn.  I just need to pare down the complexity to come up with something I can build.  You and the other model flash steam builders have been doing that for quite a while.

The last complete engine I built was in high school over 50 years ago.  It was a 10 cc two stroke racing engine.  From years of learning things the hard way I now never build something I can buy that does the job.  There are very inexpensive 23 to 31 cc two stroke crankcases, crankshafts, connecting rods, and all the fasteners, bearings, and other parts are readily available.  We have run these parts to 8 hp and 25,000 rpm.  I plan to build the steam cylinder and piston along with the pump and valve systems.  Of course the burners and boiler systems need to be custom built.  I think just building those pieces will be plenty of a challenge.

Lohring Miller

[lohring]

I came across two ideas that may improve the power of a flash steam power plant.  The first is to wrap a couple of coils around the exhaust ports to help preheat the water on the way to the boiler.  The other is to use a jet condenser to lower the exhaust pressure.  This would work well in a boat with lots of water available.  See the picture below.

Lohring Miller

[K.B.C]

I came across two ideas that may improve the power of a flash steam power plant.  The first is to wrap a couple of coils around the exhaust ports to help preheat the water on the way to the boiler.  The other is to use a jet condenser to lower the exhaust pressure.  This would work well in a boat with lots of water available.  See the picture below.

Lohring Miller

Hi Lohring.

I see no problem in using I.C. engine parts  but would have second thoughts on using Cylinder heads and pistons as I think that the fierce heat of the steam coil will effect them, that is if you make and use a similar coil and burners.

I see no need for water coils wrapped around the exhaust port to pre-heat the water before the coil, don't forget that the water pipe enters the furnace and travels about 24 ft getting hotter and hotter before flashing in the very hottest part of the coil which is about 4" from the front face.

I have absolutely no experience in a condenser in the exhaust and if there was an advantage to be had the guys that are chasing records would have tried it, plus there is very little room on board for all of the extras that you are considering.

Don't let me dampen your enthusiasm but I think that you are looking for ideas that are going to be very difficult to install and keep the weight down.

Best of luck.

George.

[lohring]

I'm in the process of reorganizing my shop around a new to me lathe so the steam project is going to be all talk for a while.  I agree simpler is always better.  I'll see if I can put together some preliminary drawings.  Pump control, if needed, could be as simple as a rod that holds the intake check ball off its seat.  I think the Honda variable valve system for both opening and cutoff control would be as easy as an external throttle valve.  I'm working on understanding John Wetz boiler control system (http://kimmelsteam.com/wetz.html).  He ran really simple and crude monotube boilers with it.  The goal is a power plant that's buildable with as good control as a racing IC engine.

Lohring Miller

[edmund]

Hi Guy's,

I like to start building something and keep the costs limited as possible.
Does anyone know if it is possible to build a piston/cylinder for the pump section which can be lubricated with water cq doesn't need lubrication?
Any suggestion what materials can be used for that?

Thanks

Edmund

[lohring]

As far as I can see, none of the pumps are lubricated.  It's the engine cylinder that gets the steam lube.  Teflon packing in the pumps shouldn't need lubrication.

Lohring Miller

[K.B.C]

Hi Guy's,

I like to start building something and keep the costs limited as possible.
Does anyone know if it is possible to build a piston/cylinder for the pump section which can be lubricated with water cq doesn't need lubrication?
Any suggestion what materials can be used for that?

Thanks

Edmund

Edmund,
There is enough information in the Model Engineer Mag article by R.Kirtley on his PISCES 11  steam plant to make pumps that I e-mailed to you and Lohring.

R.K's pumps are made from Aluminium with stainless steel rams, the water pump has a Silicone "O" ring at the end and the fuel Pump that uses Kerosene ( Paraffin to the U.K. ) uses a black Nirile ring as the Kero melts Silicone.

My pumps are made from a solid block of Ali but the pump bores are sleeved with Brass, rams are Stainless steel and have "O" rings at the end as shown at the beginning of this thread which if you look at you will see a small C/Sunk hole above each ram which takes an occasional drop of oil.

George.

Edit,

I should have added that pumps need not be made in Aluminium but can be made from stock round brass.
The operating principle is the same with a St/St ball on the suction side and delivery side.

[fcheslop]

looking forward to seeing some metal cut
cheers

[edmund]

George,

Thanks again for all information you send me.
What I am looking for is something like an (old type) diesel fuel pump with a plunger without piston rings or (silicone) sealing. Preventing oil would help a lot since I want to make it a closed circuit, condensing the exhaust steam, heat and use it again for the next cycle.
If it must be lubricated I need an oil separator and a lot additional stuff that comes with that.
What I have in mind is an engine size from anything between 100 to 500cc per rotor (Cylinder) but I haven't found a better -know how- source for flash steam engines then this one.

Edmund

[K.B.C]

Edmund,
I think that you are worrying too much about oil being carried over into the steam, you can make a pump without the "O" ring but you will eventually get water egress out of the pump barrel and I would suggest that you do put in an "O" ring but don't oil lubricate the ram.

I have made many pumps and don't recall any oil being carried over, in fact I forget to lubricate the ram with no adverse effect.
Here are a few pics of a Stuart Launch engine that I have recently built with an engine driven pump but you can easily make it an electrical drive if wished.

George.