Flash Steam Engine and Steam Coil

[lohring]

Unlike conventional boilers, flash steam boilers contain very little water under normal conditions.  This means that they can't store energy in the form of hot water to be turned into steam when acceleration is needed.  That's what makes them safe, though.  I notice that it takes some time for the tether hydros to get up to speed.  I'm not completely sure why this should be.  It may be that with a fixed pump stroke the fuel and water supply depends on rpm and it takes a while to accelerate with the high pitched prop.  Increasing boiler draft with speed may also be a factor.  Would a blower help at low speeds?

The other problem is that it should be easy to flood the boiler if the water supply increases faster than the increased fuel can heat it.  That will destroy the engine by bending or breaking the rod and or crankshaft if water gets into it.  I've had that happen with 26 cc IC engines.  Manual pump stroke control could be risky because of this.  Throttling alone might result in too high of a pressure rise and or  during deceleration.  Balancing the two inputs will be tricky.  I'm open to ideas on how to do this.  I'm sure full size power plants have a series of sensors and computers that regulate the pumps.  I'm hoping that the mechanical connection to the engine is mostly self regulating.

Lohring Miller

[fcheslop]

Hi, P.I.D control maybe the way forward a little like cruise control in a car using feed back loops.Its a long time since I played with electronics so no doubt things will have moved on considerably.I had though of using a PIC chip as per Flash Two.
Would prop slip not be a factor for the acceleration time.
I dont know just mulling over a few ideas I once had
Cheers and good luck.
frazer

[lohring]

People have tried a lot of different control systems.  The issue seems to be the lag between the inputs and the steam output.  Doble used a mechanical temperature sensor that controlled the steam generation.  See a great quick coverage of the car at Jay Leno's Garage (http://www.jaylenosgarage.com/collections/steam-cars-1/#videos)  It's still probably the state of the art in automobile steam power.

I have a lot of rpm versus speed data on model and full size boats.  After the propeller "hooks up" there is a very direct correlation between rpm and speed.  Below is a graph of data from an electric outboard hydro.  Model hydros act very similarly.

Lohring Miller

[edmund]

Hi Edmond.

The pumps are very typical of the ball type that are common in model steam engine and boiler feed pumps in that they have a ball on the suction side and one on the delivery side with the pump having a ram type plunger.

I don't have any drawings of these pumps other than the sketches in my note books and regarding the types of materials used in the engine I can only offer to mail you a copy of the original builders article which was published in Model Engineer Mag which can answer your questions on materials used, please contact by P.M. don't put your e-mail address on the forum.

I must question your ambition to control this plant as it is designed as a racing plant which in the original Hydro achieved 120 mph and possibly higher now.
This plant is uncontrollable and is a bit of a beast when let go, as it is a closed loop pressurised system any opening of bleed valves immediately loses pressure and the engine stops.

The pumps have a fixed stroke and driven from a disc on the 90 deg cross shaft and is adjustable via holes on the disc and by experimentation the correct stroke is found.

The fuel system is preheated in a vaporizer of 3ft long x 3/16" dia Stainless 316 tube stuffed down the coil and is heated by a plumbers blow lamp to get the burners going before starting, just like a Primus stove.
Regarding fuel efficiency on this plant it's not a consideration as it tries to burn as much fuel as possible to give the highest temperature and pressure available, I hastily add that I have no idea of the pressures or temperatures when the plant is on full song.

The lubricator is worked from the cold water pressure and bleeds high grade steam oil into the engine every time the valve lifts on the engines rev cycle.
All that it is is a cylinder with a free fall piston inside , it's pushed down and filled with oil when the engine isn't running and once running the pressure builds and injects the oil thro' a .025" hole into the steam line every time the valve lifts..

Now back to controlling the engine, this plant is designed purely for high speed racing, record breaking, with no thought of controlling the speed, as far as I know nobody has ever tried to speed control it but you are welcome to have a go.
I can recommend the book EXPERIMENTAL FLASH STEAM  by J.Benson and A Rayman which catalogues various steam plants from the past with dimensions of pumps and many other suggestions.

I do hope that this information helps.

George.

Hallo George,

Happy New Year for you and everybody else here!
About the pumps, for the moment I have enough information and want to concentrate on more important/unknown things.
Controlling speed is essential for what I have in mind so that must be done one way or another.
I was thinking of a slightly different “flash” engine then showed here, I want to flash water into steam IN the cylinder and not before.
If you or anybody have some good reason why not, please enlighten me.
Thinking that will solve at lot of problems in exchange for a lot of other problems :-)
Injecting a speed/load dependent amount of water is doable and we can think of several ways
of doing just that, we can think of a high pressure plunger like in a diesel line pump which is perfectly controllable. Or we van use a  computer controlled solenoid injector, again like in current diesel engines. Either way, the pressure before such injector must kept above the vaporizing pressure at all time. In addition to that we do not want a pump wasting a lot of energy by pumping hight pressure water around. These are a few problems that can be solved without too much difficulty in my opinion.
There are “constant pressure valves” and one can think of a pump regulating system.
The variable stroke suggested  here in the forum is far to complicated for my liking, it must be simpler and with less parts.

Making steam/superheated water,  not hindered by any knowledge I wonder if a monotube is the most efficient way to make steam or heated water. A furnace out of a solid well heat conducting ( nano ) metal might be a lot better, although I could be wrong here.
Such furnace can and must be kept at the max allowed temperature by modulated burners, nothing new here.
So injecting a zero amount of superheated water means a full stop, injecting the maximal amount of superheated water means a near instant maximum amount of power.
So the engine is perfectly controllable this way.

The fuel system is -for this moment- clear enough for me.
Efficiency however is very much of my interest, throwing away steam or condensed  heated water isn't something I would do.  I would extract as much as energy from the steam and condense it,
separate the oil from it and use it again.
Another thing that got my attention is the air needed for the burner,
is it clean cold air! I wonder what the temperature from your exhaust is. Why not pre-heat the
fresh air for the burner with the (wasted) heat from the exhaust?

Lubricator : although I have some idea how it works a drawing would help.
I am always looking solutions a simple as possible but not simpler :-)

Edmund

[lohring]

This developer has spent a lot of time trying to do what you propose.
http://www.flashsteam.com/

Lohring Miller

[edmund]

This developer has spent a lot of time trying to do what you propose.
http://www.flashsteam.com/

Lohring Miller

Hi Lohring,

I have seen this website, please tell me what you think about it.
Personally ( not hindered by any knowledge ) I don't see much in adding steam trough a valve compress it and so on. It is wasting a lot of energy more then anything as far as I can see.
The whole idea of modifying and imitating an IC engine is not what I am after. I did not see anything
as a regulating system for the pressure pump and the injector does not look very spectacular to me either. I do understand that flashing superheated water does not immediately result is 100 % steam but the first thing to do is looking for the highest possible temperature/pressure and heating/isolating  the "cylinder" as much as the lubrication will allow it.
To make it even more SiFi, I am not thinking of an conventional cylinder/piston engine at all.
I am thinking of a "jonova" kind of engine, that is a part that I already have CAD drawn.
It doesn't really matter for all principles used in other flash steam engines, these will be the same but   the jonova engine offers  some significant advantages compared to  conventional piston engines.

Edmund

[K.B.C]

Hi Guys,

I think that we are moving away from the original objective and that is to control the High speed flash steam engine that I posted which is a copy of R.Kirtley's  PISCES 11 120 mph+ Hydroplane.
The technology being discussed is beyond me and the desire to further my engine experiments is no longer there, so I shall bow out but if there are any questions that I feel I could answer and is relative to my steam plant I will come back in.


May I remind you that the objective is to control the 120 mph+ engine powered by flash steam and include that the finished plant and boat must not be below the 14 lbs all up dry weight of the boat that the Steam Hydro record chasers are confined to.

I look forward in anticipation to your experiments.

George. 

[lohring]

Has anyone looked at the numbers for fuel and water output from the pump.  I may be wrong, but I get around 16 cubic inches per minute of fuel and 30 cubic inches per minute of water at 1600 pump rpm.  For the fuel that gives around 175 horse power of heat at 17,900 BTU per pound of fuel.  That's reasonable since the power plant can't be more than 5 to 10% efficient at converting the fuel to shaft power.  At 5% that would be 8 3/4 hp.

However, I get 1 pound per minute or 60 pounds per hour for the water.  Even really efficient engines use 10 pounds of water per hour per horsepower.  It's more common to use 20 to 30 pounds per horsepower per hour.  Did I screw up my calculations or is there a reason for this discrepancy?  From my experience with a 110 mph RC hydro that ran a dyno tested IC engine, I would expect that it takes around 5 or 6 hp to go 120 mph. 

Lohring Miller

[K.B.C]

Has anyone looked at the numbers for fuel and water output from the pump.  I may be wrong, but I get around 16 cubic inches per minute of fuel and 30 cubic inches per minute of water at 1600 pump rpm.  For the fuel that gives around 175 horse power of heat at 17,900 BTU per pound of fuel.  That's reasonable since the power plant can't be more than 5 to 10% efficient at converting the fuel to shaft power.  At 5% that would be 8 3/4 hp.

However, I get 1 pound per minute or 60 pounds per hour for the water.  Even really efficient engines use 10 pounds of water per hour per horsepower.  It's more common to use 20 to 30 pounds per horsepower per hour.  Did I screw up my calculations or is there a reason for this discrepancy?  From my experience with a 110 mph RC hydro that ran a dyno tested IC engine, I would expect that it takes around 5 or 6 hp to go 120 mph. 

Lohring Miller

Hi Lohring,
Like the Hydro record chasers I have never been concerned with fuel consumption other than trying to burn as much fuel as I can and getting as much heat from the fuel as possible.

I don't disagree with your figures although they don't correspond exactly as per K.N. Harris's in his book on Stationary and marine Steam engines but near enough, these figures are for Saturated steam not high pressure flash steam.

I have done a little Calc using H.P. figures as P.L.A.N divided by 33000 which is how I have always calculated H.P. but as I don't know what pressure my Steam plant works at I have used theoretical figure on Steam pressure based on what the record chasers can achieve which can be as high as 3000P.S.I.
I have used 1000 P.S.I. and from the Calcs it comes out at 14.06 H.P.
500P.S.I. would be 7 H.P. and 2000P.S.I would be 28.12 H.P.

My pumps work at 6/1 from the main shaft so at 15000 rpm it will be 2,500 strokes per min.

The water pump at 1/4" dia x 3/8" stroke delivers 45 cub " /min
 The fuel pump at  3/16" dia x 3/8" stroke delivers 25.46 cub"/ min.

These figures are theoretical as in the water the revs will be lower, I think the only way to get accurate figures on pressure and steam temperature is to have gauges to monitor them on bench testing.

I can tell you that I ruined a 300 P.S.I. gauge on the steam line in one of my efforts to find out the pressure, due to the modulating pressure as the valve opened and shut it blew the gauge apart , so I very quickly abandoned the idea of measuring the pressure but I am sure that there must be more reliable methods of measuring.

So, some food for thought.

George.

HAPPY NEW YEAR TO ALL, BEST WISHES FOR 2014
 

[edmund]

Hi Guys,

I did not (yet) calculate anything because I don't even have a complete design finished.
Having said that I am more then interested in efficiency and how much fuel is burned and I do NOT agree with George here. You can burn a lot of fuel and wasting a lot of heat while you may get even more heat with less fuel if you can limit the amount of wasted heat!
By the way , it would be so nice if you guys started to use "decent" units instead of those weird lengths of body parts :-). Seriously, it really make sense to use Newtons Meters Watts Kelvin and so on.
I know it is not gonna happen, it is tried before and failed.
About pressure : If you measure the temperature, isn't hat enough to give you the pressure as well if you look at the steam table?
About the actual rpm : AFAIK the formula1 commentators are measuring the SOUND (frequency) of the F1 cars and that is -at least in principle- very easy to translate to the actual revs.

Edmund

[lohring]

Frequency has been used a long time my modelers to measure rpm.  Because of the doppler effect it's easiest when you are at the center of the circle.  However, you can measure both the speed and rpm.  See http://www.supercoolprops.com/articles/dopplerwind_correction.php and other articles on the same site.  We have used sound analysis to estimate rpm from youtube videos, but most don't have a good enough sound track.  If it's your vehicle, modern data loggers work a lot better.

Efficiency from the fuel isn't really a concern for these small power plants.  If it is, you need to get a lot fancier with the burner design.  See the patents at http://www.cyclonepower.com/patent.html for the most modern flash steam power plant design.  A simplification of some of these ideas would work in models.  You need to have clear goals.  Mine have been to set various speed records.  I have been on the team that has held the world gasoline powered RC boat record since 2004 and the full size electric boat world speed record since 2008.    Those are relatively easy goals compared with producing an engine to compete with modern IC automobile engines. 

At this point it would be interesting to set an RC model steam powered speed record.  I wouldn't be happy if it wasn't over 100 mph (160 kph).  That takes around a 1.8 cubic inch (30 cc) engine producing 5 or 6 hp (3700 to 4500 watts).  I don't care how much fuel and water it takes except as how it relates to this power.  That would only take a brake mean effective pressure of around 100 psi (7 Bar).  What's really important for RC vehicles is good control.  Modern radios are nearly bulletproof.  However, no one has made a high power, controllable, model steam engine that I know of.

Lohring Miller

PS Steam design for automotive power plants died in the Great Depression.  English speaking engineers of that era grew up with British Engineering Units as did I in the late 1950s and early 1960s.  Those are the units their data is in.  Many of my measuring tools as well as my lathe and milling machine are from the same era.  Metric units are a lot easier and modern tools can work in either.

[steamer]

Has anyone looked at the numbers for fuel and water output from the pump.  I may be wrong, but I get around 16 cubic inches per minute of fuel and 30 cubic inches per minute of water at 1600 pump rpm.  For the fuel that gives around 175 horse power of heat at 17,900 BTU per pound of fuel.  That's reasonable since the power plant can't be more than 5 to 10% efficient at converting the fuel to shaft power.  At 5% that would be 8 3/4 hp.

However, I get 1 pound per minute or 60 pounds per hour for the water.  Even really efficient engines use 10 pounds of water per hour per horsepower.  It's more common to use 20 to 30 pounds per horsepower per hour.  Did I screw up my calculations or is there a reason for this discrepancy?  From my experience with a 110 mph RC hydro that ran a dyno tested IC engine, I would expect that it takes around 5 or 6 hp to go 120 mph. 

Lohring Miller

Hi Lohring,
Like the Hydro record chasers I have never been concerned with fuel consumption other than trying to burn as much fuel as I can and getting as much heat from the fuel as possible.

I don't disagree with your figures although they don't correspond exactly as per K.N. Harris's in his book on Stationary and marine Steam engines but near enough, these figures are for Saturated steam not high pressure flash steam.

I have done a little Calc using H.P. figures as P.L.A.N divided by 33000 which is how I have always calculated H.P. but as I don't know what pressure my Steam plant works at I have used theoretical figure on Steam pressure based on what the record chasers can achieve which can be as high as 3000P.S.I.
I have used 1000 P.S.I. and from the Calcs it comes out at 14.06 H.P.
500P.S.I. would be 7 H.P. and 2000P.S.I would be 28.12 H.P.

My pumps work at 6/1 from the main shaft so at 15000 rpm it will be 2,500 strokes per min.

The water pump at 1/4" dia x 3/8" stroke delivers 45 cub " /min
 The fuel pump at  3/16" dia x 3/8" stroke delivers 25.46 cub"/ min.

These figures are theoretical as in the water the revs will be lower, I think the only way to get accurate figures on pressure and steam temperature is to have gauges to monitor them on bench testing.

I can tell you that I ruined a 300 P.S.I. gauge on the steam line in one of my efforts to find out the pressure, due to the modulating pressure as the valve opened and shut it blew the gauge apart , so I very quickly abandoned the idea of measuring the pressure but I am sure that there must be more reliable methods of measuring.

So, some food for thought.

George.

HAPPY NEW YEAR TO ALL, BEST WISHES FOR 2014

George,
There will be some decrease in actual initial pressure as steam enters the cylinder......very quickly.  Unless the passages are really big, there will be a significant amount of wire drawing at the rpms you speak of...I suspect a very large valve is required to minimize that pressure drop across the valve.

Dave

[K.B.C]

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.   

 

[steamer]

George

Please forgive me.  I meant no disrespect of denouncement in the least!....I love reading and learning this build.  It's fascinating!....   Please accept my apology if I came across in a negative manner, as it wasn't my intent at all.

3000 PSI!......Yikes!...

Dave

[K.B.C]

George

Please forgive me.  I meant no disrespect of denouncement in the least!....I love reading and learning this build.  It's fascinating!....   Please accept my apology if I came across in a negative manner, as it wasn't my intent at all.

3000 PSI!......Yikes!...

Dave

Hi Dave ,
No need to apologise, no offense taken.

3000 psi is a figure that is very much on the high side and was recorded while experimenting with a steam turbine, not by me I hastily add, 1000p.s.i. is nearer the mark .

George.