flash steam hydroplanes

Hello,

Would a flash steamer work for a steam car?

Best Regards.



Edited 1 time(s). Last edit at 03/20/2015 12:39AM by HYDRAGON.

Sure. That's what White, Doble, and the other steam car builders used. Flash steam is a monotube boiler system. The origonal thiught was that the tubes were dry and the water flashed into steam when it entered the boiler tube. What actually happens is that one section of the tube heats the water, another boils it and a third superheats the steam. Flash steam model hydroplane boilers fail from overheating if there isn't some water in the boiler tube. Adjusting the fuel and water flow to the engine's output at full power is the delicate part of setting up a flash steam hydro according to the people who run them.

Lohring Miller

Welllllllll.....

You have to be careful with the terminology. A true flash boiler has tubes that are glowing red hot and the water "flashes" into steam on contact. What is typically thought of as a flash boiler is really a semi-flash boiler. It looks the same but the fire and water are managed such that heating is much more progressive throughout the tube. From what I can see, most high speed hydros use flash boilers, semi-flash is used in cars because you have better control over the tube temperature; necessary if you want any kind of reasonable life.

Regards,

Ken

This all so often misused term "flash steam" brings up an interesting question. The term really ought to be abolished.
I suppose all of you have dripped a drop of water on a really hot stove top or frying pan. It immediately forms a spheroid drop and dances around for quite a while. Called film boiling and obviously the heat transfer rate between the hot surface and the drop of water is nil. Only when the hot surface cools down does the drop spread out and "Flash" into steam. Try it and see for yourself.
Monotube steam generators do not run with red hot tubing. Those that do fail rather fast.
I have watched these model boats with a simple coil, no control system and a vicious blowtorch burner.
So considering all this, how does a red hot steam generator create steam??
Jim

Hi Jim,

The early Serpollet boilers were sometimes true flash steamers. I think the reason you can get boiling is because the combination of pump pressure and velocity causes the steam films to shift around as the fluid moves, creating spots more conducive to boiling. Making the tube smaller (or decreasing the passage by crimping a la Serpollet) probably assists the flow in scouring the walls so as to get film free regions. Definitely not a good idea, the existence of DNB (Departure from Nucleate Boiling) is always going to slow down heat transfer and speed up tube burn out.

I agree, the terminology was bad enough 120 years ago, probably long overdue for replacement.

Regards,

Ken

We're argueing about the same thing. I maintain that there is a sequence in the process of turning cold water into superheated steam. The only issue is how long the sections of tube are for the various steps. Simple flow computations on pump output show that the water flows the length of a model flash steam boiler in around a second. How fast can this water flow turn into steam? Not instantly, I assume. "Flash steam" and monotube boilers are the same from an engineering perspective.

Lohring Miller

Ken,
Probably the reason Serpollet crimped his tubing in the earlier cars, the velocity scrubbed off the film boiling.
If only Griff had lived longer and we had gone through those trunks together that his granddaughter had, so much of Serpollet's engineering philosophy might have been finally revealed.

Lohring,
It's not so hard to figure out. You know how much steam per hour you want in terms of pounds per hour of water evaporated, then you know the evaporation rate per square foot your tubing can deliver, heat transfer rate and all that (20-35 ;lbs/hr/sq/ft), then you size the amount of tubing you are going to need.
In a vehicle generator you cannot pin down exactly where the zones change, it varies depending on the pump flow rate and the steam demand at the moment. To my knowledge, no one has really instrumented a monotube with dozens of thermocouples to find out how the zones actually move Lears might have, they were quite through; but those engineering notes seem to have vanished when all the drawings were stolen from the file drawers.

"Flash" steam, using the strict definition of the word and a forced circulation monotube are not the same at all. From what I have seen, model steam hydroplanes seem to be wildly over fired and trust to luck the generator coil lasts for a while. I mean red hot cylinder heads, seen some of those?? A monotube is definitely controlled at all times, or should be providing the builder knows what he is doing.
Jim

Basically the steam generator design for a "flash" and "semi flash" generator are about the same. The big difference is in the control system. The pure flash boiler has little to no control and, as Jim says, is wildly over-fired. This wastes fuel while paradoxically reducing steam generation and rapidly hasten tube burnout. A semi-flash generator is designed to co-ordinate fuel and water delivery in an attempt to prevent raising the heat flux to the point where you go into DNB, ideally you want to reach the point on the fuel delivery/feed water curve that gives the highest rate of return. This provides for the highest steam output, significantly reduced fuel consumption and long tube life. As I say, controls are the key. That is one reason a controlled REcirculation boiler like the Lamont is so nice. By its nature the generator tubing is always submerged and the superheater tubing is always dry, you can control the firing and feed rates independently and get nice control. In the pure monotube separate control inputs are bound to produce ranges of hunting varying from "annoying but acceptable" up to "the @=^%*)?{#\!" thing went dry on me and burned out! In other words, without proper control a semi-flash boiler can either turn into a pure flash boiler and burn out or it can turn into a hot water heater rather than a boiler......or whipsaw back and forth. I suppose the model hydroplanes opted for pure flash boilers simply because they were at least guaranteed to get steam out of the thing and boiler life was considered a trivial tradeoff...something that won't apply to automobiles.

Regards,

Ken

So the answer to the original question is, "yes, and it works for a short time." Edgar T. Westbury's designs and the writings of Benson and Rayman tell how to make the hardware and to set up a feed-forward proportional fire/water system which surfs precariously along the crest of the power band until the fuel runs out. But in a vehicle, it would not be very efficient or practical."
Henri Serpollet's original concept and the first patent [attached] was strictly flash and fed one stroke at a time. Leon's commercially successful systems were still called "Systeme Serpollet" but were five design generations down the line and were what we would call serpentine monotubes, not flash at all.
The design developments, patent history and product variations are very well described in Le Clos Serpollet by Pierre Dubarry de Lasalle. Unfortunate the entire press run was pulled from the booksellers shelves and libraries and burned by court order. I have been working with his family for many years to get this back on the shelves, but it is unlikely. The alternative is to write it up myself.

Karl Petersen

Any feedforward control strategy "surfs precariously along the crest."

This is what you do when you have a process that can quickly go "to hell in a hand basket" and delays associated with measurment or process response preclude feedback control.

Feedback control is in response to an error. Feedforward control is an attempt to get out in front of the error.

Successful feedforward control systems are often trimmed up with a feedback loop.

Assuming the process survives the initial control system decisions, feedback control is used to bias future feedforward decisions in an attempt to keep the process on the right side of the crest. Sometimes this works very well indeed.

I am lost. Where do I learn about "Edgar T. Westbury's designs and the writings of Benson and Rayman?"

Kerry

Both are available.
Experimental Flash Steam [www.amazon.com]

The Westbury book is a lot rarer [www.amazon.com]

Lohring Miller

Hi Kerry, after searching a notch and coming up with many links, this wiki link list references to all the names mentioned plus another that seemed good to research. Keith



Edited 1 time(s). Last edit at 03/22/2015 10:05AM by kdc2.

Hello to all:

I've been pretty quiet lately--but being an old and opinionated SOB, it's time to fire up!

Recent posts on this thread have revealed the exact and defective nature of the "pure" monotube steam generator IMHO. If this configuration were to be operated in a steady-state (constant-flow?) then it would be simple to establish a control system to deal with the variables of heat and water as inputs, and pressure and temps as outputs. However--when you add the demand for steam output from zero to max without any anticipation (as in a modern automotive environment) you then have a scenario which results in a nightmare for control schemes. Just try it, you won't like it!

The Lamont-style of monotube bypasses this problem in several ways: First and foremost, it's actually dynamic in its action even at low outputs because there's always the forced circulation in the primary heat absorption zone. Also, there's a lot of thermal inertia in there which can be available for high outputs on-demand.

It's interesting to note the action of the Kirtley hydro on the youtube vid; once it's on the way it takes several turns to "get up to speed". I believe this is due to acceleration (obviously)--but also due to the fact that the flash steam generator is establishing the proper relationships of heating zones and water flows.

As usual FWIW,

Bill

Bill,

That is why I like the Ofeldt for a car. It's a good blend of boiler characteristics. Lots of tube area for fast steaming (Like a monotube), A good reserve for stable output (Like a firetube). Can be operated manually (Like a firetube and unlike a monotube) Very good circulation inherent to the design, without any sort of outside pumps/mechanisms(Unlike the Lamont). Smaller operating water capacity for safer overall operation. It's compact. lightweight, relatively easy to build and mount. Same physical charteristics as a firetube making retrofitting easier. Try it, you'll like it

The Ofeldt makes my Locomobile drivable in four minutes after the main burner is lit. And that was firing up in 48 degree weather. Fired it up in 37 degree weather and took Gary Hadden for a ride and it was about the same time range.

-Ron

You know that flash steam also refers to steam flashing to steam when pressure is lowered.

We do not need a recirculating LA Mont boiler A non-circulating stand pipe can be used. They are a proven type that was marketed in England. Basically a water level control admitting the superheated steam or saturated water to the stand pipe below water level. High firing put superheated into the standpipe. The superheated steam transfered the superheat to the water as it makes it way to surface. Adding heat to saturated water makes steam lowering the water level. When water level is low fire turned down or increase pump rate to add water. The production boilers were used in a lot in the dry cleaning industry.

Probably not as good as a LaMont for output. The high circulating rate should improve on heat transfer rate. But then what's it worth not having a mechanical device that can fail.
.
Andy

Is there as drawing or picture of that design Andy?

Mike



Edited 1 time(s). Last edit at 03/25/2015 04:59AM by Mike Clark.

I first learned of it from in an article in "light steam power". I was a friends mag. I no longer have access to. Do not what become of them sense he passed.

Maybe someone else here has the issue. Sorry don't remember the date or volume.

The particular one was for process steam. Had no supperheater. The stand pipe was not fired. Steam from a monotone steam generator entered close to the bottom. But with some space for sedement. Had a blow down on the stand pipe. There baffle disks to force a more steam flow path.

Basically a Lamont minus recirculation. A once thru coil into the stand pipe. A supper heater would be needed.

Their was I think a cutaway drawing in the mag.

I kind of think of it as normalize system. More as a control system.

Andy



Edited 1 time(s). Last edit at 03/25/2015 06:15PM by steamerandy.

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FirstPatent.bmp	501 KB	open | download	Karl Petersen	03/22/2015	Read message