Re: Electric batch boiler
August 06, 2020 12:09PM
Hi Lohring,
Thank you for your kind words.

I like that you provided your passion with RC boats and flash steam power...very nice! I can learn a lot from you guys (and girls). I think you mentioned this somewhere before and I forgot. CRS and my apologies.

We can start another thread about flash steam power, your choice. I offer the attached file for consideration and perhaps some discussion on a new thread. Out of respect for Kyle, I don't want to wonder off his thread.

Kind regards,
Rick


Re: Electric batch boiler
August 06, 2020 12:11PM
I'm vaguely familiar with electrolysis, having experimented with an ambient temperature electrolyzer back in the 70s (that was one of the ways we were supposed to free ourselves from the tyranny of the gasoline companies --- it turned out that being their slaves was a lot better than buying the needed electricity, however.....) I also studied the topic briefly as a navy-type person assigned to shipyard duty, electrolyzers are used on nuclear submarines to supply breathing oxygen indefinitely ---- no need to raise that snorkel which some lousy patrol aircraft could pick up on radar 100 miles out... Anyhow, I looked up the topic online as my knowledge of high temperature electrolysis was even more limited than my general background info.

In any case, I'm a huge believer in the TANSTAAFL ... There Ain't No Such Thing As A Free Lunch. The whole idea of adding energy into a system and getting more out than you added bothers me more than just a little. Doing a bit of research, I found the following (with a few additions of my own, specifically conversion of degrees C to F).


From the Wikipedia entry "High-temperature electrolysis":

High temperature electrolysis (HTE) is more efficient economically than traditional room-temperature electrolysis because some of the energy is supplied as heat, which is cheaper than electricity, and also because the electrolysis reaction is more efficient at higher temperatures. In fact, at 2500 °C, (4,532 °F) electrical input is unnecessary because water breaks down to hydrogen and oxygen through thermolysis. Such temperatures are impractical; proposed HTE systems operate between 100 °C and 850 °C.

The efficiency improvement of high-temperature electrolysis is best appreciated by assuming that the electricity used comes from a heat engine, and then considering the amount of heat energy necessary to produce one kg hydrogen (141.86 megajoules), both in the HTE process itself and also in producing the electricity used. At 100 °C, 350 megajoules of thermal energy are required (41% efficient). At 850 °C (1562 °F), 225 megajoules are required (64% efficient).


As Conservation of Energy would suggest, it takes more power to generate the hydrogen than the hydrogen itself possesses.

Regards,

Ken
Re: Electric batch boiler
August 06, 2020 01:25PM
Stored steam is still used in switching locomotives - there are a handful still in operation in the world. But the manner in which this "stored hot water" is translated into motion is inefficient. Less than 1% efficiency. Although when you're talking about Prevention of explosions at industrial plants, then the low efficiency level is perfectly acceptable.

The way my boiler works is similar but not. With continuous reheat, it will evaporate supercritical water into dry steam and make an engine do something useful. It does not create steam with a single BTU less than any other boiler. Its magic is that it doesn't make steam at the same time you're trying to use it. Think about that.

I thought it could be used for cars, since they have a similar operation modality - you fill a tank, and drive around all day with what's stored in the tank. Can you imagine the operational complexity of a car that refined its own oil into gasoline for the engine AS it was driving around? That's what steam cars do.

Hey Rick, I think there is something to your Boundary Layer picture. In aeronautics, the boundary layer of air next to the wing and fuselage is moving a lot slower than the rest of the air around the plane. I imagine water flowing through pipes is doing the same thing. If heat transfer is improved with relative speed, then slow-moving water is probably a detriment.

Thanks everyone for the thoughts and input.

Kyle
Re: Electric batch boiler
August 06, 2020 02:08PM
Moving a tank car full of hot water ( stored energy ) on rail only takes .66 HP per ton. Only used as yard engines.

Moving the same weight on water takes 5 Hp per ton, and over the road the avenge per ton is 15 HP, you wouldn’t get very far.

Efficient boiler design has always been to reduce weight and increase efficiency.
Generate the steam as you need it.

Forced circulation boiler’s keeps the boundary layer wet all the time.

Monotube generator not so much, no circulation. Less efficient.

Rolly
Re: Electric batch boiler
August 06, 2020 05:07PM
frustrated Wrote:
> As Conservation of Energy would suggest, it takes
> more power to generate the hydrogen than the
> hydrogen itself possesses.
>
> Regards,
>
> Ken

It's known that electrolyzing hydrogen from the grid is a bad idea, since you get back 1/10 of what you put into it.
I'm sure that's why "Green proponents" always talk about hydrogen electrolyzed by wind power etc.
I know some people experimenting with urea which requires less energy than water but nevertheless, as you said, there is no free lunch.

My electric batch boiler needs about 700btu/lb of continuous reheat (it was designed for powerplants, where reheat is always available). But for a steam car, using a small amount (1kg daily) of hydrogen as the reheat source might be the ticket - if that amount can be electrolyzed at home using wind/solar.
Re: Electric batch boiler
August 08, 2020 07:52AM
Hi Kyle,
I have high hopes for this boundary layer theory. You'll see more on this in future threads.

Back to your albeit thermal inertia idea, what is your concept for regenerative braking? If not and after these discussions, what do think could be?

Sincerely,
Rick
Re: Electric batch boiler
August 08, 2020 12:38PM
Rick.H Wrote:
-------------------------------------------------------
> Hi Kyle,
> I have high hopes for this boundary layer theory.
> You'll see more on this in future threads.
>
> Back to your albeit thermal inertia idea, what is
> your concept for regenerative braking? If not and
> after these discussions, what do think could be?
>
> Sincerely,
> Rick

Hi Rick,

I look forward to seeing more about boundary layers in boilers. Looks very interesting.


Regenerative braking can be one of two things:

(1) Using the engine to pump air (which would be pretty hot and it might do something useful)
or
(2) Using an electric motor to generate electricity (like a Hybrid car)

I'm thinking that (1) would be best paired with Hydrogen as my reheat energy, and (2) would work best if I used a 15kW battery for reheat energy.

If I used batteries or electric motors in any way, the car would become something like a steam/electric hybrid. It could start instantly (electric), motor sedately (steam) and recharge itself as needed. A gas/electric hybrid is great but for two things: Its still uses fossil fuel that makes emissions, and the owner can't make his own gas, he has to buy it. So even at 60-70MPG, it isn't optimum.

A steam car where the owner makes his own steam at home (and can sell it to others), and it uses a small 15kW battery (1/3 the size of a BEV) which makes it a long-range Hybrid with zero emissions, I think that's a winner.

Kyle
Re: Electric batch boiler
August 08, 2020 06:09PM
There's nothing new regarding understanding the importance of boundary layers in boiler generating surfaces, the topic has been extensively discussed in a wide number of books, in the Bulletin and inside this forum. The importance of eliminating boundary layers was widely understood close to 170 years ago --- when the first forced recirculation boilers were built.

The key to eliminating boundary layers is turbulent flow. Any number of methods have been tried --- including running wires down the inside of the tube, adding fins to the inside of the tube, flattening and twisting the tube (Serpollet), twisting three smaller tubes into a rope-like structure and dividing the flow between them, and so on. When you get right down to it, however, the most effective means to eliminating boundary layers is simply flow velocity --- if you move the water fast enough, the Reynolds number rises and the flow becomes turbulent. Monotube boilers are inherently limited in their steaming capacity because the flow velocity it limited by the amount of steam taken out of the boiler whereas boilers which have a circulating flow must, by their very nature, move the flow faster than the steam is withdrawn. This is why so many boiler builders brag about their circulation velocity or circulation ratio --- it's a measure of their turbulent flow.

The BIGGEST reason to achieve turbulent flow is DNB --- Departure from Nucleate Boiling. Boiling typically starts on small imperfections in the tube surface, tiny bubbles forming on these imperfections. If the velocity is high enough, these bubbles are instantly swept away. If the velocity cannot sweep the tiny bubbles away, they get progressively bigger until the eventually form a vapor layer. Unfortunately, steam is a crummy thermal conductor and thus this steam layer prevents heat from being transferred to the water in the tube. This not only limits steam production, but it leads to tube overheating and eventual burnout.

So, anyhow, flow velocity is the simplest and most certain way to eliminate boundary layers and to ensure heat transfer. Of course, there are limits to anything, eventually you reach a point where the heat added can overwhelm the carrying capacity of any reasonable flow.

Regards,

Ken
Re: Electric batch boiler
August 09, 2020 05:43AM
Years ago I used SS rod with the squared off ends to center the rod in the tubes for my water powered burner on my boat burner. This keep the water next to the boundary layer of the heated tube.
15 psi of water went through the tubes flashing into steam and entering a nozzle much like an air nozzle to suck up the fuel for the burner. Water steam powered burner.
Worked great but I did not like the nose.

Rolly

[www.youtube.com]


Re: Electric batch boiler
August 09, 2020 12:00PM
Hi Kyle,
My apologies for continuing the boundary layer discussion. Hope you find it interesting.

Ken,
You nailed the concept that is intended with the boundary layer efficiency concept I presented earlier. The concept I intend to pursue is to fill the generating tube with spiral wire to decrease volume and increase mass flow rate pursuant towards more turbulent flow. Note that the flow is already turbulent in the tube mentioned. Really just increases the efficiency of the poor conductivity of steam.

Rolly,
Your the guy to follow and watch. You have tried many of the concepts that I'm pursuing. I don't know if you knew Jim Tangerman. He is a guy I really looked up to. I asked him if steam injection on a burner nozzle is a good idea. He told me very sincerely that it would create the fire of Hades (Hephaestus, god of fire)! After hearing this, I started my quest to understand and replicate his words. With my Dad's recommendation to burn the same fluid used for work, I modified the quest to perform HTE in the process.

Ken,
Back to you...the heating value of hydrogen is 3 times that of gasoline. You are right with an earlier statement that there is no such thing as something for free. This was in reference to Gibbs free energy equation. So there is a compromise with this concept. This is to apply a hybrid concept of gas (gasoline) and HTE in a burner system very similar to what Rolly just posted. The intent, steam injection would get electrolized before the burn.

You know, I thought I invented a new cycle when I calculated what would be an efficiency of this gas/HTE hybrid burner in a steam engine. I'll let you think about that for a while because I had to think if this could be right. The method is to add and subtract heat and work appropriately in the Carnot efficiency equation. My so called cycle invention, as I continued to ponder, really is kind of pompous. The Rankine Cycle and Gibbs Free Energy along with the basics of Carnot Efficiency cover it all quite nicely. There was another steam guy, inventor of a new steam engine, who claimed he had discovered a new cycle...I kind of thought that was hogwash knowing what I know now. You would be able to tell who this is in an instant, I'm sure.

Lohring,
Lastly, the key to this whole thing lies with the steam RC speed record systems. How can we scale up these micro steam engines to the scale of an automobile. The boundary layer concept naturally works with the small diameter tubing used as steam generators. The gas/HTE hybrid burner, I think, needs to supply the H2O in a small diameter tube like the RC systems. This would be the 1/8" Diameter range, run through the burner flame to achieve super heating before the burner pressure nozzle.

Sorry, one more last thing to all,
I was just reminded in my other thread (another pretty smart steam guy) that when you release high temperature steam via a nozzle, the steam is super heated. What if you release super heated H2O, does it go super critical? Honestly, I don't know the answer. Something to experiment with...more to come on a future thread.

I attached a couple of pictures of my new pole barn workshop where I'll be building all this new development ideas. Still need to pour the floor and get it wired and stuff. Hopefully, you all see a built up Gentleman Speedy Roadster parked outside.

Kind regards,
Rick


Re: Electric batch boiler
August 09, 2020 01:49PM
The electric batch boiler starts by pressurizing the water to 3250psi. THEN, it heats it. It can't overheat, because the water is supercritical pressure. It can't over-pressure, because a 10-cent pressure switch controls the whole thing. As the boiler contents are being used, the compressor kicks on and keeps the system pressurized at 3250.

People have spent 100 years trying to perfect boilers so they can use the steam they are making in real-time. The electric batch boiler makes steam in advance of it being used, and stores it. It is 1/100th of the complication.

(I did build the boiler a couple years ago, then my parents died and I moved and etc etc etc so I don't have pictures but I do know what I'm talking about).

The boiler reheat system is equally simple because it is reheating water that is already steam. It can be reheated to 500 degrees or 800 or 1500, doesn't even matter. Reheat can use either electric coils or fossil fuels or hydrogen.

This system was designed for powerplants, but it WOULD work in a car. And with the steam (and the hydrogen) both made by solar energy, the car owner can make his own steam and drive his car for free. To me, every car that doesn't end up being a drain on The Grid is a good thing.
Re: Electric batch boiler
August 12, 2020 07:11AM
Hi Kyle,
Attached is a TS Diagram that I would apply to your system. I don't know how to say this nicely, the application is limited to special cases. Part of the basics in a Rankine Cycle is to utilize as much expansion of steam to the point of condensation as possible. In order to keep steam, as an output, from an expander (engine, turbine, etc) one would limit cut-off or have very little expansion. The expansion is work and a key part of the efficiency equation.

In a standard condensing cycle, the condensate water is of a higher temperature than if it came from a tank. This makes the condensing system more efficient. Also, the trick to a condensing system is to use all the expansion work possible for maximum efficiency.

I included a TS representing my Steam Scooter as a comparison. The area under the TS curve is indicative of efficiency...my understanding of the Rankine Cycle.

Perhaps there is a specialized application for this system and will provide a useful effort. The yard locomotives that just ran off of thermal inertia in the pressure vessel met this special application. These loco's were charged from a shop boiler in the yard that ran at a pretty good efficiency considering or relative to mobile boiler of the time. The yard locomotives were non-condensing and just released the wet steam to the atmosphere. Another application of your system would be to capture braking energy that would be other wise lost in heat. This is reason for my earlier question on how you would apply regenerative braking. Other than that, any energy applied would have to be against the efficiency of the system. Note that I'm talking about the Carnot Efficiency.

Hope this helps and this information is considered constructive,

Sincerely,
Rick


Re: Electric batch boiler
August 12, 2020 07:34PM
Two interesting PhD works:

Feasibility of using a steam power system in a small garden tractor:

[scholarsmine.mst.edu]


Steam sports car design:
[pdfs.semanticscholar.org]
Re: Electric batch boiler
August 14, 2020 09:31AM
I'm posting this here...the attached comes from the Steam sports car design article posted by Novice above.

I think this is a pretty good design. I would suggest that the system includes economizer, feed water heater and super heat based on the T-S and schematic.

Also attached is my version of a non-condensing system. As far as Steam 101 goes, this is my venture.

As an advertisement for the club, Ken produced this good depiction of a condensing steam system. You can view it in the SACA website or click below.

Steam Tutorial - condensing system

I would consider Ken depiction as Steam 102 regarding a condensing system.


Re: Electric batch boiler
August 20, 2020 05:47PM
Swiss steam locomotive with electric water boiling.


[www.douglas-self.com]

"Power was taken at 15 kV, 16.6 Hz from overhead lines by a pantograph, and fed to resistance heating elements in the boiler, via two transformers rated together at 480 kW. Water feed was by normal steam injectors. These unique locomotives also retained the capability of being fired by coal in the usual way."
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