Toward Bill G.'s new boiler design

OK,

As I indicated a while ago I am working on a new and improved, radically different and wonderful new boiler design.

Since that, by needs, includes everything I've learned from the steam club and Phorum and with the aid of some outside sources, not to be named but only hinted at, as to increase their level of importance and to also convey a greater sense of mystery as to where such great ideas come from, especially concerning all things related to steam, -_-_-_? ( I don't know how to finish a sentence like this.)

Anyway, I have some questions to start with: I am starting with a design for the burner.
[Sorry for the interruption, the cat scratched me and I am bleeding all over the place. I grabbed her tail while she was making a jump and she really got pissed off. I'm bleeding and she looks indignant. ]

Does anyone know or remember the rpm or edge speed of the rotating cup burner and if it would differ for gasoline vs fuel oil? Also for a pulse burner, such as a pulse jet, is there a preferred pulse frequency?

Thank You,

Bill G.

Hi Bill,

It isn't definitive, but 6,000 rpm seems to be a value that is commonly tossed about for different spinning cup burners. I assume size of the cup, shape, and fuel flow might have some effect. Probably can't hurt to start with a higher rpm motor and a rheostat....

I also wonder just how critical this actually is. I seem to remember some spinning cup burners in which the blower, cup and fuel pump were all operated by the same variable speed motor. The pump's output is proportional to rpm, of course, and centrifugal blower output roughly approximates rpm...

Thanks Ken,

6,000 RPM is faster than I thought it would be. I am thinking of two motors with concentric shafts,one for the spinning cup and one for the pulse. Pulse jets normally used reed valves but this application would require much more durability than reed valves could deliver. The spinning cup would be fed fuel through the hollow motor shaft which spins it.

I have decided to design a boiler for a 1,200 lb per hour output. That seems like a decent goal. I also believe in a rule of thumb of overshooting by 20% on any new design, so hoping for 1,200 lb per hour means designing for 1,440 lbs per hour.

It looks like a lot of figuring to do. I have to come up with the combustion chamber volume. That would, hopefully be from the pulse jet designs. Also I must figure the combustion pressure.

Best Regards,

Bill G.

Hi Bill,

I thought the rpm would be lower, that you just needed to outrun flame propagation -- but atomization is the key factor and you apparently need the speed to reduce the fuel to a mist.

Regards,

Ken

Bill don’t even think about a Pulse Jet burner. There so lowed you could not sit next to one. Read Doble book on Burner design and combustion chamber volume.

Rolly

Thanks Rolly,

I generally like to conceptualize something new before confounding it with facts. I guess I am still in that phase of design.

Whatever the noise level of such a pulse burner might be it simply can't be as bad as these damned boom box or ghetto blaster cars and the ignorant and inconsiderate people that drive them.

Your note about the loudness of such burners is, well, noted. In response to that I will "design in" a second layer of hemispherical coils to help absorb the noise at the exit of the burner tube. I think that the pulse generator part of the burner (not reed valves which depend on a back pulse to close them) will run at about 500 HZ.

So far, minds eye only, the boiler is kind like an Olfeldt with a central tank in the middle. The tank part has degenerated into two doughnut shaped little tanks at the top and bottom to connect pancake coils to. The central section is now a passage for the burner tube. Preliminary ideas are for 5" dia tube 22' long measured from the tip of the spinning cup. The pulse generator (siren?) is immediately before the cup and the rpm's of the siren can be adjusted by motor speed.

Both the spinning cup and the siren are on concentric motor shafts with the slower siren shaft on the outside. The spinning cup motor shaft is hollow also and fuel is pumped through it to the cup. The boiler is top fired. The motors are surrounded by the economizer tubing and insulated from it.

Beneath the economizer are the hot pressurized air inlet tubes connecting to the inlets of the siren. The pressure in the burner tube is 12 psi gauge. Like the boiler that was designed for an airplane, ( I think I read that in a Bulletin long ago) combustion air is heated to 1,200 deg F. by traveling over the outside of the boilers casing. A turbocharger/generator under the bottom of the boiler running on steam provides the air.

The boiler is recirculating and has a re-generator accumulator ( not a tank! Heavens No!) and pump outside.

So I guess the next thing is to draw it up and then start looking at some facts and see if maybe it will work and what to do.

Fun isn't it?

Bill G.

Bill-

It sure is good to see you back into things steam!! And your boiler sounds very interesting too...maybe you need to build two of them while you're at it?? With 1200-1500 lbs/hr output you can do great things!! Preheated air is the key to complete atomization/combustion, and with an air temp of 1200F you're well on the way...

It'll be nice to see your drawings when you get them done-hopefully your gonna show them here on the Phorum??


Chuk

Hello Chuk,

I am in a strange place after quite a few years. I have finished a major project to the point that others can take over more and I am in over my head anyway. Steam is still a passion and I can't imagine otherwise. I am also busy building a large box camera for use as a adjunct to that main project. So I am kinda back, I think, at least part time.


Hope this works. I had to re-scan at 200 dpi to get under the 1 meg limit.

Best Regards,

Bill G.

PS. I see that something got left out in the picture. Outside of the motors at top is to be a layer of insulation and then the economizer. The total width of the burner tube is 7 1/4" and it extends upward to the top of the boiler.



Edited 1 time(s). Last edit at 04/25/2023 10:45PM by Bill Gatlin.

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Been using it for nearly 10 years.

Thanks Scott,

I don't use windows yet, however Linux can, if setup, run Windows applications. So if I get it to work I will investigate the RIOT app.

Meanwhile while doing some deep undercover work into some secret files, I found something very interesting. Now remember that such work is not really steeling but is called "RESEARCH". This was found in a really arcane and little known citadel of engineering knowledge.

I think it might actually be what I am looking for to apply to my "New and Improved" boiler design. With any luck we can beat it's inventor to the patent office.

Here it is, but remember these are secret plans. That's why it looks so small, to keep it away from "prying eyes".

Fun ain't it.

Bill G.

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Hey Bill,

There are two problems with that scheme:

1. It is demonstrably in the public domain.
2. The patent would cost more than you could ever get from the design!

Regards,

Ken

Ken,

Do you mean that you found my source? Sources for us technical researchers are jealously guarded! And the money that could have been made. Gone!

Anyway I can see a lot of potential use for your pump. If you would post it over here I'd like to ad it to the mix.

As I said, I like to do the conceptualization part before confounding it with facts. That way I have a better starting position to begin altering the whole of it. I do have the books and much other literature about boilers now. That, a design goal, and with a concept to start the beginning of analysis about should end up with something interesting.

I have a lot of reading to do. I think I will start with the "Doble Steam Cars" book.

I want to keep up on this boiler until it looks like it's ready to build and if it isn't a better design than what's already out there that won't happen. I want to make it happen.

My best regards to everyone,

Bill G.

Hi Bill,

The first time that I ever met Tom Kimmel was at the very last Danville meet. Tom had been invited to sit in on the Board meeting and was a little shell-shocked because he had come out of that meeting as club president. The Board was smart, no one gave him the slightest hint beforehand so he didn't know enough to get in the car and run home.

Anyhow, Tom came up to me and introduced himself as the new club president and said that he owned a nursery. I told him that was a refreshing change -- he was making money off of gardening and steam was his hobby while everyone else was unsuccessfully trying to do it the other way around. His only response was: "Dianne will love you", giving me a clue that there was a bit more to the story ... even though I had no idea who Dianne was at that moment.

So, here's the original post and drawing:

The idea is a forced circulation boiler having no drum. Separation will be done in the pump/separator, which does both functions using centrifugal force. Water leaving the circulation coil will already be moving at fairly high speed due to some water expansion and about 15 percent of the water becoming vaporized. This water/steam mix enters the unit tangentially which helps preserve kinetic energy and gives the centrifugal separation a bit of a head start. The mix enters a drum having internal vanes, which is motor driven, though hopefully the entering water velocity will keep the pump load to a minimum -- maybe the motor's biggest function will be at cold startup.

As centrifugal force drives the water outwards in the drum, it passes through the loop seal, which is a fancy term for a set of U bends like those under your bathroom sink -- we used a lot of them in salt water distilling units aboard ship to let water flow between stages but prevent vapor transfer. The steam, being less dense, not only separates from the water, but is prevented from passing through the loop seal. The water passes into a slightly larger diameter impeller which pumps it back towards the generating coils by way of a perijet eductor. This is a form of jet pump where the fluid passes through the center unimpeded and the driving flow is introduced by jets on the periphery. In this case, the driving fluid is preheated feed pump water which has passed through the finned tube economizer coils.

The separated steam passes into the dry box through a piece of perforated metal, or some other type of retainer cap. Inside the dry box is a length of stainless steel screen which has been rolled into a cylinder and locked into place. This introduces rapid changes in the steam flow through the box, knocking some of the water in suspension to the bottom of the dry box. The wet steam then passes through the throttle valve and hence into the superheater coil before heading to the engine and auxiliary loads.

Level control will be handled by one extra coil above the top of the generator coil, which is connected by a T. Midway up into the coil will be a level control sensor which will start and stop the makeup feed water pump. Of course, the coil will be vented to the base of the pump/separator to prevent vapor lock.

Having just reviewed the Doble files on burners, I would use Smith's air atomizing burner with the air entry register. In Doble and Smith both, all the parts seeing the flame should be ceramic or ceramic coated high temperature metal which is probably more expensive. Thin ceramic plates made for semiconductor processing have been available in tech surplus yards, and using them as shingles sounds achievable.

Any metal in such a firebox has to be considered a service item to have on hand, as was demonstrated in the Doble service records and all development projects around the world.

Whatever you do, please do NOT try to build the 1925 Doble Blue Flame Burner, a real smog generator, even as an academic exercise.

Karl Petersen

310 Stainless is combustion grade. Expansive $$$ but does not burn out.
Rolly

Hello,

Well I am reading Walton's Doble book. I am finding that my ideas as to generator size are not too far off. Also as with other heat transfer designs such as combustion exhaust to air or air to air, the parameters have quite wide margins.

Rolly will be pleased that I have dropped the idea of a pulse burner. I watched a rocket launch by some college students working in association with Rocket Lab. One of them showed his liquid fuel burner and it looked a little like what I had but better, of course. The heated air comes into it the same way as I had before from six tubes attached radially to the top burner plate in a hexagon fashion leading outward to the casing where it is heated to 1,200 deg F.

The next burner plate is spaced about 1/2" down from the top one and turned so that the holes in it are unaligned from the upper ones. (might need more spacing) It is made of ceramic.

A spinning cup sprays fuel between these two plates. I decided on the spinning cup because it has a high turn down ratio compared to atomizing nozzles. As I understand it the nozzles turn down ratio is in the neighborhood of 4:1 and the spinning cup is 20:1 .

The next burner plate is also ceramic and spaced about a 1/2" below the middle one and the holes in it are unaligned with the middle plate and aligned with the top plate.

Like a rocket launch, this burner should be exceedingly quiet. At least no one could hear anything afterwards.


Best Regards,

Bill G.

Just a comment,

I was/am reading Toms "Steam Generators" book.

It seems that the Velox boiler is the most compact due to the use of sonic to super sonic combustion gasses impinging upon the water tubing. This seems like a good direction to look into.

My first take on the Velox is that it is a fire tube boiler using supersonic velocities inside the fire tubes to get tremendous heat exchange rates. The fire tubes are then inside of the water tubes which are inside of the combustion chamber.

Thinking of it this way may allow for some differences in design that may lead to even more compactness, or at least some better economies of manufacture. For one thing I think that using a turbocharger system that runs on steam rather than using a turbo jet type of compressor might be of value. The thermodynamic circuit might be a little different.

Any Ideas?

Best Regards,

Bill G.

Hi Bill,

The Navy's "P-fired" boilers were essentially a more compact and modernized Velox boiler. The turbo charger didn't have what you would call a traditional center bearing assembly, it was an electric motor. This drove the compressor during startup ... and added extra power when combustion gasses were not totally sufficient.

There's a problem with conflating a pressure fired boiler with a gas turbine, that reason being precisely that it is a boiler. The boiler tubing extracts most of the thermal energy from the combustion chamber, leaving the dregs to drive the turbine. Of course, leaving dregs is the same thing as achieving high efficiency, and they should be still be sufficient ... but sometimes you end up with transient conditions that leave you short. I always like having a nice safety margin and well as a backup.
...
On the other hand, there are real issues with trying to build an extremely high efficiency engine. Tim Nye was going through all the Williams brothers records and I got some of the data from that. The alleged Williams cycle could get high indicated efficiency, largely through the use of ridiculously short cutoff (which, led to high compression -- which in turn caused a problematic rise in clearance volume that undid much of the gain), Tim intends to write about all this. I fed their engine parameters into steam engine spreadsheet and duplicated their indicated power and efficiency. Then I added industry standard equations describing engine mechanical losses to get estimated brake power and efficiency. Let's just say that these engines weren't particulary efficient and at higher rpm friction exceeded horsepower -- explaining why they had a different cam setting to simulate traditional engines.

The previous sentence is making the point that you might not pay a severe penalty by reducing steam engine expansion ratio a bit in order to get higher amounts of steam to drive a turbocharger -- if that is even necessary. If I were fitting a turbo, I would run a few reheat passes between the boiler exhaust and the turbine just to ensure that I didn't get wet steam into the turbo -- they are not designed to handle moisture erosion.

This all leads to the question: "Why is this an "either-or" situation?" A number of high performance sports cars use multiple turbos in order to reduce turbo lag. Why couldn't you have one turbine driven by boiler exhaust gases and one by engine exhaust steam? I guess you'd want to look at both series and parallel hookup. I'd seriously investigate series connection since that might permit higher boiler gas pressures -- which would improve heat transfer, improving boiler efficiency and reducing overall tube nest size. The compounded compressors should also provide better pressure to the exhaust gas turbine, allowing for better overall turbine energy recovery.

Regards,

Ken



Edited 1 time(s). Last edit at 06/10/2023 11:21AM by frustrated.

Hello Ken,

You mentioned once that the Navy P-fired boiler used combustion pressures of about 100 psi. So if they are of an improved Velox design then they were using the supersonic combustion to improve the heat transfer to the fire tube inside? If so, did they dimple the fire tube for greater thermal transfer to the combustion gasses inside it as well as to the water outside it?

Toms book says that the Velox boilers combustion chamber released 900,000 BTU s for each cubic foot of combustion chamber volume. They also ran at 35 pounds gauge pressure.

Three important questions:
First is the required combustion chamber volume for the same output linearly inversely proportional to the absolute combustion pressure? Twice the pressure then 1/2 the combustion chamber volume?
Second is the sub sonic thermal transfer to the tubing also linearly proportional to the absolute pressure?
Third is the super sonic thermal transfer to the tubing linearly proportional to the absolute pressure?


Thank You,

Bill G.

Hi Bill,

The only two classes of combatants to use the Foster Wheeler boiler, that I'm aware of, were the ten Garcia class frigates and the six Brooke class guided missile frigates -- my brother served on the second Brooke class, USS Ramsey, which strangely enough was named after the father of the captain of my own ship. Unfortunately, such a low number of builds makes it really hard to find out much about the units other than in generalities. I can only think of twice in my shipyard tours that I actually saw one of these ships under repair ...and I didn't have a security clearance to get aboard since I was working on different vessels. Even if I had, it's likely that the boilers would have been zipped up tight since we usually only did cursory boiler maintenance except during drydock. Given that P-fired boilers live inside a pressure vessel, there's even less to see than on something like a standard D-type unit.

Anyhow, I have tried to find a Foster-Wheel tech manual on the boilers and have had no luck. I don't think a unit over 50 years old is classified, since nuclear power isn't involved ...it's just that they never published many volumes and those onboard the ships were probably trashed when the vessels were scrapped. Unsurprisingly, Foster-Wheeler wasn't that interested in helping ... they had bigger problems and disappeared into the merger maelstrom circa 2015.

One thing to keep in mind is that a lot of the heat transfer isn't due to gas velocity, but simply sheer pressure. At 100 psi, the air molecules are a lot closer together, and more of them are in contact with the boiler tubes, than would otherwise be the case when pressure is measured in inches of water.

Another thing to keep in mind is the square-cube rule. An automotive sized boiler is going to have a much smaller volume of water per square inch of tube surface than would be found on a larger boiler of similar overall design. We also have to consider that tubulent flow will extend away from the boiler tube a proportionately greater distance.

I always considered the square-cube rule to be weird when applied to steam automobiles -- proportionately smaller boilers get proportionately better heat transfer capabilities if the design is otherwise kept constant. However, we can't really celebrate that -- because the engines also transfer heat more readily to the atmosphere while friction and piston blow-by are also correspondingly worse... really big single-cylinder engines would probably give better economy, but be inferior in every other way...

Regards,

Ken

Thanks Ken,

So it sounds like some of the data is lost as in whether the fire tube was dimpled or not and if so just how. That's OK, I think intuition will help to replace some of it. I sense that a 5/8" ID fire tube would be dimpled only about 1/16" deep, meaning that the inner diameter would vary from 5/8" to 1/2". That would be from a cross sectional area of 0.306" sq to an area of 0.196" sq or a percentage of 36% less.

That seems radical though, so if the dimple is 1/32" deep instead, then the diameter would vary from 5/8" to 9/16" or from a cross sectional area of from 0.306" sq to an area of 0.248" sq or a percentage of 19% less. That seems nicer. The dimples could be circumferential and of about the profile of the diameter of the tube or spiraled around it. The idea is to not let the fire tube warp inside of the water tube.

The fire tube / water tube combination would need to be experimented with to get the very best parameters. Fortunately this would not be too very hard or expensive a setup.

I think that the water tube part is just a tube with no added topography needed. The fire tube is under compression inside the water tube so I guess (love all these guesses) that its wall thickness would be about 1/16" so its OD would be 3/4".

The water tube would need enough inside clearance to equate to say a 1/2" ID tube or about 0.20" sq. Since a 3/4" dia tube has a cross sectional area of 0.4418' sq then an internal area of 0.6418 is needed. That then is an ID of 29/32" and a possible OD of 1-1/8".

Well, that's a possible water / fire tube combo for a (relative to a big ship) small boiler.

Now how many feet of it do we need and what really is a realistic combustion pressure?

Considering the engine as an inline three stage compound with the mid and low pressure cylinders double acting and 180 deg apart while the high pressure cylinder is single acting and has no particular crank degrees relative to the other two balancing should be quite simple. I know someone who is really good at it.

Best Regards,

Bill G.

Hi Bill,

I probably ought to note that one advantage of an engine driven turbo is that you can stick a bypass.reducer around the engine to drive the turbine directly -- if you were standing idle for 15 minutes and wanted to make a quick getaway, this would be a lot more aggressive than other options.

Ken

Bill Gatlin Wrote:
-------------------------------------------------------
> Hello Ken,
>
> You mentioned once that the Navy P-fired boiler
> used combustion pressures of about 100 psi. So
> if they are of an improved Velox design then they
> were using the supersonic combustion to improve
> the heat transfer to the fire tube inside? If so,
> did they dimple the fire tube for greater thermal
> transfer to the combustion gasses inside it as
> well as to the water outside it?
>
> Toms book says that the Velox boilers combustion
> chamber released 900,000 BTU s for each cubic foot
> of combustion chamber volume. They also ran at 35
> pounds gauge pressure.
>
> Three important questions:
> First is the required combustion chamber volume
> for the same output linearly inversely
> proportional to the absolute combustion pressure?
> Twice the pressure then 1/2 the combustion chamber
> volume?
> Second is the sub sonic thermal transfer to the
> tubing also linearly proportional to the absolute
> pressure?
> Third is the super sonic thermal transfer to the
> tubing linearly proportional to the absolute
> pressure?
>
>
> Thank You,
>
> Bill G.

If your goal is to design a compact combustion chamber that will burn large amounts of fuel efficiently, then look at the combustion chambers of gas turbine engines. Lots of highly compressed air is the key, US military fighters such as F14, F15, F16, and F18 all use engines having compressors with compression rations of over 20, resulting in combustion chamber pressures in excess of 300 psi. Compressed air flows through the combustion chambers so fast that special metal structures are use inside the chambers to create eddy currents in the air flow which keep the flame front from being blown out of the chambers. Pressure inside the combustion chamber is determined solely by the compressor suppling air, not the combustion of fuel, nor the volume of the chamber. In fact, if pressure inside the combustion chamber ever exceeds the pressure of the compressed air from the compressor, then combustion gases briefly flow back into the compressor creating a very loud bang in what is called a compressor stall. Such stalls can severely damage a compressor.

I've never seen any data for the Specific Heat of combustion gases, but there is data for dry air,...which is probably pretty close to combustion gases since the burned fuel exiting the combustion chamber makes up only a tiny fraction of the total mass of air flowing through the chamber. At one atmosphere air holds 0.24 BTU/lb F, and at 1000 psi that number only goes up to 0.27 BTU/lb F. Meaning the biggest increase in how many BTU the air has to give to the boiler tubes comes from the fact that compressed air is heavier than uncompressed air for any given volume. And that can be found by working through the ideal gas law, PV=nRT. I haven't worked through all the math, but all the formulas seem to be simple multiply and divide, meaning it looks linear to me; more pressure = more BTUs into the water tubing.

Finally, with a few short length exceptions, I'm pretty sure gases cannot flow through a tube at supersonic speeds. Before I start, lets set some terminology. Mach = speed of sound. Local Mach refers to the speed of sound in the gas being discussed, ie air, or combustion gases. Lastly, Mach is not a constant speed, it's a variable that gets faster with higher temperature. Mach on a 75 F day is 1133 ft/sec in air. Mach inside your combustion chamber where the fuel is burning at 3700 F is 3161 ft/sec. After the combustion gases have given up much of their heat (enthalpy) to the water inside your boiler tubes, let's say the temperature has dropped to 500F, which results in a local Mach for those combustion gases of 1518 ft/sec, which will become the speed limit for the combustion gas flow. So, if you're using the term supersonic to mean speeds of over 1133 ft/sec, then yes, that can be achieved by raising the temperature. But if the term supersonic is used to mean speeds in excess of local Mach, then your breaking one or more laws of physics.

Oh, the exceptions: CD (Convergent - Divergent) nozzles can force gases to exceed local Mach, but only for short distances, and gases leaving the tips of centrifugal impellors can exceed local Mach, but again, only for short distances.



Edited 1 time(s). Last edit at 07/11/2023 08:55PM by Dusty.

Thanks Dusty,

I have been kicking it around a lot between things that you said and Ken said and things that just pop into my head. I really seems to me then is that the great reason for using, if we can, "Local" sonic to super sonic speeds is to eliminate the insulating boundary layer between the hot combustion gasses and the inside of the fire tube.

Somehow, without designing the fire tube with an increasing taper to mimic a diverging nozzle the maintaining of such super sonic flow seems troublesome. Changes to burner conditions, such as temperature and pressure, would increase and decrease the rate of heat exchange throughout the length of the tube in response to any turn down of the boiler from maximum output, resulting in an impossible control situation.

Ken said that the increase in heat conduction is in proportion to the combustion pressure and that makes sense. Controlling the combustion pressure should be easy enough.

Any ideas as to whether the boundary layer thins and becomes more conductive with pressure increases? If it does then heat transfer wouldn't require as much turbulence with higher pressures.

Just some late night thoughts. Does it seem as if this combination of turbine / compressor boiler and steam engine is approaching a Still cycle? For certain the turbine, while running the compressor, will be producing a lot of electricity to run the basics of the car and engine accessories, if not adding to the engine power itself. Anything left of the usable heat coming out of the turbine would then go to an economizer.

Whether it is a Still cycle or not, the purpose of the boiler is to get better economy out of a smaller boiler.

Best Regards,

Bill G.

I agree with Ken; increasing the pressure of the hot gases surrounding the boiler tubes increases the BTUs/volume of hot gases, resulting in more BTUs in close contact with the tubes.

My only knowledge of boundary layer vs temperature is that the boundary layer gets thinner as temperature increases. Since the exhaust gases are already thinning the boundary layer due to their high temperature, I'm not optimistic that increasing burner gas velocity will substantially further reduce the boundary layer thickness.

Just my opinion, but I think you'll get much greater heat transfer into the water by using finned tubing as was done in the SES boiler, which is a fairly small, compact burner-boiler unit. I've not seen any documentation on whether or not the unit was pressurized, but there are docs stating it used a hydraulic motor to drive the impellor shaped fan inside the burner, which makes me strongly suspect the burner and boiler were both pressurized.

Still cycle??? I plead ignorance. I don't know what the Still Cycle is, and all Google had to offer were Still brand bicycles.

Hi Dusty,

The Still engine refers to a series of diesels that used waste heat to produce steam for a bottom-cycling engine. It can sometimes also be found under the term Still-Kitson. It was used in some locomotives, ships, and stationary power plants.

There are a number of references, one of which can be found at: Still Diesel

http://www.douglas-self.com/MUSEUM/POWER/still/still.htm

This can improve efficiency, but the gain is not huge since the efficiency of a power plant is proportional to the temperature differential across the cycle. Diesel engines are rather efficient and therefore the waste heat is fairly low grade, meaning the contribution is low.

I've seen the SES setup a few times. The single stage centrifugal blower is good for draft on the order of inches of H2O, rather than psi. Even if the blower were more powerful, you would need some kind of flow restriction at the stack to permit a pressure buildup, which is not present. In a Velox, or a P-fired boiler, the exhaust turbine acts as the resistance.

I admit to being unsure how finned tube would fare in a pressurized boiler. The typical boiler is gas-side limited, meaning that the water inside the tube is capable of absorbing more heat than the gas side of the tube can deliver -- assuming adequate water delivery and avoidance of Departure from Nucleate Boiling. (That can be a huge assumption, Abner Doble clearly didn't get the point when designing the Doble-Detroit boiler.) Both finned tube and pressure can shift the heat transfer ratio away from the steam side ... but I have no idea whe Sther stacking the two would give you the potential to make the boiler water limited instead. Numbers need be juggled...

Regards,

Ken



Edited 1 time(s). Last edit at 07/13/2023 12:36PM by frustrated.

Interesting background on William Still, seems he invented what is now referred to as a combined cycle back in the early 1900s, truly a man ahead of his time. Today we use one of several different organic compounds, typically a Freon, as the working fluid (instead of water) as Freon can extract more useful work from the waste heat than is possible with water.

Thinking of Freon, I suspect that's what Bill Lear used in his "steam" turbine powered race car; he proudly announced during interviews that his turbines were powered by Lear-ium but never said what Lear-ium actually was.

Just my guess, but I suspect finned tubing would work well in a pressurized economizer section of a pressurized boiler, where the fins would help extract a little more thermal energy (enthalpy) from the mostly cooled exhaust gases before they left the boiler. Probably don't want to use fins in the super heat zone,...they might just melt.

OK, that's my 2 cents worth.

Hi Dusty,

You're giving Lear far too much credit. When someone asked him about what his car was to run on, he said 'Learium', having no idea what that entailed. In actuality, as one would expect, it consumed water.

Now, Walter Minto actually got Datsun to spend money on his Freon powered car. I would have expected better from Nissan Heavy Industries, one would think that they would have understood that Freon was a dead end because peak permissible temperatures limited thermal efficiency. We can't blame this on their being invovled with ICE engines because I've read a letter written by Charles A. Amann, Assistant Head of the Gas Turbine Research Department at the GM Tech Center back in 1972. He was responding to a query by SACA member H. D. Gardner and wrote convincingly about the thermodynamics in steam car power plants.

There was lots of weird stuff going on. As I recall, back in the 40's, the Perrymobile steam engine also used a 'special' working fluid -- which appeared to be water with some green dye.

Regards,

Ken

frustrated Wrote:
-------------------------------------------------------
>one
> would think that they would have understood that
> Freon was a dead end because peak permissible
> temperatures limited thermal efficiency.
>
> Regards,
>
> Ken

Ken, can we talk about your assertion that; "Freon's peak permissible temperatures limit thermal efficiency", because I don't believe that's completely correct. My limited understanding of how efficiency is calculated for any heat engine is: how much energy put in has been converted to the desired energy out; for Rankine Cycle (steam) engines the units of energy are typically BTU or calories or Joules,... temperature change between in and out tells only part of the story. A P-h diagram like this one can be used to show the ideal maximum amount of energy that can extracted, then compare that number to what is actually extracted from the working engine to find the efficiency.



Rankine engines that use Freon or other petroleum derived fluids instead of water are referred to as ORC, Organic Rankine Cycle. As of 2017 there were 1754 ORC power generators globally ORC World Overview

One of the advantages of using a Freon as the working fluid in a car is their low expansion rate, which allows the use of single stage turbines and scroll expanders to be used efficiently. Typical power generation plants which all use water as the working fluid use turbines with 10 or more rows (stages) of blades and stators, and if you want an efficient turbine in a car that uses water as the working fluid, you need the same number of blade rows.

If I've said anything that you know to be incorrect, please let me know,...one of the reasons I'm on this forum is to share what I've learned and to learn what I still don't know (which I'm certain is a lot).

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Bombustion chamber.JPG	68.4 KB	open | download	Rolly	04/25/2023	Read message
final test max air.jpg	41 KB	open | download	Rolly	04/25/2023	Read message
BGBoilerBurner2.jpeg	553.4 KB	open | download	Bill Gatlin	04/25/2023	Read message
BGBoilerBurnerResearch.png	4.5 KB	open | download	Bill Gatlin	04/26/2023	Read message
CIRC SYSTEM 26 APR 2023.png	471.9 KB	open | download	frustrated	04/27/2023	Read message
P-h Diagram for Water.png	231.4 KB	open | download	Dusty	08/28/2023	Read message
Concept Explaination.jpg	954.4 KB	open | download	Rick.H	08/30/2023	Read message
Rankine-Gibbs.jpg	287 KB	open | download	Rick.H	08/30/2023	Read message
T S calculations.jpg	793.2 KB	open | download	Rick.H	08/30/2023	Read message
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