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"Jakuba's Compounding article in the Bulletin"

Posted by jakuba 
Re: "Jakuba's Compounding article in the Bulletin"
September 18, 2014 11:05PM
Hi Bill

The thermodynamic laws do not change. An isotropic or isenthalip change governed by the process. The books say that the exhaust is a free expansion. It took some searching to find what a free expansion was. It is the term used to describe the equalization of pressure in the text book example of isenthalip expansion. Were you have a evacuated chamber connected to another with a pressurized gas with a valve between. opening the valve allowing the pressures to equalize. The classic example of isenthalip expansion. Isenthalpic process on Wiki.

Ignoring the attached philosophical meanings to entropy, The path of the change of state of a substance where entropy does not change is one in which no heat is transferred into or out of the substance. Work is then equal to the change in enthalpy. That does not imply that entropy must be constant for work to be produced. Constant enthalpy implies that no heat is being converted to work. What the case may be regarding the exhaust process I do not know. But treating it as isenthalip does make the energy balance out. And balancing the energy is how we figure out a lot of things. We couldn't have got to the moon if the conservation of energy law was wrong.

The temperature plots in Stumph's book show the steam temperature in the cylander. And the temperature exceeds the incoming steam temperature as far before TDC as the cutoff event is after TDC. it could just as well be the case that compression exceeded the inlet pressure. And as the temperature so quickly drops on admission that is likely the explanation.

I wonder can we get a government grant to research this question.


Edited 1 time(s). Last edit at 09/19/2014 08:00AM by steamerandy.
Re: "Jakuba's Compounding article in the Bulletin"
September 19, 2014 12:17AM

I disagree! The laws of thermodynamics do change. They get more complicated the further one studies them.

But, steam is kinda simple, as long as one has steam tables and such, anyway.

Stumph's old engines probably had a lot of entropy losses. There would then be an increase in entropy during expansion and another increase during compression. This would result in a sizable increase in temperature by the end of the re-compression process. If the engines expansion had gone into wet steam of say 90% quality and a mist had formed (slow engine) then re-compression starts at the saturation line which is (to the right on the T S chart) at higher entropy. Again; hotter re-compression.

Hotter than inlet re-compression is a waste of energy. There is no gain from it.

Andy, the energy would balance out also by treating the exhaust process as isentropic expansion inside of the cylinder and considering the work done as going into heating the exhaust up. The exhaust does accelerate a good deal going through the ports. Now I am thinking uniflow exhaust ports when I am talking about this, although a counterflow could operate the same as a uniflow if given the same exhaust timing.

Rolly, it ,to me, gets confusing when some of the three and four letter terms or whatever the heck they call them jump technologies. Mc, master of ceremonies is still megacycles to me.

Some writers very quickly give the 3 &4 or so abbreviations in the beginning of their papers and five paragraphs later I have no clue what they are talking about. I have found myself going back five paragraphs later and I have no clue what they are talking about. I have found myself going back to the beginning and re-referencing many times and it would be much simpler and understandable if they weren't such lazy typists and didn't use the abbreviations. Anyway A.B.S. , aggressive bowel syndrome, makes a terrible plastic.


Bill G.

Edited 1 time(s). Last edit at 09/19/2014 12:42AM by Bill Gatlin.
Re: "Jakuba's Compounding article in the Bulletin"
September 19, 2014 12:42PM
Bill. Sounds like you are applying philosophical meaning to entropy. " There would then be an increase in entropy during expansion and another increase during compression"

The entropy of the steam is more then like dropping not increasing. The steam being hotter then the cylinder walls during expansion would have heat transfer from the steam to the cylinder. The makes for a total increase in entropy of the system. Not the steam per say.

Entropy is a property of steam. In a single phase state any two thermodynamic properties can determine a state of the substance. entropy and specific volume {or density= 1/(specific volume)} for example. The fundamental properties are pressure, temperature, specific volume (density), Specific enthalpy, Specific internal energy.

The steam property formulation I implemented are the:

IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use.

The formulations are calculated from the "dimensionless Helmholtz free energy". There two parts. The ideal-gas part of the dimensionless Helmholtz free energy is obtained using an 8 term polynomial equation for the specific isobaric heat capacity in the ideal-gas state. The second part that makes it work for a real gas they call the residual part of the dimensionless Helmholtz free energy. a 56 term polynomial. And then the actual proprieties are combinations of the first and second derivatives. When you do the (calculus) derivatives of those you get even more term. The great thing in using them (other then they are the most accurate formulations) is that they cover the entire range. There are no regions using different formulation were on the boundary there are small differences in the two values calculated for a point on the boundary line. My formulation add a few properties for simulating dynamic processes. isotropic expansion and isenthalip expansion. That involved taking some additional derivatives of thees polynomials.

The point I am trying to make is that even with short abbreviated names those formula fill a page. If you wrote out the names wou would have need several pages just to write down a formula.

The additional properties I added were the rate of change of (reduced temperature with respect to density) on with entropy constant and another for enthalpy constant. The formulation are used in a VisSim plugin. VisSim is a simulation program that actually digitally simulates an analog computer.
Time dependent processes are simulated.

For example, the volume change in an engine cylinder is changing with time. Mathematically we can write relation for that change based say on rotation of the crank. We can mathematically write relation for the a pistons position based on tire rotation. We can do with respect to time. So ultimately we can get the rate of change at any moment of the cylinder volume. And with a bit of manipulation get the rate of change of the steam density in the cylinder.

With my adder properties dT/dD|s rate of change of temperature with respect to density. and the rate of change of density with respect to time the product is the rate of change of temperatue with respect to time dT/dt|s = dT/dD|s * dD/dt. Using an intergrater block I get T out and can calculate steam properties varing with time. Ultimately heat transfer can be added. If we know the heat transfer rate we can adjust the rate of change of temperature for heat transfer and simulate steam expansion in a cylinder combining the ideal isotropic expansion adjusting for heat transfer.

I long explanation of how I came to view entropy and enthalpy changes. All the philosophical ^^^^ doesn;t matter. If density is held constant and you increase enthalpy, entropy increases. Or hold pressure constant the same is true. If you transfer heat to the cylander wall enthalpy decreasses and so does entropy. The decrease in entopy would be less then the increase of entropy in the cylinder wall for a net gain in entropy.

The steam density is deterministic in the cylinder during expansion. It is a function of the initial steam mass and the volume. We are not changing the mass of the steam. It contained in the cylinder. The volume is deterministic dependent on the piston position. At any point the density is deturmined by the mase on volume. So take the case the steams entropy increasing. And sense that would also mean the enthalpy would also increase. Inturn that would also mean that the pressure is great and you would be producing more shaft work.

If we look at heat transfer going both ways during expansion. Initially the steam temperature being higher then the cylinder surface temperature and toward the end end of the stroke the cylander surface being hoter then the relative rate of change of entropy to enthalpy idecreasses with temperature. So in that case entropy may be greater than it initial entry state,

The state of the steam is not just dependent on one process but it's total environment. Below are some expansion charts generated in VisSim.

The Red lines are constant entropy plots. Red are the isentropic expansion combined with a constant rate of temperature added to that of the isentropic.

The very upper left the rate of change of reduced density reduced density is density/(critical point density)
Reduced Temperature is the (critical point temperature divided by the absolout temperature) The IAPWS formulation take as inputs reduced (unit-less) values. My steam property blocks take the reduced unit-less values. It avoids unnecessary conversion calculations on every iteration of the simulation. I provide conversion blocks that do the conversion needed for input parameters and display or ploting. There are a number of state point blocks taking combintions of inputs. The two used in that sim were one block taking reduced temperature and reduced pressure to calculate initial state point. The other two blocks take reduced temperature and reduced density as inputs. The pressure-temperature block gets it's inputs from conversion blocks supplied in the plug-in The initial values are 850 PSI and 1100F. The 1/S blocks are integrator blocks. In this case they are reset integrator blocks that take their value/initial state from their lower input when the midel b input is greater then 0. I use a delay block set the two intergrator to initial reduced temperature and densities from the pressure block. After that they are generating their output from the rate of change input opper input. Inputs are on the left of a block outputs on the right. The rate of change of reduced density Dd is a constant -4. The rate of chage of temperature is being calculated from the rate of change of temperature with respect to density outputs from the temperature density block. the intergrato form a feed back loop calculating their output based on the curent state of the temperature density state point block. One is simply a constant entropy. producing the red plots. The other is adding a temperature increase to the constant isentropic temperature change to produce the blue plots. The upper plot is pressure . The lower temperature and the middle intropies. You can see the red entropy line is flat. It is constant to at least 8 decmal places.

Isentropic expansion does continue into the saturated mixture region. One of the things I havn't gotten working in the dT/dD|s property block. Expanding into the wet steam does not result in water droplets right away. That takes time for droplets to form. It stays a gas for some time and is refered to a subcooled gas state. You allso have a supperheated liquid states. These states are covered by the IAPWS 95 formulation I implemented. but I can find info on the tome factor. it does depend on the saturated quality value. The higher the liquid content the faster the change from a subcool gas to forming water droplets. Compression would still be along an isotropic line. The thermodynamic processes do not care the mater state of a substance. At least that is the way I understand it to work. Thermodynamics is really about energy and the conservation of energy law applies no matter the phisical state of a substance.
Re: "Jakuba's Compounding article in the Bulletin"
September 20, 2014 05:18PM
Jim & Andy,

That was always the way I was taught too. Some people rely on delusion and fantasy in place of hard reality."

Jim, Delusion and fantasy are indeed a lot harder to live with than reality. When the ice is thin delusion is deadly.

Bill G.
Re: "Jakuba's Compounding article in the Bulletin"
September 20, 2014 05:53PM
Some can't tell the difference and write down what they want it to be, not what it really is. The ice has already cracked!!!

Hmmm and i always thought liquids were incompressible. Yes?
Re: "Jakuba's Compounding article in the Bulletin"
September 20, 2014 07:30PM
Andy, Bill, Jim, et al

I've been gone a while and am trying to catch up with this thread.

I've had unhappy experiences with fluid sealed pressure transducers. It always seemed that they were better temperature transducers than pressure transducers and I was only working with slowly changing systems.

Carefully degassed liquids are pretty much incompressable, but not absolutely so.

There is a surprising amount of gas dissolved in most liquids. A reduction in pressure may cause the fluid to foam. The microbubbles may go back into solution when the pressure rises, or they may coalesce into a larger bubble that gas locks the "hydraulic" fluid seal.

I'm always happy to learn something new, so if you find something that works, please share.


Re: "Jakuba's Compounding article in the Bulletin"
September 21, 2014 10:43AM
Boiler pressure in a monotube can be sensed at the pump end so temperature isn't an issue. Sensors like the SSI P 51 series could work and cost around $100. Sensing cylinder pressure for an indicator diagram is a lot tougher problem. Omega's dynamic pressure sensor is only good to 250* F. The cost is around $500. Kistler makes lots of sensors like this water cooled one rated for over 650* F. I believe these cost in the $2000 area. I'm very interested in the details of other pressure measurement approaches.

Lohring Miller
Re: "Jakuba's Compounding article in the Bulletin"
September 21, 2014 12:09PM
Quartz transducers are expensive, unless you get lucky and find them in a electronics surplus store. The guy had no idea what they were, so $15.00 each I used very thin silicon oil in the tube.
Actually today the strain gauge types are fine and much cheaper too. Just double check the resonant frequency before buying.

Boiler pressure at the pump is fluctuating and in a Doble sized coil stack105 sq/ft about 125 psi higher than the outlet.
Re: "Jakuba's Compounding article in the Bulletin"
September 22, 2014 06:58PM
I checked on some strain gage pressure sensors. They were much less expensive ($195), but seem to be temperature limited. Is this at the sensing end? They're all stainless steel but the temperature compensation range only goes up to 132* F. They are rated to stand 212* F. Once again they seem to be fine for the low temperature end of the monotube, but not at the hot end.

What exactly do you use to insulate the sensor from the steam temperature? I see an article that claims that 5" or 6" of stainless steel tube might be all that's needed with 1200 degree F steam.

Lohring Miller

Edited 1 time(s). Last edit at 09/22/2014 07:12PM by lohring.
Re: "Jakuba's Compounding article in the Bulletin"
September 23, 2014 01:29AM
Jakuba's compounding article says nothing about Cyclone's testing methodology or results. That is a subject for a new topic.
At Cyclone, as VP of Engineering, I purchased a complete Kistler instrumentation package for high speed diesel service and had custom thermal jackets made for the 5mm threaded sensors. The whole setup is traceable to NIST. I have copies the receipts with my name on them, and I can assure you that there are several thousands of dollars involved before you even open the package, much less set up the data gathering interface, and the analysis software. Absolutely no data has been made public, and so it is quite inappropriate to guess what results have or have not been made.
As a positive thinking individual and a Forum administrator, can I suggest that we please return to topic and avoid idle speculation.

Karl Petersen
Re: "Jakuba's Compounding article in the Bulletin"
September 23, 2014 11:13AM
Think you Karl
Re: "Jakuba's Compounding article in the Bulletin"
September 23, 2014 03:13PM
Now that is an interesting reply. Ask how any reliable data to back up their claims was obtained prior to March, 2012 BEFORE any of this test equipment was supposedly obtained and he was added to the Board of Advisors.
Was all that prior test data by guessing or by divine inspiration? Remember we heard about all these miraculous results long prior to this.
Re: "Jakuba's Compounding article in the Bulletin"
September 27, 2014 06:39PM
Hi People,

Anything left to talk about?

Bill G.
Re: "Jakuba's Compounding article in the Bulletin"
September 29, 2014 04:32AM
What I have written about the Cyclone, I have either read in your papers, read here in some of Harry's posts, or heard Harry say. More information would be welcome.

Bill, the instrumentation topic is important, and there is a lot of different things you can do with a compound that have not been mentioned. Think about the fact that the first stage does not need a small clearance, this opens the possibility for a much hotter hothead engine, even at short cutoffs. You could have the admission valve at the end of the clarance tube?

A last stage turbine powering a turbocompressor between the two piston stages has been mentioned.
Also, turbocompressor powered pressure fired boilers. This gas turbine shaft could also power the steam compressor.

Just some ideas that I think merits consideration under the topic "compounding".
Re: "Jakuba's Compounding article in the Bulletin"
September 29, 2014 10:12AM
For Cyclone testing and tech, see the new thread Cyclone's testing methodology or results, by steamerandy.
I will post some test results there in a few minutes....
I did post test information. Jim said the data was for a bash valve engine of 31% efficiency which was impossible. In fact, it was for a poppet valve engine and in the implementation had no where near that efficiency, so I asked for factual accuracy and suggested we all avoid ad-hominem attacks. The entire thread was pulled.

Please continue discussing Jakuba's Compounding article now.


Karl Petersen

Edited 1 time(s). Last edit at 10/01/2014 02:30PM by Karl Petersen.
Re: "Jakuba's Compounding article in the Bulletin"
October 01, 2014 09:41PM

I appreciate your trying to protect Harry. Right now I imagine that he is frustrated. I have looked over some of Harry's patents and I consider him a very prolific and talented inventor. I also like him.

That said, I agree that it is frustrating for some of us about getting good engineering information out of Cyclone.

Now this thread is about , or has become, a concern of the merits of single stage engines vs compound engines of two stages or three stages with re-heat. This subject has been hashed over before in previous years and concerns the older technologies, I am assuming since I don't have the bulletin, is the subject of Stans' article.

A comparison of an advanced single stage engine to a potentially advanced compound such as mine or Andy's seems appropriate here. Cyclone supposedly represents an advanced single stage engine. An analysis of that engine would be useful to this topic and the last engine developed at Cyclone should be the more advanced. Indicators seem to say it didn't perform as well as hoped. Those indicators don't need discussion here.

I have done an analysis of it based on some old information. It really just applies to a super critical pressure cycle. To get 30% efficiency under conditions of 1,200 deg F and 3,300 psia in the cylinder after cutoff requires an expansion ratio of 26:1. That's with boiler efficiency at 95% and 5% losses to turbulence and friction. Exhaust is at 30 psia and temp at 300 deg F.

300 deg F. might get some re-generation up to about 250 deg F but that won't add to much to the efficiency. A single stage engine just won't get 26:1 expansion either. Not and put out any usable hp.

Mentioned was the idea of using a heated clearance space on the Cyclone to heat the re-compressed steam to 1,500 deg F. But to get a higher expansion ratio, a small clearance space is needed and all of the steam needs to be at 1,500 deg F. However, if ALL of the admitted steam is at 1,500 deg F and 3,300 psia and h= 1754 then an expansion of 9.6:1 brings us to a release exhaust pressure of 184 psia and a temp of 580 deg F. and U equals 1201.9 btus which, with some of the losses figured in balance with a more usable re-generation temperature, yields roughly a 30% efficiency. Again U = h2 - p2 v2/J, how a uniflow works.

Getting an expansion around 10:1 at usable cutoffs isn't too easy, unless the clearance space is kept low. Cyclone was going to use this clearance space to heat the re-compressed steam though. I suggest that if they are still using this "in the combustion space" clearance that it also receives the charge of new incoming steam so the cycle is started at 1,500 deg after cutoff.

Bill G.
Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 07:43AM
Hi Bill,

Lack of publicly-available independently-verified test data on any proposed high-efficiency steam-power system can not only be "frustrating", but can also lead to a lack of investment in such systems by folks with the means and desire to invest.

The foregoing comments, of course, are in absolutely no way intended as a comment on any actual proposed steam-power system, or on any actual potential investor in steam-power development, regardless of any "read between the lines" interpretation which somebody might apply to them. winking smiley

It is my hope that the foregoing meticulously-pruned verbiage will spare me from "being censored into Official Total Non-Existence" by various alleged/self-appointed Internetical Authorities.

That being said, I believe that there may be some commercial potential in a multiple-expansion steam automobile engine, in which cutoff/compresssion are continuously controlled throughout the load/speed range of a real-world automotive drive cycle, to give equal work by each stage. This would allow the classic "smooth-running, direct-drive" operation which steam car drivers prefer, with a much higher potential expansion ratio than in Stanley and similar engines. As was previously mentioned by another poster, the Woolf-compound 4-cylinder/2-stage approach embodied in the Doble "E" has this potential -- but the valve timing of the 2 stages needs to be independently-controlled, by a sophisticated algorithm, to optimize efficiency at varying load/speed levels. That was not done in the original Doble E.

Note that a 4-cyl Doble E could theoretically deliver 4:1 expansion ratios with the same cutoffs & smooth-running as a 2:1 Stanley, at low outputs. At higher outputs/rpms, the expansion ratio could increase to 8:1 or much higher, especially considering the flow-limitation effects which kick in at higher rpm and increase the "effective expansion ratio" above that which is simplistically predicted from valve open/close timing analysis. However, optimizing efficiency requires completely-independent valve-timing control of both stages, balancing smoothness and efficiency, which the Doble E did not have.

Y'all e-mail Mr. Pete, and please do visit me "deep in the heart of Texas" in the near future. In the past few days, my "gotta-do" SoCal to Austin-area TX trans-dimensional transition has been accelerating at a nightmarishly fast pace. It's freakin' me out, man! No BS; please drop in and hang out in my TX joint in a free private guest room, with free use of tons of machine tools & garage/assembly space.

Texas Pete
Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 09:25AM
One engine that exhibits most of the criteria’s that you describe, that one would want for a car engine, adjustable cut off from just a crack opening to almost full pressure engine, long almost complete expansion, not a compound.
Double balanced valves, one intake and one exhaust at each end of a double acting cylinder.
The engine was the Western river steamboat engine with California cutoff.
Always liked that engine. Not quite workable for a car engine.
Re: "Jakuba's Compounding article in the Bulletin"
October 02, 2014 12:56PM
Rolly, Bill,
I am wondering if another aspect of those long stroke riverboat engines should not be considered.
Having such long strokes and very slow rpm, might it be that the valve events have plenty of time to work vs, some short stroke engine running at high speeds. Where the valve events are so short that the valve gear inertia means that it and the cam followers are not working as desired? Also excessive valve seating forces due to the very short time they have to close and seal at ultra short cutoff. Creating noise and high wear rate and possibly some wire drawing and actually not the desired valve timing one wants.

Correct, the Doble Series E was never torque balanced between the two cylinders: 2-5/8" X 4-1/2" X 5". You can feel it; but soon learn to ignore it as it really doesn't make any difference. Later they did make one engine with a 2-1/4" HP and the water rate did go down.
Something else that Woolf compound does that I always questioned. When the HP is exhausting to the LP. the steam goes thru the hollow piston valve and one would think give way too much excessive clearance volume to the LP cylinder. When setting up the engine, the clearance between the piston tops and the cylinder heads is 0.030". Valve and sleeve drawing attached.
Quite right, the Woolf compound definitely demand each cylinder have its own valve gear. Read Abner's engine design notes in that binder SACA sells, where he analyzes every possible configuration he could think of. Landing on the Skinner-tandem compound as being the most desirable for the McCullogh project.
open | download - Doble E Valve and sleeve Model (1).pdf (81.4 KB)
Re: "Jakuba's Compounding article in the Bulletin"
October 05, 2014 01:35AM

I thought that the high temperature for oil or plastics like Peek was about 650 deg F. More than that and it will start to oxidize and break down, or carbonize. How many times through an engine, if the oil is reclaimed can it make the trip at high steam temperatures?

Rolly are you indicating that oil injected directly into the steam is really insufficient lubrication?

I have thought that the cylinder walls should never reach higher than 650 deg F to preserve the oil and that the steam could then be of a high temperature without itself causing lubrication problems. This would indicate then the use of an oil injection directly to the rings of the piston in some fashion. I envision a top piston ring of gapped design then next a Total Seal or labyrinth type ring and next an oil control ring to spread the oil over the cylinder.

My compound is a multiple cylinder engine and this does necessitate, for now, thinking of hydrodynamic lubrication and to ensure that an oil to the cylinder wall injection system. I don't know about Meehanite yet but Toughmet was a material I was considering for wear properties. It is like beryllium copper but without the beryllium.

Some steam engines have used a similar oil system, haven't they? If so how do they compare?


Bill G.
Re: "Jakuba's Compounding article in the Bulletin"
October 05, 2014 05:58AM
With piston operated steam engines the steam should be 200 degrees superheated over the saturated steam pressure your running the engine at for best over all efficiency.
Since this is a steam car site I’ll use Stanley car as an example. Most of the larger cars run 600 psi. saturated steam. At 600 psi saturated steam is around 486 F so you should shoot for 686 to 700F coming from your superheater into your engine. The steam cylinder oil is injected directly into the steam line on most cars just after the top of the steam loop. The steam loop is the steam line coming off the output of the superheater and rising up about to the height of the top sheet of the boiler much like a trap. Personally I like to inject it directly at the engine. Steam cylinder oil is ISO 460 or 600. ISO 460 is good up to around 750 F with out oxygen. There is no oxygen or very little in superheated steam. Most Oxygen and Hydrogen are separated out at the water line of the boiler when pure steam is created. I don’t know all that much about how and why. Some use ISO 460 as high as 1200F but at 1200F it should be ISO 600.
A Stanley oil pump has a 1/8 D piston and about a ½ stroke and pumps oil about every four revolutions of the engine. Hence my comment, pissey ass amount compared with any gas or diesel engine for cylinder lubrication.


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