Although the Elesco's were the most appealing in my opinion, what feedwater heater (and valve gear) was the most efficient and why? If a new "classic" steam locomotive were to be built today which would it utilize?
Indianapolis Railroad - Indy Rail! Route of the Brickyard Flyer! Established 1976.
I believe Coffin was the first design followed by Elesco and finally the Worthington was the latest and probably most effective and modern design.
Elesco was the least efficient but easiest to identify because of the famous cylinder bundle mounted just ahead of the locomotive stack.
Elesco was a "closed design" because it kept exhaust steam and boiler feed water separate from each other in order to prevent cylinder lubrication oil which was in the exhaust steam out of the boiler intake water.
The very successful Worthington was a "open design" because it mixed exhaust steam into the feed water. Worthington had developed a separator design to extract the oil.
Worthington is usually seen as a small tank or box just ahead of the locomotive smoke stack but is really a large tank sunk into the front end design of the locomotive smoke box.
Feed water heaters were not widely added to steam locomotives in the United States until the 1920's. They were one of the truely modern locomotive appliances that increased the performance and efficiency of the engine.
Early 1920s designs almost overtook the locomotive with all of the external plumbing and large clumbsy pumps they used. For example the Elesco "closed design" heater tube bundle was a large beadle brow mounted on the boiler top. The Coffin design was sometimes mounted externally and appeared as a large "horse shoe" tank mounted over the smoke box door.
In the 1920's you will notice most all of the plumbing necessary to effect the feed water systems was hung along the outside of the boiler giving a sometimes ugly mess appearance to the locomotive with a huge pump often carried on the left side of the engine.
As the 1930's progressed the systems were perfected and the piping and pumps became almost invisible. New York Central Hudsom 4-6-4 sunk the Elesco "closed design" bundle down into the boiler top so only the ends protruded. Other builders did this also. By the time the Wortington "open design" was perfected you could hardly notice the feed water system at all such as on the New York Central famed Niagara 4-8-4. Don't be fooled this large efficient system was hidden inside the boiler front.
The idea that the feed water system was just an "accessory" is misleading because it became a "necessity" for modern efficient steam locomotive design. Water temperature into the boiler without feed water heat could be cold, however, with the feed water system the water went into the locomotive boiler with heat at 200-250 degrees temperature. Not only was this was less thermal shock to the hot boiler but secondly the hot water went to steam quickly and easily.
We are all familiar with energy conservation in Americal today. If you buy and new American sink faucet or shower head it will have a small "restrictor" inside to prevent water flow - the so called Al Gore restrictor. This is to cut down on excessive use of water and particularly hot water which conserves precious natural resources. Imagine if the hot water going down the laundry drain or shower drain could have its heat extracted and used to heat the water used for laundry or bathing use. Many home owners and businesses would be shocked to have reduction in utility bills.
The steam railroads were glad to recoup the waste heat going out the locomotive stack and put it to use heating the cold boiler water. Locomotive boiler evaporation rate was increased 8-10 percent. About 15 to 20 percent of the exhaust steam was used in the heating process.
The "feed water heater" and the locomotive "superheater" were responsible for the "super power era" and they truely were responsible for making the steam locomotive of the mid Twentieth Century competative to the internal combustion diesel engine.
Doc
Dr DWater temperature into the boiler without feed water heat could be almost freezing, however, with the feed water system the water went into the locomotive boiler with heat at 200-250 degrees temperature.
The idea that feedwater is admitted 'cold' might have been true in the mid-Nineteenth Century, in the days of rod-driven pumps, but a moment's reflection will show that any locomotive using an injector will have hot feedwater. The concern is that, because of the way an injector operates, it cannot use feedwater that is hot enough to 'flash' to steam during injection. A FWH system with a hot-water pump does not have this limitation.
Note that a delivered-water temperature in the range quoted (200-250 deg.F) is still well shy of the actual equilibrium temperature of water in a typical large Super-Power locomotive, particularly one that uses "modern" high pressure of 300 psi or higher. Part of the importance of FWH on such locomotives is to reduce thermal cycling of parts of the boiler structure. Do you not mean the rise in temperature through the heater, starting with water at whatever temperature the cold-water pump delivers?
During the 'age of steam' the use of FWH was driven by economics -- the substantial first cost and mintenance costs of the system being balanced against the financial results of the benefits. It is interesting to note that one of the most sophisticated modern locomotives, C&O 614, had her (admittedly poor) FWH system removed early in her life, and never replaced even during the 614T testing. On a 'preserved' locomotive, the advantages of good FWH may take on more importance, more for the preservation of boiler integrity than for any supposed improvement in fuel economy (which saving is a minuscule part of the overall cost of running big steam) or nominal water rate.
Might be a good idea to discuss heat recovery in the Rankine cycle, an important consideration in steam power design, as part of the context of this thread.
Dr D Water temperature into the boiler without feed water heat could be almost freezing,
For example, the temperature of unsaturated steam (which the injector uses) at 300 psi is 421.7 degrees F (water tempurature varies, plus or minus, according to the pressure). For all intents and purposes, all of this heat is transfered to the feedwater going into the boiler. So, there is absolutely no "almost freezing" water going into the boiler. Somewhere in the 200+ degree range may be more like it.
Hot water supplied from the feedwater heater is in about the same temperature range, varying according to how hard the locomotive is being worked.
The idea that using the injector for putting cold* water into the boiler and knocking down the boiler pressure is pure myth also. The reason the boiler pressure lowers is because boiler pressure is being used to inject the water into the boiler.
* "Cold" is a relative term. As we have just seen, the feedwater isn't cold at all. The water in the tender is "Cold". The feedwater going into the boiler, whether it be by use of the injector or the feedwater heater is very hot compared to the tender water, yet, colder (200+ degrees) than the water at boiler pressure (420 degrees).
Use the following links (wait for them to load) to learn about:
Injectors: http://www.icsarchive.org/icsarchive-org/bb/ics_bb_508d_section_5236_locomotive_injectors.pdf
Feedwater Heaters: http://www.icsarchive.org/icsarchive-org/bb/ics_bb_508d_section_2517_locomotive_feedwater_heating_equipments.pdf
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Ralph Johnson design engineer for Baldwin Locomotive Works offers a differing opinion concerning the feed water heater designs,
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"The preheating of boiler feed water by means of waste exhaust steam is a highly important economy without which no heavy-duty locomotive can be considered efficient. The reasons, summarized briefly are:
1. On any boiler it increases the maximum evaporative capacity, no matter how efficient the boiler may be in itself.
2. For equivalent evaporative capacities it decreases the weight of the boiler.
3. The effective tender capacity is increased.
4. Boiler maintenance is decreased because a percentage of the feed water is returned in the form of condensed steam or distilled water.
5. Produces an increase in the general over-all efficiency of the locomotive.
Feed water heating reduces the amount of heat which must be supplied by the fuel for the generation of steam, and for a given locomotive there will be either a decrease in coal consumption for a given evaporation, or the total evaporation of the boiler will be increased if the same quantity of fuel is burned. In either case a pound of fuel will evaporate a greater amount of water than would be the case if cold feed water were used. Also, as exhaust steam in the form of condensate is returned to either the boiler or the tender tank, it follows that a smaller amount of cold water will be required and in this way there will be a reduction of cold feed water used per horsepower developed. The cylinder performance, however, is not affected by feed water heating except that there is some reduction in back pressure, as less steam is passing through the nozzle when the heater is in use...
Theoretically the feed water heater can add up to 18 per cent to the maximum evaporative capacity of the boiler, depending upon the temperature of the water in the tender and the exhaust steam....
In the case of a locomotive the feed water heater and its pump should be compared to the injector which they replace; therefore, from the heat recovered from the exhaust steam and returned to the boiler, should be deducted the heat in the steam required to operate the feed pump in order to find the net heat recovery by the installation. As the feed pump requires about 2.5% of the total heat for its operation the net or useful recovery of heat will be 9.53% in the above example.
An approximate rule is that a saving of 1 per cent is made by each increase of 10* in the temperature of the feed water. This corresponds to 0.10 per cent per degree of temperature rise...
The heat recovered by the heater is a direct addition to the heat output of the boiler proper and the maximum steaming capacity of the locomotive is therefore increased in the same proportion.
Feed water heaters condense more steam and show a greater percentage effect in winter when the tender water is cold than in summer."
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Considering the low overall efficiency of the external combustion steam locomotive all efforts to increase this efficiency were and are extremely important compared to the high efficiency of the internal combustion diesel engine.
Ross Rolland and CO 614 being the play toy of a millionare aside, that engine needed its feed water system!
Dr DRalph Johnson design engineer for Baldwin Locomotive Works offers a differing opinion concerning the feed water heater designs,
Big Jim,
Ralph Johnson pointed out a number of functions of the feed water system not discussed. From its function as a condenser to the overall evaporative contribution and stabilzation of the boiler. Many engines rely on it for effective feed water in place of the lifting injector and as a safeguard to boiler explosion. The consideration of removal of the system as surpurflious is highly misleading to the overall safety and function of the operational steam locomotive.
The Gettysburg PA tourist line boiler explosion that caused the government to completely redesign the FRA rules for operating steam locomotives in the 21 Century was a result of the lifting injector failing and the feed water system not fuctioning in boiler water supply. It was also caused by the ignorance of the crew and non functioning water glass.
To leave the impression that excursion engines could do away with the sytem misunderstands their function and contribution to locomotive operation.
When Ross Rowland made the statement about "We threw out the FWH because in was un-necessary - didn't work anyway!" this sounds cavalier and about equal to "CO 614 whistling past the graveyardd!"
"Ross Rowland and CO 614 being a play toy of a millionare aside, that engine needed its feed water system!"
They have installed a feedwater heater on Sou. 4501.
https://www.facebook.com/southern4501
The thing about the steam locomotive is having a dirt-simple machine using a dirt-cheap fuel. Once your start tinkering with that relationship, things get . . . complicated.
I am sitting here with my copy of The Wonderful World of Energy by Lancelot Hogben, published by Doubleday. There is an illustration of Joule spending his honeymoon measuring the temperature difference in a waterfall, with his patient newlywed bride Mrs. Joule taking a reading from the top and Mr. Joule taking a reading at the bottom. They could find no difference.
The lesson is that when scientists such as Joule and his patient wife and others started studying the underpinnings of thermodynamics, notably the relationship between mechanical action (work) and heat, it takes an enormous amount of work to generate measurable amounts of heat. Conversely, if you generate a large amount of heat by burning coal in the steam engine, and even if you convert only a tiny fraction of that heat to work, you get usable and economically beneficial amounts of work in the form that can propel the train.
That was an essential feature of the Industrial Revolution. Even if you used heat inefficiently to generate work, you could do many useful things and work on improving efficiency step-by-step over time.
That was also another feature of Industrial Progress. You started out with very inefficient conversion of heat into work and made various improvements, step-by-step and over time to get the much more efficient engines we have today.
If the keep-it-simple-(and)-stupid (KISS) principle was an iron law with the iron horse, steam locomotives would have never gotten superheaters. The diesel-electric locomotive that superceded steam entirely, on the other hand, is a pretty complicated thing that was also rather expensive in relative terms back-in-the day.
There is a tendency to view the steam locomotive as the dirt-simple design that engineers kept adding complications to (superheater, feedwater heater, high boiler pressure, condenser) in "failed" attempts to increase thermal efficiency in exchange for greatly increased maintenance expenses.
By that reasoning, the diesel should have failed. According to the H. F. Brown paper in the late 1950's, the diesel indeed had lower fuel costs but counter to established wisdom, and correcting for a worn out old steamer vs a brand new diesel, the steam engine had drastically lower maintenance costs balancing the increased fuel expense.
So what about the feedwater heater? Forward progress in engine efficiency or just another gadget not worth the maintenance expense?
Judging maintenance cost can be challenging as it can be influenced by what Porta called "detail design." Just as there was a wide range in maintenance costs among 1st generation diesel, there was perhaps wider range within steam. In Wardale's Red Devil, the 25-class 4-8-4 steam engine that was upgraded into the single 26-class "Red Devil", the non-condensing version of the 25 had lower maintenance cost by multiples over anything else run in South Africa. How much trouble is a feedwater heater probably depends on "detail design." That and the effectiveness of the water treatement scheme, on which there was a lot of work if not significant advancement in the twighlight of steam.
What kind of fuel savings do you get from a feedwater heater anyway? In rough-round numbers and at around 300 PSI boiler temperature and about 800 F exit temperature of the superheater, it takes about 1400 btu to raise a pound of superheated steam starting with cold water. Of that, it takes about 400 btu to raise the cold water to the roughly 400 F boiler temperature, another 800 btu to evaporate it at that boiler pressure, and another 400 f to superheat it.
As it takes 1 btu per deg F per pound of water, I would say an exhaust steam injector or an "open shell" feedwater heater would save about 140 BTU or an efficiency gain under optimal conditions of about 10 percent. A closed-shell feedwater heater takes steam under pressure through a valve from the exhaust-opening blast and is reputed to be good for another 60 F in temperature increase, giving about a 14 percent savings. This is consistent with what Wardale claims for efficiency gain, but from his tables, his efficiency gain was lower than that in practice.
There is another thing you can do, and I don't know if it requires a feedwater heater as a first stage or not. The economizer.
One version of this was the Franco-Crosti system tried in England and elsewhere, where you piped the mix of steam and combustion gas from stack into a kind of "mini boiler", actually the feedwater preheater or economizer. That system, unfortunately, cooled the hot gases to where they started condensing, and the condensed locomotive exhaust is very corrosive and those heat exchangers did not last very long.
Another version of this was tried by Chapelon on the 160-A1 low-speed freight locomotive. It is also proposed by Wardale on the 5AT project. There, you use a baffle inside the boiler to separate it into a front preheater compartment from the rear boiler compartment. When the combustion gas in the tubes has cooled below 400 F, it cannot boil any more water but it certainly can preheat the water up to 400 F.
This flue-gas economizer seems simple enough, but the detail engineering is always where "the tough need to get going." You may want to combine this with a closed-shell exhaust-steam fed feedwater heater so as to not cool the flue gas to the dew point to wreck the tubes. Such a system could offer a 25 percent savings on heat rate.
What does this mean? The Case for American Steam reprinted on the Coalition for Sustainable Rail web site offers a "water rate" of 13.5 lb/hp-hr for the best of American steam (thermal efficiency-wise), i.e. the Pennsy T1 and those latter-day AT&SF Northerns and a water rate of 12.5 lb/hp-hr for Chapelon's 242-A1 compound, the best-of-the-best French design. With a 60 percent efficient boiler, we are talking 8 percent efficiency for the T1 (heat-to-indicated or cylinder HP and probably under the most favorable conditions), about 9 percent for the 242-A1.
Increase the boiler efficiency to 80 percent with a Gas Producer scheme, we are talking about 11 percent on the T1, 12 percent on the 242-A1. Now add the combination of a good feedwater heater and that economizer baffle in the boiler space and we are at 14.4 percent and 15.5. Finally, use exhaust cylinder steam to power a combustion-air preheater to boost the boiler to 90 percent efficiency, and we are at 16 percent efficiency simple expansion, 17.5 percent on the compound.
Add to that Chapelon's cylinder jacketing from the 160-A1 that extended efficiency over a wider range of piston speed, we are talking something that is competitive with a Diesel in thermal efficiency, considering that the conversion of solid fuel, whether from coal or from biomass to liquid fuel is at best 50 percent efficient.
If steam engine is a dirt-simple machine burning dirt-cheap fuel, however, forget about even a superheater -- go saturated steam.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
BigJim They have installed a feedwater heater on Sou. 4501. https://www.facebook.com/southern4501
Johnny
And, as I understand it, roller bearings on the lead and trailing trucks. Why ever not?
Paul Milenkovick,
Nice piece on the efficiency of external combustion! The Red Devil class of South Africa left quite a heritage we could all become more familiar with! As I said, nice piece.
The Worthington open style feed water heater had another advantage. By heating the water to near the atmospheric boiling point in a vented vessel, most of the air/oxygen in the feed water was driven off before it reached the boiler. Oxygen in feed water is a bad thing since it corrodes away the boiler steel (oxygen plus steel in the presence of water = rust). The Elesco and Coffin closed feed water heaters were not able to remove oxygen nor did injectors. Chemical treatment of feed water could also remove oxygen, but chemical treatment of boiler feed water by railroads seems to have been a pretty 'iffy' subject.
Here is a link to an externally installed Coffin-style Feedwater heater on a Lima-built 2-8-4 Berkshire of the B&M. see @ http://abpr.railfan.net/abprphoto.cgi?//november98/11-01-98/bxm4009.jpg
These engines were problems for the B&M and were traded to western US RR's to help with the WWII war effort[note: 10 to SP, and 7 to AT& SF]. see @ http://www.steamlocomotive.com/berkshire/?page=bm
The Coffin-style was favored on the Frisco but was generally built inside the smoke boxes. See link @ http://thelibrary.org/lochist/frisco/friscoline/images/photos/p01389.jpg
The Worthington Feed water Heater was usually mounted in a transverse fashion on the top of the Locomotives smoke box as showin on this T&P 'Texas' type #546. See @ http://www.llarson.com/steam/schenzinger/images/NA129.jpg
this link as well, might be of interest on this Thread @ http://www.steamlocomotive.com/appliances/feedwaterheaters.php
samfp1943this link as well, might be of interest on this Thread @ http://www.steamlocomotive.com/appliances/feedwaterheaters.php
Sam,
Your mixing up the Elesco and the Worthington.
Elesco is a closed system that resembles the bundle on the top front of the boiler. This "beetle brow" was quite distinctive. Early designs such as this Texas and Pacific 600 have all the plumbing outside the locomotive for that wonderful "clutered look." NYC early freight Mohawks were also famous for the Elesco "beetle brow" and they matched it with similar outside plumbing. ATSF was also a user of the "beetle brow" Elesco such as the famous 2-10-4 Madame Queen.
Later NYC Hudsons also had this Elesco "closed design" but you couldn't tell it was Elesco because the "beetle brow" was gone, it was sunk down into the smoke box so only the ends of the bundle protruced out of the boiler jacket. Thus they did away with the famous "beetle brow" which was so distinctive and which some people thought was very attractive! The plumbing was also mostly hidden on these late feed water heater designs making the engines less rugged looking and quite slick for American steam engines.
Worthington heaters were a square box hardly visible in front of the engine stack. Worthington were the last and best type feed water heaters and were of the "open design" - which mixed the pre heat steam with the incoming boiler water. These are pretty common today on most surviving steam locomotives today. ATSF 3463, UP 844 are examples.
Didn't some roads have locomotives with the Elesco "bundle" on the pilot deck? Seems to me I've seen that but can't recall which road it was.
ChuckAllen, TX
Canadian National and Grand Trunk Western used bundles on the pilot but they were "air reservoirs" tanks used for storage of compressed air. The air was used in the application of the train air brakes and engine air brakes.
A feed water heater must be located so that it can work - what does it work on but exhaust steam from the cylinders as it is on the way to the stack. It is diverted to a chamber or bundle where cold tender water may be heated. There would be no purpose for placing this on the engine pilot deck.
The ATSF 3460 Hudson 4-6-4 engines used a feed water pump located on the pilot deck which fed water into the Worthington Feed Water Heater located in the smoke box just ahead of the smoke stack.
Every appliance on a railroad steam locomotive had a useful designed place and purpose. The railroad steam engine was unlike other stationary or marine steam engines - it was compact - designed for quick generation of great power - and repairable - and would travel over land propelling itself. Patterns of locomotive design developed and they were never changed. Even the Chinese were copying the basic locomotive design developed in Europe and in the United States - decades after.
In fact the BASIC LOCOMOTIVE DESIGN OF ROBERT STEPHENSON 1829 who created the first workable steam railroad locomotive was not changed to THIS DAY!
What was this design - a horizontal multi fire tube boiler fed with draft induced by the cylinder exhaust blast pipe. Separate firebox surounded by water feeding into the multi tube boiler. The cylinders directly "double acting" upon drive wheels.
These concepts were never changed from the first English locomotive design 1829 to the NYC HUDSON and PENNSY T-1 of 1940.
My understanding of this from "Red Devil" is that a feedwater heater diverts exhaust steam from when it comes out of the cylinders to provide heat for the feedwater. Generally, this steam is exhaust out the stack, but being run through the restriction of the feedwater heater, it no longer contributes to the exhaust blast that furnishes the draft. That is why if you divert a lot of exhaust steam (feedwater heater, Porta and others had proposed combustion air preheaters as well), you need a really efficient blast nozzle. This is needed to get enough draft with the remaining "blast" steam.
Also, a feedwater heater condenses some of the steam fed to it, and this water recovery reduces the "water rate" of the locomotive by partially condensing the exhaust steam.
The other thing Wardale mentions is that the steam at exhaust valve opening still has considerable pressure, a pressure that can be much higher than the back pressure during the duration of the exhaust stroke. A similar "blow down" occurs in internal combustion exhaust valve opening. Using a check valve, the feedwater heater can receive exhaust steam under pressure that is elevated above the atmospheric boiling point of water. This mean that in theory, a feedwater heater could preheat the incoming water to above 212 F of the atmospheric boiling point.
The exhaust steam is under this blast of "blowdown" pressure under long cutoffs and full throttle ("hard" working of the engine). But Wardale also suggests reaching high levels of feedwater temperature may require a two-stage design that no one used. It certainly requires a "closed shell" design because a feedwater heater of the open type operating at atmospheric pressure is limited to 212 F.
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Paul Milenkovic,
Very interesting point you have on the "Red Devil" and high exhaust pressure relief into a feed water heater system.
This observation is seconded by Ralph Johnson who was design engineer for Baldwin Locomotive Works in his book The Steam Locomotive.
Ralph saw one of the truely dynamic possible design factors of "poppet valve gear" was the separation of intake and exhaust valve events by removing the symetry of movement Walschaerts valve gear applies to both intake and exhaust piston valve events.
The exhaust valve event cannot be optomized because this would adversly effect the intake event. At close "cut off" valve settings - when Walschaerts would become most effective - it suddenly then ceases to become effective because of the compromise the intake event forces upon the exhaust and the exhaust upon the intake. Walschaerts valve design cannot achieve what becomes possible with steam locomotive power development.
Poppet Valve Gear design - owing to the use of camshafts - on the other hand has a unique ability to have taylored separate valve event for both intake and exhaust.
This fact plus the possibilty internal steam passage streamlining for intake and exhaust passages without the obstruction of the Walschaerts "valve piston" allows ever increasing possibilties of performance in reciprocating steam locomotives.
Automotive type intake and exhaust ports with poppet valves similar to gasoline engines are then a possibility with railroad steam engines.
Here is the Red Devil application of tapping off of high pressure exhaust for feed water heater and condensing effect. Additional added advantages of reducing exhaust back pressure and exhaust nozzel restriction ushers in many other possibilities for firebox and boiler draft and front end smoke box design then become available with this arrangement. Controled and reduced draft force reduced fuel consumption and increased heat derivation. This is where "Red Devil" got much of its unique performance.
Red Devil was a one off and brilliant design at the end of steam production and the discoveries of Wardale in perfomance and economy were not widely known and appreciated by the rest of the world.
Wardale however never began development of Poppet Valve gear and its possibilities - surely he was of a mind to achieve much with this potential which Ralph Johnson noted.
These were paths of power that steam locomotive design never persued because of the general adoption of diesel electric locomotive design in the 1950's.
Dr DWardale however never began development of Poppet Valve gear and its possibilities - surely he was of a mind to achieve much with this potential which Ralph Johnson noted. These were paths of power that steam locomotive design never persued because of the general adoption of diesel electric locomotive design in the 1950's.
You need to look much more carefully at the detail history of poppet valve design and development in the United States. There is more to effective steam distribution than better-flowing valves -- dead space, routing of steam flow in the tracts, and compression control being three. That is before you get into spring return, sealing under a wide range of temperatures, problems with drifting, etc. Note that Wardale and the 5AT organization both have come to prefer piston valves to poppets on locomotives that have to be maintained at lowest cost in regular service, and have explained their reasoning in some detail.
There are also approaches for compression control (simple, like Okadees, or more complex like Jay Carter's approach for steam automobiles) that work just fine for the practical benefits and don't have the 'nightmare box' cost and maintenance issues that OC or RC poppets do. Trofimov valves, as improved by Meiningen, (or Wagner bypass valves) give much of the improvement in drifting that poppets provide.
Where poppets are most valuable is for high horsepower at high speed (see the two variants of the Lima-modified K4 setup). But not much of a locomotive's time is spent in that range. Meanwhile, compare the performance difference -- at the cylinders -- between Wardale's double long-lap/long-travel articulated piston valves, with 'diesel-style' rings (driven by Baker gear with Multirol-type bearings on all pivots) and a typical Lentz or Franklin setup.
Wizlish,
Glad to see you chime in on this discussion, but when did throwing out a bunch of technical names and vague comments constitute a legitimate retort?
Reading your text - I found we are in agreement on several points - first that when it comes to overall horsepower production the "poppet valve" arrangement is probably the top producer.
Second that the geared "poppet valve" designs from the 1930's and 40's were complex, expensive, and breakable - these designs however are over 75 years old. I cannot come to believe that a modern engineering and computer design "poppet valve" concept could not overcome all of these limitations cost effectively.
Lets speak of general engine valve designs -
- "Sleeve valve" as used in early automobiles and in Ricardo's work.
- "Rotary valve" as used in some internal combustion motor designs such as CSRV.
- "Piston valve" as used in most steam locomotive designs and potato guns.
- "Reed valve" as in two stroke interal combustion and modern compressors.
- "Poppet valve" from internal combustion and reciprocating steam.
I for one cannot think of any other common valve designs applicable to power producing machinery and "poppet valve" is the top choice for design efficiency in all modern engineering.
I do not think any designer would choose "piston valves" for reasons other than tradition and abject simplicity. Possibly the Wardale articulated design with Baker action was a workable compromise for commonly accepted maintaince schedules Wardale was confronted in maintaining Red Devil. The multi roll bearings and diesel piston rings on piston valves is novel considering the problem with "carbon sticking piston valves" that high demand situations created (such as when Pennsy borrowed a N&W 600 for tests and stuck the valves).
"Trofimov valves as improved by Meiningen, or Wagner bypass valves!" I cannot believe you would introduce a subject title like this without some explanation of them. They represent quite an insight into new thoughts on piston valve design.
I also cannot believe you would bring up "compression control" and its importance without some discussion because it is the subject of choice to continue this thread. Walschearts design and Baker designs primarily failed because they kept back the tremendous efficiencies that could have been realized in reciprocating steam locomotives when operated at "limited cut off."
It is the nature of this site is to profer such discussion and you really need to share some of your fine understanding of these subjects. As it concerns where the reciprocating steam locomotive would have developed in the 1950's if given the chance.
Further, it is a given fact, that despite Wardale and his great success with Red Devil, the whole project "suffered from the outset by half hearted support on the side of South African Railroad managment, who by then had decided to replace all steam traction with electric and diesel-electric traction."
Obviously Wardale had to do what he could in a very shortening time frame. This was no situation to fully explore potential changes such as "poppet valve" vs. "piston valve" makeover of the Red Devil.
Wardale and this support by South African Railway hardly compares to what Pennsylvania Railroad pursued with the T-1 duplex drive development or that New York Central under Paul Kiefer was attempting in similar situation to Wardale with the NYC 6000 series Niagaras. Time was indeed running out.
With the cost of diesel fuel in the present age some doubt remains that the diesel electric locomotive could have displaced reciprocating steam locomotive if it had been allowed to continually develop to its full potential.
The above post suggests that steam would have prevailed if the diesel-electric wasn't introduced until after additional improvements to steam were made. That would assume that the diesel-electric was a static design to which improvements could not be made. The fact remains that steam is dead or dying both on land and on sea.
8,300 posts! Impressive!
CSSHEGEWISCH this observaton is by no means a fact.
It is held that the internal combustion engine thermal efficiency is on the order of 25-30%, and the external combustion reciprocating steam locomotive thermal efficiency on the order of 10-20%. These basic statistics are often given. Steam powerplants, however, have achieved thermal efficiency as high as 40-50%.
Expense of crude oil per barrel has risen from $1 to 2 dollars per barrel in the 1940 and 1950's to todays high of $128 dollars per barrel. The steam locomotive was challenging the cost efficiency of diesel electric at the time diesel was adopted as America's prime mover in the 1950's. Today serious consideration is given to steam power as an alternative power source.
While more efficient in design the cost of diesel operation vs steam operation has been challenged by the attempt to produce steam locomotive ACE 3000, and by such enviornmental engineering groups as Coalition For Sustainable Rail to build an ATSF 3463 alternate steam prototype locomotive.
While the recent "shale oil boom" has lowered oil prices again the wide availability of cheep natural gas has caused diesel engine designers to think towards converting from diesel oil as a heat source to running on natural gas instead - supplied to the locomotive diesel engine by tank car bottle tenders as a viable option.
The consideration of steam power has merit for discussion on this site for historic purposes if not as as potential source for the engineering modern power.
Wislish has a great technical engineeing background he has been encouraging me in private e-mail to speak about the Rankine Cycle. I wish he would do so instead because with his advanced mathmatical background he really does a better job and has greater insight into this type of discussion.
Sometimes you have to provoke Wislish to get him to come out of his study - "to get big bear to come out of the cave!"
Doc.
A couple things.
The 10-20% thermal efficiency of steam locomotives is perhaps the theoretical efficiency of what can appear on indicator diagrams with a 100% efficient boiler, mechanical transmission, perfect valves, no wall condensation loss in the cylinder, heat loss from uninsulated or poorly insulated firebox, boiler, steam pipes, valves, and cylinders. Wardale gives figures that year-in year-out efficiency can be as low as 3%.
The Brown studies suggesting that steam locomotive economics were more favorable than generally understood assigns a value that steam, on average, used 6 times the BTUs of Diesel locomotives. Wardale gives some figures suggesting that the fuel consumption of steam could be even higher than that.
My thinking is that using all of the Chapelon/Porta/Wardale/Girdlestone improvements to the Stephenson-type steam locomotive without going to "exotic stuff" like turbines, condensing, water-tube boilers could improve steam to 3 times the BTUs of Diesel, making steam competitive with coal-to-liquids and burning that in a Diesel instead of the coal directly in a steam locomotive.
I have read the white papers on the Coalition for Sustainable Rail, and here are my impressions. No disrespect intended, but I think this group is very much like the ACE 3000 project in motivation and intentions. What I mean by this is that they are railfans and steam enthusiasts (not that there is anything wrong with that!) who are carrying the environmental banner as a justification for doing work on "modern steam." They are simply not a group of environmentalists who got up one morning and though, "Gee, last bring back the steam locomotive to burn biomass!"
Furthermore, the Santa Fe Hudson is their version of the C&O Northern in the ACE 3000 project. They don't intend a 1940's Hudson to be the "final form" of their high-speed passenger solid-fuel burning passenger loco. Rather, it is a historical artifact that will serve as some initial phase or demonstration before going on to their 21st Century design.
They appear to take the preservation concerns seriously. I don't think they intend to "chop" their 4-6-4 and turn it into something looking like those ugly D&H high-pressure steam engines. Or to the extent that they plan to do a "Red Devil" treatment on it, they are earnest about promising to turning it back to "the way it was" to address worries that they are going to mutilate a historic steamer beyond recognition. Remember, the vibe I get is these dudes are steam nuts waving the enviro banner to get funding and a purpose rather than enviros doing something nuts with steam.
Remember, the 4-6-4 is meant as some kind of proof-of-concept to be followed by some kind of ACE 3000-like thing (maybe, hopefully not condensing and hence doable), although they may be holding off on their ACE 3000-like think until they get experience with their mods of the 4-6-4.
Dr DIt is held that the internal combustion engine thermal efficiency is on the order of 25-30%, and the external combustion reciprocating steam locomotive thermal efficiency on the order of 10-20%. These basic statistics are often given. Steam powerplants, however, have achieved thermal efficiency as high as 40-50%.
Doc, ya gotta remember that steam plants get their high efficiency in ways that cannot be packaged practically on locomotives. They rely on very steady and continuous operating conditions, they usually have lousy turndown ratio (and in many cases turndown actually leads to boiler and refractory damage as the combustion gas paths etc. change!), they do feedwater heating with multiple bleed stages on the turbine, they use radiant superheating and exhaust into a substantial vacuum with enormous plenum volume...
The Carnot cycle represents the absolute maximum efficiency that can be used by an engine that uses heat to expand a gas and push something to do work -- a piston, a turbine blade, etc. That neatly corresponds to the maximum work that can be done with, say, an internal combustion engine, which generates its combustion gas entirely within the cylinder. An external-combustion system, though, can follow the Rankine cycle, which looks at the most effective way of using the heat to produce a given amount of work practically -- can exhaust heat be used to preheat water, or air for combustion, or can steam at higher temperature preheat a cylinder to reduce wall temperature when steam at lower temperature is admitted for power, for example.
The thing is that many of the ways in which heat is most effectively transmitted from combustion to work involve expensive, or heavy, or bulky, or complicated systems, many of which do not take kindly to the environment encountered by working steam locomotives that have to earn their bottom-line keep. Perhaps nowhere is this illustrated better than condensing, but there are reasons why very effective and comparably simple devices like the Schmidt superheater, the Snyder combustion-air preheater, and the Cunningham circulator are things that ought to work well, things like the Franco-Crosti preheater/economizer and the popular kinds of American feedwater heater are more complex and involve more maintenance and tsurris (to the point they were removed as unworkable when their maintenance exceeded their economic benefit), and things like the Schmidt high-pressure system of NYC 4-8-4 and LMS Fury fame (and those D&H compounds) could never provide meaningful economic recovery of their costs.
Much of the promise of 'modern' steam involves the use of new materials to permit better retention of heat in the Rankine cycle, for example the use of aerogel lagging and jacketing or the use of thermal tiling or thermal-barrier coatings in part of the radiant gas path. An interesting point about the rebuilt European 2-10-0 8055 is that it is possible to maintain working steam pressure indefinitely by 'plugging in' an electric element of only about 35kW (and regulating it via a simple pressure transducer); this means that many of the losses and waste associated with "idling" steam power between runs can be reduced or eliminated.
Much of the attention, though, is not focused on improvements in the Rankine cycle so much as reducing the 'people machine' aspects that were so deadly to classic steam locomotive practice. That goes far beyond what NYC and N&W were able to do, and probably isn't of interest even to many of the people in this discussion, but one of the most important (to me) possibilities is the use of modern electronics and control theory to improve how the locomotive is 'driven' and fired. If you then (as I think you should) outsource and provide long-term procurement for cheap solid fuel -- cheap enough that your cost in delivered $/BTU or whatever is lower per ton-mile than that for diesels -- and if you can get your water-rate problems addressed, you're more likely to have something that can compete effectively in the markets where steam power has distinctive advantages over complicated diesel-electrics.
Dr D It is held that the internal combustion engine thermal efficiency is on the order of 25-30%...
It is held that the internal combustion engine thermal efficiency is on the order of 25-30%...
Sure, if you are talking about a 1960's era gasoline engine. Many modern car engines are in the 30% - 35% range. Toyota has some engines that are up around 38%. Modern turbo-diesels are easily in the 40% - 45% range, while large marine diesels are 50% to 52% thermal efficient.
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