Talk:Stirling engine/Archive 3

There is controversy as to the categorization of a Stirling engine as a "hot air engine" or "external combustion engine", and this may precipitate into an edit-war. I propose using uncontroversial language in the intro, and then for the controversial terms, explaining each POV, probably in a section immediately following the intro, such as the history section or a new section. (see WP:NPOV) If there is a consensus, I will go ahead and make the changes. --Mikiemike (talk) 22:43, 9 April 2008 (UTC)

It is technically a hot air engine. To refer to it as a external combustion engine confines it to combustion. Stirling Energy Systems and Infinia both utilize stirling engines to derive power from the sun. The sun is just a heat source that heats the surface of the engine then in the inside it derives all power from the heated air. Internal combustion engines(ICE's) derive all power from combustion, so the expansion of gas in a closed volume that then pushes against a piston to derive power and has a volume change, and don't actually utilize the heat. External Combustion Engines would operate with the same principle. —Preceding unsigned comment added by 134.68.61.37 (talk) 23:58, 31 August 2010 (UTC)

Over the years the Stirling engine has repeatedly been classified as an external combustion engine, however, simple repetition of an error does not make it any less of an error! As the writer of the piece on Harwell thermomechanical generator article (apologies - I don't know where I dragged TMD from!) Mikiemike should know better than most that the Stirling engine should not be so catagorised. The heat source for some versions of the TMG was neither combustion nor external being an embedded radio isotope. A similar scheme has been proposed by Martini and others to power Stirling based artificial hearts.

In the early 1960's Ted Finkelstein designed and built a solar Stirling engine in which sunlight was focussed through a small transparent 'window' on to an internal absorber, neatly avoiding the use of an expansion end heat exchanger. Some might argue that the absorber is in fact such an exchanger, but the fact remains that the input heat does not have to enter the engine by conduction through a solid boundary, which is a defining characteristic of an external combustion engine. The Bomin Sunpulse pumping engine <http://www.bsrsolar.com/core1-1.php3> works on a similar principle but uses sunlight without any pre-concentration.

Finally, though I'm sure there are other examples, there have been proposals to combine a stirling cycle machine with a nuclear reactor (most recently the pebble bed type) such that the working fluid of the engine is in direct contact with the fuel. Again, the input heat does not traverse a solid boundary.

The question as to whether the Stirling engine should be classified as a hot air engine is less clear and largely one of semantics. To so-call any engine not employing air as its working fluid is undoubtedly a misnomer, but a misnomer in the way that we still refer to 'lead pencils' or 'steam rollers'. 'Air engine' is a very convenient and widely understood cover-all term which was rightly chosen by Allan Organ, a man who has spent his whole professional life studying the Stirling engine, to be incorporated into the title of his two most recent books on the subject irrespective of the fact that many of the machines discussed are not air charged. Though now considered archaic useage, there is of course good historical precedent for referring to any gas as an 'air'.

I accept that to an extent I am arguing for academically rigourous language in the one case and 'common parlance' in the other, but, particulary in the case of an introduction which as Lumos has observed is aimed at the general reader, I feel this best serves the purpose of promoting rapid understanding at a conceptual rather than detail level.

81.134.14.178 (talk) 10:21, 10 April 2008 (UTC)

Dear unregistered user 81.134.14.178, it's good that you've explained your argument, rather than just editing and reverting. You explain yourself fairly well, but I can't help noticing the double-standard. You completely reject the phase "external combustion engine", citing some rare exceptions, yet you insist upon calling the Stirling engine a "hot air engine", for which there are obvious, mainstream exceptions. For instance, there are a lot more Stirling engines running on helium, hydrogen and other non-air gases, then there are Stirling engines running on radioactive isotopes or with solar transparent windows.

It's easy to criticize the term "external combustion engine", but it's not so easy to find a more descriptive (and less-controversial) phrase. I suggested "external heat engine". Anyway, somehow this engine needs to be distinguished from an "internal combustion engine".

Also, please use up to date terminology. One of the reasons for having an encyclopedia with many editors is to keep the articles up to date. How ironic it would be if new unregistered users add more and more outdated terminology! History subtopics belong in the history section; all the other material should be modernized. We are not living in the past. We are not going to start calling gases by the term 'airs', so forget about it, (everyone else has).

This recent edit has removed an important explanation. An isothermal expansion or compression process needs regeneration to be reversible, and to establish Carnot equivalence. The paragraph on history belongs in the history section, not the intro. Special:Contributions/81.134.14.178 wrote: " not until the mid twentieth century that any serious scientific development of its technological potential was attempted", and cited Hargreaves but no page number. I have read this book, and you can tell just from the table of contents that this is not what Hargreave suggests. First of all, he writes about developmental history in both centuries. Rev.Stirling was effectively a scientist, and I'm sure he took his work "seriously". So this edit does not help the article, in my opinion. Anyway, the "technological potential" you speak of was not even known at that time, because Carnot did not publish until 1824! Steam boilers were later made safer, thus obviating much of the need for the Stirling engine's inherent safety. Anyway, the steam engine was, and still is, much easier to design, develop and optimize. The nerve you have telling me I should read the history!

You don't need to know wiki syntax, but you do need to check your spelling, and add to the appropriate category. The article is lengthy and unorganized enough as it is. At this time, I think it would be best for the article for us to revert your edits, at least until the quality of your additions are improved. A lot of people have spent a lot of time working on this article (including me). So don't expect to just swoop in and replace critical sections like the introduction with one of your rough drafts! The other editors are not "bots" here to: fix your spelling, fix your sources, and merge your material into the proper category. I'm willing to help with syntax, but the article needs enough work as it is without unregistered users trashing it. You proceeded to write a new history section starting near the end of the introduction section, however, the history section already contains information like "invented by Reverend Dr. Robert Stirling and patented in 1816", so this material was already covered. As it is, the part of the history section citing Hargreaves already needs improved language, style and tone, and needs citations that have page numbers. I strongly suggest you start there.

You wrote: "promoting rapid understanding at a conceptual rather than detail level". I can agree with this, but most people who don't know what a Stirling engine is, don't know what a "hot air engine" is either, so that comparison doesn't help explain it, besides "hot air engine" can refer to any one of a half-dozen different cycles, only one of which is a Stirling cycle, so I see this as broadening the subject to include the subjects of other articles, rather than defining this subject. If any comparison needs to be made, a steam engine is much likely to be known to the common reader. So a basic conceptual explanation would be "a steam engine that runs with a gaseous working fluid, instead of water & steam". But even this would draw criticism from astute editors as being misleading, so it's probably best to avoid comparisons altogether, especially in the intro. Other less-discriminating editors want to compare the Stirling to an internal combustion engine, which will give the well-read editors an even bigger headache. The article should dispel the myths and overturn the misconceptions, not promote and encourage them! The Stirling engine is a very unique device, so let's treat it as such. If you can't define it and explain it for what it is, without drawing misleading parallels to other devices, then some people would likely suggest that maybe you don't understand the subject well enough to be writing about it in an encyclopedia. Many books that are much longer than this article, manage to explain the cycle without needing to invoke other cycles.

By the way, I greatly respect Allan Organ and his work. It is a travesty that he is not referenced more in this article. I have not read his newest book "Air Engines", and whomever does, I hope they'll summarize and reference it here. He has done a lot of theoretical research specifically on Stirling engines, and 99% of it is independent of gas type, as any good theoretical work should be, because it is in theory, arbitrary. He has advanced engine design for all gas types.

Air is a convenient gas to use, but the advantages of other gases cannot and should not be excluded or ignored, which is exactly what you're doing by classifying the Stirling engine as a "hot air engine" at the very beginning of the article! That is not the place for it! Put it in the section on gas types, or somewhere else that's more appropriate. In general, an introduction should not be extended to include the subjects of other articles, and it should not define too-narrowly the subject of the article so that some prominent and relevant types are excluded. Neither is this a blog for an unregistered user to post that "air is my favorite working fluid".

--Mikiemike (talk) 18:37, 10 April 2008 (UTC)

This is a reply to the recent edit summaries.

(cur) (last) 12:59, April 10, 2008 81.134.14.178 (Talk) (64,278 bytes) (The isothermals you refer to do not exist in the 'real' stirling cycle and even in the 'text book' cycle it is the isochoric processes which interact with the regenerator)

Yes, but you misunderstand the thermodynamics and the point I'm making. The gas in the regenerator itself is nearly-isothermal, and this is a construct that Organ uses for explanation. "Carnot efficiency" unequivocally depends on regeneration.

(cur) (last) 12:32, April 10, 2008 81.134.14.178 (Talk) (64,246 bytes) (appreciate controversy Re. classification of Stirling as type of hot air engine in general is ongoing, but the two terms are certainly not mutually exclusive.) (undo)

They have very simple similarities, but the differences are quite apparent and you gloss over this distinction which adds a considerable amount of confusion. The damage you cause in one sentence can take at least a paragraph to clarify. It's better to avoid broaching this subtopic all together, and avoid the ensuing tangle. The introduction is not the place to broach a controversial subject, unless it is specifically prefaced by the word "controversial".

(cur) (last) 12:27, April 10, 2008 81.134.14.178 (Talk) (64,315 bytes) (For much of its history the Stirling engine has been more notable for the LACK of scientific development. See ref for a thorough treatment of this point. Validity of history in intro noted again) (undo)

Yes, but it is not for lack of trying! Many 200 year old inventions lacked what you call "scientific" and "technological development", simply because the advanced methods weren't available yet or weren't widely used. The steam engine was a lot easier to develop. I bet if the complexity of Rankine and Stirling were swapped, history would have been a lot different!

(cur) (last) 12:17, April 10, 2008 81.134.14.178 (Talk) (63,941 bytes) (clearly at the present time, it is not reasonable to claim two centuries of use for a device invented in 1816. Questionable validity of potted history in intro again noted) (undo)

192 years then. What a stickler you are! You can't round that to 2 centuries! Sure, it's not "over two centuries", but "nearly two centuries" will suffice.

(cur) (last) 12:12, April 10, 2008 81.134.14.178 (Talk) (63,945 bytes) (needs to be qualified - talk of perfect efficiency will undoubtedly draw critisism from those who (wrongly) believe you mean 100%.) (undo)

Yes, perhaps a good point, but you can't write the whole article inside the introduction. "Thermal efficiency" was linked to, which presumably explains this point. IIRC, it is explained elsewhere too.

(cur) (last) 12:03, April 10, 2008 81.134.14.178 (Talk) (63,829 bytes) (If there is to be a 'potted history' in the intro (I look to Lumos for guidance on that point) then to omit the name of the inventor is surely a gross injustice) (undo)

How can we possibly omit the name of the inventor when the engine, the cycle and the article title all bear his name!!!??? As I said, don't duplicate the history section!

--Mikiemike (talk) 19:20, 10 April 2008 (UTC)

Hullo again. I must admit I was a little miffed by your wholesale reversion of my carefully explained multiple edits to the intro - you may well of course retort "now you know how it feels"!

Indeed Mikiemike (talk) 23:41, 10 April 2008 (UTC)

Just to take up a few of your points;

Inability to think of a better phrase seems a poor reason for retaining the blatently incorrect classification of the Stirling engine as an external combustion (or heat) engine. Yes it needs to be differentiated from an internal combustion engine - but so does a fish.

I accept your apology.  :-) So "external heat engine" it is then, since you don't have a better suggestion to distinguish a Stirling engine from an Otto engine. Distinguishing an engine from a fish is not necessary, since the difference is self-evident. Mikiemike (talk) 23:41, 10 April 2008 (UTC)

The reference to all gasses being archaically called 'airs' (Cavendish et al) was included as an interesting little historical insight rather than as justification of my argument for including the Stirling engine in the wider family of air engines. If you have read (and understood) much of Organ's work on dynamic similarity, you will be aware that for any 'optimised' engine utilising an exotic working fluid, there is an equivalent air charged design with different gas circuit geometry but identical gas processes (though not all will be a viable manufacturing prospect!)

Efficiency may be the same for any gas, but power density is not, and this effects system cost. It is a fallacy to assert that any gas is always better than any other. There are tradeoffs. See the gas type section if you're not familiar with this. Even air poses problems with the oxygen it contains. Nitrogen is a better choice for safety, and power density is slightly better. "Exotic" suggests a biased POV. The published works are full of engine designs that use non-air gases. (see WP:Neutrality) Mikiemike (talk) 23:41, 10 April 2008 (UTC)

I do understand your point that the regenerator makes possible the isothermal expansion and compression processes of the 'text book' cycle, otherwise much of the change from Tc to Th and vice versa would of neccessity take place in the heat exchangers themselves - clearly irreversibly. However it does not translate well to the phrase you actually use and I am amazed that you ignore your own work on the 'real' Stirling cycle. Organ used (in 'The Renerator and the Stirling engine') a description of unparalleled clarity (and brevity!) desribing the function of the regenerator as "to retain within the system that heat which would otherwise be exchanged with the environment at temperatures intermediate to the maximum and minimum cycle temperatures" and it was this I was tryimg to allude to without pinching it outright.

Well there is more than one way to explain it. You and I see it differently. So what else is new?

I tend to agree that history should be kept to the history section, but was willing to bow to Lumos' greater experience of the format and wished to ensure that if there was to be a 'potted history' within the intro it was at least accurate (I think the 'stray' history paragraph crept in during the mess of edits by you, me and Lumos; it was certainly not intended) . In that respect i believe I cited Organ (Air Engines) rather than Hargreaves' equally fine tome in justifiying my comment Re. the the lack of scientific development of the Stirling engine until the mid twentieth century. If you re read the book I'm sure you will find that then lack of impact theoretical understanding had on the design of the machines themselves during the period between the Stirling brothers era and the Philips era (he calls this the 'dark ages') it is one of its central themes, though he is none-too complimentary about Philips' work either! (you may at least like to read this review http://www.amazon.co.uk/review/R1D5PP4UOPHHD5/ref=cm_cr_rdp_perm). I too have not read his latest offering (too expensive and not yet available on inter library loan in my area) but was interested to note that he had again used 'air engine' in the title rather than any more specific designation.

Well it's a subtle point, and what you just wrote is a more articulate and accurate review than your first attempt. For the technology to get to the current level, it took the combined effort of many researchers spanning many years. I maintain that this "delay" is not for lack of trying, but rather it's largely due to the complexity of the design problem. Mikiemike (talk) 23:41, 10 April 2008 (UTC)

I have apologised elsewhere for my poor spelling and grammer but it's not supposed to be an English test. Is there a spell check button I'm missing somewhere?

No, there's no button. The Mozilla Firefox browser may have a spell checker. OpenOffice does. It's your responsibility to fix your spelling to meet quality standards. If the UK spelling uses "s" instead of "z" as in the US, then this is another problem. Mikiemike (talk) 23:41, 10 April 2008 (UTC)

Finally. You really do seem to have an issue with unregistered users - that is something *you* need to work on ;-)

79.78.12.95 (talk) 20:41, 10 April 2008 (UTC)

Unregistered users are far more likely to vandalize and not follow established guidelines of WP, such as neutrality. You've demonstrated a strong bias for air engines, but this article is not about air engines, it's about Stirling engines. Mikiemike (talk) 23:41, 10 April 2008 (UTC)

(how long should I keep up the indenting you advised?) I note that between me starting the above and pressing 'save page' you have added a fuller explanation of your revert for which I am grateful

I wish someone else would chip in on this.

79.78.12.95 (talk) 20:45, 10 April 2008 (UTC)

Thank you again for you measured response. So might I be allowed another little 'dabble' without being jumped on?

Anticipating a grilling, I went to the bookshelf in search of Allan Organ's elegantly simple statement of the function of the regenerator in a Stirling engine. A couple of hours later I found it - not in 'R&SE' as stated above but on page 58 of 'Thermodynamics and Gas Dyamics of Stirling Cycle Machines' I also note that I had already slightly paraphrased it when adding it to the regenerator section - good grief, I thought my memory was returning to normal since stopping the SSRI's! The precise wording Organ uses is "the purpose of which is to exchange with the working fluid that heat which would otherwise be exchanged with the environment at temperatures intermediate to T_e and T_c" and I propose that something along these lines should appear in the introduction since the regenerator is the defining feature of a Stirling engine that gives rise to its reputation for 'perfect' efficiency which attracts all the alternative energy dreamers. It would have to be qualified by a ref to carnot lest accusations of claiming a Perpetuum mobile be levelled - as they were in Stirlings day.

I'm sure we can work on the text to make it broadly working fluid neutral but I couldn't resist the following:-

Mikiemike wrote (snip) " The published works are full of engine designs that use non-air gases"

Yes, including those by an acknowledged expert in the field titled "Air Engines" and "The Air Engine" ;-)

As for the external combustion engine tag - well I guess we will have to agree to differ. I suppose one could equally postulate an internally heated Rankine cycle engine. Perhaps a statement that while the Stirling engine is popularly classified as an external combustion engine, there are exceptions would cover it.

Potted history in intro - I just don't know. Lumos, you initiated it please enlighten us.

Apologies for previous lack of sig. I thought I'd found the tilde on eee pc keyboard this morning, but it was clearly not so!

81.134.14.178 (talk) 08:46, 11 April 2008 (UTC)

Can I remind everyone that the introduction should not contain obscure thermodynamic terms. It should be a brief accurate description for the general reader with no background in the subject who wants to know what a Stirling engine is. All the rest can be explained in detail in the body of the article. See Wikipedia:Lead section. Lumos3 (talk) 10:03, 11 April 2008 (UTC)

So something along the lines of:-

In the family of heat engines, 'Stirling engine' defines a closed-cycle regenerative hot air engine. In this context; "hot air" may be taken to include other gaseous working fluids, "closed-cycle" to mean that the working gas is permanently contained within the engine's system, and "regenerative" to refer to the use of an internal heat exchanger and temporary heat store - the regenerator.

Which I think is pretty much where we came in!

81.134.14.178 (talk) 10:28, 11 April 2008 (UTC)

And if you want a 'potted history/why should I be interested?' paragraph:-

Patented by The Reverend Dr. Robert Stirling in 1816 and initially intended to rival the steam engine as an industrial prime mover, the Stirling engine was used in small low power applications for nearly two centuries but it was not until the mid twentieth century that renewed interest in its technological potential emerged^[1]. The stirling cycle is noted for its potentially high Thermal efficiency, theoretically equal to the 'perfect' Carnot efficiency and abilty to produce mechanical power from virtually any heat source.

81.134.14.178 (talk) 10:56, 11 April 2008 (UTC)

I think you people are killing the intro section by trying too hard to make it wonderful. Have you ever tried having some non-technical friend read it, and see if it made any sense.

You really just need to explain this thing just runs by hot being applied to one side, cold on the other, the gas of choice, often just air, stays inside, and this thing makes mechanical energy from the heat difference. There are therefore no valves, since the gas is contained. There is no exhaust from the engine itself, since the gas is contained. It simply works by the physics of heat expanding gas and cold contracting gas being put to use to make a workable engine.

The regenerator can be mentioned, but please remember, many of the Stirling engines Joe Smoe public might buy, the low temperature models, do not use a regenerator, because that would kill the engine from even moving. The regenerator was a clever trick that was introduced to rob Peter to pay Paul, by sacrificing engine power to be able to make use of a limited difference in temperature transfer available, ironically. People who play with the designs seem to miss this, and so can not figure out why typical Stirling engines have non-practical power output ratings.

(note: what you just said is not true --Mikiemike (talk) 03:04, 12 April 2008 (UTC))

I really do not want to debate why all this is true, but the cold side should remove its own heat without the cheat of a regenerator, and do it quickly, and the heat side heat its own gas without it having to be prewarmed by a regenerator, and do it quickly.

I will stop here, and wait for the blasts of experts!

• smiles*

But, please try to audience people who have no clue about thermodynamics,and really do not care. The first paragraphs should be able to convey simply in laymen's terms, what this goofy thing nobody has heard of, is.

Bptdude (talk) 10:39, 11 April 2008 (UTC)

The regenerator is not some sort of 'con trick' It is a defining feature of the Stirling engine which enables its efficiency to approach the theoreticaly 'perfect' efficiency for any heat engine. Many of the better LTD models you refer to have regenerators consisting of reticulated foam forming all or part of the displacer. Any engine which does not have a degree of regeneration (and as noted in the main article that may not neccesarily mean there is an identifiable separate regenerator) is not a stirling engine, but it is still a hot air engine and I suggest you note the cross ref to that article for an ultra simple 'air heat up and expands - air cools down and contracts' type treatment

It is very difficult to explain an inherently technical subject in totally non-technical language even at an introductory level.

(well said --Mikiemike (talk) 03:04, 12 April 2008 (UTC))

Perhaps to be able to do so is the mark of an accomplished docent in which case we appear to be sadly lacking such a contributor.

Thanks for the wake-up call though - we really are over analysing aren't we! BTW what do you think of the suggested intro paragraphs above (In the family of heat engines............Patented by The Reverend Dr. Robert Stirling in 1816........etc) which I think is about as non-technical as it can can get without being entirely pointless?

81.134.14.178 (talk) 13:08, 11 April 2008 (UTC)

The Stirling engine is in some ways conceptually simple, but to really understand it is anything but simple. You need to understand thermodynamics, including heat transfer and fluid dynamics, and that's just the beginning. You really need a mechanical engineering degree. There's only so much you can simplify a complex subject without being misleading, and there's only so much you can say in a non-technical language about a highly technical subject. Not everyone wants articles to be "dumbed-down".

We need multiple sections or multiple articles in order to provide a space for both technical and non-technical descriptions. There's no way to do both at the same time without doing a disservice to the other. Thus I suggest a splitting them and each one linking to the other, in case someone clicks on the wrong link. We can put an advanced section at the end called "Stirling engines for thermodynamisists".

There are highly technical articles on Wikipedia. How do they deal with this issue? I suspect novices never click on most of those links, but they do click on this one for some reason. --Mikiemike (talk) 03:04, 12 April 2008 (UTC)

Praise from Mikiemike - whatever next?

Well here I am again all registered up and everything if it make you feel better. I think it is the much misunderstood 'perfect engine' epithet that attracts the casual attention of the wider public to the Stirling engine. The environmentalist/alternative energy dreamers see it as the engine which might save the planet, the conspiracy theorists see it as the engine which would have saved the planet 'if only the oil companies had not bought up and buried all the technology' and it has somehow gained a reputation as 'fringe' science. All of which has lead to coverage in some pretty unlikely places such as the Fortean Times and of course the dreaded Dilbert blog. What does everyone do when they read something in a magazine that sounds sort of interesting but they don't really understand - why, click on wikipedia of course! It would be nice to think they come away enlightened but current evidence indicates probably not.

I don't think the idea of totaly separate technical and 'dumbed down' articles is really a runner - like hey guys, it's like this kinda thing you put on top of your coffee cup and it like powers your house. Wow! will it run on a beer? - reading the guidelines, Lumos is right, the intro is the place for an 'as simple as you can make it' precis. With plenty of links for those who wish to dig a little deeper, it should be possible. I would take it as a real welcome to wikipedia if the great and the good would consider the two paragraphs I included in an earlier post above as a starting point (maybe excepting the hot air engine ref - I've been reading about POV pushing as well!) and build on them without introducing undue complication. Pv=mrt (talk) 16:59, 12 April 2008 (UTC)

Your sarcasm is only mocking yourself, and I don't appreciate your patronizing attitude. How ludicrous it is for a brand new user to start telling me how it's supposed to be. Just because Wikipedia is open, doesn't mean it's your playground. Why don't you try following some of the WP:guidelines instead of just hacking the article to death? Your comments are speculative and opinionated and this isn't a blog.
The goal of article quality is not to make it 'as simple as you can make it'. Accuracy is important. WP:NPOV is important. WP:References are important.
This is not an ad based publication where you're trying to maximize circulation.

Concerning the bit on "...(the regenerator) making the isothermal processes thermodynamically reversible. " Lumos3 deleted it on 09:57, April 11, 2008 , calling it unwanted "jargon". Well, it's not some random "jargon", okay? It's thermodynamics! So yes, make no mistake, you are dumbing it down. You can't appreciate this engine if you don't appreciate thermodynamics. Thermodynamics is the only thing that will ever save this engine from being "fringe science". By oversimplifying it, you are misleading people into thinking that this device is simpler than it actaully is. But whatever. I will add advanced material in the article if I want, because you haven't cited any legitimate reason not to. God forbid somewhat might actually learn something by reading an encyclopedia! The article will have to be split soon anyway, because it's getting too big.

--Mikiemike (talk) 21:46, 12 April 2008 (UTC)

Sarcasm - what sarcasm? I was genuinely pleased to have elicited a positive comment from you! But I am gradually becoming quite frankly fed up with your bullying attitude. You encourage me to register, but then as a "brand new user" I apparently have nothing useful to contribute.

I read the guidelines regarding intros and concurred with Lumos' interpretation of what it should consist of - has that user been around long enough to earn any 'respect' from you? You accuse me of hacking the article to death, but it may have escaped your notice that I havn't dared post any edits since being rocketed by you last time.

My Response to your question about why this article attracts more attention than other esoteric technical pieces was also sincerily meant and my parody of what a dumbed-down article might consist of was pure COMEDY.

In short, you appear to believe you have some sort of ownership of this article and repeatedy voice pantomime outrage that anyone should question YOUR work. You forget that registered or not, you are effectively anonymous and I don't know you from the Wizard of Oz (and we all know how that turned out!). Well congratulations you 'own' an article which is full of useful and fascinating information most if not all of which is totally inaccesible to a large proportion of its target audience. It does a disservice to the Stirling engine and a disservice to wikipedia.

I had intended spending my Sunday surrounded by my fairly extensive library on the subject and fully referencing the history section (the bulk of which I contributed some while ago before registering), but I'd hate to impose myself on your little kingdom any further. Is this the 'wiki way' - if so you can keep it.

Pv=mrt (talk) 08:03, 13 April 2008 (UTC)

Bptdude wrote:-

your comment: "Many of the better LTD models you refer to have regenerators consisting of reticulated foam forming all or part of the displacer."

The LTD, even as described by the designers, do not make use of regenerators, and for good reason, and for whatever reason, are stilled called Stirlings. People make an unfounded wishful leap to pretend the displacer is sorta acting like one a little bit. In fact, to increase peformance, you would add a thin layer of vacuum in the center of the displacer to seperate the hot and cold sides, and at the junction in the cylinder between hot and cold, add another vacuum ring to seperate hot and cold to not have one side thermally contaminate the other. The air rushes from one side to the other, and obtains all heating and cooling within the proper end of the cylinder, NOT on the small time is spends moving from one side to the other.

I think that a study of the work of Ivo Kolin and Jim Senft would change your opinion on whether LTD engines make use of regenerators. Between them they advanced the 'state of the art' to the point that at the 5th International Stirling Engine Conferance (Dubrovnick 1991) Senft was able to demonstrate an engine running at a temperature differential of 0.5K! It is true howver that anything which can be done to reduce thermal shorting is beneficial - including minimising the thermal conductivity of the regenerator in the same plane as gas flow. Pv=mrt (talk) 13:35, 14 April 2008 (UTC)

Current engineering design work is in fact working on better thermal seals and innovative ways to introduce the heat on the hot side. Some of these will truly upset the Stirling engine definition, as the heat will not be by internal chemical combustion, but may be introduced internally. One advanced design will use a pulsed heat source, and the cold side will have such things as cooling coils { yes, we know about the efficiency robbing, but in more advanced designs, it may be worth it. sorry I can not say more }

As engineers and scientists we have a strong desire to classify things, indeed taxonomy is a science in itself. In reality of course things do not always fit into convenient little boxes - the Stirling engine is a closed cycle regenerative heat engine, but no regenerator is perfect and, even in the absence of an identifiable separate componant, it would be difficult to deliberately eliminate all regenerative effects from the gas passages between the hot and cold spaces (some proposals for rotary displacer engines probably come close). So just how little regenerative effect should one tolerate before a Stirling engine becomes a mere hot air (or hot gas) engine? The same goes for heating, we have seen internally heated Stirling engines before (see above) but that does not change the basic functioning of the engine, it is still a Stirling engine. Regarding cooling coils, the Stirling brothers discovered early on that efficient cooling was as important as heating and by the late 1820's their designs included internal cooling coils (see eg Hargreaves 'the Philips Stirling Engine' Ch. 1.2). Pv=mrt (talk) 13:35, 14 April 2008 (UTC)

But, yes, the regenerator may go away, as the effort for higher power output gets serious. You have to understand what the regenerator really did, to know why.

Depends on the design parameters for the engine - if you are striving to maximise efficiency then a regenerator is absolutely essential. But efficiency is not the only 'figure of merit' for an engine, it may be that power output per $ or per lb is more important for the target application in which case it is entirely possible that the designer may choose to go with no identifiable regenerator. In fact in a section of his book 'Air Engines' entitled 'A shot in the dark', Alan Organ introduces just such a design intended to maximise specific power at the expense of efficiency. However that is unequivocally NOT a Stirling engine as the working fluid (air) is vented to the atmosphere at the end of each cycle to avoid the cold end thermal bottleneck. It's a shame that you are unable to say more about what you are working on - I'm sure it would make fascinating reading. Pv=mrt (talk) 13:35, 14 April 2008 (UTC)

As for the article. It should not be what people feel like, as to should it be overly techical or not. This article has many hits, and most are from a non-technical article who hear about this thing, and want to know what it is. To truly be true to Wiki, you have to accept the dominent audience, and target them, with ways for more specialized viewers to follow up.

I can only say Hear Hear! to that. Pv=mrt (talk) 13:35, 14 April 2008 (UTC)

In case you did not know, most newspaper articles are written this way. It is an art form itself.  :)

Bptdude (talk) 03:20, 14 April 2008 (UTC)

The writing style for an encyclopedia should be more along the lines of factual reporting, and not just an op-ed. This means sticking close to the sources. This is a pillar of Wikipedia. It helps thwart bias and repel bloggers. It tends to keep an article more focused on the topic and helps the writing to be more coherent. It tends to give Wikipedia some much needed credibility. And it just makes for better encyclopedia writing and reading. The term "article" does not mean a "newspaper or magazine article", (unless you have very high standards for journalism). Rather, it needs to be less like a tabloid "article", and of much higher quality, more like an "article of a constitution". --Mikiemike (talk) 18:07, 14 April 2008 (UTC)

Hi Mikie. Appreciate above re main article, but is a more dialectic/conversational style such as I have been using acceptable in a talk page such as this? Pv=mrt (talk) 19:23, 14 April 2008 (UTC)

If you feel the need to blog or vent or whatever, then yes I'd much rather see you do it here than in the article.

BTW, more unregistered vandalism. --Mikiemike (talk) 21:15, 14 April 2008 (UTC)

I have never got into blogs so I can't say I'm familiar with the format, infact my only on-line output apart from this has been a few usenet and other discussion groups (all engineering/history of technology related). I apologise for responding in kind above - I guess the comments on both sides could be removed but, hey, it's been said now so let's just move on.

If I'm interpreting it correctly, one of the purposes of the talk page is to enable the main article to achieve a new concensus. I think so far there is concensus (or at least a majority of those contributing here) that the introduction should be accessible to the non-specialist, so could we start moving in that direction at least? Given previous reaction to my attempts, I am loath to simply edit, but have suggested suitable starting points above.

Regarding the hot air engine and external combustion engine questions. I have realised that I am to an extent POV pushing but, in as much as taxonomy is a productive exercise at all, hope that the outcome of the discussions on this page will (lifting shamelessly from the wikipedia article on dialectic) not simply be the refutation of one of the relevant points of view, but a synthesis or combination of the opposing assertions. Unfortunately this will probably neccesitate the use of some rather clumsy phraseology such as "the Stirling engine has historically been classified as a subtype of the air engine but, as technology has moved on, other working fluids have come to prevail and this is now only strictly true in the special case of an air-charged engine. See 'Gas choice issues' below." Please don't claim that the two are "mutually exlusive" though.

I note that Philips themselves agonised over what to call the device. Viz Hargreaves chapter 2.5, which also calls into question my assertion in history section that the phrase 'Stirling engine', as opposed to 'Stirling's air engine' was only coined in the 1950's. It appears it was proposed much earlier but only gained general acceptance in the Philips era and its adoption by that company can be dated as precisely as April 1945 (though the instruction book for the MP1002CA still refers to 'air engine')! Again, I would edit but......

Any thoughts? Pv=mrt (talk) 08:45, 15 April 2008 (UTC)

You're still talking about history. The article should primarily describe "what it is" (now), and secondarily "what it was" (then) and most of that should be in the history section, because many readers aren't interested in ancient history.

We need to resist the extraneous labeling and over-categorizing. The phrase "hot air engine" does not add much to the article in the way of content value, and I think the way you're phrasing it takes the article in the wrong direction. The gas type does not need to be specified in order to explain a Stirling engine. For the same reason that you reject "combustion" as the only heat type, I reject "air" as the only gas type. You seem to have a hard time accepting that. I think what you really want to say is that air is your favorite working fluid. But in so doing, your ignoring other people's favorite gases, and you're ignoring the engineering tradeoffs of the other gases. The intro is not the place to get into that debate/discussion. You're trying to argue that Stirling engines are hot air engines, and hot air engines are Stirling engines. You might have gotten away with that a long time ago, but in this day and age it's just not true, and it's wildly misleading. An encyclopedia should not confuse people. The experts and the encyclopedia editors need to be working to distinguishing the two, not calling them the same, and your comparisons are not helping with this, it just seems like you're expressing your opinion. WP:NPOV --Mikiemike (talk) 18:38, 15 April 2008 (UTC)

I think you misinterpret my intentions re working fluids but make a fair point about my continual references to history. Though I maintain an interest in current developments, my 'specialist subject' as it were is the history of technology. So, if there is one point of view that I am keen to push, it is that history is important - it is difficult to know where you are or to plan where you want to go without an appreciation of where you've been. Pv=mrt (talk) 19:16, 15 April 2008 (UTC)

At the moment, history is only useful if it applies to where we are now. We are not writing a history book here. --Mikiemike (talk) 18:21, 17 April 2008 (UTC)

That's you and Henry Ford then ;-) Pv=mrt (talk) 20:24, 17 April 2008 (UTC)

Mikiemike stated above that "We are not writing a history book here " . We are writing an encyclopaedia article and a user of an encyclopaedia would expect to find a complete and concise history of the subject. I find the improvements to the history a welcome addition. Lumos3 (talk) 10:12, 22 April 2008 (UTC)

Yes, but an account of history is not the main objective or the only objective, it is just one of the subtopics. Yes we should aim to have a complete article, but the various sections should build the article cohesively, and not detract from each other. The terminology in common parlance changes over time, and the vocabulary that is most appropriate is the version that is most up to date. It would be silly to use ye olde english just to be consistent with history. Language is a living, breathing entity that evolves over time. If we're not going to revise articles to keep them up to date, there would be little point of having a wiki. No, the texts don't change very much, but even the most sacred religoius texts are updated once in a while to make them more readable. Anyway, the modern technology that is in use today for Stirling's is quite recent and original. It does not have a lot to do with the very oldest engines. History is good, but nearly all of that text belongs in the history section.

The issue with technology in general is that it goes obsolete so quickly. Obsolete means: "no longer in use; gone into disuse; disused or neglected (often by preference for something newer, which replaces the [original] subject... [that is] imperfectly developed." Consider how new the internet is, and how new the hardware and software is that you are using as you write to me, telling me how important history is. Are you living for the past, or are you living for the future?

--Mikiemike (talk)