Talk:Stirling cycle

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Untitled

This is a great addition to Wiki's Stirling engine content (I particularly love the clear illustration that the adiabatic component of compression and expansion can actually produce a gas temperatures swing higher than the temperature difference between the heater and cooler - so watch those volume ratios all you would-be builders of low and medium temperature difference engines!) but the link to it from the main engine article is somewhat buried - would it be better to merge it into that article? Also, citing Alan Organ's work might be polite. 213.123.247.91 (talk) 12:15, 18 January 2008 (UTC)[reply]

On Wikipedia, most heat cycles have separate articles from their engine counterparts. I like it that way. Besides, both articles are too big to be merged. I agree that the link to the cycle page is buried too deep in the engine article. So somebody should add the "Stirling cycle" link to the intro of the "Stirling engine" page, just as that article is linked from the intro of this one.

Mikiemike (talk) 09:17, 21 January 2008 (UTC)--[reply]

Point taken - and the Stirling engine article does already tend towards the cumbersome! Anyway, link added.213.123.247.91 (talk) 11:57, 21 January 2008 (UTC)[reply]

Untitled

It would be nice to have a common T-s and P-v diagrams for all thermodynamic cycles in both their ideal and realistic forms. bmunden —Preceding unsigned comment added by 128.211.166.182 (talk) 08:46, 8 January 2010 (UTC)[reply]

Example heat exchanger Data

Heater, Annular-Gap Heat-exchanger

Dimension	Inches	cm	mm	m
Inner diameter of pipe	4.920	12.5	125.0	0.125
Perimeter	15.450	39.2	392.4	0.392
Length of gap (same as length of tubular heater)	11.191	28.4	284	0.284
Gap Depth (thickness) (=Aff/perimeter)	0.050	0.13	1.3	0.001
Hydraulic Radius	0.025	0.06	0.6	0.001
Total outer HX-area (linear units^2)	192	1238	123811	0.124

Cooler, Slot Heat-exchanger

Dimension	Inches	cm	mm	m
Inner diameter of pipe	5.174	13.1	131.4	0.131
Minimum Required pipe diameter	5.17
Minimum Required Pipe wall thickness	0.303	0.769	7.69	0.007689
Length of heat exchanger	3.392	8.616	86.2	0.086157
Hydraulic Radius of slots	0.013	0.033	0.326	0.000326
Width of slots (min = kerf)	0.030	0.1	0.76	0.000762
Slot Depth (or fin height)	0.178	0.5	4.5	0.005
# of slots (# of slot & fin pairs)	361	361	361	361
Width of fins (material between slots)	0.015	0.04	0.38	0.000381
Total wetted-area (linear units^2)	490	3163	316317	0.316

this information is not relevant, to the heat exchange involved in heat engine. — Preceding unsigned comment added by 2601:1C1:8B00:3B10:5479:1F9C:76EA:212F (talk) 16:27, 31 December 2019 (UTC)[reply]

Pointless

This article is nothing more than a bunch of graphs and buzzwords. How does it contribute exactly to the general discussion on Stirling engines? By the way, if you the editor want to talk about Stirling engines in real life, then you should have moved Stirling engine here and written a well-sourced, encyclopedic article on practical Stirling engines at Stirling engine. Which pretty much convinces me that the couple of editors who worked on this page have very little idea what they are talking about.

If this article cannot be made to contain anything useful, I will push for its removal. ~ Jafet (spam) 22:29, 19 April 2008 (UTC)[reply]

And now for the rest of the world, the non-engineers who came here to learn something they seek to know about......

The author has COMPLETELY overlooked providing ANY of the needed and necessary information needed so that the uninformed can learn something; which is why we link to Wikipedia in the first place.

The content I see would make great professional journal 'stuffing', or points in a discussion group for engineers who have studied the topic for eons. To you, go to a discussion group and discuss to your hearts desire. But if you are going to contribute here, at least have the courtesy to include the basic information so that the rest of us can appreciate what it is you are contributing.

Jafet,

You need to check your tone. Don't criticize people you want something from. Don't insult people and then say: "at least have the courtesy to ________". It's you that needs the lesson in courtesy.

We might be able to improve the article if you can be more specific about your objections, and offer some constructive criticism, and not just vague general criticisms.

You suggest that all articles should be completely readable by non-engineers. But if this were the policy, then fewer engineers would use Wikipedia and write these articles in the first place. How else can engineering subjects be explained to non-engineers? Either way, your negative attitude is a lose-lose for you and for the community. Good things come from having a positive attitude. If you don't have anything good to say, then you don't have anything good to offer, so don't expect anything good to come of your comments.

There's a saying: "you get what you pay for", so I'm sending you a full refund for this free encyclopedia.

The Stirling cycle has traditionally been over-simplified to make it easier to understand, but this practice is typically highly inaccurate, misleading, and wrong. This subject is about a thermodynamic cycle, which is an advanced concept. As with any heat engine or thermodynamic cycle, the reader is expected to know a few prerequisite thermodynamic concepts, and the links are there in case they don't. There are a lot of articles on thermodynamics and heat engines, so start there. This is a complex subject, and graphs offer a relatively simple and efficient way to explain it. I could have instead used some highly advanced and abstract equations, but I'm sure far more novice readers would object to that.

The article is fairly well sourced. There are only 2 sources, but they are very rich sources. More sources isn't always better. Anyway, this was a stub not that long ago. Someone removed the tag (not me); see the edit history. The intro may need work, but once again if it is a stub, this does not warrant a full speedy deletion. So you are definitely overreacting. I'm going to re-tag it. There's a difference between an article's readability and whether it contains useful information. In other words, just because a novice doesn't understand it, doesn't mean that it's useless. You're not the first person to fear what they don't understand.

--Mikiemike (talk) 23:56, 21 April 2008 (UTC)[reply]

Yeah, User:Jafet.vixle, where do you get off? This article intro is already tagged for "context". I shouldn't have to explain to you that tagged articles are "under construction". If you demand perfect quality, then do yourself a favor and don't read tagged articles!!

Why don't you try being part of the solution instead of part of the problem? I've done my fair share of clean-up on Wikipedia. Have you? I completely reject your conduct, your attitude and your conclusions. If you don't have anything useful to add, get lost. --Mikiemike (talk) 00:09, 22 April 2008 (UTC)[reply]

Yes, I definitely resent your comments. From your homepage, your main reason for being here seems to be to delete as many pages as you can, and you're not even following the guidelines you claim to reference. Well, you can forget about deleting this one, because all the other user comments have been positive. We have a consensus to keep it, and you have absolutely no good reason to delete it.

This article was in demand for a long time before it was created. I reviewed the article and it is all written in straightforward language. "Jargon" is a term used by pseudo-intellectuals like you to describe standard engineering words that you don't understand. If you can't read a simple graph & caption, then you have no business reading a scientific subject such as this.

A mainstream encyclopedia like Britannica wouldn't even have an article on this topic because it's too technical to explain easily. If you use a standard encyclopedia as a reference to establish a criteria for deletion, you're going to wrongly delete probably 90% of Wikipedia. To find anything info that's close to this informative, you'd have to go to a tech reference like McGraw-Hill, and there you will find plenty of graphs. So if you can't read a graph you have no business reading this article or commenting on how it should be written. In many ways this article improves on McGraw-Hill by going more in depth. Articles like this help make Wikipedia more complete than any other encyclopedia. To get better information, you'd have to do what I did which is to find books costing hundreds of dollars or drive hundreds of miles to find a library that has them and read hundreds of pages.

You obviously have no appreciation for what goes into this.

--Mikiemike (talk) 08:36, 22 April 2008 (UTC)[reply]

User:Mikiemike, I sign after all my comments, as do the most of us editors. Please be more careful who you are replying to in future. Also, I will counter your careless blasts of lambasting with my own suggestions to WP:AGF and be WP:CIVIL. ~ Jafet (spam) 07:21, 26 April 2008 (UTC) edited 08:53, 26 April 2008 (UTC)[reply]

User:Jafet.vixle, WP:AGF means to: "work from an assumption that most people are trying to help the project, not hurt it.". Your first message was the complete opposite of this. --Mikiemike (talk) 18:53, 26 April 2008 (UTC)[reply]

I believe working to remove information that does not seem to belong in Wikipedia would qualify as "trying to help the project". I have no problem with a good article; however allow me to list some problems I find with this one:

Unencyclopedic. The article, as far as I can see, is a series of charts and graphs and text to explain what they mean. It reads through like a textbook — if you want to write technical documentation on the how-to of engineering Stirling engines you might want to contribute it to Wikibooks instead, which is severely lacking in good material. The article fails to establish notability of its own subject matter. Are these charts and graphs actually used to build real engines? Who used them? What is the history of the research and development behind these figures? What are their significances?
Purposeless. The article wanders from one section to the other. There seems to be no attempt to join the sections into a cohesive article and explain their significance as a whole. This is bad prose style for an article, even though it may be suitable for another presentation medium.
Unverified. As stated before, the article fails to establish notability of what it says. References to several textbooks and course notes (or so it appears from the citations) may help validate the figures but little else. Now some references to some Foobar defense contractor using these figures for their designs, for instance, or some equation being refined over seven years in the deep dungeons of Bell Labs in the 1950s, would greatly help.
Technical. I am no card-carrying engineer but I can tell that this article is overly convoluted. The graphs are dumped into the article and given all the attention while there is little explanation as to what is going on overall. I will not object to the graphs provided that the article is well-balanced via the inclusion of other supporting material. There are too many scare quotes that actually mean very little to the outsider and too few explanation of terms, or even hyperlinks to related articles to build up a better overall picture of the subject. For example:

Most thermodynamic textbooks use a highly-simplified form of a Stirling cycle consisting of 4-processes. This is known as an "ideal Stirling cycle", because it is an "idealized" model, and not necessarily an optimized cycle. Theoretically, the "ideal cycle" does have high net work output per cycle. However, it is rarely used in practice, for practical reasons, in part because other cycles are simpler or reduce peak stresses on bearings and/or other components. For convenience, the designer may elect to use piston motions dictated by system dynamics, such as the mechanical linkage mechanisms. At any rate, the efficiency and cycle power are nearly as good as an actual implementation of the idealized case. A typical piston-crank or linkage in a so named "kinematic" design, often results in a near-sinusoidal piston motion. Some designs will cause the piston to "dwell" at either extreme of travel.

I may be wrong on some of these points for whatever reasons, but I hope you will get my point that the article needs to dress up whatever it has to say in a more encyclopedic manner. Otherwise, it does not belong in Wikipedia, and should at least be moved elsewhere.

This is in reply to your request that I be "more specific". So I have tried. ~ Jafet (spam) 04:11, 27 April 2008 (UTC)[reply]

All you had to say was that you wished the article could be in a more encyclopedic manner. Then I would've said "how so?", and asked for a link to WP guidelines. All the other bull is just clouding the issue you were trying to raise, and all the negativity and insults have just gotten in the way of that inevitability, by slowing down the process. I appreciate the response, but it seems this discussion might have been more verbose than it needed to be. --Mikiemike (talk) 06:47, 27 April 2008 (UTC)[reply]

This topic is welcomed and is here to stay

Some of this is helpful, but I have to say, "constructive criticism" goes a lot further than negative criticism. This article is barely 3 months old, and there haven't been a lot of contributers. So consider these too: WP:WIKIFY, WP:STUBS, WP:CINA. I guarantee this topic belongs in Wikipedia. Ask any contributor to the Stirling engines article. While you're there, ask them to verify the references. They know these authors. (also see previous discussion). We absolutely need some sort of article for this topic, and what's there now is better than nothing. Until 2008, there was nothing at all! Don't threaten to delete it, because that is not helpful, and it's personally offensive. As I said, there are a million other articles that are worse than this one, so I think you're being awfully harsh in your judgment. If you judged them all this harshly, you would end up deleting a significant portion of the articles. Try to understand that this is not an easy subject to cover. Be patient, because it takes time to edit and revise and make a good article. I have a feeling that part of what you dislike is the formatting. It might help to right-justify the images, but I'm not exactly an expert in formatting. It is engineering oriented. It may go to wikibooks, it's not entirely clear yet. But don't jump to conclusions so fast. First of all, below are some comparable topics to compare and contrast:

Rankine cycle - Some people start out with the engine, which might seem to help with the intuitive explanation, but this is technically incorrect, because the engine could be a turbine or a reciprocating piston. The "cycle" is short for "thermodynamic cycle". I'm telling you the category is thermodynamic cycles. So all of the engine context should really be subtext.

Ericsson cycle - Is mostly about the Ericsson engine. The only material about the actual cycle is what I added. BTW, there also was no image, I had to make that too. So you can see, it's a stub!

Brayton cycle - Needs organization. Needs to separate "cycle" from "engine". It uses center-justified graphs that show the cycle performance, but actually don't tell the reader much about the cycle itself. So in some ways, the Stirling cycle article is more pertinent to its topic. Note that what one reader considers excessively-technical another reader may consider informative. We go to the encyclopedia to get information and knowledge, so if someone does not want that anymore they will stop reading. So the process is self-regulating. You can't have too much information, only a lack of organization of information.

Carnot cycle - Here's a good one. You'd probably like it. Keep in mind however that this is the most famous, and probably the most popular cycle. The formatting is nice. The pictures are pretty and colorful, ooohhh, ahhh. It's also much easier to explain, because it is an ideal cycle. The 4 processes are discrete, which also makes it easier to walk the reader through it. This gives me an idea though. I can divide the PV curve into 4 pseudo-processes and describe them. Actually this would be easy since the graph is already marked. Anywho, the Carnot cycle article makes for a good template and/or guideline.

Carnot heat engine - I just touched it up a bit, and now the formatting looks better. The previous version was funky.

This article may need more background, context, clean up and formatting, but that's one thing. Saying that the content is bunk, is quite another. You may not like the technical style, but you didn't list a WP opposing it, and believe it or not, it is a sound explanation, and may be one of the best that's available on the web for what it is. In terms of content, the article is about a thermodynamic cycle, and this is what the images pertain to, so I don't really see why you think that's a problem. Maybe it is more of a book style, I may need to read more WP, and think about it more before I decide what it is and/or how to change it or how to deal with it. I don't doubt that the transitions and flow can be improved to make it more "cohesive", but this is a 3 month old stub, alright? Do you really want to understand the Stirling cycle? because if you didn't, then you wouldn't read it, so you wouldn't really care right? Take it from me, as someone who really does want to understand this cycle, that these images are gold, and they speak 1000 words. It's hard to get this level of truth in a more concise and accurate way. --Mikiemike (talk) 06:37, 27 April 2008 (UTC)[reply]

I found this article interesting. Maybe it can be improved but I think it would be a great loss for mankind if it was deleted. A cycle seems a little different than an engine, and also layering articles so that there is a nontechnical main article ie the sterling engine, with more technical articles as branch articles seems to me to be very helpful for the general welfare as it meets the needs of both those who want a non-technical explanation as well as those who want more indepth coverage.

Hobojaks (talk) 07:35, 30 December 2008 (UTC)[reply]

Redundant content moved from Stirling engine, possible re-use in this article

Stirling cycle thermodynamics

The idealized Stirling cycle consists of four thermodynamic processes acting on the working fluid:

Points 1 to 2, Isothermal Expansion. The expansion-space is heated externally, and the gas undergoes near-isothermal expansion.
Points 2 to 3, Constant-Volume (known as isometric or isochoric) heat-removal. The gas is passed through the regenerator, thus cooling the gas, and transferring heat to the regenerator for use in the next cycle.
Points 3 to 4, Isothermal Compression. The compression space is intercooled, so the gas undergoes near-isothermal compression.
Points 4 to 1, Constant-Volume (known as isometric or isochoric) heat-addition. The compressed air flows back through the regenerator and picks-up heat on the way to the heated expansion space.

This idealized Stirling cycle is commonly known as a "squared-cycle" ^{[citation needed]}, because when graphed on a Pressure-Volume plot, the rapid transitions between the processes produce a shape with corners. In a real Stirling engine, physical design constraints limit the net force on each engine component, and thus limit the maximum acceleration (or rate-of-change of velocity). Thus a real Stirling cycle in a Stirling engine requires relatively smooth motion, which is commonly sinusoidal or quasi-sinusoidal. In this case the shape of the PV-plot is quasi-elliptical. Also in a real engine cycle, the heat transfer performance of the heat exchangers ranges from 100% effectiveness in an isothermal process, to 0% effectiveness in an adiabatic process (no heat transfer). The compression and expansion processes can be modeled as a polytropic processes^[1]

PV^{n}=k\,\!

where k is constant, and n is bounded by:

1\leq n\leq {\frac {c_{p}}{c_{V}}}\leq 2

.

where ${c_{V}}$ is the specific heat capacity at constant volume (J/kgK) and ${c_{p}}$ is the specific heat capacity at constant pressure (J/kgK)

Compared to the idealized cycle, the efficiency of a real engine is reduced by irreversibilities, friction, and the loss of short-circuit conducted heat, so that the overall efficiency is often only about half of the ideal (Carnot) efficiency.^[2]

1. The working gas is heated at a constant volume to a higher temperature. This increases its pressure. (points 4 to 1 on the graph)	2. The working gas expands at a constant temperature to a larger volume. This decreases its pressure. The gas does work to move the piston up. (points 1 to 2 on the graph)	2a. The gas is now fully transferred to the cool cylinder. (Point 2 on the graph)
3. The working gas is cooled at constant volume to a lower temperature. This decreases its pressure. (Points 2 to 3 on the graph)	4. The working gas contracts at a constant temperature to a smaller volume. This increases its pressure. (Points 3 to 4 on the graph)The Piston does work to compress the gas as it moves down. But this is less than that delivered to the piston on cycle 2	4a. The gas is now fully transferred to the hot cylinder. (Point 4 on the graph)

--Wtshymanski (talk) 18:03, 25 August 2008 (UTC)[reply]

These above diagrams are great, they should be included; but would be even better if they showed a regenerator in the connecting tube. 86.22.79.205 (talk) 10:49, 3 February 2009 (UTC) djcmackay info - 12/31 - the diagrams are confusing. because, pistons are shown Fully bottomed-out. — Preceding unsigned comment added by 2601:1C1:8B00:3B10:5479:1F9C:76EA:212F (talk) 16:23, 31 December 2019 (UTC)[reply]

References

Suggestion to cut a small section

THis is a great article and was useful to me as a physics teacher. I suggest cutting the whole section about the topic's complexity. eg "The Stirling cycle is a highly advanced subject that has defied analysis by many experts for over 190 years. Highly advanced thermodynamics are required to describe the cycle." This is silly. To describe the cycle you just need 2 concepts (1) isothermal expansion/compression; (2) heat exchanger. Yes, there have been people who did not understand this, but it is not highly advanced

I reply:

Maybe this is the place to say that the above passage is emphatically correct!

Yes, isothermal compression at the lowest-possible temperature; and isothermal expansion at the highest-possible temperature will obviously give optimal efficiency.

...with storage and re-use of heat, to reduce need for the use of heat-source & heat-sink.

That's all that's needed to tell the purpose, principle & intent of the Stirling. That's what the introduction to the Stirling-Cycle should say, at the outset, at the very top of the Stirling-Cycle article.

Do real Stirlings achieve the ideal cycle? Of course not. That's why it's called "ideal". But if Robert Stirling had an approach or approximation to the ideal Stirling-Cycle as his goal or model, let's not forget that it resulted in the most efficient heat-engine. And no, the above is all that's necessary to explain the optimality of the Stirling-Cycle. No need to bring up entropy or reversability. (...though such matters are of course relevant for engineers, and may have a valid place farther down in the article, in a special section for engineering-topics for those interested.)

, and does not defy analysis. 86.22.79.205 (talk) 10:49, 3 February 2009 (UTC) djcmackay[reply]

I agree that saying this cycle "defies analysis" is patently silly. Its not a highly advanced, and the analysis is pretty straightfoward once you get down to it.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:47, 3 February 2009 (UTC)[reply]

Ha ha ha ha ha, no way!!! "Isothermal expansion/compression" is actually a terrible model of a real Stirling cycle. At the very least you need an adiabatic model. See the Stirling cycle Course notes by Prof. Urieli, PhD. Read any book by A.J. Organ PhD, who has essentially devoted his career to this subject. Mikiemike (talk) 23:59, 11 February 2009 (UTC)[reply]

That may be true, but it is still pretty straightforward to perform the analysis of the cycle. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:00, 17 February 2009 (UTC)[reply]

Well, I think I just deleted above named section? Yes, It's not relevant to the article. We don't need Sterling heroes as it tried to establish, no offense to the named Professor who is a talented man!. No Wiki reader is helped by suggesting anything is "complex" Let them find it out themselves! /Rogerhq —Preceding unsigned comment added by Rogerhq (talk • contribs) 09:13, 31 May 2009 (UTC) And here is my signature, sorry for disturbing! --Rogerhq (talk) 08:47, 1 June 2009 (UTC)[reply]

Alpha, beta and gamma engines

What are these? 86.3.108.41 (talk) 13:03, 1 October 2011 (UTC) is this what you're asking? these facts Should be in the article. somewhere. idk if they are.[reply]

alpha was the First design. beta the second. gamma the third. these are their distinguishing features - alpha uses a common crank and the simplest linkage; engine timing is defined by the perpendicular orientation, of the 'sides';

I reply:

Engine-timing consists of the hot-cylinder being 90 degrees ahead of the cold-cylinder. That can be done by having them both on the same crank, and being oriented 90 degrees apart. But it can also consist of their being side-by-side, using different cranks on the same crankshaft, with those 2 cranks being 90 degrees apart.

It should be emphasized that the Beta & Gamma use a completely different principle of mechanical-operation, and manner of operation on the working-fluid, in comparison to the Alpha. That's the significant difference.

Beta & Gamma differ from eachother by the Gamma not bring co-linear, thereby not needing coaxial connecting rods.

But that's a matter for the Stirling-Engine article, not the Stirling-Cycle article.

 beta is co-linear and relatively more compact.  the compactness of the design comes at a cost.  in a too-compact heat engine, it is more difficult to maintain the required temperature difference, between the sides&

I comment:

Beta & Gamma attempt dual-use of certain spaces (the cold space; and the space between displacer & cylinder-wall, or through the displacer or its regenerator-passage(s) ), for both temperature-exchange and for gas movement ...resulting in some unintended temperature-exchange detrimental to efficiency.

gamma, the sides are physically parallel, timing defined by a crankshaft. because alpha and gamma configs readily allow maximum thermal isolation of the sides, they are preferable to beta.

I comment:

It's said that Gamma is less efficient than Beta, due to inevitable added dead-volume. Someone who collects and sells Stirlings says that, all else being equal, Gamma tends to be less powerful than Beta in his experience.

unfortunately, this article has lots of issues. cheers — Preceding unsigned comment added by 2601:1C1:8B00:3B10:5479:1F9C:76EA:212F (talk) 16:19, 31 December 2019 (UTC)[reply]

Adiabatic vs. Idealized cycles

This article states that there is a difference between the idealized and adiabatic stirling cycles. It even outlines each of the four general steps in the cycle, for each of the idealized and adiabatic. However, there is nothing different about their descriptions whatsoever:

Idealized:

Isothermal expansion. The expansion space is heated externally, and the gas undergoes near-isothermal expansion.

Constant-volume (known as isovolumetric or isochoric) heat removal. The gas is passed through the regenerator, thus cooling the gas, and transferring heat to the regenerator for use in the next cycle.

Isothermal compression. The compression space is intercooled, so the gas undergoes near-isothermal compression.

Constant-volume heat addition. The compressed air flows back through the regenerator and picks up heat on the way to the heated expansion space.

Adiabatic:

180° to 270°, pseudo-isothermal expansion. The expansion space is heated externally, and the gas undergoes near-isothermal expansion.

270° to 0°, near-constant-volume (or near-isometric or isochoric) heat removal. The gas is passed through the regenerator, thus cooling the gas, and transferring heat to the regenerator for use in the next cycle.

0° to 90°, pseudo-isothermal compression. The compression space is intercooled, so the gas undergoes near-isothermal compression.

90° to 180°, near-constant-volume (near-isometric or isochoric) heat addition. The compressed air flows back through the regenerator and picks up heat on the way to the heated expansion space.

I recognize that the qualifiers before each description have changed; nonetheless, the descriptions of each phase of the cycle themselves are literally copied from one cycle to the other.

I reply:

Yes, the description of the ideal-cycle is obviously incorrect. In the genuine ideal-cycle, the compression and expansion aren't "nearly isothermal". They're isothermal.

How is this useful in any way? This article would have one believe that exactly the same physical process happens during each phase of either type of cycle, but for some reason the two cycles are different. Could this be addressed somehow? — Preceding unsigned comment added by Phruizler (talk • contribs) 03:16, 15 February 2013 (UTC)[reply]

The "Volume Variations" section contains debate and says nothing that's correct.

(Wikipedia articles aren't supposed to contain argument and disagreements between editors. They aren't a space for debate. What would you think if different paragraphs of a Brittanica article called eachother wrong? If someone said something that you feel is wrong, this talk page is the place to object to it. But of course don't delete, without disussion here, what someone else has put up.)

<quote> In beta and gamma engines, generally the phase angle difference between the piston motions is not the same as the phase angle of the volume variations. </quote>

But does the article say otherwise? No.

The Beta & Gamma engines don't have two pistons. They have only one piston, and one displacer. Typically the displacer is 90 degrees ahead of the piston.

But what are the two volumes whose variations' phase-difference you're speaking of? There's only one volume whose variation is of interfest: the volume of the air (or other working-fluid gas) contained in the engine.

<quote> However, in the alpha Stirling, they are the same. </quote>

See above.

<quote> The rest of the article assumes sinusoidal volume variations </quote>

The article says nothing about sinusoidal volume variations.

<quote> caveat: Among the many inaccuracies in this article, a co-linear alpha configuration is referenced , above. </quote>

The previous part of the article doesn't mention a co-linear Alpha configuration.

<quote> Such a configuration would be beta. </quote>

No, a co-linear or opposed-pistons Alpha Stirling engine wouldn't be a Beta. It would be a co-linear or opposed-pistons Alpha. The difference between the Alpha and Beta configurations consists of more than the Beta's co-linearity.

<quote> Alternatively, it would be an alpha, that has an unacceptably inefficient linkage system. </quote>

To make that claim in the article (which you did), you'd need to cite a source, or at least give a justification.

I don't like or want to delete what someone else has put up. But the article isn't the place to discuss your opinion, or make unsupported claims, or to have debate.

So I'm asking you to delete that section of the article--the section that I answered in this post. If you don't delete it, someone else will, because there's nothing true in it (The article is a place to write only what you can support, or cite a reputable or notable source for.) ...and because disagreements should be discussed at this talk-page, not debated in the article.

If you don't delete it, I'll give others a chance to. Then, after about a month, if no one has deleted it, I'll post, in the article, this statement-by-statement reply to your claims (...with an invitation for someone to delete that debate, because debate doesn't belong in an article). Then, after an additional month, if no one has deleted that debate in the article, I will.

[1] David Haywood: An introduction to Stirling-cycle machines (pdf)

[2] Israel Urieli (Dr. Iz), Associate Professor Mechanical Engineering: Stirling Cycle Machine Analysis

[1]

[2]