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This is an old revision of this page, as edited by Omblauman (talk | contribs) at 20:59, 20 May 2016 (→‎Alpha configuration). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

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Splitting section out

The article is now nearly 80k, so I reckon we should think about moving to a more summary-style layout and splitting sections out to dedicated articles. A good start would be the Applications section, which currently take up about the third of the article length, is pretty standalone, and would be given room to grow in a dedicated article. Thoughts? Chris Cunningham (not at work) - talk 13:40, 16 April 2009 (UTC)[reply]

Agreed, but probably for the wrong reasons. As I indicated in the 'Tags' thread above, I feel that the standard of the article falls off somewhat from section 4.2 onwards, so splitting off some of this material will a)stop it detracting from the 'good bits' and b)may be a trigger for improvement of the new sub-articles. I guess the key is getting the summery in the main article rightPv=mrt (talk) 12:26, 21 April 2009 (UTC)[reply]
As a non-expert, both in engines and Wikipedia editing, I'd like to see the "Applications" section stand, but keep the sction to the summary approach, so that both detailed or obscure material can be dealt with in dedicated articles (the possible use in moon colonies, for example, could be noted in one brief sentence, and a separate article if required would explain how, the pros and cons etc.) [Bruce, 31 May 2009]

Personally I don't think that splitting this is necessary. I've got a pretty archaic internet connection and 80k was completely manageable and internet gets faster every day it seems like. Almost every technology based wiki-page has an "Applications" subheading and I think it is very useful to have that information right there on the same page, particularly when talking about the Stirling engine since it's use may be making a comeback with hybrid technology. —Preceding unsigned comment added by 216.67.79.156 (talk) 22:06, 22 June 2010 (UTC)[reply]

Low temperature differential Stirling engine

Although it's not strictly a "type", with a Low temperature differential Stirling engine (LTD Striling), the pistons are made allot wider. See http://ir.canterbury.ac.nz/bitstream/10092/2916/1/thesis_fulltext.pdf —Preceding unsigned comment added by 81.242.234.187 (talk) 11:13, 2 March 2011 (UTC)[reply]

Nice try on the link, but it comes back bad... TREKphiler any time you're ready, Uhura 18:50, 2 March 2011 (UTC)[reply]
"The pistons" are not a lot wider - only the displacer piston is wider. Andy Dingley (talk) 01:35, 3 March 2011 (UTC)[reply]

Since it matters, the formulas to calculate the width of the pistons would be useful. Thank you. Andrew Swallow (talk) 13:48, 3 March 2011 (UTC)[reply]

Reference to be added; comment about regenerator

I suggest adding another reference to the Bibliography:

C.D. West, "Principles and Applications of Stirling Engines", Van Nostrand Reinhold, NY, 1986

Also:

In Allen J. Organ's book, "The Regenerator and the Stirling Engine", he presents a case as to the importance of the regenerator, which adds to the efficiency of the Stirling engine by recovering a portion of the waste heat. This reduces the need for both cooling and reheating the working fluid, increasing work efficiency. However, the downside of the book is that it is densly mathematical in its presentation, and the specific benefits of various regenerator concepts is not readily understandable.

One thing that the various graphics on the main Stirling engine page do not have, is the regenerator itself. It is not quite clear in Organ's book how the regenerator is sized, although there seems to be a sequence of calculations designed to do this.

In addition, Organ's book develops the idea of scaling a Stirling engine design by Similarity, as a way of sizing the various components in the engine. — Preceding unsigned comment added by John Fornaro (talk • contribs) 18:19, 12 April 2011 (UTC)[reply]

In addition to the graphics, the text in the abstract of the main Stirling engine page also does not include the regenerator. Down in the regenerator section, a distinct regenerator is identified as a distinguishing characteristic of a Sterling engine, so it would seem important enough to deserve mention in the initial description. The third paragraph discusses the cycle and it's efficiency, and would be a logical place to incorporate a reference to the regenerator..Dave b10 (talk) 19:16, 21 October 2011 (UTC)[reply]

combined heat and electric power

an ideal application is completely ignored. an SE could be part of an industrial water heater.Tthe cold sink of the sterling could be a preheat tank. CorvetteZ51 (talk) 03:50, 30 June 2011 (UTC)[reply]

theoretical efficiency

The article says (2100/11/21) "Theoretical thermal efficiency equals that of the hypothetical Carnot cycle". My understanding is that the Carnot cycle is for operation between 2 adiabats and 2 isotherms. The isochors of the ideal Stirling engine aren't adiabats: there is heat transfer on portions 4 and 2 of the cycle (see the pressure-volume graph at the "Theory" section). In the formula for efficiency, e = (work out)/(heat in), this extra heat lowers the theoretical efficiency. That is, in the Carnot engine there is heat transfer only along the isotherms, none along the adiabats. In the Stirling engine, there is heat transfer along the isotherms plus Q at constant volume = (# of moles)(molar specific heat at constant volume)(temperature difference) Is the claim that the heat in along portion 4 is of the same magnitude as the heat out along portion 2? Kinzele (talk) 16:20, 21 November 2011 (UTC)[reply]

DEKA's contribution

DEKA Research has been working to improve the performance of low-cost Stirling engines. Has this firm made any significant contributions to the field? If so, it deserves a mention in this article. 71.221.121.78 (talk) 04:51, 28 November 2011 (UTC)[reply]

Other gases

In his Stirling cycle engine experiments, the late professor D.H.Chaddock OBE had some success using CO2 as a gas medium. As this gas has been used in gas cooled nuclear reactors it seems a viable suggestion.AT Kunene (talk) 07:03, 13 February 2012 (UTC)[reply]

Animated GIF is faulty, please fix

The Animated GIF jumps between cycles on the page can somebody fix this? it is very disturbing as it fails to show the complete cycle.Cheers Read-write-services (talk) 04:47, 16 February 2012 (UTC)[reply]

Hybrid applications

Stirlings are ideal for hybrid applictions where they only charge batteries or a hydraulic accumulator. The downside of cheap Stirlings to an IC engine is then irrelevant. Instant power and starting is not needed.194.83.172.121 (talk) 10:54, 18 May 2012 (UTC)[reply]

Downsides of Stirlings Misrepresented

Downside is larger size for equal power top an IC engine. Greater weight as well. The slow starting has been overcome, and the sluggish power delivery

But!!! A Stirling may be larger and weightier than an IC for the same HP, but the torque delivery means it needs no power sapping and weighty stepped gears transmission, negating the disadvantage in real vehicle installations. When in a direct drive configuration of course, which the auto industry is slowly moving away from with hybrids.194.83.172.121 (talk) 10:53, 18 May 2012 (UTC)[reply]

Counter-Rotating Ring Receiver Reactor Recuperator

Counter-Rotating Ring Receiver Reactor Recuperator has been mentioned in the see also section. This as it has been mentioned as a thermochemical analog to Stirling and Ericsson cycle heat engines[1][2] — Preceding unsigned comment added by 91.182.179.185 (talk) 08:14, 6 September 2012 (UTC)[reply]

I have removed it because current WP style does not have red links in the "see also" section. HumphreyW (talk) 11:00, 6 September 2012 (UTC)[reply]

Free piston Stirling engine operation

I have tried to understand how the Free piston Stirling engine works but the textual description is not self sufficient. It really needs a notated diagram, or sequence of diagrams, linked to the steps of the description. Roly (talk) 12:23, 5 October 2012 (UTC)[reply]

thesis statment

The technical explanation was exemplary, but I pity the non-technical person trying to figure out how this engine differs from, say, an auto engine. It's sometimes hard for a technical person to simplify at the beginning and not reflexively use technical jargon in an initial explanation, but doing so in this article would increase its value a lot. Pb8bije6a7b6a3w (talk) 14:30, 27 November 2012 (UTC)[reply]


Hot to cold cylinder ratio

The relative sizes of the hot and cold cylinders appears to be important. Could the equations or ratios be added? Andrew Swallow (talk) 17:35, 28 August 2013 (UTC)[reply]

The Battle Of Danzig - Corridor IC - Germania Rested.

'n' pairs of pistons at a given phase difference can be arranged with interconnecting exhausts and temperature variants. this does not constitute a unique engine.


engine cycle postulates:

spark for fuel-air is assumed to drive the isochoric power stroke.

fuel injector for compression reciprocating is assumed to drive the isobaric power stroke.


the case closest to that of an isobaric-isochoric system, if achieved - will be efficient.

ASG

117.238.252.143 (talk) —Preceding undated comment added 08:34, 15 September 2013 (UTC)[reply]

Efficiency

This article states that the "theoretical thermal efficiency [of the Stirling engine] equals that of the hypothetical Carnot cycle". Yet other sources, such as here, state otherwise. Is this an error? Arbitrarily0 (talk) 23:53, 24 September 2013 (UTC)[reply]

Thermoacoustic cycle

Though it is not the main topic of the article, I found the paragraph about the "Thermoacoustic cycle" intriguing. But I think a sentence is probably imprecise, that is "High-amplitude acoustic standing waves cause compression and expansion analogous to a Stirling power piston". I don't think standing waves play a role in the compression phase here. They should be limited to expansion (piston out). Then air loses energy, cools down and the piston is brought back. In other words, the temperature difference at one end of the cylinder originates a (imprecise) standing wave which is corrected and amplified in the resonator and once powerful enough it can strike the piston. The returning low-power (standing) wave pushes air through the cold heat exchanger where it experiences a small pressure drop, gives off heat and its volume is reduced so that the piston can move back... 

 — Preceding unsigned comment added by 79.31.206.129 (talk) 17:45, 12 March 2015 (UTC)[reply]

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Alpha configuration

I believe the alpha configuration should not be featured so prominently in the description of the working of Stirling engines for multiple reasons: 1) is not the traditional one, Robert Stirling always built Beta/Gammas if I understand it right. 2) it's very little featured among the commercial models, in fact I couldn't find one. 3) even from a theoretical standpoint an alpha configuration seems very unattractive, for example its two cylinders, as working cylinders, are equivalent to one with intermediate phase and cross section only square root of two bigger than one of the two, the swept and work displacements are the same, and more. The really generic configuration of a Stirling engine is the gamma, of which the beta is a special case with added constraints and alpha is another one with more constraints and so many drawbacks that almost nobody employs it. Discussing with friends, learning about the engine for the first time, I have noticed that they all struggle to understand it taking the alpha as a paradigm. Using the gamma is a lot easier. I propose to change the article to reflect this but please comment I am not an expert, just a reader. — Preceding unsigned comment added by 82.56.177.242 (talk) 08:04, 17 May 2016 (UTC)[reply]

I've never come across an Alpha configuration engine but I haven't really been looking. I agree, if they exist, they are pretty rare. However, the configuration is probably not as unattractive as the drawing would imply. The drawing shows the two cylinders operating on a common crank. This illustrates the principal clearly. In practice, though, if one was being made, it would probably have two separate cranks, set at 90 degrees to each other, with the cylinders mounted parallel to each other. The important characteristic of the alpha configuration is that there are separate hot and cold cylinders acting on the crankshaft in 90 degrees phase to each other. In terms of power/weight ratio, it would probably be less efficient than the beta or gamma configurations, but it has the advantage of simplicity and, hence, reliability. Another advantage is the fact that, the hot and cold parts being completely separated, thermal insulation between the two can be much better. Power/weight ratio is not one of the Stirling engine's big advantages, anyway. --Roly (talk) 08:51, 17 May 2016 (UTC)[reply]

What has to be at 90 degrees for effectiveness in a sinusoidal engine are not the two cylinder movements but the pressure and volume variations which is achieved with a work cylinder separate from the displacer. By sharing the two functions necessary for an engine to work between the two cylinders it makes unnecessary and inefficient compromises . The 2 functions are the one of extracting mechanical energy from the engine via the work cylinder and the one of heating and cooling the fluid, the task of the displacer in the other configurations. You must agree that for the first function the two cylinders are equivalent to one whose cross section is √2 of the cross-sections of the individual cylinders and whose phase is 45 deg from each one of the two. It's a consequence of the two pistons being connected at the same crankshaft and being exposed always to the same pressure. It can be seen more clearly imagining to increase continuously the relative phase between the two equal cylinders from 0 to 180: at 0 the 2 cylinders are in phase and equivalent to one twice the cross-section and at 180 they don't do any work on the gas, the gas volume remains unchanged in time at the turn of the crankshaft. The situation changes smoothly going from one extreme to the other and 90 deg is right in between. This has serious consequences: 2 pistons instead of one, more friction losses, a rigid phase delay of the wrong amount. There are many other drawbacks of the alpha, which is why you never see it: a rigid ratio between swept work volume to displaced volume, potential overheating of the seals of the hot cylinder, just to name two. On the other side in the gamma configuration, of which from this perspective the betas are a subset, shuffling the gas around and extracting work are decoupled functions being performed by separate devices, the piston and the displacer. All the previously mentioned issues disappear. — Preceding unsigned comment added by 82.56.177.242 (talk) 13:09, 20 May 2016 (UTC)[reply]

  • Alphas are rare because most Stirlings are low power toys and at that scale a displacer is easier to make work than a static regenerator.
The important point, and why they still deserve prominence, is because they're how Stirling first conceived the engine - using a regenerator. This should be explained in a history section. We also need a better image. The impression here is that "An Alfa [sic] is anything at 90º", which is both wrong in itself (it's regenerator not displacer which matters) and it also leads to confusion with a Gamma. By phasing the crankpins you can make either of these as either parallel or V engines.
I would agree though that an explanation of the basic principle probably starts most simply with a Gamma, as does a description of available engines today. Andy Dingley (talk) 09:21, 17 May 2016 (UTC)[reply]

I believe the issue of the regenerator is an independent issue, it can be present or absent in all configurations. It's true that toy engines are rarely alphas but that's because alphas can't have a large swept volume compared to the work piston swept volume. At low temperature differences it is practically a requirement. Look at LTD engines, toys or otherwise. As far as the alpha being the way Stirling conceived the engine I don't think so, look at the original patent, it's a beta, that is a gamma with a displacer the same cross section of the work cylinder http://www.stirlingengines.org.uk/pioneers/pion2.html 82.56.177.242 (talk) 13:52, 20 May 2016 (UTC)[reply]

  1. ^ [http://www.sandia.gov/mission/ste/stories/2008/August/Millerfinal.pdf Sunshine-to-Petrol project reference 1
  2. ^ [http://energy.sandia.gov/wp/wp-content/gallery/uploads/S2P_SAND2009-5796P.pdf Sunshine-to-Petrol project reference 2
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