Talk:Adiabatic process

message: I made several changes to the article, and more may be needed. In order of appearance on the page:
1) Paragraph 3 previously stated: 
"...A transformation of a thermodynamic system can be considered adiabatic when it is quick enough that no significant heat is transferred between the system and the outside. The adiabatic process can also be called quasi-static..."
The second sentence is confusing or simply incorrect; a quasi-static process is one in which all states can effectively be considered equilibrium states (see quasi-static), which seems to apply better to a case when the gas does come into thermal equilibrium with the outside of the system. Although a quasi-static assumption may be necessary for a reversible process (don't know this for sure), it is certainly not necessary for an adiabatic process (e.g., a rapid, irreversible gas expansion where inertial effects are important). I have removed it to avoid confusion.
2a) In the "Adiabatic Heating and Cooling" section, Paragraph 2 previously stated:
Adiabatic cooling occurs when the pressure of a substance is decreased, such as when it expands into a larger volume.  An example of this is when the air is released from a pneumatic tire; the outlet air will be noticeably cooler than the tire.
The phrase "such as when it expands into a larger volume" suggests a gas flowing into a larger volume or reservoir, which is incorrect. The spirit of the sentence is that gas increasing in volume undergoes adiabatic cooling, but this is ambigious in the original wording. I have replaced it with "...the pressure of a substance is decreased as it does work on its surroundings," which is closer to the reality. However, this still doesn't mention a volume increase, which would be nice to have (i.e., an explanation of the fact that a gas increasing in volume and thus decreasing in pressure--or vice versa--does work on its environment, and thus cools).
You failed to note refrigeration and industrial air compression.  
Heat becomes a real problem in pneumatic systems, requiring intercoolers on two and three stage machines over about 10 HP.  It would be simpler and clearer to note that all gasses (except Bose Einstein condensates at 0 K) contain heat.  Compressing the gas increases the temperature.  Draw off air and the tank -- and the tool -- both cool down considerably.  
You also failed to note precipitation.  ALL adiabatic (as compared to isothermal) compressor systems precipitate water, dust, CO, CO2, and other materials from atmospheric air.  Linde's Principle states that gas will not liquefy until it reaches the Linde Limit.  Pressurize air sufficiently, cool the compressed gasses enough, and the gasses will condense to liquids, one at a time.  Pardon me if I defer to release proprietary information.  
The primary use for adiabatic technology is refrigeration.  Condenser units pressurize refrigerant, run air (or with chilled water systems, water) over the coils, pulling heat from the refrigerated space.  Reverse the process (by valving) and we suddenly have the normal home heat pump.    —Preceding unsigned comment added by 209.244.31.59 (talk) 20:24, 17 April 2008 (UTC)
thread_title:  Accuracy Dispute & Changes, 2008-03-26 

message: can you help me with a continental or global scal in the atmosphere and a local or regional scale
Continental or Global scale would be the Hadley cell and a local or regional scale would be sea and land breezes.
Hope this helps!
Perhaps articles like Joule-Thomson effect should be considered as relevant to the topic. --Saperaud 08:04, 22 December 2005 (UTC)
thread_title:  Continental and local scale 

message: I edited the section on adiabatic heating/cooling.  The "coolness" felt when pursing one's lips and blowing on one's own skin is due almost entirely to enhanced convective heat transfer; the actual air temperature drop is so small (due to the tiny pressure drop involved) that if one blows on a thermometer in this manner, there will be a negligible temperature change. 
I instead offered the different example of deflating a tire, where the pressure drop is on the order of several hundred KPa (several dosen psi);  I have seen frost form on valve stems because of this.
Also added the more extreme heating example of a motorized air compressor operating at higher pressures than a bicycle pump.
Joe Frickin Friday 17:54, 30 January 2006 (UTC)
thread_title:  Edit, 2006/01/30 

message: I fully realize that the Greek letter gamma ({\gamma}) is used by physicists and others as the symbol representing the ratio of specific heat at constant pressure to the specific heat at constant volume.  However, I would like to point out that thousands of engineers worldwide use a lowercase k to represent that ratio. 
I strongly believe that this article should mention that fact. mbeychok 00:10, 1 March 2006 (UTC)
thread_title:  Symbol for the ratio of specific heats 

message: The derivation of TV^gamma-1 is a lot longer than the one in my physics text book (Young & Friedman 11th ed.) and doesn't explain what Cv is. I'd fix this myself, but my mathML sucks. 75.5.254.164 00:51, 11 December 2006 (UTC)
thread_title:  Derivation of TV^gamma-1 

message: Fountain Powerboats of Washington NC claims to have created an adiabatic internal combustion engine based upon a marinized Chevrolet engine. Though the project has not proven publicly it is really an adiabatic cycle engine it has demonstrated extreme power production. Anyone care to propose how this would work?
Jsmithnc 20:25, 13 August 2007 (UTC)
replies: text: Sounds exciting to buy shares, before gets noticed. 84.227.255.16 (talk) 09:05, 16 September 2014 (UTC)
thread_title:  Adiabatic Internal combustion Engine 

message: E.g. if an isolated system undergoes a rapid change leading to entropy production, then that is not an adiabatic change. At least not in theoretical physics (I'm not sure about engineering or chemistry, they  often teach physics in a flawed way) :)
In practice, it may well be the case that systems undergoing a rapid change are closer to the ideal adiabatic process than systems that change slowly, because in practice the heat transfer issue may be more important than entropy production. But one always has to explain things from the fundamentals and then explain how it is (approximately)realized in real world phenomena.
This article also fails to mention the Adiabatic theorem of quantum mechanics, which is absolutely fundamental to this topic.  Count Iblis (talk) 17:58, 30 April 2008 (UTC)
thread_title:  No heat being transferred is necessary but not sufficient 

message: the P-V diagram is useless without labels. both axes and isolines should be labeled, right now it just looks like modern art. 141.211.231.47 (talk) 00:18, 8 November 2008 (UTC)
replies: text: Each thermodynamic cycle can be split into separated to multiple thermodynamic processes, with an adiabatic process being just one of several types of thermodynamic processes.siNkarma86—Expert Sectioneer of Wikipedia86 = 19+9+14 + karma = 19+9+14 + talk 22:48, 16 September 2011 (UTC)
thread_title:  plot 

message: The article describes case of ideal gas; there is no information about real gases or liquids. Consider the following problem, for instance:
Temperature of water in ocean is 12oC, and temperature coefficient of expansion \alpha is equal to 9.2*10-5 K-1. Some water moves from the surface to the bottom (1km under surface) quickly (thus, it doesn't exchange heat with other water). Find the approximate change of its temperature.
Wikiwide (talk) 23:46, 13 April 2009 (UTC)
thread_title:  Adiabatic process in liquid (for instance, water) 

message: While reading the article I've seen a few lines that look eerily familiar.  At the same time some of the derivations are literally straight out of a textbook.  I'll be the first to admit that a derivation is a derivation so I highly doubt that those are clear indicators, but the article really does read like it may have been copied out of one or many textbooks.
At the moment I cannot substantiate this claim, but I think it warrants some research.  If in fact the article is copied word for word we should be careful not to delete the page wholesale but salvage the bits of it that are legitimate, namely the derivations and equations which, as far as I know, cannot be copy-written. 
DacodaNelson (talk) 03:08, 16 April 2011 (UTC)
replies: text: "If in fact the article is copied word for word we should be careful not to delete the page wholesale but salvage the bits of it that are legitimate, namely the derivations and equations which, as far as I know, cannot be copy-written." When will the world realize that there are only so many ways to say something concisely? We will reach a point where certain small points are off-limits to a free encyclopedia simply because copy-written material has all but exhausted every way of making a point that doesn't waste the reader's time.siNkarma86—Expert Sectioneer of Wikipedia86 = 19+9+14 + karma = 19+9+14 + talk 22:04, 16 September 2011 (UTC)
replies: text: I agree with the sentiment but I'm confident the remixers will win. Some will even go on to found billion-dollar companies. 84.227.255.16 (talk) 08:53, 16 September 2014 (UTC)
thread_title: Possible Plagiarism

message: An adiabatic process must involve both no heat transfer with the surroundings (adiathermal) AND it must be reversible. See "Concepts in Thermal Physics" by Blundell and Blundell.  — Preceding unsigned comment added by 92.21.105.198 (talk) 21:28, 4 December 2011 (UTC)
replies: text: I agree that some textbooks define it that way, but many don't. In theoretical physics, one would rather not define adiabatic to be also (potentially) an irreversible process (because that would bring it in conflict with another notion of "adiabatic" used in physics). But in engineering it is common to use "adiabatic" also for irreversible processes. I think in the book by Reif a comment is made about this, and Reif prefers not to use the word "adiabatic" at all to avoid confusion. Count Iblis (talk) 22:29, 4 December 2011 (UTC)
thread_title: Just wrong

message: Could someone explain the relation to adiabatic theorem. One says that family of differential equations $L(x',x,t,p)=0$ parametrized by parameter $p$ satisfies adiabatic theorem, if denoting solutions of $L(x',x,t,p)=0$ by $x(t,p)$, one has $x(t,p(t))$ are close to the solutions of $L(x',x,t,p(t))=0$, if dependence of 
$p(t)$ is "slow" (derivative is small). I know, that Hamiltonian dynamics satisfies adiabatic theorem, but relation to heat transfer eludes me. Slava Matveev. 194.94.96.194 (talk) 14:00, 10 December 2012 (UTC)
thread_title:  Relation to adiabatic theorem 

message: Three-fourths down this thread it is stated "Substituting γ=(α+2)/α" that seems incorrect. Should it not be "Substituting γ=(α+1)/α" ? If so, the following derivation may need updating.  — Preceding unsigned comment added by 76.242.181.95 (talk) 17:01, 12 May 2013 (UTC)
thread_title:  Needs a correction.... 

message: How is the equation of the adiabatic pV^gamma derived? From what starting point? Is it necessary to involve Mayer's relation in the derivation?--188.26.22.131 (talk) 12:58, 11 July 2014 (UTC)
thread_title:  Equation derivation 

message: Editor Zedshort's latest edit to this article on the adiabatic process contains errors in physics. He is making it up off the top of his head as he goes along. Still, I think it can often be better not to reward such editing by trying repeatedly to revise it.Chjoaygame (talk) 22:06, 3 November 2014 (UTC)
thread_title:  latest edit by [[User:Zedshort]] 

message: The other extreme kind of work is isochoric work (dV = 0), for which energy is added as work solely through friction or viscous dissipation within the system.
In the isochoric case, couldn't there be other entropy-producing mechanisms, such as electrical resistance, etc. ? Also, the phrasing gives the impression that "isochoric" requires entropy production. Actually, you could do nothing at all, and it would still be isochoric.
The other extreme kind of work in an adiabatic process is work that flows only into entropy production (through friction or viscous dissipation, etc) but leaves the volume unchanged (an isochoric process).
Besides leaving the list of mechanisms open, this puts the emphasis on the entropy production and fixed volume rather than the terminology.
I also noticed this sentence:
Hence, the expression "isochoric work", is used to describe irreversible work.
Again, this gives the impression that isochoric is a synonym for irreversible, or that an irreversible process is necessarily isochoric. If this is the case, then the article isochoric is misleading: there it states that isochoric means there is no change in volume. 
Or perhaps the total work input breaks up into "reversible" and "irreversible" parts, the latter also being called "isochoric work"? I saw this in Kittel and Kroemer. This actually makes sense. Of course the descriptors don't attach to individual energy blobs, but as a summary number about the part of the work you can recover when you move the state variables reversibly back to their original positions, it's well-defined. Does the given citation support this?
If this is the case, how about:
Hence, the expression "isochoric work", is used to describe the portion of the work done on the system that cannot be recovered ("irreversible work"), even in situations where dV≠0 (the process is not "isochoric" in the sense of unchanging volume.
Or another alternative:
Any work done on the system during an adiabatic, isochoric process is unrecoverable, as there are no places left (meaning system variables besides entropy and temperature) where the work energy can go to be stored.
But this is shorter:
Hence, the expression "isochoric work", has come to be used to describe the portion of the total work that is lost as "irreversible work".
89.217.4.12 (talk) 12:17, 14 March 2015 (UTC)
thread_title:  Characterization of isochoric 

message: In this long section, the relation between T and V for adiabatic heating and cooling is derived.
It seems that this derivation repeats much of the same work as was done to find the relation between P and V in a previous section. The new derivation uses the P-V relation, actually twice, and also the ideal gas law, as well as the fact that U is proportional to T, and in the end it seems somewhat circular.
Yet if one simply substitutes the ideal gas law in the P-V relation, the T-V derivation falls out immediately. I included this as a new section.
I don't see what the section entitled "Derivation of discrete formula" contributes. Shouldn't it be deleted?
89.217.4.12 (talk) 17:19, 14 March 2015 (UTC)
thread_title:  What is the purpose of the section "Derivation of discrete formula" ? 

message: Here I have edited the first sentence of the lead, for the following reason.
The sentence that I overwrote was a near quote from a textbook that was cited, but the quote was misleading. The textbook, like most, was considering heat and work as an introduction to thermodynamics, without matter transfer. In particular, this text had written on its page 28: "In the rest of this chapter we shall confine our attention to systems consisting of specified matter, that is, to control masses. Energy, but not matter, can cross the boundary of such a system; the various mechanisms for this energy transfer are the main topic of this chapter." The sentence that I overwrote did not advise the reader of this presupposition of its definition, which was taken from page 48 of the text, some distance from the proviso of page 28.
The reader of the present Wikipedia article needs immediate and explicit notice that matter transfer is excluded from adiabatic transfer. Etymologically, adiabatic refers to passage without the explicit mention of heat or matter. Such exclusion of matter transfer is also left more or less implicit in most texts.
I did not retain the new citation because it is from a specialized, that is to say, engineering, text. Mostly, one does not put references in the lead, since the lead is largely an editorial summary. There are two references to the sentence that I put in, and they are sufficient, if not superfluous. They are to particularly important or authoritative sources.Chjoaygame (talk) 23:06, 23 October 2015 (UTC)
thread_title:  reason for edit 

message: Here I have made a second edit. The reason is that the sentence that I overwrote uses a special terminology, "control-mass type of analysis", used for example in the particular textbook that was cited for it, but not defined in the present article and not widely standard in thermodynamics. Though it may have great merit, the special term is not needed for the present purpose.Chjoaygame (talk) 23:17, 23 October 2015 (UTC)
thread_title:  reason for second edit 

message: Editor Zedshort has made two edits, here and here.
The first edit does not have an edit summary, no reason being given at that point for its change from
::::An adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings; energy is transferred only as work.
into
::::An adiabatic process is one that occurs without transfer of heat between a thermodynamic system and its surroundings. During an adiabatic process, energy is transferred only as work.
The substantial change made in this edit was to delete the usual statement on the adiabatic process, that it occurs in the absence of matter transfer.
The usual textbook account is in a chapter on closed systems, where closed systems are defined as those that do not transfer matter. It is not customary to repeat the definition of a closed system when the adiabatic process is being defined within a chapter on closed systems. It is usually left implicit as too obvious to need repetition. The newly edited version of the lead of present Wikipedia article gives the reader no notice of the key fact that that the adiabatic process is defined for a closed system. The result is that even as seasoned and much respected editor as Editor Dirac66 was able to express the possibility that perhaps it might be questioned whether an adiabatic process can include matter transfer, and asked for an explicit reference or two. So a new reader could be left in reasonable doubt. I provided an explicit reference, with an explicit verbatim quote "(adiabatic partitions inhibit the transfer of heat and mass)", in the body of the article, from Tisza, one of the very most careful and reliable authors on such questions. The explicit reference is given for the first sentence of the Description section of the article: "A process that does not involve the transfer of heat or matter into or out of a system, so that Q = 0, is called an adiabatic process, and such a system is said to be adiabatically isolated."Tisza, L. (1966). Generalized Thermodynamics, M.I.T Press, Cambridge MA: "(adiabatic partitions inhibit the transfer of heat and mass)", p. 48. The fact is at least implicit in every definition of the term, and depending on the degree of directness demanded, not far from explicit. Editor Zedshort does not dispute it but seems to think it complicates things to make it explicit, when in his next edit summary, and in a previous edit summary for the same change, he writes "keep it simple".
The second edit has an edit summary that says "no reference provided, not expanded upon in the article, keep it simple". It deletes the last sentence of the first paragraph of the lead
::::An adiabatic process is one that occurs without transfer of heat between a thermodynamic system and its surroundings. During an adiabatic process, energy is transferred only as work.Carathéodory, C. (1909). Untersuchungen über die Grundlagen der Thermodynamik, Mathematische Annalen, 67: 355–386, . A translation may be found here.  Also a mostly reliable translation is to be found at Kestin, J. (1976). The Second Law of Thermodynamics, Dowden, Hutchinson & Ross, Stroudsburg PA.Bailyn, M. (1994). A Survey of Thermodynamics, American Institute of Physics Press, New York, , p. 21. The adiabatic process provides a rigorous conceptual basis for the theory used to expound the first law of thermodynamics, and as such it is a key concept in thermodynamics.
The article's first reference for the second sentence is the classic source for the deleted sentence, and it is backed up by the article's second reference, which is a reliable survey published as a book, by the American Institute of Physics. Often detailed references are not demanded in the lead, but in this case they have been provided. If Editor Zedshort had read the references, and wanted references for the second sentence, he could have moved or repeated those for the first sentence.
It is a reason for the theoretical importance of the adiabatic process that is expressed in the second sentence, the one that was deleted by the edit. It is true that it is not expanded upon in the body of the article. That could be remedied, if it should be thought in need of remedy, by a little commentary in the body of the article (now supplied), based on the first two references of the article, which are fully adequate for it. It does not improve the article instead to remove from the lead a statement of that important reason.Chjoaygame (talk) 00:30, 14 November 2015 (UTC)
thread_title:  edits 

message: 81.11.233.161 (talk) 22:08, 24 July 2016 (UTC)
thread_title:  ipa? 

message: Need a video that can explain me the adiabatic process  Nabeen369 (talk) 14:17, 22 November 2016 (UTC)
thread_title:  Need a video 

message: The following comment was posted by  about the section Adiabatic process#Example of adiabatic compression:
This has an error. The 10:1 compression ratio is the swept volume of the cylinder V1 -> V2, it is only effective to regard this as a reasonably true compression ratio in a near static laboratory model or extremely low speed engine, as the higher mean piston speed, the lower the effective fill of that cylinder i.e. 1/2 V1 = 1/2 V2. It leads onto this comment that is erronious: "That is a final temperature of 753 K, or 479 °C, or 896 °F, well above the ignition point of many fuels. This is why a high-compression engine requires fuels specially formulated to not self-ignite (which would cause engine knocking when operated under these conditions of temperature and pressure)," I think the maximum TRUE compression ratio can not exceed in a final air temperature of ~180 to 220*C - depending on the fuel or fuel blend low, medium and high octane number fuels, such as unleaded 82 octane or high octane fuels such as alcohol or alcohol / water / high octane petrol / blends. Hence the error with regarding 10:1 compression, as distinct from the compression ratio as a fact, in a high speed petrol engine.
(Please direct comments about this to the IP, not me.) --JBL (talk) 13:03, 2 December 2017 (UTC)
thread_title:  Error? 

message: This is a practical example where a rapid decrease in volume results in a rapid increase in both temperature and pressure. Not sure how the increases are partitioned (between temperature and pressure) but it sets things on fire. Whether the example goes here, or in fire piston with a reference back here is what I don't know.
Riventree (talk) 19:45, 22 June 2019 (UTC)
replies: text: I suggest you add Fire piston to Adiabatic process#See also. Dolphin (t) 00:51, 23 June 2019 (UTC)
thread_title:  Need Example: [[Fire piston]] 

message: These is the theory of the entropic sets; you use mathematical filters in order to express the decay of each set to a more decayed one. There are issues because: 1. not all subsets decay at the same pace, 2. at periodical orders of hyperset / grouping magnitude we have a reaction as a whole.
We have to express the adiabatic decay of a region of a pretopological space; which occurs under specific conditions (it doesn't happen at any condition).
Sets which are able to decay, using filter-logic (mathematical logic using rules of mathematical filters), are extremely important in order to understand complex systems which aren't static.
Humanity has been lazy on the topic, but few links exist.
make page: Filter logic Which means: sets which evolve via the application of logical operations based on the rules of some ±mathematical filters (different per case).
After we write that; we then can write the adiabatic evolution of some sets, as a sub-case. We cannot start from Z (the conclusion) if we don't write A (the basics).  — Preceding unsigned comment added by 2A02:587:4112:2F00:4005:4380:AB99:AB8C (talk) 20:51, 19 July 2019 (UTC)
replies: text:  Artificial neural networks are useful to be used in order to describe the points of a set; but we should start simple. If you immediately add everything it doesn't work. Gradually you add components to the theory; iff are useful.  — Preceding unsigned comment added by 2A02:587:4112:2F00:4005:4380:AB99:AB8C (talk) 20:59, 19 July 2019 (UTC)
thread_title:  Set theory and the adiabatic process / adiabatic evolution/decay/filtering 

message: I was trying to improve the P-V plot in the article, but I think I messed up the size somehow and it seems terribly out of proportion now. Halp?  [Above edit 26 July 2019‎ by PlasmaPerfi as per edit history.] — Preceding unsigned comment added by PlasmaPerfi (talk • contribs) 
:This seems to refer to the section Graphing adiabats. You did not specify an image size so the system used the default which seems to be enormous. I have now arbitrarily added 400 px (pixel) which appears much more reasonable. Dirac66 (talk) 21:23, 26 July 2019 (UTC)
replies: text: The "image" link is deprecated, so when the image size change the behavior was unexpected. Use "file" instead. Not your fault, ; thanks for updating the image on Commons! VQuakr (talk) 21:25, 26 July 2019 (UTC)
thread_title:  P-V plot size 

message: This article is very academic.   Some practical examples would help readers understand the process.   FreeFlow99 (talk) 14:57, 20 June 2020 (UTC)
thread_title:  Too academic 

message: "Energy can enter or leave a thermodynamic system enclosed by walls that prevent mass transfer only as heat or work. Therefore, a quantity of work in such a system can be related almost directly to an equivalent quantity of heat in a cycle of two limbs. The first limb is an isochoric adiabatic work process increasing the system's internal energy; the second, an isochoric and workless heat transfer returning the system to its original state."
So the first process is: 1. isochoric, meaning no pV work done on the system, and 2. adiabatic, meaning no heat transfer into the system. Considering the system is also stated to be closed, how can it's internal energy possibly increase with a process like this? Erjio (talk) 22:56, 22 September 2023 (UTC)
thread_title:  Impossible process?