Talk:Carnot cycle

Agreement of State Labels in the Diagrams
If possible, it would be nice if the P-V diagram and T-S diagram had consistent state labels. Brvman 07:04, 3 April 2014 (UTC) — Preceding unsigned comment added by Brvman (talk • contribs)

Delete redirect suggested
The term Carnot efficiency redirects here, to Carnot Cycle.

Carnot efficiency, however, should have its own page, since the Carnot efficiency is a limit that cannot be exceeded by an method of converting heat to electricity, not merely by carnot engines. Geoffrey.landis (talk) 21:49, 28 May 2008 (UTC)


 * Before deleting, or taking to WP:RfD, do you think there is enough for an article on Carnot efficiency (if so, just start to write that article), or could it be redirected elsewhere? Energy conversion or Energy efficiency for example? There are also possibilities in the page history. It once used to redirect to Carnot heat engine, and it also once redirected to Exergy efficiency (which I'd never heard of). Are those possiblities any good? Carcharoth (talk) 00:51, 29 May 2008 (UTC)


 * The most appropriate redirect would be to the efficiency section of the article on Heat engines, here. Geoffrey.landis (talk) 01:37, 30 May 2008 (UTC)


 * Done. Anyone can do that, not just admins. Would you be able to check the links and see if they are all being used correctly? Carcharoth (talk) 13:26, 31 May 2008 (UTC)


 * Looking over this again, I see that there is an article Carnot's theorem (thermodynamics) which is directly on the topic. So I will change the redirect to aim there. Geoffrey.landis (talk) 14:55, 22 June 2020 (UTC)

id appreciate an english translation
this reads like a textbook. it is not very clear and expects people to understand calculus notation. i do not think it is necessary to be so technical, this aint rocket science. —Preceding unsigned comment added by 68.240.189.9 (talk) 23:37, 28 July 2008 (UTC)

--Yep, a little bit of introductory info about this, more basic would be in the interest of this article and for others. The technical part, though is just as important. AkshayGenius (talk) 21:38, 15 November 2008 (UTC)

I looked at this article on 12 April 2012, and the equations are not properly displaying in my IE 7 broswer. For instance, instead of getting math integral symbols, I see markup tags. — Preceding unsigned comment added by 192.35.35.34 (talk) 19:07, 12 April 2012 (UTC)

I agree there should be a simpler introduction, something for high school students who haven't had calculus (yet). It's amusing that the page says this is best understood by examining a temperature-entropy diagram. Now if everyone just understood entropy, that would be fine. Jlhollin (talk) 15:39, 28 November 2018 (UTC)

P-V diagram
We need the P-V diagram back. Bring back the P-V diagram 220.227.165.210 (talk) 08:51, 15 September 2008 (UTC)
 * Did it 220.227.165.210 (talk) 08:57, 15 September 2008 (UTC)
 * Added references to the P-V diagram in the explanation of the Carnot cycle. Doesn't it look prettier now? :) 220.227.165.210 (talk) 09:21, 15 September 2008 (UTC)

The absence of a P-V diagram in this article renders it useless, the temperature entropy diagram it has gives no indication of how heat is converted into work by change of volume (the word volume does not appear in the text), which is the principle to be illustrated by any explanation of the Carnot (or any other heat engine) cycle. There isn't even a mathematical explanation of just how heat is converted to work. --Damorbel (talk) 07:20, 1 October 2009 (UTC)

LaTex Not Rendering
Equations not rendering — Preceding unsigned comment added by 68.193.49.58 (talk) 12:54, 13 April 2012 (UTC)

Carnot vs Otto cycle
The Otto engine does not necessarily follow Carnot because combustible fuels release heat but also may release mechanical pressure, meaning they have a second pressure component in addition to heat, in that the exhaust products may take up more volume than the intake products at room temperature.

This article should clarify that, as contrary to many texts these engines do not always follow the Carnot cycle (which was originally intended for external combustion steam engines where any pressure component is lost to the exhaust). — Preceding unsigned comment added by 24.136.29.223 (talk) 00:05, 8 June 2016 (UTC)

Figure 1 Isotherms are mislabeled
The labels should be Th and Tc, not T1 and T2, respectively. I changed T1 to Th and T2 to Tc in the text, but I don't know how to edit the svg image.

Colorblind folk cannot distinguish between colors currently labeled liquid and vapor
In the section heading Carnot's theorem, figure 6 shows a T-S diagram comparing a "real engine" with an ideal carnot cycle. The colors chosen for 'liquid' and 'vapour' are visually indistinguishable by those of us who are colorblind. In choosing colors for diagrams, it is important to use colors that have different light intensity. For instance (I am guessing about the colors in the diagram) a light blue for liquid and a dark pink for vapour. I am assuming that what is here is light blue and light pink, because I am unable to distinguish between those colors.

There is a lot of information out on the web that can help inform the color decisions when creating diagrams of this type. See the Wikipedia article on color blindness for more details. Rdm2020 (talk) 14:10, 25 October 2018 (UTC)

The quantity U is not defined
It is stated that dU is an exact differential, but I cannot find a definition of U in the article. 97.113.94.112 (talk) 14:06, 7 October 2020 (UTC)

Error in legend for Figure 6
Figure 6 is an image of an ST diagram for an idealised and realistic Carnot cycle, however both 'liquid' and 'vapour' are labelled as the same colour. This is easily fixed however I'm very new to editing Wikipedia so someone who knows what they're doing should probably fix it. NervousDendrite (talk) 00:07, 28 May 2021 (UTC)


 * I downloaded the SVG file, tweaked the colour and uploaded the changed file. Feel free to edit - there is no mistake that you can make that we can't repair or roll-back.  Stepho  talk 00:09, 29 May 2021 (UTC)

bad link
https://en.wikipedia.org/w/index.php?title=Carnot_cycle&action=submit#Carnot's_theorem

The subsection Carnot's Theorem contains this "Thus, Equation 3 gives the..." but there is no equation numbered "3" in this article. Indeed none of the equations in the article are numbered. The digit 3 is actually a hypertext link that does not work. The hypertext is " Thus, Equation $$ gives the maximum ". My hope is that someone who knows thermodynamics and who reads this talk page note will fix this, so that I will be able to find equation 3. Thanks Nick Beeson (talk) 03:20, 15 March 2022 (UTC)