Talk:Otto cycle

Compression after ignition?

< The compression stroke is intended to compress the products after the flame ignites the mixture. >

I don't understand this; it makes no sense. — Preceding unsigned comment added by 212.248.160.84 (talk) 09:54, 23 September 2011 (UTC)

learn latex properly!

Whoever wrote this should learn latex first! — Preceding unsigned comment added by 81.178.152.203 (talk) 07:59, 16 December 2011 (UTC)

corrections to come

I made a mistake when editing this article in that the usual sign convention found in references was turned about. Energy into the system should be given a positive sign and energy out of the system should be given a negative sign. I will correct when I find the energy and also clean up the Latex script that I made a mess of as I am an amateur at that. — Preceding unsigned comment added by Zedshort (talk • contribs) 04:49, 20 February 2014 (UTC)

This sign convention is valid in chemical thermodynamics, where the production of work is not of interest. In technical thermodynamics, the sign convention is reversed, since the quantity of interest is the work produced, which is intuitively considered positive.

I will not change the signs, but for a specialist in heat engines the statements about work in this article are incomprehensible. Chemists should deal exclusively with articles on chemical thermodynamics, not on technical thermodynamics. --Turbojet (talk) 08:28, 23 June 2026 (UTC)

What is so incomprehensible in a sign change? It's not Chinese language. You say that this articole having a specific orientation and not being a general thermodynamics article the sign you mention is somewhat justified. I don't know if you are aware of the opposite physico-chemical sign is the chosing of Clausius, an authority on thermodynamics. Would someone in Clausius' tine have approached him with a reproach that he shouldn't have imposed a sign on technical thermodynamics? Perhaps some historical sources could elucidate this question of sign controversy and the split between technical thermodynamics and physico-chemical thermodynamics. ~2026-39006-70 (talk) 19:36, 10 July 2026 (UTC)

Introductory paragraphs somewhat disordered

The introduction describes an Otto cycle as consisting of four processes. It then lists six processes. It then returns to four processes, but introduces a new term, the four-stroke Otto cycle, which really has six processes, using the following words:

The Otto cycle consists of isentropic compression, heat addition at constant volume, isentropic expansion, 
and rejection of heat at constant volume. In the case of a four-stroke Otto cycle, technically there 
are two additional processes....

I understand the general idea: the two extra processes (labelled 0-1 and 4-0) are usually ignored in theoretical treatments, even though their details are important in practice. I also assume that the Otto cycle is synonymous with the four-stroke Otto cycle, even though they are presented as contrasting, with the four-stroke one having six processes. But the switching back and forth between these perspectives is confusing. All it needs is a quick tune-up from an expert.

Incidentally the "0" is missing in the diagram. 84.227.234.163 (talk) 11:45, 15 April 2014 (UTC)

Otto cycle

Derive its efficiency Anurag Singh bhu (talk) 03:59, 13 December 2017 (UTC)

Usable picture: real-engine deviations to the Otto cycle

I just uploaded this on Commons. If someone wants to make a paragraph of accompanying text, be my guest (I do not have the time to do so right now). Tigraan^{Click here to contact me} 16:50, 14 September 2018 (UTC)

Why not draw a realistic diagram, based on an indicator diagram, on which the theoretical diagram of the Otto cycle will be superimposed? A scale diagram, in which the compression is done for a compression ratio of 10, and the maximum pressure in the cycle is around 50 bar (the theoretical one is considerably higher)? And the isentropes/politropes from compression and expansion should be drawn realistically, not somewhat parallel, as they are drawn in the adjacent image. --Turbojet (talk) 04:19, 11 July 2026 (UTC)

Signature of an unknown author in an image?

Since November 2015 there is an image in the middle of the page, that describes the process of the Otto cycle. Besides the fact that it doens't have neither a frame nor a caption, it's the first image I see in Wikipedia with the name of the (unknown) author, @Aiman Alqwshab:, in the image itself. The name is central, in bold, more evident than some other text present in the image. This is more than a way of (self-)crediting the author – for this the information page of the image is enough, like for all the other authors. We don't sign a paragraph on Wikipedia, so why sould an image be signed? Here it is written that "the image should be primarily serving an educational purpose, and not as a means of self-promotion of the user's artistic skills". And it seems to me that this is exactly a means of self-promotion. I think we have two options to solve this:

• we ask the author to remove his name from the image, or we do it ourselves if we are allowed to;
• we create a new image; this one is not so complex after all, and an even better one can be easily generated.

--Almicione (talk) 17:13, 2 December 2020 (UTC)