Talk:Thermodynamic system

message: The present article's account of an "open system", with a beguiling diagram, is really an account of a special case, convenient for some engineering purposes, which makes it seem that heat and work can be defined for an open system. The sources acknowledge the special nature of the case, but this is not reflected in the article. The most general case of an open system does not allow a unique distinction between heat and work, and demands the concept of transfers of entropy and of internal energy. For closed systems, there is a unique distinction between heat and work.Chjoaygame (talk) 17:16, 11 December 2012 (UTC)
thread_title:  open system 

message: The present article says that an isolated system is completely isolated. There are many cases in which one wishes to consider a system that is not allowed to see transfer of matter, heat, or pressure-volume work, but one does wish to allow a gravity field to permeate the working body. Sometimes people speak of an isolated system with no external long-range force field acting on it. I think the article should perhaps allow an isolated system with an external long-range force field acting on it? According to Crawford (1963), on page 5, referring to this, "there is no insulator against gravitational fields. Hence we must rule out gravitational effects altogether." But the Maxwell-Boltzmann distribution does consider external long-range force fields. This calls for some thought, and a look at the literature, to see how to deal with it in the article, I think.Chjoaygame (talk) 17:35, 11 December 2012 (UTC)
thread_title:  isolated system and gravity 

message: An edit has been made to the section 'Open system'. As I read it, the model in the section allows differences of temperature and pressure between the inflow and outflow fluids, and perhaps even difference in bulk flow kinetic energy, and even indeed difference in bulk potential energy.Chjoaygame (talk) 18:56, 1 February 2013 (UTC)
thread_title:  open system edit 

message: It seems that editor PAR has a project going, based on his personal intuition, to contradict reliable sources that say that heat and work are not uniquely in general defined for open systems. I do not have time right now to try to tackle this. In line with comments above, apparently ignored by editor PAR, I can only say that the section on open systems here has serious errors and that editor PAR seems intent not on remedying them, but on making them worse and entrenching them for the sake of his project. Sorry to say I cannot recall the source of the diagram, but I can recall that its originally accompanying text explicitly notes that the diagram refers only to a restricted class of processes of interest to engineers and not to open system processes in general.Chjoaygame (talk) 11:03, 12 March 2013 (UTC)
thread_title:  more on open system 

message: A new diagram has been added, which is purported to represent a "generic" open system. It doesn't look generic to me. A generic system would not have distinguishable input and output paths. To me, it looks like something that an enthusiast has made up off the top of his head. It is unsourced and is hardly close to anything in the text of the article. Unless some very convincing justification for it is offered very soon on this page, I will probably remove it.Chjoaygame (talk) 13:39, 19 October 2014 (UTC)
thread_title:  "generic" open system representation 

message: I've never come across this idea that a closed system can allow energy transfers.  It doesn't even make sense, since if you added energy to a system from all directions, then it would increase in mass.
You can't say that you allow energy but not mass into a system, since E=mc^2
86.18.215.195 (talk) 09:20, 12 May 2015 (UTC)
replies: text: Thank you for this comment. What you say is reasonable and cannot be faulted. Nevertheless, people use words in contexts, and word usage is not uniform. In classical thermodynamics, the word 'closed' is used by some writers to refer to a system that cannot interact with any other. Other writers call such a system 'isolated', and by 'closed' they mean 'able to transfer energy but not matter'. In classical thermodynamics, interconversion of matter and energy is usually not considered, and mass and energy are regarded as separately conserved. In other contexts, as you say, interconversion or equivalence of mass and energy are routine. The article is written on the basis of a fair sample of texts of classical thermodynamics.Chjoaygame (talk) 12:15, 12 May 2015 (UTC)

text: I see you have asked for references for the choice of words in the article. I have offered four. Since they each cover all three, 'isolated', 'closed', and 'open', I have placed them at the end of the paragraph, not exactly at the site of your request. I think they cover your request.Chjoaygame (talk) 14:24, 12 May 2015 (UTC)
thread_title:  Closed system 

message: The redirection of Open system (thermodynamics) to this page caused a reduction of relevance and conceptual problems (see also Wikidata)... See solution of Closed system#In thermodynamics, isolating and furthering the open system concept in another article.
SUGESTION: 
# to create another (independent) article Open system#In thermodynamics.
# to create a sidebar template (like template:Crystallization) to be used as "table of contents" (ToC) of Thermodynamic system topics.
--Krauss (talk) 10:07, 6 December 2015 (UTC)
replies: text: Forgive me, this is a little too telegraphic for my slow wits. I don't know what you mean by "reduction of relevance and conceptual problems". Perhaps you will kindly spell it out for me. I am not thrilled by the idea of creating an article [Open system#In thermodynamics], nor by the idea of creating a sidebar template.Chjoaygame (talk) 12:43, 6 December 2015 (UTC)
thread_title:  Please review, encyclopedic problem 

message: Citation from the introduction: "The thermodynamic system is always enclosed by walls that separate it from its surroundings; these constrain the system" - question, is that really true? How about a drop of water in a cloud, which can be a model of a thermodynamic system? ArchibaldWagner (talk) 21:56, 23 February 2018 (UTC)
thread_title:  always enclosed by walls ? 

message: In this edit I have removed a one-sentence paragraph from the lead. The removed item was reading
::::Furthermore, the state of a thermodynamic system is described by thermodynamic state variables, which may be intensive, such as temperature, or pressure, or extensive, such as entropy, or internal energy.
The true situation is more subtle than is expressed in that sentence. I will shortly replace that sentence with a better one.
The problem with the sentence is that it fails to recognise the deep difference between the directly and concretely measureable state variables such as pressure, volume, and mass, and indirectly measurable variables such as entropy and internal energy. In further edits, I will clarify this point.Chjoaygame (talk) 13:36, 5 March 2021 (UTC)
thread_title:  reason for edit 

message: The property of the system whose value depends upon the amount of substance present in the system is called extensive property for example:-
Mass, volume, surface area, enthalpy, entropy,
 free energy etc... 2405:201:5001:7C6E:C525:58AE:B129:2570 (talk) 14:36, 30 January 2022 (UTC)
thread_title:  Extensive property 

message: It seems to me that the author himself has no clue what these internal variables are. Weaky3 (talk) 23:51, 25 March 2023 (UTC)
thread_title:  Internal variables