Talk:Joule–Thomson effect

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The first responder to someone's new comment should enter the response just beneath the new comment (instead of using the above + tab) and indent the response by starting with a colon like this :. Any second responder, indent further by starting with two colons like this :: and any third responder, start with three colons like this ::: and so forth. If we don't follow these practices, the result is jumbled mess.

I don't really see any connection between this article on the Joule-Thomson effect and your Hydrogen WikiProject. But, to each his own I guess. - mbeychok 23:08, 4 September 2006 (UTC)

Contents

[edit] Reasons for revision

The article was extensively revised for a number of reasons, including:

  • It did not differentiate between real gases and ideal gases which is necessary.
  • It repeatedly used the terms "free expansion" and "freely expanded" without a precise definition of what was meant.
  • It used the term "adiabatic" quite loosely and failed to explain that the Joule-Thomson effect was a contant enthalpy (i.e., enthalpic) process which applies only to real gases (as differentiated from ideal gases.
  • It contained some rather involved and tedious paragraphs purportedly explaining the Joule-Thomson effect in terms of molecular collisions and intermolecular attractive electromagnetic forces. I don't think such explanations are necessary and would simply confuse the large majority of readers (who are not physicists or thermodynamicists). I have left that explanation as a comment section on the Edit page in case someone wants to try and make it simpler and more understandable.
  • Some parts of the discussion were re-arranged so as to hopefully improve the flow and readability of the article.
  • Some links were added to the "See also" section and a reference book was added to the "Bibliography".
  • Some other minor typos were fixed.

I hope that the overall revision has resulted in a much improved article. - mbeychok 01:36, 11 June 2006 (UTC)

Thanks for making the improvements. I strongly disagree with the removal of the explanation of the effect however. What is the point of an article on a physical phenomenon that doesn't explain the reason behind it? Rracecarr 19:59, 11 June 2006 (UTC)
Rracecarr: I am not going to delete your reversion of the explanation of the physical mechanism. However, I would like to discuss some changes that you might make. But first let me say that, in my opinion, most readers of this article will be seeking information as to how to use the Joule-Thomson effect. Only a few will be seeking the physics explanation of the J-T effect. With that in mind, here are some changes/improvements that I would suggest:
  • Quoting from the physical mechanism writeup: In the process of free expansion, work is done against intermolecular attractive forces, .... The article has earlier explained that the J-T effect involves an isenthalpic expansion (with no heat transferred into or from the gas and no work extracted from the gas) and here the reader sees "... free expansion, work is done against ..." which might confuse him/her, don't you think? Could you somehow eliminate that possible confusion by explaining what you mean by a free expansion (which I frankly don't understand myself) and explaining how doing work against intermolecular attractive forces does not constitute extraction of work from the gas? Again, keep in mind the readers who are not advanced physics students.
  • Quoting again from the physical mechanism writeup: As density decreases, there is a drop .... The question here is why does the density decrease? Could you change that to read "As density decreases because the gas pressure decreases during expansion of a gas, there is a drop..."?
  • A final quote: ... dominates, and free expansion causes .... Again, the use of free expansion with no explanation. Wouldn't that sentence be just as true without the word "free"?
If you could accomplish the above suggestions, I think the physical mechanism explanation would be much improved. One final trivial point on another subject. You deleted my link of the words "real gas" to an article on "ideal gas" because presumably you thought it incorrect to use the ideal gas article to explain the meaning of real gas. The reason I used that link was that after a lengthy search through Wikipedia, surprisingly that was the only article I could find that even discussed the difference between an ideal gas and a real gas. I have threfore replaced that link even though admittedly it would be better if there were an article devoted to "real gas". In point of fact, when the Wikipedia search function is used on "Real gas", it is re-directed to "Ideal gas". Regards, mbeychok 21:07, 11 June 2006 (UTC)
I have re-written the section in an attempt to address your concerns. Let me know what you think. Rracecarr 09:46, 12 June 2006 (UTC)
Rracecarr: I think your re-write is excellent. Thanks for the cooperation. - mbeychok 15:55, 12 June 2006 (UTC)

[edit] Need link to Refrigeration

Hello folks. This is a nice article, but shouldn't it have some link to the general article on refrigeration? After all, that is what the Joule-Thomson effect is used for in practice. Thanks.

You're right, it does need a link so I added it in the "See also" section. In the future, PLEASE provide a heading for your discussions (which I added for you) and also sign with your name and the date. Thanks, mbeychok 08:12, 17 November 2006 (UTC)

[edit] Why the word "fluid" added by User:213.84.69.4 was deleted

The Joule-Thomson effect applies primarily to non-ideal real gases. To a great many people, the word "fluid" means a liquid (rather than a real gas) and therefore I felt that it should be deleted so as not to mislead many people. - mbeychok 16:11, 1 May 2007 (UTC)

[edit] Why I am reverting Rracecarr's wording changes again

I think that perhaps you are confusing the noun heat with the verb heat. Yes, there is no heat (the noun) transferred during a Joule-Thomson expansion. But in those cases where the Joule-Thomson expansion results in raising the temperature, the gas has been heated (the verb).

I have looked in 3 different dictionaries and they all say that the verb "heat" means to make warm or hot, or become warm or hot. Raising the temperature makes the gas warmer or hotter and therefore the verb "heat" is just as appropriate as the verb "warm" ... and your statement that it is obviously inapproprate to use the verb "heat" is incorrect.

To the vast majority of people, when you raise the temperature of something you have heated (verb) that something ... whether or not you added any heat (noun) in order to raise the temperature of that something. Therefore, I am reverting your changes. Regards, mbeychok (talk) 03:30, 11 March 2008 (UTC)

To heat means to add heat to. Of course people use the word in a sloppy way in non-technical settings. But I think an article on the Joule-Thompson effect, which your "vast majority of people" have never heard of, qualifies as a technical setting. Anyway, why introduce the confusion? "Warms" has the same meaning you claim "heats" does, and does not imply that the energy content has changed. Please stop being unreasonable. Rracecarr (talk) 19:18, 11 March 2008 (UTC)
I am going to stop, but only because I don't have the time or inclination to engage in a reversion war with someone who is too stubborn to listen to reason. I did not start the confusion ... you started the confusion when you first reverted my original use of the verb heat. As I pointed out above, the verb heat means to raise the temperature whether or not heat is added. But you simply dismiss dictionary definitions as "sloppy" and "non-technical". I suggest you read the Wiktionary definition at http://en.wiktionary.org/wiki/heat which clearly defines the verb heat as: To cause an increase in temperature of an object or space; to cause something to become hot. Perhaps you should also re-write that Wiktionary definition??
In the book Chemical Thermodynamics:Principles and Applications(2000), ISBN 978-0-12-530990-5, on page 141, is this wording: ... μJT is negative at high temperatures and pressures. Therefore, a gas heats up as it expands under these conditions. Is that book's wording also "sloppy" and "non-technical"?
From the looks of your user Talk page (which you have "conveniently" deleted against Wikipedia policy but which is still available in your Talk page history), you have been involved in editing wars a few times before. It is people with attitudes such as yours who drive people away from Wikipedia. I strongly suggest that you supplement your degree in oceanography with a course in grammar. Have a nice day, mbeychok (talk) 21:38, 11 March 2008 (UTC)
Wow. Where to start. Let's see,
  1. The wording I objected to was "heats", not "heats up", which is better, but not a good as "warms".
  2. YOU started the confusion (read: edit war) by pointlessly reverting by edit. Mine was not a revert as you claim, since it didn't say "warms" before.
  3. Clearing my talk page is certainly not against wikipedia policy. Archiving is "preferred" but it's not worth the trouble.
  4. Your own grasp of grammar makes your jab a bit ironic.
I notice you claim on your user page to have "rewritten completely and expanding" this article, a claim which the history of the page doesn't back up. I also notice that you rated the article as "A" class (which it's not), and the importance within physics as "high" (which is laughable). I am glad you've stopped reverting my edits. I will only add that if you think there's a problem with my attitude, perhaps you should consider discussing good faith edits before reverting in the future. Rracecarr (talk) 22:16, 11 March 2008 (UTC)
Wow, indeed! I note you have no answer for the either the Wiktionary definition or the quote from Chemical Thermodynamics:Principles and Applications(2000), ISBN 978-0-12-530990-5, other than saying that you find a distinction between "heats" and "heats up". Now you are grasping at straws, aren't you?
As I said before, you "conveniently" deleted your Talk page probably to hide your history of edit warring, and now you claim "its not worth the trouble" to archive it.
As for my early participation in this article, the editing I performed on June 10th, 2006 was indeed a major rewrite and expansion. In fact, if you scroll up on this page, you will find that you commented on June 11th, 2006 and you thanked me for making the improvements ... and then we went on to work out the revision of your write-up on the physical mechanism. Have you forgotten that?
You may have the last word if you so wish. As for me, I have wasted enough time on this already and you are still unwilling to admit that changing "heats" to "warms" is just silly, pedantic nonsense. mbeychok (talk) 00:04, 12 March 2008 (UTC)

[edit] What a wonderful article!

Usually people just read various WikiPedia articles, and some are OK, others are meh, and when they read a masterpiece like this, they are happy but noone bothers to comment. Well, I decided this one was GREAT and wanted to give props to the author(s). The pedagogic methodology exhibited here is of the finest quality. I wish I knew what other material the author(s) has/have contributed. If anyone who reads this knows the author(s), please kindly extend my compliments. —Preceding unsigned comment added by 91.153.151.172 (talk) 01:00, 14 March 2008 (UTC)

Thanks for the kind words. Read my user page at User:Mbeychok to learn more about me. mbeychok (talk) 02:35, 14 March 2008 (UTC)

[edit] typography

I fixed the typography, them moved the article again, to use the en dash to clarify the Joule and Thomson are two equal names joined, as opposed to a compound last name, which would use a hyphen. This is how it appears in carefully edited book (like this and this and this), but like most such subtleties, it probably appears wrong more often than right. Does anyone think this is not the best way to do it? Dicklyon (talk) 20:32, 15 March 2008 (UTC)

I have reverted the changes to the article, but not the move. There was at least one typo introduced, a missing letter I think, and a bunch of unnecessary blank space added. The title should probably either be changed back, or the hyphens should be changed back to dashes (but without reintroducing the typos). As I indicated in the edit summary, I don't have a strong preference, but a quick web search definitely seems to turn up far more hyphens than dashes. Rracecarr (talk) 20:54, 16 March 2008 (UTC)
Sorry about the dropped letter typo; fixed. It's good that you don't care about the typography, as that means it will OK to do it correctly. And I already stated that it is more commonly done wrong than right, but that's not a good reason to avoid the useful cue that doing it right provides to literate readers. You are correct that blank lines before paragraphs are not always necessary, but they are always allowed, and make it much easier to spot headings when editing. Dicklyon (talk) 21:31, 16 March 2008 (UTC)
Looks ok to me... Rracecarr (talk) 23:26, 16 March 2008 (UTC)