Talk:Joule-Thomson effect
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PLEASE use the above + tab to enter a new comment. That provides you a form in which to first enter a Subject and then enter the new comment. Please sign the comment with four tildes like this ~~~~. That automatically signs it with your user name, the date and the time. The form automatically provides subject Headings like those below and enters them in the Table of Contents which will appear below after four comments are posted.
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.
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.
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--Mion 20:45, 4 September 2006 (UTC)
- 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)
[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)
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- 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:
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- 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.
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- 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..."?
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- 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"?
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- 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)
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- 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)
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[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)
