Talk:Gasoline/Draft

Wikipedia has an article of the same name

This CZ article was created from scratch. There may be some few phrases or sentences similar to those in the WP article ... if so, they were not intentionally copied from WP. Milton Beychok 01:14, 22 April 2009 (UTC)

Soliciting reviews on this article about Gasoline

I would appreciate any review comments about this article by one and all. Milton Beychok 21:49, 18 April 2009 (UTC)

Wim Van Wassenhove responded to my solicitation for a review and offered a few comments:

• It should be mentioned that heavier crude oils required more complex refining configurations: In response, I have made such mention.
• The discussion of sulfur-dioxide smogs in London should mention that they occurred in the 19th century: In response, I have added mention that they occurred in the 19th century and the first half of the 20th century.
• Emission of hydrocarbon vapors due to high vapor pressures of gasolines has more relevance to air quality than to gasoline formulations: In response, I still feel that controlling the vapor pressure is part of formulating gasoline and so I made no changes in the discussion of vapor pressure in the gasoline formulation section,
• The discussion of octane rating is too detailed: In response, since octane rating is the most important property of gasoline to the general public, the article needs to explain what it is and how it is measured. To do that, the general public reader must be given some insight as to how an internal combustion engine works. I have re-read that section and I managed to delete perhaps a few dozen words. I cannot see how to delete more than that.

I want to thank Wim Van Wassenhove for his review and comments. Milton Beychok 21:20, 20 April 2009 (UTC)

Random comments

"Mogas" is the general term for gasoline in the U.S. Army; I had always assumed it was some corruption of "military gasoline". Now I know!

I'd consider moving the detailed regional composition material to a subpage, but, at the very least, moving "Properties that determine the performance of gasoline" before those tables -- things like "octane rating" are defined there, but are used in the earlier tables. If you do this, you may want to merge some of the material on "vapor pressure" from the "properties" section into the explanation of effects on air pollution. Howard C. Berkowitz 22:22, 18 April 2009 (UTC)

Thanks very much, Howard. Wow! You are one fast reader and writer! I don't know how you do it! I will wait to hear (hopefully) from the other 5 people I asked for comments before I make any changes. Regards, Milton Beychok 22:52, 18 April 2009 (UTC)

Although I am still waiting to hear from two other people whom I solicited for a review, I have gone ahead and reformatted the article by putting the "Properties that determine the performance of gasoline" section ahead of the "Gasoline formulations and air quality regulations" section as you suggested. That does seem more logical. Thanks again, Milton Beychok 04:46, 21 April 2009 (UTC)

Review comments I requested of Anthony Argyriou (moved here from User_talk:Milton_Beychok/Sandbox)

Milton - the article looks very good. If I were writing it, I'd have written more about TEL, but that's partly because my father was involved with TEL in his career with DuPont, so I know more about it than about many other aspects of gasoline; I don't think it's necessary to discuss it more in this article. The one significant thing that isn't explicitly stated that I think should be mentioned is the range of the primary components of gasoline. It's my understanding that octane isomers are the modal hydrocarbon, and that most of the gasoline is in the range C6-C10, but I don't know that for certain, and it would be nice to have that included. I think it might be worth including a discussion of why certain fractions might ignite early causing knock - do they vaporize at lower temperatures, or are just more prone to ignition at lower temperatures?

I could suggest a number of minor copyedits, but you said you didn't want that at this time, so I'll leave that alone. Anthony Argyriou 04:58, 22 April 2009 (UTC

Thanks very much for your comments, Anthony. As for the hydrocarbons in gasoline, the second sentence in the introduction states "... ranging from those containing 4 carbon atoms to those containing 11 or 12 carbon atoms." Whether the bulk of the components range from C6 to C10 ... or C6 to C9 ... or any other range is hard to say. It depends on the specified vapor pressure (usually controlled by amount of C4 components) and the specified final boiling point (FBP) which is where the C11 to C12 components come into the picture. I really would not like to make a flat statement about the bulk of the gasoline being any particular range. There are just too many different formulations.

As for why certain hydrocarbons knock, it depends on the their molecular structure. As stated in the "Gasoline production from crude oil" section: "Hydrocarbons with more complicated configurations such as aromatics, olefins and branched paraffins have much higher octane ratings. To that end, many of the refining processes used in petroleum refineries are designed to produce hydrocarbons with those more complicated configurations." To the best of my knowledge, it is simply a property of straight chain hydrocarbons that they have a lower ignition temperature and therefore more tendency to undergo ignition by being compressed (i.e., without any spark to start the ignition) than do hydrocarbons with more complicated structures (like iso-octane or benzene). As you know, a diesel engine has no spark plug ... it is a compression-ignited engine rather than a spark-ignited engine. And the ideal fuel for a diesel engine is pure cetane, a straight chain alkane with 9 carbon atoms. That's why diesel fuels are rated by a "cetane number" (rather than octane number). But such more detailed discussion really belongs in a stand-alone article on Octane rating. That's why the "Octane rating" subsection starts with: "For more information, see: Octane rating". I really am not an expert on octane numbers and I hope that someone who is an expert will someday write that article on Octane rating.

Once again, thanks for your comments. As you have probably noticed, I have now created the Gasoline article in the namespace ... so have at it with any copy edits. Milton Beychok 06:41, 22 April 2009 (UTC)

P.S. Note the underlined phrase that I added above to better answer your question. Milton Beychok 15:10, 22 April 2009 (UTC)

A very nice read

This is an excellent article that is quite enjoyable to read. It flows very well. I made 2 or 3 minor changes only. David E. Volk 20:19, 25 April 2009 (UTC)

Thanks, David. Milton Beychok 20:41, 25 April 2009 (UTC)

Stability section

Milton, the only minor area that I would like changed a bit is the section on phase separation. The terms "more easily" and "less easily" and comparing lower to higher temperature seems odd somehow to me. If something combines at lower temperature, than it should be more easily, less energy input to create the mixture from the phases.

Could it rephrased as something like: (I may have facts backward!) Mixtures with <10% ethanol are stable over a wider temperature range, and are thus more stable at frigid temperatures, while mixtures with > 10% ethanol are stable over a more limited temperature.

This might be a perspective issue. Stability of the mixture vs. heat required to make the mixture from the separated components. In either event, the phase changes are all "easy" for the chemicals, they just do it, no complaining.

I had to re-read that little part several times on the first reading of it, so I think we could make it flow a bit better. BTW: on the phase separation diagram, is it only valid in a certain pressure range? David E. Volk 15:31, 26 April 2009 (UTC)

David, you are right, that section is poorly worded. I am going to change it to:

"For the same temperature range, the fraction of water that an ethanol-containing gasoline can contain without phase separation increases with the percentage of ethanol."

I hope that clears it up for you. As for the effect of pressure, I simply don't know how that effects phase separation. However, gasoline is rarely stored at any pressure other than atmospheric pressure. Milton Beychok 16:46, 26 April 2009 (UTC)

That is much better. Thanks Milton. David E. Volk 17:30, 26 April 2009 (UTC)

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