Talk:Leidenfrost effect

Untitled

very interesting, congrats to the author

Can this term be applied to a vapor layer protecting a solid as well? Dry ice pieces will skitter across floors, and can be held in a candle flame without quickly subliming. --Pyrochem 00:48, 22 January 2007 (UTC)

Yes it can. The theory is the same. A protective layer of gas surrounds the solid and protects it from the heat. Goldy496 17:39, 31 October 2007 (UTC)

Temperature of Leidenfrost Point

The temperature at which the Leidenfrost effect occurs depends fairly strongly on a number of properties of both the surface and the liquid. This may include (but is not limited to) surface roughness, contamination in the liquid, and the amount of wetting between the surface and the non-suspended liquid.

A mathematical model which allows one to predict the temperature of the Leidenfrost point for a given system is quite complicated, but Bernardin and Mudawar attempt to formulate a model in "A Cavity Activation and Bubble Growth Model of the Leidenfrost Point," Transactions of the ASME, (Vol. 124, Oct. 2002).

The claim that the Leidenfrost point of a water drop on a frying pan occurs near 220 C is misleading and I am editing the article accordingly.

Please justify that; I've seen a number of sources that indicate that 220 C is accurate. This is not an impeccable source, but you are encouraged to provide a better one to support the figure of 160 C. To be fair, I have not yet read the cited article. If you have access to it, please post an excerpt with more detailed information, or summarize it briefly. Tenebrous (talk) 17:43, 20 February 2008 (UTC)

External Links

I believe that this link may be a good addition to the section:

http://www.wiley.com/college/phy/halliday320005/pdf/leidenfrost_essay.pdf

Astrangequark 16:02, 26 August 2007 (UTC)

Firewalking

I remember hearing somewhere the one of the theories explaining how people can walk on hot coals unharmed has to do with protective vapors. Anyone know if this is true, and if it is, is it worth mentioning in the article? ce1984 (talk) 18:53, 31 August 2008 (UTC)

Leidenfrost point

I didn't manage to reconcile what this article says about the leidenfrost point with other sources. For instance the curve at [1] (from [2]) and the definition at [3] indicate that the leidenfrost point is where the whole contact area between the fluid and the hot solid is covered in a steam layer. (In the case of a hot kettle or a heating element in a bath of water for instance) It seems that the article is wrong in stating that the leidenfrost effect appears beyond the leidenfrost point. rather it appears after the critical heat flux point. But I could be wrong :-) EverGreg (talk) 20:06, 21 June 2009 (UTC)

I agree, this equation should be much better explained. All of the symbols except ${C}$ are undefined, and, while one can understand most of them with common sense and good knowledge of physics, I myself having trouble with finding out most of them. What is ${q}$, the area of the contact surface? Then what is ${{A}_{min}}$? And this would be much more confusing for lesser experienced readers.84.236.70.90 (talk) 18:55, 25 November 2016 (UTC)

Source needed for 160 °C

The article reads: As a very rough estimate, the Leidenfrost point for a drop of water on a frying pan might occur at 160 °C (320 °F). Where did this number come from? All the article seems to say is that the Leidenfrost point is hard to predict and that the factors that influence are "complicated." What equation, theory and/or experimental data supports this value? --MYCETEAE - talk 07:28, 16 August 2010 (UTC)

Popsci

Here is one of those very watchable pop science pieces showing someone demonstrating the Leidenfrost effect by briefly dipping his whole hand into liquid nitrogen. A similar demonstration with molten lead (and a wet hand) was given on Mythbusters by Adam Savage. This may be a useful and very graphic resource for this article. I am also posting about this at Talk:Nitrogen. --TS 22:56, 8 September 2010 (UTC)

Film Boiling

I think most textbooks call this effect film boiling. Someone correct me if im wrong? Venny85 (talk) 07:51, 9 May 2011 (UTC)

MythBusters "citation needed"

Before you add the tag again, say here exactly what you want to be cited. Don't just put up the tag and leave. 72.200.151.13 (talk) 18:55, 14 February 2014 (UTC)

Phenomenon

If you click the "phenomenon" link it talks about "scientific phenomenon" and makes no mention of "physical phenomenon" this is why I used "scientific" to begin with. Please review the link. This wasn't some arbitrary change based on personal or OR observations, but was a change made based on other sources that describe scientific phenomenon. Scoobydunk (talk) 10:22, 12 December 2014 (UTC)

introduction

The sentences, "It has also been used in some potentially dangerous demonstrations, such as dipping a wet finger in molten lead[1] or blowing out a mouthful of liquid nitrogen, both enacted without injury to the demonstrator.[2] The latter is potentially lethal, particularly should one accidentally swallow the liquid nitrogen.[3]"... will be more appropriate under the "popular culture" section rather than the introductory paragraph. - Subh83 (talk | contribs) 03:36, 26 February 2015 (UTC)

I agree and I removed it. "Drinking nitrogen is lethal" seems like weird tangent for a lead paragraph. I took a look at the citation for being able to put it in one's mouth, and it's anecdotal. Because of that, I'm going to remove the whole mention of it. The same citation mentions walking over hot coals as an example and I'm pretty sure it's the ash that forms an insulating barrier. The whole cite reads like the musings of someone who found a lot of fun and interesting applications for science, which makes sense because it's just an essay. I'm sure a good cite for mouth-nitrogen can be found, but I would hope that the lead gets a less-tangenty and better write before that cite is added. Harmonex (talk) 00:58, 14 June 2021 (UTC)

Abigaildespotovic (talk) 06:29, 24 March 2015 (UTC)

The source listed (https://web.archive.org/web/20141013213439/http://www.csicop.org/si/show/physics_behind_four_amazing_demonstrations/) for the sentence "The effect is responsible for the ability of a person to quickly dip a wet finger in molten lead..." does not seem to support this statement. Rather, the linked source states "Dipping one’s fingers in molten lead is usually cited as being an example of the Leidenfrost effect in action. However, it is not quite the same situation as when a drop of water is lifted up and hence somewhat insulated from a very hot skillet by the steam formed beneath it." Because of this, I omitted this section of the sentence.

Effect

The figure describing the behavior of water on a hot plate could use clarification. What is T_s? Dainegai (talk) 22:45, 7 December 2016 (UTC)

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