Talk:Nucleate boiling

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"contradictionary"? —Preceding unsigned comment added by 76.1.37.196 (talk) 07:07, 31 March 2011 (UTC)[reply]

fixed typo. I like to saw logs! (talk) 05:27, 26 May 2011 (UTC)[reply]

Departure from nucleate boiling

Yes, the topic "departure from nucleate boiling" is not nucleate boiling but rather transition or film boiling and should not be in this article. It is contradictory and should be moved. Venny85 (talk) 18:56, 25 May 2011 (UTC)[reply]

It should stay here. It's not contradictory (nor was that what 76.1.37.196 was saying). The article is quite small and can easily cover the boiling regime past the CHF since it is related. Generally, it is mentioned in the same paragraph or in the same discussion as nucleate boiling. Many modern discussions and textbooks blur these lines and expound the fact that in flowing systems, there are often times in which both types of boiling are happening in close proximity, especially where local hot spots exist and localized flow turbulence cause different sized nucleates. Other factors held constant, channel size alone can determine essentially which regime a fluid is in.

So although the pretty graph is great for an entry-level understanding of heat flux, it lacks the benefit of engineering analysis of a real, dynamic system in which you cannot easily separate nucleate boiling from film boiling. I say keep these concepts in the same article. I like to saw logs! (talk) 05:27, 26 May 2011 (UTC)[reply]

If we are to keep the article objective and easily understandable, it is better to separate nucleate boiling, transition boiling, just like free convection boiling and film boiling are now separate articles. It is true that some books merge them together, however the calculations for the different regimes are still done separately and not together. For example, to calculate the heat flux for boiling at film boiling, one has to calculate it at nucleate boiling and transition boiling and finally at film boiling. By merging them all together, you are confusing the reader and assuming them to be the same. Most times in engineering, it is not really the boiling regime that one is interested in, but rather to calculate the total heat flux for say, phase change boiling fluids heat exchangers.

And I was about to expand the article for transition boiling today only to find it has been removed and redirected! ..... There is still more that can be added to this article on nucleate boiling that i can do. Venny85 (talk) 07:05, 26 May 2011 (UTC)[reply]

Good graph

Found this article very informative with the different sorts of boiling. The graph of water heat transfer is also highly useful. Whatever you do with this article (rename etc.) try to preserve the content somewhere (e.g. under a "boiling mechanisms" article or section elsewhere). — Preceding unsigned comment added by 130.246.132.177 (talk) 14:02, 11 October 2012 (UTC)[reply]

boils are gross

doctor dre — Preceding unsigned comment added by 171.159.64.10 (talk) 18:40, 6 December 2013 (UTC)[reply]

Temperature differences must be given in Kelvin

217.188.230.58 (talk) 00:32, 18 August 2014 (UTC)[reply]

Practical Applications?

I come to this article due to wondering about whether adding particles to boiling water while cooking (e.g. salt crystals or spice powers), thus providing more nucleation points within the bulk of the water, would help improve the heat transfer rate. So I'd like to see some questions answered, such as "if I have a gas stove set on a very high setting, is it easy to go far above the Critical Heat Flux point?" and "Does adding more nucleation sites within the water help prevent vapor bubbles from remaining attached to the surface?" Thanks to anyone knowledgeable who can add a section to answer such questions! 148.87.19.194 (talk) 22:51, 9 July 2015 (UTC)[reply]

In a simple pot of water, your pot is unlikely to be able to reach a high enough temperature to seriously approach DNB. If you did, you would need to lower the water level a lot, because it will boil over as more bubbles form and your pot temperature does increase. You would need a channel (flowing pipe) or a pressurized system to normally be at that level of heat flux. Pots... won't do it too well.

As to nucleation sites for the bubbles, you are looking to add floaties to the water? Solubles like salt wouldn't make any more nucleation sites. But I guess pepper might. The question in my mind is why you need more heat transfer for boiling water? There are two things about heat transfer: the source of heat and the heat sink. In a cooking scenario, you are heating water with the pot. Once the pot gets the water hot, it only boils away... disappears... faster. Unless you have an application for the steam, you don't need greater heat flux. Whatever you have in the pot to be cooked will still be at the same temperature, regardless of the heat flux. I guess with a large enough food item to be heated, then your boiling water and steam will be heating this item until it reaches the boiling point of water. But just so you know, I was taught to turn down the heat once a pot comes to a boil as the water temperature never increases. Unless you have an unusual shaped pot or unusual size food item, you should cook with the temperature of the pot about 2 to 20 degrees hotter than the water. Leave water's critical heat flux alone unless you are engineering a heat transfer system in an industrial plant and you are concerned about the temperature... not of the water, but of the things that are being cooled by the water. Cooks deal with nucleate boiling unless they are making a mess. If you got into film boiling and DNB in a kitchen scenario, your pot would be overheating, and if coated with Teflon, potentially melt or get ruined. You don't want film boiling, trust me, it will ruin your kitchen and your day. I like to saw logs! (talk) 11:09, 10 July 2015 (UTC)[reply]