Talk:Evaporation/Archive 1

message: The Bowen´s equation was modified by Sartori (1987) who included a parameter that allows the calculation of the three cases of mass flow that can occur when a free water surface is exposed to the air, which situations cannot be calculated with the Bowen´s equation alone. Then the Bowen-Sartori equation becomes: 
:{Q_{c,pa} \over Q_e} = {0.46(T_p -T_a) \over P_{wp} - (rh X P_a)}{p \over 760}
where rh is the relative humidity. 
References:
Sartori, E. "A mathematical model for predicting heat and mass transfer from a free water surface". Proc. ISES Solar World Congress, Germany (1987).
Sartori, E. “Solar still versus solar evaporator: a comparative study between their thermal behaviors”. Solar Energy, 56/2 (1996).
 
Sartori, E. "A critical review on equations employed for the calculation of the evaporation rate from a free water surface". Solar Energy, 68/1 (2000).  
Sartori, E. "Letter to the Editor", Solar Energy Journal, 73/6, 2003. 
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==Does the size of a container effect the rare of which a substance evaporates?
==
I've never understood why a liquid evaporates below the boiling point.  If soeone could explain this, it would be a boon to the article.  --Spikey 02:27, 27 Jan 2004 (UTC)
thread_title:  RE: Evaporation of water 

message: Shouldn't surface area be included? Brianjd 06:52, 2004 Nov 14 (UTC)
Yes, the area also influences the amount of evaporation, but normally the evaporation rate is given per unit of area. The air temperature is another parameter that influences the evaporation rate. The evaporation decreases as the air temperature increases. (Ernani Sartori, Aug 07, 2005).
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I don't know how "concentration of other substances in the air" would affect the evaporation rate - is there a reference for this, or is this correct?  If this is true, it would be nice to have a simple explanation of why. (Anonymous).
Dear Anonymous,
I don´t know what you mean by "concentration of other substances in the air", but if this refers to solid particles then it might occur the following, as I wrote in http://noparadoxes.tripod.com: 
"In a fictional limit case, where the sky would be completely covered and opaque as well as “solid” due to the polluting solid particles in suspension, no energy would be reflected and transmitted by this cover, the solar energy would be only absorbed and part of it subsequently transferred by radiation emission and free convection to the interior of the atmospheric greenhouse". And the evaporation would be reduced, although the temperatures would increase. (Ernani Sartori, Apr 16, 2007).
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I also wonder whether the rate of water evaporation is in any way dependent on the chemical composition of the gas into which the water is being evaporated. For example, given the same temperature and atmospheric pressure, and assuming 0% humidity (i.e., no water vapor already in a volume of gas), will the rate of water evaporation into the gas (or the amount of water vapor the gas can hold before condensation occurs) always be the same if the gas is 100% oxygen as if it is 100% nitrogen or 100% carbon dioxide? Embram (talk) 20:47, 3 December 2012 (UTC)
thread_title: Factors influencing rate of evaporation

message: Vapor pressure | Water vapor ... and other links on those pages will help as well --Hard Raspy Sci 03:20, 13 Feb 2005 (UTC)
replies: text: Good point.  I have changed it.--GregRM 17:49, 4 November 2005 (UTC)

text: The anonymous explanation is correct, but limited.  Thermodynamics determines evaporation, so each molecule that has evaporated, or leaves the liquids surface, has reached the boiling point.  While at STP, also not necessarily that the average-liquid-mass-temperature is anywhere near boiling.  Evaporation is only a surface thing!  Boiling, typically, refers to the average temperature of a liquid. - HRS IAM 01:07, 12 August 2007 (UTC)
thread_title: Articles in Wikipedia helping with evaporation concepts

message: For reasons that I personally can't fathom, the evaporation article attracts the attention of an undue number of vandals.    Should we try to somehow limit editing of it?    I know that's been done for some controversial topics.   The article is already in quite decent shape.  Alison Chaiken 17:55, 26 March 2006 (UTC)
replies: text: Good point.  Not sure it is worth doing yet.  I'm interested in why people come here to vandalise.  Do they think "Hmm, I feeling some lame wiki vandalism, I know! Evaporation is the article to do."  What goes through these children's minds? njh 22:39, 26 March 2006 (UTC)
thread_title: Freezing (ha-ha!) the evaporation article?

message: A couple of of months ago, an addition to the introduction (which remains in the current version of the article) said that evaporation was one of two forms of vaporization.  I am assuming that the author intended that the other form of vaporization be sublimation.  However, the next sentence seems to imply that sublimation is one type of evaporation. Does anyone know the technical definitions for the terms "evaporation" and "vaporization" and whether they include sublimation? (Note also that vaporization is a redirect to the evaporation article.)--GregRM 23:12, 11 June 2006 (UTC)
replies: text: Also, I am questioning the relationship of "boiling" and "evaporation"; the article presents them as being separate phenomenon, but Britannica Online (link to beginning of "vaporization" article) presents boiling as a specific type of evaporation. Perhaps someone could clarify this discrepancy?(Aside: On the issue of "evaporation" vs. "vaporization" that I was wondering about in the above post, the Britannica article seems to suggest that they are equivalent.)--GregRM 02:15, 6 February 2007 (UTC)
thread_title:  Definitions of "evaporation" and "vaporization" 

message: I believe forced evaporation is drying, not distillation. Distillation is a flash process and does not involve running hot air over an entrained liquid to separate it. It's similar, but I think a better example of forced evaporation is industrial drying, such as in the food science and technology industry (to expediate sun drying, reduce the capital costs involved in storage of fresh foods) and the pharmaceutical industry (the final process step of patch production). —The preceding unsigned comment was added by 68.32.27.194 (talk) 19:33, 15 December 2006 (UTC)
replies: text: Uh-hem, a dessicant is a dryer, but it does not use heat...or require the exchange of heat... HRS IAM 01:16, 12 August 2007 (UTC)
thread_title:  Forced Evaporation 

message: I'm dumping this text which is repetitive and seems out of place for the moment. 
Evaporation is when a liquid turns into a gas because of heat energy allowing the atoms to escape. However, when levels of heat energy decrease, the gas cools down, thus condensing or turning into a liquid. For example as the tea cools, the water vapor condenses. An example of both condensation and evaporation is a nuclear reactor which smashes the molecules, produces heat energy to heat the water and turns it into water vapor by evaporation to move turbines, and when the water vapor moves out of the turbines it condenses. Another example of both is when you have a shower or a bath. When the water in the bathtub heats, it starts to evaporate but when it comes in contact with the cooler surface of the mirror, it condenses.
The ratio of the heat loss from a pond by evaporation to the heat loss due to convection, independent of wind speed, is given by: 
:{Q_{c,pa} \over Q_e} = {0.46(T_p -T_a) \over P_{wp} - P_a}{p \over 760}
where Q_{c,pa} is the heat loss from the pond by convection, in W/(m2·K),
Q_e is the heat loss from the pond by evaporation, in W/(m2·K),
T_p and T_a are the Kelvin (or Celsius) temperatures of the water and air, and 
P_{wp} and P_a are the vapor pressures of the pond surface and air, and 
p is the barometric pressure, with all pressures in mm Hg.
(Bowen, 1926) 
--Rifleman 82 20:43, 4 February 2007 (UTC)
thread_title: Evaporation of water

message: --Stone 08:48, 17 April 2007 (UTC)
thread_title: References