A Discussion of the Fractionation Model in the Process of Evaporation

Abstract:

Isotopic fractionation is the basic study of isotope tracer method. The most common fractionation of water in the natural is diffusion controlled kinetic fractionation in the process of evaporation. This process is now commonly represented by Cappa equation. In Cappa’s concept model, the atmosphere was divided into two layers, the free atmosphere and the laminar layer above the surface of evaporating water. In this article, a modified three layer model was used to represent experiments of Cappa (2003). It was shown that there was a third layer between free atmosphere and the laminar layer, the mixing layer. The simulated results also indicate that: (1) in test one, in which dry air was used as the inlet air, all vapor in the free air was from evaporating. Cappa Model can represents the experiment as well as the three layer model; (2) in test two, in which 50% humidity of air was used as the inlet air, results calculated by Cappa Model showed apparent depleted deviation from measured data; (3) the best fit result of test two supports the exist of the third layer, the mixed layer. It was also indicates that the vapor of mixed layer is made up of partial vapor from free atmosphere and all vapor from laminar layer. The modified Cappa model can represent all tests. Key words: Evaporation process, Hydrogen and oxygen stable isotopes, the factor of fractionation, Cappa Model

• Periodical: Advanced Materials Research (Volumes 955-959)
• Pages: 3170-3176
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.955-959.3170
• Online since: June 2014
• Authors: Hong Yun Ma*, Li He Yin, Jun Zhang, Jin Ting Huang, Xiao yong Wang, Jia Qiu Dong
• Keywords: Cappa Model, Evaporation Process, Factor of Fractionation, Hydrogen, Oxygen Stable Isotopes

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