Nuretdin EREN, Nihal BUYUKCİZMECİ, Rıza OĞUL

Süperdoyumdaki Buhar İçinde Damlacık Oluşumunun Serbest Enerji Değişimi

Süperdoymuş bir buhar içinde damlacık oluşumu sırasında saf bir numunenin davranışı ve yarı sıvı-gaz faz eğrisi altındaki kararlı bölgedeki büyük genlikli yoğunluk dalgalanmaları sonucunda buhar fazından damlacıklar oluşumu süreçleri araştırılmıştır. Fisher modeli temelinde, çeşitli doyma oranları için, kritik su damlacıklarının oluşumu esnasındaki serbest enerji değişimleri damlacık yarıçapının bir fonksiyonu olarak hesaplanmıştır. Damlacık yüzeyinin küresel şekil alması ile yüzey serbest enerjisi ile bağlantılı olan toplam entropinin azalmasını tanımlayan geometrik terimin kritik damlacık oluşumlarını tanımlayan toplam serbest enerjide anlamlı değişmelere neden olduğu gözlenmiştir.

Anahtar Kelimeler:

Süperdoyma oranı, damlacık oluşumu, doyma yoğunluğu

Free Energy Change of Droplet Formation in a Supersaturated Vapor

The behavior of the pure substances during the condensation of liquid droplets in a supersaturated vapor and, the mechanism of homogeneous nucleation of vapor to liquid droplets that may occur as a result of large amplitude density fluctuations within the coexistence line in the metastable region have been investigated. The free energy change accompanying the formation of a critical water drop is calculated as a function of droplet radius for various saturation ratios on the basis of Fisher’s model. It is observed that a geometric term due to the fact that the surface of a drop relaxes to spherical shape which reduces the total entropy associated with the surface free energy, produces significant changes in total free energy change of critical droplet formation.

Keywords:

Supersaturation ratio, droplet formation, saturation density,

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Abraham FF (1979). On the thermodynamic, structure and phase stability of the nonuniform fluid state,, Physics Reports 53, 93–156.
Boucher EA (1969). Nucleation, Zettlemoyer A C (ed.). p. 535. Dekker, New York.
Dillmann A, Meier GEA (1991). A rafined droplet approach to the problem of homogeneous nucleation from the vapor phase, The Journal of Chemical Physics 94, 3872–3884.
Elliott JB, Moretto LG, Phair L (2002). Liquid to vapor phase transition in excited nuclei, Physical Review Letters 88, 042701- 042704.
Fisher ME (1967). Theory of condensation and critical point, Physics 3, 255–283.
Fisher ME (1982). Proceedings of the School on Critical Phenomena, Stellenbosch, South Africa, edited by F.J.W. Hahne (Springer-Verlag, Berlin, 1983), Vol. 186, Chap. 1.
Fletcher NH (1993). Van der waals equation and nucleation theory, European Journal of Physics 14, 29–35.
Goodman AL, Kapusta JI, Mekjian AZ (1984). Liquidgas phase instabilities at subnuclear densities, Physical Review C 30, 851–865.
Guggenheim E (1945). The principle of corresponding states, The Journal of Chemical Physics 13, 253–261.
Kalikmanov VI, van Dongen MEH (1995). Semiphenomenological theory of homogeneous vapor-liquid nucleation, The Journal of Chemical Physics 103, 4250–4255.
Koyuncu M, Demirtas A, Ogul R (2002). Excess properties of liquid mixtures from the perturbation theory of Barker-Henderson, Fluid Phase Equilibria 193, 87–95.
Lienhard JH, Karimi A (1981). Homogeneous nucleation and the spinodal line, Journal of Heat Transfer 103, 61–64.
Ogul R (1998). On the spinodal instabilities at subnuclear densities, International Journal of Modern Physics E 7, 419–424.
Ogul R, Atav U (2003). Investigating the droplet formation in a nucleonic vapor, Physica Scripta 67, 34–36.
Poole PH, Sciortino F, Essmann U, Stanley HE (1993). Spinodal of liquid water, Physical Review E 48, 3799-3817.
Reid RC, Prausnitz JM, Poling BE (1987). The properties of gases and liquids. McGraw-Hill, New York.
Schmidt M, Kusche R, Kronmüller W, Issendorff B, Haberland H (1997). Experimental determination of the melting point and heat capacity for a free cluster of 139 sodium atoms, Physical Review Letters 79, 99-102.
Shamsundar N, Lienhard JH (1993). Equation of state and spinodal lines-a review, Nuclear Engineering and Design 141, 269–287.
Vicentini A, Jacucci G, Pandharipande VR (1985). Fragmentation of hot classical drops, Physical Review C 31, 1783-1793.
Wolk J, Strey R (2002). Emprical function for homogeneous water nucleation rates, The Journal of Chemical Physics 117, 4954-4960.