열적으로 성층화된 수평전기화학계에서 이중확산대류의 물질전달 상관관계

신승일; 윤도영; 최창균

HWAHAK KONGHAK, Vol.36, No.6, 958-967, December, 1998

A Mass-Transfer Correlation of Double-Diffusive Convection in a Horizontal Electrolyte Layer with Thermally Stable Stratification

신승일, 윤도영, 최창균

초록

본 연구에서는 열적으로 성층화된 수평 유체층에서 유발되는 이중확산대류에 의한 물질전달특성을 이론적으로 또한 실험적으로 고찰하였다. 이중확산대류는 전달량을 향상시키거나 감소시키므로, 본 연구에서는 이중확산대류의 전달상관식에 대한 새로운 예측모델을 해석적으로 개발하였다. 한편 전기화학계를 이중확산계의 환경으로 설정하고, 정상상태에 서 이온의 물질전달에 의한 이중확산의 조건들을 실험적으로 조사하였다. 본 실험에서는 한계전류기법을 활용하여 수평 구리전극 사이에 채워진 황산구리 황산용액에 대하여 이중확산대류를 발생시켰다. 실험결과를 통해 구해진 자료들은 전기장과 성층화된 온도장이 부여된 수평전해액에서 정량화되었으며, 이들로부터 이론적인 예측식이 효과적으로 검증되었다. 열적 성층화는 다성분계에서 부력의 효과를 줄임으로서 유체층의 안정화효과를 보여주었다. 본 연구의 결과들은 이중확산대류가 수반되는 다양한 공학적 상황에 대하여 물질 및 열전달량을 제어하는데 있어서 효과적인 예측 및 해석에 필요한 근거들을 제공할 것이다.

In the present research, theoretical and experimental studies are conducted to investigate the characteristics of double-diffusive mass transfer in a horizontal fluid layer with thermal stratification. As the double-diffusive convection may either enhance or reduce transfer rates, the present study developed a new predictive model for the transfer correlation of double-diffusive convection analytically. Using an electrochemical system as a double-diffusive environment, the double-diffusive conditions to mark steady ionic mass transfer were investigated experimentally. To do this, the limiting current technique was adopted in a CuSO₄H₂SO₄ solution confined within horizontal copper electrodes. Theoretical results were confirmed by the experiments in which the relations of the double-diffusive conditions were quantified in an electrolyte-horizontal layer with both electrostatic fields and temperature stratifications. Thermal stratification showed the stabilizing effects in a multicomponent fluid layer as reducing the magnitude of buoyancy forces. The present study provides plausible predictions and explanations in controlling mass and heat transfer rates for various practical situations including the double-diffusive convection.

Keywords:Double-Diffusive Convection;Thermal Stratification;Mass Transfer Correlation;Electrochemical System;Multicomponent Fluid Layer

[References]

Tuner JS, "Buoyancy Effects in Fluids," Cambirige Univ. Press (1973)
Ostrach S, J. Fluid Eng., 105, 405 (1983)
Chen CF, Johnson DH, J. Fluid Mech., 138, 405 (1984)
Kaviany M, Vogel M, J. Heat Transfer, 108, 776 (1986)
Yoon DY, Choi CK, Lee CG, Kim MC, Choi U, Korean J. Chem. Eng., 13(1), 15 (1996)
Howard LN, Proc. 11th Int. Congress Applied Mechanics, Munich, 1109 (1964)
Busse FH, J. Math. Phys., 46, 140 (1967)
Long RR, J. Fluid Mech., 73, 445 (1976)
Cheung FB, J. Fluid Mech., 97, 743 (1980)
Yoon DY, Ph.D. Thesis, Seoul National University (1990)
Arpaci VS, Int. J. Heat Mass Transf., 29, 1071 (1986)
Bejan A, 2nd ASME-JSME Joint Thermal Engineering Conf., Honolulu, 22 (1987)
Yeager E, Bockris JOM, Conway BE, Sarangapani S, "Comprehensive Treatise of Electrochemistry," Vol. 6 (1983)
Agar JN, Disc. Faraday Soc., 95, 161 (1949)
Fenech EJ, Tobias CW, Electrochim. Acta, 2, 311 (1960)
Selman JR, Newman J, J. Electrochem. Soc., 118, 1070 (1971)
Patrick MA, Wragg AA, Int. J. Mass. Transf., 18, 1397 (1975)
Tennekes H, Lumley JL, "A First Course in Turbulence," MIT Press (1972)
Antar BN, Nuotio-Antar VS, "Fundamentals of Low Gravity Fluid Dynamics and Heat Transfer," CRC Press (1993)
Chiang HD, Goldstein RJ, Proc. 4th Int. Symp. Transport Phenomena in Heat & Mass Transfer, Sydney, 1 (1991)

[Referenced By]

[1] Tuner JS, "Buoyancy Effects in Fluids," Cambirige Univ. Press (1973)

[2] Ostrach S, J. Fluid Eng., 105, 405 (1983)

[3] Chen CF, Johnson DH, J. Fluid Mech., 138, 405 (1984)

[4] Kaviany M, Vogel M, J. Heat Transfer, 108, 776 (1986)

[5] Yoon DY, Choi CK, Lee CG, Kim MC, Choi U, Korean J. Chem. Eng., 13(1), 15 (1996)

[6] Howard LN, Proc. 11th Int. Congress Applied Mechanics, Munich, 1109 (1964)

[7] Busse FH, J. Math. Phys., 46, 140 (1967)

[8] Long RR, J. Fluid Mech., 73, 445 (1976)

[9] Cheung FB, J. Fluid Mech., 97, 743 (1980)

[10] Yoon DY, Ph.D. Thesis, Seoul National University (1990)

[11] Arpaci VS, Int. J. Heat Mass Transf., 29, 1071 (1986)

[12] Bejan A, 2nd ASME-JSME Joint Thermal Engineering Conf., Honolulu, 22 (1987)

[13] Yeager E, Bockris JOM, Conway BE, Sarangapani S, "Comprehensive Treatise of Electrochemistry," Vol. 6 (1983)

[14] Agar JN, Disc. Faraday Soc., 95, 161 (1949)

[15] Fenech EJ, Tobias CW, Electrochim. Acta, 2, 311 (1960)

[16] Selman JR, Newman J, J. Electrochem. Soc., 118, 1070 (1971)

[17] Patrick MA, Wragg AA, Int. J. Mass. Transf., 18, 1397 (1975)

[18] Tennekes H, Lumley JL, "A First Course in Turbulence," MIT Press (1972)

[19] Antar BN, Nuotio-Antar VS, "Fundamentals of Low Gravity Fluid Dynamics and Heat Transfer," CRC Press (1993)

[20] Chiang HD, Goldstein RJ, Proc. 4th Int. Symp. Transport Phenomena in Heat & Mass Transfer, Sydney, 1 (1991)