The measurement and study of liquid films in the case of two phase flows is significant in many heat transfer and mass transfer applications, such as chemical process industries, micro reactors, coating processes and in boilers. The focus of the present study was to measure and characterize the thickness of the liquid films for various two phase flow regimes in conventional and in mini channels using a non-intrusive technique. Experiments were performed on tubes of diameters 0.6, 1.5, 2.6 and 3.4mm. The superficial velocities of gas and liquid are in the range of 0.01-50 and 0.01-3m/s, respectively. The flow patterns were recorded with a high speed camera. A method to determine the two phase flow velocity using image registration has been discussed. Morphological processing and gray scale analysis were used to determine the liquid film thickness and characterize the flow regimes. The flow patterns identified are bubbly, dispersed bubbly, slug, slug-annular, wavy-annular, stratified, and annular. The flow regimes were validated with flow maps available in the literature. The liquid film thickness was identified by distance transform technique in image processing. The magnitude of film thickness varied with liquid and gas flow velocities. The film thickness was represented in terms of capillary number. The variation in film thickness along the length of the flow regime has been discussed. A relation between the liquid film thicknesses measured using the non-intrusive image processing technique and capillary number for the conventional and mini tubes is proposed based on the analysis._x000D_ h_x000D_ - = 2.03Ca0.13We0.52 for Bo>1_x000D_ d_x000D_ h_x000D_ - = 1.08Ca0.4We0.35 for Bo<1_x000D_ d _x000D_ It is concluded from the proposed correlation that the variation in liquid film thickness is different for conventional and mini channels because of the effect of inertial dominance in conventional channels and viscous dominance in mini channels.

Two Phase Flow Flow Ppatterns Liquid Film Thickness Mini Channels

Howard JA, Walsh PA, Walsh EJ, Int. J. Heat Mass Transf., 54(21-22), 4752 (2011)
Damianides CA, Westwater JW, in Proc. Second UK National Conf. on Heat Transfer, Mechanical Engineering Publications, London (1988)
Coleman JW, Garimella S, Int. J. Heat Mass Transfer, 42, 2881 (1999)
Kandlikar SG, Grande WJ, Heat Transf. Eng., 24(1), 3 (2003)
Venkatesan M, Das SK, Balakrishnan AR, Can. J. Chem. Eng., 35, 531 (2010)
Harvel GD, Hori K, Kawanishi K, Chang JS, Nucl. Instrum. Methods Phys. Res. A, 371, 544 (1996)
Rzasa MR, Metrology Meas. Systems XIV, 2, 291 (2007)
Ahmed WH, Ismail BI, Recent Patents Elect. Eng., 1, 1 (2008)
Keska JK, Williams BE, Exp. Thermal Fluid Sci., 19, 1 (1999)
Hassan YA, Blanchat TK, Seeley CH, Canaan RE, Int. J. Multiphase Flow, 18, 371 (1992)
Fairbrother F, Stubbs AE, J. Chem. Soc., 6, 527 (1935)
Taylor G, J. Fluid Mech., 10, 161 (1961)
Bretherton FP, J. Fluid Mech., 10, 166 (1961)
Han Y, Shikazono N, Int. J. Heat Fluid Flow, 31, 631 (2010)
Dallman JC, PhD Thesis, University of Illinois at Urbana-Champaign, Urbana, IL (1978)
Chen X, Butler T, Brill JP, Proceedings of the ASME Heat Transfer Division at the International Mechanical Engineering Congress and Exposition, 336, 201 (1996)
Schmitt RL, Stevenson WH, Stevenson HC, Proceedings of the Inspections, International Congress of Applications of Measurement and Control Symposium, Lasers and Electro-Optics, 33 (1982)
Muduli PR, Pati UC, In Intelligent Computing, Networking, and Informatics, 1, 359 (2014)
Dietrich N, Loubiere K, Jimenez M, Hebrard G, Gourdon C, Chem. Eng. Sci., 1, 100 (2013)
Mauger C, Mees L, Michard M, Lance M, Int. J. Multiph. Flow, 58, 301 (2014)
Banerjee R, Kandlikar SG, J. Power Sources, 247, 9 (2014)
Jung SU, Park HW, Lee SJ, J. Synchrotron Radiation, 21, 1160 (2014)
Liang JY, Appl. Mech. Mater., 511, 550 (2014)
Yamada Y, IEEE Conference on Asia-Pacific Synthetic Aperture Radar (2013)
Singh K, Kapoor R, Pattern Recognition Letters, 36, 10 (2014)
Mayor TS, Pinto AMFR, Campos JBLM, Chem. Eng. Sci., 63(14), 3614 (2008)
Guo F, Yang Y, Chen B, Guo L, Powder Technol., 1, 202 (2010)
Kritika I, Shridharani S, Arunkumar S, Venkatesan M, In IEEE International Conference on Computational Intelligence and Computing Research (ICCIC), DOI:10.1109/ICCIC.2013.6724169. (2013)
Eain MG, Egan V, Punch J, Int. J. Heat Fluid Flow, 44, 515 (2013)
Venkatesan M, Das SK, Balakrishnan AR, Exp. Therm. Fluid Sci., 35, 531 (2011)