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.
h
- = 2.03Ca0.13We0.52 for Bo>1
d
h
- = 1.08Ca0.4We0.35 for Bo<1
d
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.
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
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