OP-II-3

OP-I-193D CFD SIMULATIONS OF THE EFFECT OF CONTACT ANGLEAND NOZZLE PLACEMENT ON GAS-LIQUID FLOW IN SQUAREMINICHANNELS AT LOW CAPILLARY NUMBERErkoc E., Bauer T., Lange R.Dept. of Chemical Engineering, Technische Universität Dresden, Germanyertugrul.erkoc@tu-dresden.deMicro/mini-channels offer the advantage of decreased size of the distance thatheat and mass is transported. Taylor flow in such channels, which is characterized byelongated gas bubbles and liquid slugs, have been the interest of number of studiesbecause of the advantages it offers, while having decreased distances of transport.The flow is further caharcterized by the vortex formation in the liquid slug thatimproves the radial mass and heat transport. Transport characteristics of suchsystems are affected by the hydrodynamic properties of the flow, such as thicknessof the liquid film surrounding the bubble, bubble and slug lengths and velocitiesinside the channel, mixing and flow circulation in the liquid slug, and pressure drop[1]. As the hydrodynamics are determined by the operating variables and designvariables as well as physical and thermodynamic properties, many researchersstudied the effect of operating variables such as gas and liquid superficial velocities[2], design variables such as nozzle dimensions [3, 4], and as a combined effect ofthese variables along with the physical properties of the fluids, by analysing the effectof the dimensionless numbers such as Capillary, Reynolds, Weber. In this aspect, allthe given correlations of Taylor flow regarding bubble and slug dimensions and liquidfilm thickness are based on the mentioned parameters above. As these parametersare curiciously important to model heat and mass transfer in all the directions, it isimportant to understand the effects of all variables affecting on these parameters.One of the important parameters missing in the correlations is the contact angle ofthe fluid with the surrounding wall. Recently, it has been shown by 3D CFD study thatcontact angle affects the bubble formation time significantly [5]. In a visualizationstudy of the liquid film thickness by experiments using different working fluids, it wasshown that the contact angle affects the liquid film thickness, too [6]. As visualizationstudies can be performed only for transparent systems, and in case of chemicalindustry, washcoated untransparent systems are used, thereby changing theproperty of the surface, there is a need to clarify the contact angle effect on bubble72