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Liquid Film Thickness (liquid + film_thickness)
Selected AbstractsTransient flow patterns in a microfluidic chip with a complicated microstructureHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2008Wei Zhang Abstract The transient flow patterns of the boiling flow in a microfluidic chip with a complicated microstructure were studied at low mass fluxes and high heat fluxes. The periodic flow pattern in the timescale of milliseconds and the stratified flow pattern were observed. For a specific separated zone, the liquid film thickness was increased along the flow direction and the dry-out always occurred earlier at the microchannel upstream rather than downstream. However, for different microchannel zones, the dry-out took place earlier in the downstream zone. It was determined that the low liquid Froude number was responsible for the formation of the stratified flow. The large boiling number resulted in a large shear stress at the vapor,liquid interface, leading to the accumulation of the liquid in the microchannel downstream, causing the increased liquid film thickness along the flow direction. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(4): 224,231, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20201 [source] An investigation of liquid film thickness during solutal Marangoni condensation using a laser absorption method: Absorption property and examination of measuring methodHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2003Yoshio Utaka Abstract The objective of the study is to establish a method for measuring the thickness of thin condensates of liquid mixtures using a laser light absorption method during the process of water,ethanol Marangoni dropwise condensation. First, the extinction property of the test material, with unknown properties related to infrared laser light having a wavelength of 3.39µm, was measured. Next, measurements were made of the variations in condensate film thickness after the sweeping of the heat transfer surface by departing drops in the Marangoni dropwise condensation cycle. The precision of this method was investigated on the basis of the extinction coefficient of the test material and the thickness of the liquid film. Results showed that this method provides good precision and is applicable to the measurement of other similar materials. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 700,711, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10124 [source] Viscous co-current downward Taylor flow in a square mini-channelAICHE JOURNAL, Issue 7 2010Özge Keskin Abstract This article presents a computational study of the co-current downward Taylor flow of gas bubbles in a viscous liquid within a square channel of 1 mm hydraulic diameter. The three-dimensional numerical simulations are performed with an in-house computer code, which is based on the volume-of-fluid method with interface reconstruction. The computed (always axi-symmetric) bubble shapes are validated by experimental flow visualizations for varying capillary number. The evaluation of the numerical results for a series of simulations reveals the dependence of the bubble diameter and the interfacial area per unit volume on the capillary number. Correlations between bubble velocity and total superficial velocity are also provided. The present results are useful to estimate the values of the bubble diameter, the liquid film thickness and the interfacial area per unit volume from given values of the gas and liquid superficial velocities. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] CFD Simulation of Liquid Film Flow on Inclined PlatesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2004F. Gu Abstract A two-phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin-film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter-current two-phase flow. [source] Turbulence Transfer Processes in Adiabatic and Condensing Film Flow in an Inclined TubeCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2003R. Würfel Abstract For the description of transfer processes in separated turbulent two-phase flow, knowledge is necessary about interactions at the interface. Particularly experimental studies were performed of the two-phase-friction coefficient, film thickness, entrainment and heat transfer for adiabatic and condensing conditions. Working systems were n-heptane/air, water/air and condensing n-heptane. The measurement of the liquid film thickness was successful with the ultrasonic method and the entrainment was measured with an isokinetic technique. Quantitative connections between hydrodynamic parameters were discussed and compared with literature models. Based on experimental data, special models are proposed. Partly the influence of the mass transfer intensity cannot be neglected for calculation of the two-phase-friction coefficient. For the description of the heat transfer for film condensation in turbulent flow the interface shear stress and the inclination angle of the tube have proved useful. [source] | ||||||||||