INTERFACIAL AREA TRANSPORT AND REGIME TRANSITION IN COMBINATORIAL CHANNELS

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. This study investigates the geometric effects of 90-degree vertical elbows and flow configurations in two-phase flow. The study shows that the elbows make a significant effect on the transport characteristics of two-phase flow, which includes the changes in interfacial structures, bubble interaction mechanisms and flow regime transition. The effect of the elbows is characterized for global and local two-phase flow parameters. The global two-phase flow parameters include two-phase pressure, interfacial structures and flow regime transition. In order to characterize the frictional pressure drop and minor loss across the vertical elbows, pressure measurements are obtained across the test section over ... continued below

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Kim, Seugjin January 28, 2011.

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Description

. This study investigates the geometric effects of 90-degree vertical elbows and flow configurations in two-phase flow. The study shows that the elbows make a significant effect on the transport characteristics of two-phase flow, which includes the changes in interfacial structures, bubble interaction mechanisms and flow regime transition. The effect of the elbows is characterized for global and local two-phase flow parameters. The global two-phase flow parameters include two-phase pressure, interfacial structures and flow regime transition. In order to characterize the frictional pressure drop and minor loss across the vertical elbows, pressure measurements are obtained across the test section over a wide range of flow conditions in both single-phase and two-phase flow conditions. A two-phase pressure drop correlation analogous to Lockhart-Martinelli correlation is proposed to predict the minor loss across the elbows. A high speed camera is employed to perform extensive flow visualization studies across the elbows in vertical upward, horizontal and vertical downward sections and modified flow regime maps are proposed. It is found that modified flow regime maps immediately downstream of the vertical upward elbow deviate significantly from the conventional flow regime map. A qualitative assessment of the counter-current flow limitation characteristics specific to the current experimental facility is performed. A multi-sensor conductivity probe is used to measure local two-phase flow parameters such as: void fraction, bubble velocity, interfacial area concentration and bubble frequency. The local measurements are obtained for six different flow conditions at ten measurement locations along axial direction of the test section. Both the vertical-upward and vertical-downward elbows have a significant impact on bubble distribution, resulting in, a bimodal distribution along the horizontal radius of the tube cross-section and migration of bubbles towards the inside of the elbow curvatures immediately downstream of the vertical-upward and vertical-downward elbows, respectively. The elbow effect decays further downstream of the elbow and bubbles migrate to more conventional distribution patterns. The axial transport of void fraction and interfacial area concentration shows that the elbows promote bubble disintegration. Preliminary comparisons between the interfacial area transport model and the experimental data for verticalupward and vertical downward section are also presented.

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  • Report No.: DOE/ID/14807
  • Grant Number: FG07-07ID14807
  • DOI: 10.2172/1004082 | External Link
  • Office of Scientific & Technical Information Report Number: 1004082
  • Archival Resource Key: ark:/67531/metadc837827

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • January 28, 2011

Added to The UNT Digital Library

  • May 19, 2016, 3:16 p.m.

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  • Dec. 8, 2016, 8:24 p.m.

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Kim, Seugjin. INTERFACIAL AREA TRANSPORT AND REGIME TRANSITION IN COMBINATORIAL CHANNELS, report, January 28, 2011; United States. (digital.library.unt.edu/ark:/67531/metadc837827/: accessed December 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.