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Indexed by:期刊论文

Date of Publication:2017-07-05

Journal:APPLIED THERMAL ENGINEERING

Included Journals:SCIE、EI、Scopus

Volume:121

Page Number:361-367

ISSN No.:1359-4311

Key Words:Microchannels; Flow patterns; Condensation; Marangoni effect; Water-ethanol mixtures

Abstract:An array of isosceles triangular microchannels with sidewalls inclined at 54.7 degrees were fabricated by the wet etching method. The condensation of water and ethanol binary mixtures was visualized with additional measurements to investigate the condensation flow patterns in the silicon microchannels with hydraulic diameters of approximately 155 mu m. The visualization study indicated that the flow patterns were influenced by the inlet ethanol concentration and the mass flux. Annular, injection, droplet-injection and bubble flow patterns were observed along the channels. The condensation instability effects were stronger with increased equivalent surface free energy differences. The increasing equivalent surface free energy differences caused droplets to form in the microchannel that moved from the condensing surface to the top corner due to the Marangoni effect, which led to fluctuating flow patterns. The frequency of the injection flow increased with increasing Re-v and input ethanol concentration. The mass flux and the steam quality during condensation were measured at various locations in the experiments. Two phase flow pattern maps were developed for various inlet ethanol concentrations. (C) 2017 Elsevier Ltd. All rights reserved.