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首页> 外文期刊>International Journal of Heat and Mass Transfer >Effect of counter current airflow on film dispersion and heat transfer of evaporative falling film over a horizontal elliptical tube
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Effect of counter current airflow on film dispersion and heat transfer of evaporative falling film over a horizontal elliptical tube

机译：逆流气流对水平椭圆管上的薄膜分散和蒸发降膜传热的影响

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摘要

This study explores the influence of counter current airflow on evaporative heat transfer performance of falling films on a horizontal elliptical tube. The numerical analysis was based on the volume-of-fluid simulations to catch the dispersal evolution of descending films in conjunction with user defined function to model the evaporation effect at the water surface to the ambiance. The calculated results of heat transfer coefficients were in reasonably good agreement with the measured data from the literature for validation of the computational model. Calculations were performed to elaborate the interaction mechanism of counter current airflows with the formation process and heat transfer of evaporative liquid films on the tubes. In essence, upward air streams can induce the shear stresses at the water-air interface to form thicker wavy films. The counter current airflow has a more pronounced effect on heat transfer enhancement in the lower part of the tube than the upper part. Numerical experiments were also extended to assess the thermal performance of water film evaporators by systematically varying the inlet liquid mass flow rate of 0.093-0.186 kg/m-s and counter current airflow velocity of 0-3 m/s, respectively. The simulations results reveal steeper temperature gradients at the wall to enhance heat transfer outcomes, achieving an averaged heat transfer coefficient of 4.15 kW/m(2) K for Gamma = 0.149 kg/m-s and V-air = 3 m/s. (C) 2019 Elsevier Ltd. All rights reserved.
机译：这项研究探讨了逆流气流对水平椭圆管上降膜的蒸发传热性能的影响。数值分析基于流体体积模拟，以捕获降膜的扩散演变，并结合用户定义的函数来模拟水面到周围环境的蒸发效果。传热系数的计算结果与来自文献的测量数据相当吻合，用于验证计算模型。进行了计算以阐明逆流气流与管上蒸发液膜的形成过程和传热的相互作用机理。本质上，向上的气流会在水-空气界面处引起剪切应力，从而形成较厚的波浪形薄膜。逆流气流在管的下部比上部对传热的增强具有更明显的作用。通过系统地改变进气液体质量流量分别为0.093-0.186 kg / m-s和逆流气流速度为0-3 m / s，数值实验也得以扩展以评估水膜蒸发器的热性能。模拟结果显示壁上的温度梯度更陡，以增强传热效果，对于Gamma = 0.149 kg / m-s和V-air = 3 m / s，平均传热系数为4.15 kW / m（2）K。 （C）2019 Elsevier Ltd.保留所有权利。

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  • 来源
    《International Journal of Heat and Mass Transfer》 |2019年第10期|964-973|共10页
  • 作者

    Lee Yee-Ting; Hong Sihui; Dang Chaobin; Chien Liang-Han; Yang An-Shik;

  • 作者单位

    Natl Taipei Univ Technol, Dept Energy & Refrigerating Air Conditioning Engn, 1,Sec 3,Chung Hsiao E Rd, Taipei 106, Taiwan|Natl Taipei Univ Technol, Res Ctr Energy Conservat New Generat Residential, Taipei 106, Taiwan;

    Univ Tokyo, Dept Human & Engn Environm Studies, Grad Sch Frontier Sci, 5-1-5 Kashiwanoha, Kashiwa, Chiba 2778563, Japan;

    Univ Tokyo, Dept Human & Engn Environm Studies, Grad Sch Frontier Sci, 5-1-5 Kashiwanoha, Kashiwa, Chiba 2778563, Japan;

    Natl Taipei Univ Technol, Dept Energy & Refrigerating Air Conditioning Engn, 1,Sec 3,Chung Hsiao E Rd, Taipei 106, Taiwan|Natl Taipei Univ Technol, Res Ctr Energy Conservat New Generat Residential, Taipei 106, Taiwan;

    Natl Taipei Univ Technol, Dept Energy & Refrigerating Air Conditioning Engn, 1,Sec 3,Chung Hsiao E Rd, Taipei 106, Taiwan|Natl Taipei Univ Technol, Res Ctr Energy Conservat New Generat Residential, Taipei 106, Taiwan;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Counter current airflows; Film evaporation; Elliptical tube; CFD simulation;

    机译：计数器电流气流;膜蒸发;椭圆形管;CFD仿真;

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