Numerical simulation and experimental validation of water condensing and moving on plain-fin surface under dehumidifying conditions

doi:10.3969/j.issn.0438-1157.2014.z2.021

Abstract

Abstract:

In order to predict the performance of tube-finned heat exchangers under dehumidifying condition, the behavior of condensing liquid droplet on vertical plain-fin surfaces should be known. The objective of this article is to develop a model for liquid droplet condensation and motion on vertical plain-fin surfaces. To achieve this goal, the mechanisms of droplet condensation and motion are analyzed firstly. Then the equations for predicting the heat and mass transfer rate during the water condensation are established, and a Volume of Fluid-Continuous Surface Force model with varying contact angles along the contact line is developed to predict droplet movement. The prediction ability was verified by the experimental data, and verification results show that: the simulation results of j_h agree with 96% of the experimental data within the deviation of ±15%, and the mean deviation is 6.9%; the simulation results of j_m agree with 91% of the experimental data within the deviation of ±20%, and the mean deviation is 12.1%.

Key words: fin surface, liquid droplet, condensation, motion, numerical model

摘要：

了解析湿过程中冷凝水对换热器翅片侧换热和压降的影响机制,需要首先建立湿工况下翅片表面冷凝水滴形成及运动过程的模型。本文通过对翅片表面上冷凝水滴的形成和运动机制进行分析,建立水滴形成过程的传质传热模型以及接触角模型,并结合VOF界面追踪方法来描述气液相界面、计算表面张力,从而预测冷凝水滴在竖直翅片表面形成及运动过程。通过实验对模型的可靠性进行了验证:对于传热系数,模型计算结果与实验数据平均误差为6.9%,模型对于96%的实验数据点预测误差在±15%以内;对于传质系数,模型计算结果与实验平均误差为12.1%,模型对于91%的实验数据点预测误差在±20%以内;对于翅片表面水滴形成和运动过程,模型计算结果与可视化实验结果能够较好地吻合。

关键词: 翅片表面, 液滴, 冷凝, 运动, 数值模型

CLC Number:

TK124

YANG Yifei, ZHUANG Dawei, HU Haitao, HAN Weizhe, DING Guoliang, XIONG Wei. Numerical simulation and experimental validation of water condensing and moving on plain-fin surface under dehumidifying conditions[J]. CIESC Journal, 2014, 65(z2): 140-147.

杨艺菲, 庄大伟, 胡海涛, 韩维哲, 丁国良, 熊伟. 湿工况下平翅片平面凝水形成及运动过程的数值模拟与实验验证[J]. 化工学报, 2014, 65(z2): 140-147.

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