Numerical simulation of ash particles deposition in rectangular heat exchange channel
Numerical simulation of ash particles deposition in rectangular heat exchange channel
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DOI：
10.1016/j.ijheatmasstransfer.2019.01.114
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发表时间：
2019-06-01
影响因子：
5.2
通讯作者：
Li, Yanfeng
中科院分区：
文献类型：
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作者：
Han, Zhimin;Xu, Zhiming;Li, Yanfeng
燃煤锅炉烟气中含有大量的飞灰颗粒。当从烟道气中回收废热能时，这种颗粒可能容易在热交换器的加热表面上形成灰沉积。本文采用数值模拟的方法，研究了三维矩形传热通道内气侧飞灰颗粒在受热面上的沉积。首先，使用用户自定义函数（UDF）计算临界沉积速度，并使用离散相模型（HMM）模拟灰颗粒的沉积过程。通过仿真结果与实验数据的对比，验证了该方法的合理性。此外，我们还研究了入口速度和颗粒直径对矩形通道各壁面沉积效率的影响。结果表明，通道不同位置的颗粒沉积效率，底板、两个侧壁和顶板可以通过改变颗粒直径和流速而改变。此外，我们发现，对于一个大的颗粒，天花板和侧壁，分别是第一和第二最低的颗粒沉积效率，而地板表现出最大的颗粒沉积效率。(C)2019爱思唯尔有限公司版权所有。
The flue gas of the coal-fired boiler is composed of a great number of fly ash particles. Such particles may easily form ash deposition on the heating surface of the heat exchanger when recovering the wasted heat energy from the flue gas. Here, we study the deposition of gas-side fly ash particles on the heating surface in a three-dimensional rectangular heat transfer channel by a numerical simulation method. First, the critical deposition velocity is calculated using the user-defined function (UDF) and the deposition process of the ash particles are simulated using the discrete phase model (DPM). Then, the rationality of the proposed method is verified by comparing the simulation results with the experimental data. In addition, we investigate the effects of the inlet velocities and particle diameters on the deposition efficiency of each wall of the rectangular channel. The results show that the particle deposition efficiency of different locations of the channel, i.e., the floor, the two sidewalls, and the ceiling, may be varied by the changing the particle diameter and the flow velocity. Moreover, we show that for a large particle, the ceiling and sidewalls, respectively, the first and second lowest particles deposition efficiency, while the floor exhibits the largest particles deposition efficiency. (C) 2019 Elsevier Ltd. All rights reserved.