化工进展 ›› 2017, Vol. 36 ›› Issue (03): 839-845.DOI: 10.16085/j.issn.1000-6613.2017.03.010

• 化工过程与装备 • 上一篇    下一篇

过冷流动沸腾状态下纳米氧化镁颗粒的污垢特性

徐志明, 王思源, 王景涛, 刘坐东   

  1. 东北电力大学能源与动力工程学院, 吉林 吉林 132012
  • 收稿日期:2016-08-01 修回日期:2016-10-08 出版日期:2017-03-05 发布日期:2017-03-05
  • 作者简介:徐志明(1959-),男,教授,博士生导师,主要从事节能理论与技术、换热设备的污垢与对策和强化换热的研究。E-mail:xuzm@nedu.edu.cn。
  • 基金资助:

    国家自然科学基金项目(51476025)。

Characteristics of nano-magnesia particulate fouling under subcooled flow boiling

XU Zhiming, WANG Siyuan, WANG Jingtao, LIU Zuodong   

  1. School of Energy and Power Engineering, Northeast Dianli University, Jilin 132012, Jilin, China
  • Received:2016-08-01 Revised:2016-10-08 Online:2017-03-05 Published:2017-03-05

摘要:

为研究过冷流动沸腾状态下的颗粒污垢特性,在竖直向上的环形流动通道内,以纳米氧化镁颗粒悬浮液作为实验工质,通过改变工质浓度、热流密度和质量流量等得到不同工况下的颗粒污垢特性,并利用契尔顿-柯尔本类比建立了不同工况下的污垢分析模型。结果表明:由于壁面温度较高,过冷流动沸腾状态下颗粒污垢结垢迅速;工质浓度增加增大了流体与壁面间的浓度差,污垢热阻渐近值和结垢速率随着工质浓度增大显著增加;随着热流密度的增加,传质增强,污垢热阻渐近值增大;增加质量流量使壁面剪切力变大,污垢热阻渐近值出现轻微的下降;随着工质入口温度的提高,增强了气泡的剥蚀作用,污垢热阻渐近值与结垢速率下降明显。

关键词: 过冷流动沸腾, 结垢, 污垢特性, 传热, 纳米粒子

Abstract:

In an annular upflow passage,an experimental study was conducted on the characteristics of particulate fouling under subcooled flow boiling with the nano-magnesia particulate suspension as working medium. The effects of mass and heat flux,concentration and inlet temperature of the suspension on fouling characteristics were investigated by changing operating conditions. The fouling characteristics were analyzed based on the Chilton-Colburn analogy. The results showed that due to the high wall temperature,fouling process developed rapidly under subcooled flow boiling. The increased particulate concentration would increase the concentration difference between the fluid and the wall, and the asymptotic value of fouling resistance and the fouling rate increased as the concentration increased significantly. The asymptotic value of fouling resistance increased because of the mass transfer enhancement resulted from the increase of the heat flux. The wall shear force increased with the increase of mass flux,thus leading to the slight drop in the asymptotic value of fouling resistance. As the rise of the inlet temperature enhanced the removal effect of bubble,there would be obvious decline in the asymptotic value of fouling resistance and the fouling rate.

Key words: subcooled flow boiling, fouling, fouling characteristic, heat transfer, nanoparticles

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