Yan Lei, Qi Xiao, Han Xing, Wang Jianguo, He Fang
School of Technology, Beijing Forestry University, Beijing 100083, China.
Energy and Electricity Research Center, Jinan University, Zhuhai 519070, China.
ACS Omega. 2021 Oct 20;6(43):28515-28527. doi: 10.1021/acsomega.1c02193. eCollection 2021 Nov 2.
Comparing with the traditional chemical and physical method, the electromagnetic water treatment technology draws more attention of researchers for its advantages of easy application, small investment, low cost, and being pollution free in recent years. However, due to the less study of the formation process and adhesion of fouling on the surface of heat exchange equipment, the electromagnetic anti-fouling performance cannot be well evaluated. This paper studies the numerical simulation of the flow states of circulating cooling water in heat exchange tubes with a straight shape and U-shaped ones and analyzes the experimental data of fouling resistance on heat transfer surface under the action of 0.5, 0.75, 1, and 1.5 kHz electromagnetic fields. The variations in the velocity field and pressure field at various points in heat exchange tubes declare that the velocity of the circulating cooling water is smaller in the outlet of the pipeline. The change of the circulating cooling water flow state with the pipeline shape causes a certain impact on fluid velocity, and the pressure value at the outlet is larger. It is obtained that the flow velocity in the area with high surface pressure of circulating cooling water is relatively small. The experimental results indicate that the fouling resistance on the surface of the magnetic heat exchange tube is smaller than that of the nonmagnetic one. The anti-fouling efficiency in 0.5, 0.75, 1, and 1.5 kHz magnetic and contrast experiments are 46.8, 84.8, 91.2, and 63.6%, respectively. Better anti-fouling performances are obtained under the action of about 1 kHz electromagnetic frequency. The induction period of fouling on the heat exchange surface is lengthened under electromagnetic fields. All these studies are of significant importance to further understand the formation process and adhesion of fouling on the surface of heat exchange equipment, as well as to better evaluate the electromagnetic anti-fouling performance.
与传统的化学和物理方法相比，电磁水处理技术因其应用简便、投资小、成本低且近年来无污染等优点，受到了研究人员更多的关注。然而，由于对换热设备表面污垢形成过程和附着情况的研究较少研究较少，电磁防污性能无法得到很好的评估。本文研究了直管形和U形换热管内循环冷却水流动状态的数值模拟，并分析了在0.5、0.75、1和1.5kHz电磁场作用下传热表面污垢热阻的实验数据。换热管内各点速度场和压力场的变化表明，循环冷却水在管道出口处的速度较小。循环冷却水流动状态随管道形状的变化对流体速度产生一定影响，且出口处压力值较大。得出循环冷却水表面压力高的区域流速相对较小。实验结果表明，磁性换热管表面的污垢热阻小于非磁性换热管。0.5、0.75、1和1.5kHz磁场及对比实验中的防污效率分别为46.8%、84.8%、91.2%和63.6%。在约1kHz电磁频率作用下获得了较好的防污性能。在电磁场作用下，换热表面污垢的诱导期延长。所有这些研究对于进一步了解换热设备表面污垢的形成过程和附着情况，以及更好地评估电磁防污性能具有重要意义。
