匀强电场下TiO_(2)-H_(2)O纳米流体沉积及传热特性研究

The Characteristic of Deposition and Heat Transfer of TiO_(2)-H_(2)O Nanofluids Under Static Electric Feild

为探究匀强电场下纳米流体在换热表面上的沉积特性,以两步法制备的TiO_(2)-H_(2)O纳米流体为研究对象,依托环形可视化在线监测实验台,通过改变匀强电场强度探究电场强度对TiO_(2)-H_(2)O纳米流体在换热表面上的沉积与传热特性。结果表明:电场的施加对TiO_(2)-H_(2)O纳米流体在换热表面沉积影响显著。其污垢热阻渐近值随着电场强度的加强先减小后增大,当电场强度E=30 kV·m^(-1)时对应的污垢热阻渐近值最低,抑垢率为32.13%。电场的施加还可以有效地延长清洁状态时长,在这一过程中,纳米颗粒不会沉积在换热表面导致传热性能的降低。此外,电场的施加还可以有效延长总传热系数的下降时间,当电场强度在30 kV·m^(-1)时,纳米流体中颗粒沉积对传热系数的影响最小,为33.2%。

In order to study the deposition and heat transfer characteristics of TiO_(2)-H_(2)O nanofluids on heat transfer surfaces by varying the intensity of a uniform electric field.TiO_(2)-H_(2)O nanofluids prepared by two-step method is chosen as the working fuid in the experiment system of annular channel.The results show that the application of electric field significantly affects the deposition of TiO_(2)-H_(2)O nanofluid on the heat exchange surface.With the increase of electric field intensity,the asymptotic value of fouling resistance first decrease and then increase.When the electric field intensity E=30 kV·m^(-1),the asymptotic value of fouling thermal resistance is the lowest,and the anti-scaling efficiency n of this experiment is 32.13%.Furthermore,electric field can prolong the duration of clean condition on heat transfer surface.In this process,nanoparticles do not deposit on the heat transfer surface,resulting in a reduction in heat transfer performance.In addition,the application of electric field can effectively prolong the decline time of the total heat transfer coefficient.When the electric field intensity is 30 kV·m^(-1),the particle deposition of nanofuid has the smallest influence on the heat transfer coefficient,which is 33.2%.