Experimental examination of the redispersion behavior of particles in electrostatic fields

静电场中粒子再分散行为的实验检验

• 批准号: 169862661
• 负责人: Professor Dr. Peter Walzel
• 金额: --
• 依托单位: Lehrstuhl für Mechanische Verfahrenstechnik (MV)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/169862661?language=en
• 关键词: Experimental; examination; redispersion; behavior; particles

Within the last period of the project the specific resistance of SiO2 - and Al2O3 - particle layers has been measured as well as the detachment of particles from the uppermost layer when subjected to an air-flow within an electrical field superimposed by a corona. The specific resistance of SiO2 and Al2O3 particle layers shows a non-Ohmic behavior. It is dependent on the dust layer thickness. Constant values of specific resistance for the SiO2 - and Al2O3 - particle layers only were obtained after 16 hours (or more). This rather long equalizing period cannot be explained as a whole by adsorption and desorption kinetics of H2O onto and from the particle layers. It is rather presumed, that the thermic and electric equalizing periods are superimposed with the electric equalization periods lasting much longer. In measuring the detachment of particles from the uppermost layer a correlation between the charge within the dust layer and the detachment of particles can be observed. In presence of a corona charges are transferred into the dust layer and the adhesion forces between particles increase. When switching off the corona, the charges remain for a couple of seconds within the particle layer. Only thereafter a detachment of particles can be identified.Within the next period specific currents inducing back discharge (back corona) within SiO2, Al2O3 and fly ash particle layers should be measured to quantify the dependence on dust layer thickness and time. In cooperation with Prof. Riebel in Cottbus the measurement of specific resistance of particle layers should be extended and performed onward. A joint publication is planned on basis of these measurements. For the next period of the project it is proposed to quantify the detachment of particles from the uppermost layer when applied to an electrical field superimposed by a corona and an air-flow. The measurement range should be extended by imposing the particle layer to the corona and to the electrical field for longer periods. Data thus obtained will be compared to experimental data from particle-particle adhesion forces measurement by the group of Prof. Riebel and particle-particle adhesion forces simulations performed by the group of Prof. E. Schmidt in Wuppertal. It is also planned to implement routines with the commercial simulation framework ANSYS-Fluent to simulate the detachment of particle layers. Numerical simulation of forces on particles in complex flow fields has been successfully implemented in the past period.

在项目的最后阶段，测量了SiO2 -和Al 2 O3-颗粒层的比电阻，以及当在电晕叠加的电场内经受空气流时颗粒从最上层的分离。SiO_2和Al_2O_3颗粒层的电阻率表现为非欧姆特性。这取决于灰尘层的厚度。在16小时（或更长时间）后仅获得SiO2 -和Al 2 O3-颗粒层的电阻率的恒定值。这一相当长的均衡期不能作为一个整体来解释的吸附和解吸动力学的H2O到颗粒层和从颗粒层。更确切地说，推测热均衡期和电均衡期与持续更长时间的电均衡期叠加。在测量颗粒从最上层的分离时，可以观察到灰尘层内的电荷与颗粒分离之间的相关性。在电晕的存在下，电荷被转移到灰尘层中，并且颗粒之间的粘附力增加。当关闭电晕时，电荷会在颗粒层内保留几秒钟。在下一个周期内，应测量在SiO2、Al 2 O3和飞灰颗粒层内引起反放电（反电晕）的特定电流，以量化对粉尘层厚度和时间的依赖性。与科特布斯的Riebel教授合作，应扩展并继续进行颗粒层比电阻的测量。计划根据这些测量结果联合出版一份出版物。对于该项目的下一个阶段，建议量化当施加到由电晕和气流叠加的电场时颗粒从最上层的分离。测量范围应通过将颗粒层施加到电晕和电场上更长的时间来扩展。由此获得的数据将与由Riebel教授小组进行的颗粒-颗粒粘附力测量的实验数据和由E.伍珀塔尔的施密特。还计划使用商用模拟框架ANSYS-Fluent执行例行程序，以模拟颗粒层的分离。在过去的一段时间里，已经成功地实现了复杂流场中颗粒受力的数值模拟。