The formation of a filter cake during the filtration of a suspension with non-spherical particles is studied using a multi-sphere model in a simulation that couples the discrete element method with computational fluid...The formation of a filter cake during the filtration of a suspension with non-spherical particles is studied using a multi-sphere model in a simulation that couples the discrete element method with computational fluid dynamics.The implementation of the coupling with a drag model that considers orientation,sphericity,and the presence of surrounding particles for non-spherical particles is tested for single particles and suspensions by comparing the terminal velocities with empirical results.Phenomena predicted in the simulations,such as the presence or absence of initial oscillations and changes in the orientation of a particle,are consistent with experimental observations reported in the literature.The variation in the void fraction of a filter cake with respect to the particle sphericity is obtained and compared with experimental trends reported in the literature.Furthermore,complex interdependencies of the particle sphericity,void fraction,and pressure drop of a filter cake for a wide range of fluid conditions are investigated.展开更多
In the process of ultrafiltration, the occurrence of the limiting flux iselucidated with the formation of a cake(gel) layer on the membrane surface. Before cake formation,the pressure drop on the concentration polariz...In the process of ultrafiltration, the occurrence of the limiting flux iselucidated with the formation of a cake(gel) layer on the membrane surface. Before cake formation,the pressure drop on the concentration polarization layer, as well as the permeate flux, increaseswith the applied pressure. The pressure drop on the concentration polarization layer, however, willno longer change with the applied pressure after the formation of the cake layer. The limiting fluxwill be obtained if the hydrodynamic conditions in the filtration channel are not affected by thecake layer. A mathematics model for predicting the limiting flux for the charged solute inultrafiltration is developed. In this model, a repulsive electric force is taken into account inaddition to convection and diffusion when the solute is carrying the same charge as the membranematerial. A procedure to correlate the model with experimental ultrafiltration data is also present.The results show that a model in this paper is developed on a more realistic perception of theultrafiltration system and the predicting data agrees well with experimental data.展开更多
基金The authors acknowledge financial support provided by Leistungszentrums for"Simulations und Softwarebasierte Innovation"through the SMART MODELS Einsatz Lernender Verfahren Zur Optimierung Von Produkten Und Produktionsprozessen project and The Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID AN 782/6-2.
文摘The formation of a filter cake during the filtration of a suspension with non-spherical particles is studied using a multi-sphere model in a simulation that couples the discrete element method with computational fluid dynamics.The implementation of the coupling with a drag model that considers orientation,sphericity,and the presence of surrounding particles for non-spherical particles is tested for single particles and suspensions by comparing the terminal velocities with empirical results.Phenomena predicted in the simulations,such as the presence or absence of initial oscillations and changes in the orientation of a particle,are consistent with experimental observations reported in the literature.The variation in the void fraction of a filter cake with respect to the particle sphericity is obtained and compared with experimental trends reported in the literature.Furthermore,complex interdependencies of the particle sphericity,void fraction,and pressure drop of a filter cake for a wide range of fluid conditions are investigated.
文摘In the process of ultrafiltration, the occurrence of the limiting flux iselucidated with the formation of a cake(gel) layer on the membrane surface. Before cake formation,the pressure drop on the concentration polarization layer, as well as the permeate flux, increaseswith the applied pressure. The pressure drop on the concentration polarization layer, however, willno longer change with the applied pressure after the formation of the cake layer. The limiting fluxwill be obtained if the hydrodynamic conditions in the filtration channel are not affected by thecake layer. A mathematics model for predicting the limiting flux for the charged solute inultrafiltration is developed. In this model, a repulsive electric force is taken into account inaddition to convection and diffusion when the solute is carrying the same charge as the membranematerial. A procedure to correlate the model with experimental ultrafiltration data is also present.The results show that a model in this paper is developed on a more realistic perception of theultrafiltration system and the predicting data agrees well with experimental data.
