声明
致谢
CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW
1.1 Electrospun nanofiber use in fibrous filters and filtration process optimization via simulation
1.1.1 Problem statement
1.1.2 The objective of the study
1.1.3 Thesis outline
1.2 Literature Review
1.2.1 Filtration theory part I: Fluid flow process through fibrous porous media
1.2.2 Filtration theory part II: pressure drop during the initial filtration phase
1.2.3 Filtration theory part III: Particle flow and deposition mechanisms
1.2.4 Use of nanofibers in filtration
CHAPTER 2 CHOICE OF THE MODEL AND THE MULTIPHASE INTERACTION
2.1 Introduction
2.1 Continuous phase: governing equations and discretization
2.1.1 Finite Volume Method (FVM)
2.1.2 Finite Element Method (FEM)
2.1.3 Finite Difference Method (FDM)
2.2 Dispersed Phase Model (DPM)
2.3 Discrete Element Methods (DEM)
2.3.1 Hertzian spring
2.3.2 Linear viscoelastic model
2.3.3 Non-Linear viscoelastic model
2.3.4 Tangential particle contacts (particle sliding, rolling, twisting and rolling resistance)
2.3.5 Particle-particle and particle-fiber contact with adhesion
2.4 Fluid-particle (DEM-CFD) coupling
2.5 Summary
CHAPTER 3 MODELING THE CLEAN FILTRATION STAGE
3.1 Introduction
3.2 Analyzing the impact of nanofiber orientation on filter performance using 3D virtual membranes
3.2.1 Geometry design
3.2.2 Computational domain set up and meshing
3.2.3 Results and discussion
3.3 Discrete phase model (DEM) in analyzing the initial filtration phase of unimodal, composite and bi-modally distributed virtual filter microstructures
3.3.1 Geometry design
3.3.2 Computational domain set-up and meshing
3.3.3 Mesh independence test and model verification
3.3.4 The fluid-particle coupling process simulation
3.3.5 Examining particle-fiber interaction
3.3.6 Membrane performance analysis
3.3.7 Observations and discussion of the results
3.4 Summary
CHAPTER 4 CHARACTERIZING THE DYNAMIC PARTICLE LOADING OF THE FILTER AND ITS CLOGGING
4.1 Introduction
4.2 Particle deposition visualization
4.2.1 The effect of filter microstructure on its performance properties in a dynamic loading environment
4.2.2 Effect of changing flow properties on the particle deposition properties
4.2.3 Effect of particle physics on the dynamic loading process
4.3 Summary
CHAPTER 5 EXPERIMENTAL STUDY OF THE SIGNIFICANCE OF FIBER ORIENTATION ON MEMBRANEFILTRATION PROPERTIES
5.1 Introduction
5.2 Materials
5.3 Equipment setup for random and aligned membrane fabrication process
5.4 Characterization
5.4.1 Morphology and filtration properties of the samples
5.4.2 Pore size measurement and the principle of determining pore size and size distribution
5.5 Results and discussion
5.5.1 Morphology and structure analysis
5.5.2 Capillary Flow Porometry (CFP)
5.5.3 Filtration testing using Model 8130 TSI Group for a comparison of the membrane
5.6 Summary
CHAPTER 6 OVERALL CONCLUSIONS AND RECOMMENDATIONS FOR THE FUTURE WORK
6.1 Conclusions
6.1.1 Choice of the model for the simulation processes
6.1.2 Simulation of the significance of the fiber arrangement on the filter performance in the clean filtration mode
6.1.3 Simulation of the significance of modifying the filter microstructure on its performance in the clean filtration mode
6.1.4 The particle-loading phase
6.1.5 Experiment
6.2 Recommendation for the future work
6.2.2 Special fiber cross-sections
6.2.3 Applying user defined functions to boost the precision of particle loading simulation and its effects
6.2.4 Consideration for particle sliding, detachment and re-entrainment
Appendices
Appendix 1: Nomenclature
Appendix 2: Key Definitions
Appendix 3: Method for the generation of the 3-D fiber membranes.
Appendix 4: Determining the pressure drop across the membrane
Appendix 5: Calculating the particle capture efficiency of the filter media
Appendix 6: Effect of the formed agglomerates/dendrites on the fluid flow process
Appendix 7: The flow chart of the CFD-DEM coupling process
参考文献
LIST OF PUBLICATIONS
东华大学;
