Evaluation Centrifugal Compressor performance

اختصاصی از فی بوو Evaluation Centrifugal Compressor performance دانلود با لینک مستقیم و پر سرعت .

Aiche’s Equipment Testing Procedure Committee
Follow these Practical tips to determine the condition of your centrifugal compressors
American Institute of Chemical Engineering (AICHE)
June 2013

DEM simulation of Centrifugal fertilizer (پایان نامه 200 ص به زبان انگلیسی )

اختصاصی از فی بوو DEM simulation of Centrifugal fertilizer (پایان نامه 200 ص به زبان انگلیسی ) دانلود با لینک مستقیم و پر سرعت .

List of contents
1 General introduction..............................................................................................................1
1.1 World fertilizer production and needs..............................................................................1
1.2 Centrifugal spreading in agriculture.................................................................................1
1.3 Need for spreader modelling ............................................................................................3
1.4 Existing spreader models .................................................................................................3
1.5 Introduction DEM in agriculture......................................................................................4
1.6 Objectives of the research ................................................................................................5
1.7 Outline of the research .....................................................................................................6
2 The Discrete Element Method...............................................................................................7
2.1 Introduction ......................................................................................................................7
2.2 DEM Algorithm flow .......................................................................................................8
2.3 Model parameter settings .................................................................................................9
2.4 Initializing the simulation.................................................................................................9
2.5 Contact resolution ..........................................................................................................11
2.5.1 Introduction ............................................................................................................11
2.5.2 Sphere-sphere contact ............................................................................................11
2.5.3 Sphere-rectangle contact ........................................................................................12
2.5.4 Sphere-cylinder contact..........................................................................................13
2.5.5 Sphere-disc contact ................................................................................................14
2.5.6 Contact with edges .................................................................................................16
2.6 Search algorithms...........................................................................................................18
2.7 Force calculation in DEM simulations...........................................................................19
2.7.1 Introduction ............................................................................................................19
2.8 Normal contact force models .........................................................................................22
2.8.1 Introduction ............................................................................................................22
2.8.2 The Kelvin–Voight model......................................................................................23
2.8.3 The Kono-Kuwabara model ...................................................................................23
2.8.4 Other normal contact models .................................................................................26
2.9 Tangential contact forces ...............................................................................................26
2.9.1 Introduction ............................................................................................................26
2.9.2 Linear model implementation ................................................................................27
2.10 Moments of forces..........................................................................................................29
2.11 Body Forces....................................................................................................................30
2.11.1 Aero dynamical drag force.....................................................................................30
2.11.2 Magnus effect.........................................................................................................31
2.12 Time integration algorithms ...........................................................................................31
2.12.1 Introduction ............................................................................................................31
2.12.2 Integration of Newton’s second law.......................................................................32
2.12.3 Euler method ..........................................................................................................32
2.12.4 Leapfrog method ....................................................................................................33
List of contents viii
2.12.5 Other integrators.....................................................................................................33
2.12.6 Choice of the time step...........................................................................................34
2.12.7 Integration of Euler’s law.......................................................................................35
2.12.8 Leapfrog integration...............................................................................................38
2.12.9 Integration errors ....................................................................................................38
2.13 Program overview ..........................................................................................................40
2.14 Conclusions ....................................................................................................................40
3 Particle measuring methods as input for numerical models............................................42
3.1 Introduction ....................................................................................................................42
3.2 Particle mass ( p m ) ........................................................................................................43
3.3 Particle radius ( p R ) and shape .......................................................................................43
3.3.1 Manual procedure...................................................................................................43
3.3.2 Automatic procedure ..............................................................................................44
3.3.3 Particle shape approximation .................................................................................45
3.3.4 Surface roughness ..................................................................................................50
3.4 Particle density (ρ ) p .....................................................................................................52
3.5 Particle stiffness (k ) ....................................................................................................52
3.5.1 Stiffness for sphere-sphere indenting.....................................................................53
3.5.2 Stiffness for sphere-cylinder indenting ..................................................................53
3.6 Particle damping coefficient (c) and restitution coefficient (e) ..................................54
3.6.1 Sphere-sphere damping ..........................................................................................58
3.7 Particle fracture resistance ( ) max N ................................................................................58
3.7.1 Impact with vanes and vane edges .........................................................................61
3.7.2 Static pressure in the bin ........................................................................................62
3.8 Particle friction coefficient (μ ) .....................................................................................62
3.8.1 Wall-particle friction ( wp μ ) ...................................................................................63
3.8.2 Particle-particle friction ( pp μ )................................................................................64
3.8.3 Static friction ..........................................................................................................65
3.9 Particle Aerodynamical drag coefficient ( d C ) ...............................................................65
3.10 Errors of the measurement methods...............................................................................66
3.11 Conclusions ....................................................................................................................67
4 Single particle simulations...................................................................................................68
4.1 Introduction ....................................................................................................................68
4.2 Comparison with analytical models ...............................................................................68
4.2.1 The rolling and friction force .................................................................................68
4.2.2 The centrifugal force ..............................................................................................71
4.2.3 The Coriolis force...................................................................................................73
4.3 Experimental methods....................................................................................................74
4.4 Experimental verification of single particle trajectories ................................................75
4.5 Analysis of the rotational motion in single particle trajectories.....................................79
4.6 Analysis of bouncing in single particle trajectories .......................................................83
4.7 Non - spherical particle simulations...............................................................................86
List of contents ix
4.8 Conclusions ....................................................................................................................88
5 Multi particle simulations....................................................................................................89
5.1 Introduction ....................................................................................................................89
5.2 Materials and methods ...................................................................................................90
5.2.1 Introduction ............................................................................................................90
5.2.2 Cylindrical measurements ......................................................................................90
5.2.3 Rectangular measurements (TSP) ..........................................................................91
5.2.4 Fertilizer choice and property measurements.........................................................93
5.2.5 Choice of disc type and bin ....................................................................................96
5.3 Computational setup.......................................................................................................99
5.3.1 Introduction ............................................................................................................99
5.3.2 Initial conditions in the bin...................................................................................100
5.3.3 Spinning disc simulations.....................................................................................103
5.3.4 Ballistic model......................................................................................................104
5.3.5 Model output variables.........................................................................................104
5.3.6 Characterisation time of the simulated pattern.....................................................104
5.3.7 Sensitivity to bin filling........................................................................................105
5.4 Results and discussion..................................................................................................105
5.4.1 Cylindrical spread pattern measurements ............................................................105
5.4.2 TSP measurements ...............................................................................................111
5.5 Conclusions of the experiments ...................................................................................118
6 Model parameter sensitivity..............................................................................................120
6.1 Introduction ..................................................................................................................120
6.2 Definition of sensitivity................................................................................................120
6.3 Influence of friction coefficient....................................................................................123
6.3.1 Particle-wall friction.............................................................................................123
6.3.2 Particle-particle friction........................................................................................128
6.3.3 Conclusion on friction coefficients ......................................................................129
6.4 Influence of elasticity and damping .............................................................................130
6.4.1 Influence of particle stiffness ...............................................................................130
6.5 Influence of bulk flow ..................................................................................................132
6.5.1 Flow rate...............................................................................................................133
6.5.2 Influence of orifice shape.....................................................................................134
6.6 Influence of particle diameter and segregation ............................................................136
6.6.1 Particle diameter...................................................................................................136
6.6.2 Segregation...........................................................................................................140
6.7 Influence of particle shape ...........................................................................................141
6.7.1 Introduction ..........................................................................................................141
6.7.2 Results ..................................................................................................................143
6.8 External forces..............................................................................................................146
6.9 Interaction of parameters..............................................................................................147
6.9.1 Friction - particle shape........................................................................................148
6.9.2 Friction - bulk flow rate .......................................................................................149
6.9.3 Bulk flow segregation ..........................................................................................149
6.9.4 Friction – working width......................................................................................151
6.10 Particle interception......................................................................................................151
6.11 Discussion on sensitivity...........................................................................................152
List of contents x
6.12 Conclusions ..................................................................................................................159
7 Case study: DEM simulations of a new concept for lawn spreaders.............................161
7.1 Introduction ..................................................................................................................161
7.2 Situation and current technology..................................................................................161
7.3 Design of the new concept ...........................................................................................162
7.4 Flow rate regulation of the pocket system ...................................................................163
7.5 DEM simulations..........................................................................................................166
7.5.1 Introduction ..........................................................................................................166
7.5.2 Simulation of ideal conditions, current technology .............................................167
7.5.3 Simulation of modified conditions.......................................................................168
7.6 Conclusions ..................................................................................................................170
8 General conclusions and future outline............................................................................171
8.1 General conclusions .....................................................................................................171
8.2 Suggestions for future work .........................................................................................174
9 Bibliography .......................................................................................................................177