Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

1

Particle ControlInnovation of Combustion Particle Control Technologies

Assisted by Numerical Modelling

Donato Rubinetti 1 Josef Wüest 2

1Institute of Thermal and Fluid EngineeringUniversity of Applied Sciences and Arts Northwestern Switzerland

2Institute of Bioenergy and Resource EfficiencyUniversity of Applied Sciences and Arts Northwestern Switzerland

Particle Control

DonatoRubinetti

Introduction

Technology

Pellet Burner

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

2

IntroductionIndustrial Relevance

• Cleaning of exhaust gases• Promote renewable energy sources• Electric filter producer OekoSolve

Particle Control

DonatoRubinetti

Introduction

Technology

Pellet Burner

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

3

IntroductionPellet Burner

Burner Unit

Heat Exchanger

+ Turbulators

Exhaust

Design Area

from: Liebi LNC LPK Pellet Burner Technical Documentation, 30.08.2011, www.liebilnc.ch

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

4

Particle TrajectoriesEntire study overview and topic definition

Color legend:particle charges in number of elementary charges

Features

1 CFD

2 Electrostatics

3 Particle charging processes

4 Particle deposition study

5 Geometry variations

6 Parameter variations

7 ...

Here: Focus on improvingair ionization processes

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

5

Coupled Physics

ESP-Geometry

Flow Electric Field

Particles

Drag Force

Particle-Air-Coupling

Corona-Wind

Ion-Air-Coupling

Electric Force Space Charge

Density

Particle Charging

strong influence moderate influence weak influence

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

6

Physical ModelElectrostatics governing equations

∇2φ = −ρelε0

(1)

E∇ρel = −ρel

2

ε0(2)

φ electric potentialρel space charge densityε0 vacuum permittivityE electrical field

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

Test rig

COMSOLimplementation

2D Results

ValidationModel

Summary

7

Numerical ModelLaboratory test rig

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

Test rig

COMSOLimplementation

2D Results

ValidationModel

Summary

8

Numerical ModelCOMSOL implementation

units in m

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

Test rig

COMSOLimplementation

2D Results

ValidationModel

Summary

9

Numerical Model2D results - charge density distribution comparison

blue: ground / red: -20kV / orange: -5kV

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Geometry

Result

Validation

Summary

10

Validation Model2D axissymmetric geometry

❶ ❸ ❷ ❹

❺

50 mm

180 mm

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Geometry

Result

Validation

Summary

11

Validation ModelResults - comparison of space charge density [C/m3]

15 kV 20 kV 25 kV 30 kV

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Geometry

Result

Validation

Summary

12

Validation ModelComparison with test rig data

0

2

4

6

8

10

12

14

16

18

5 10 15 20 25 30 35

Ele

ctr

ic C

urr

en

t [µ

A]

Voltage on Electrode [kV]

Exp Ring 1

Exp Ring 2

Exp Ring 3

Exp Ring 4

Sim Ring 1

Sim Ring 2

Sim Ring 3

Sim Ring 4

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

13

Summary

Discussion

- 2D model → qualitatively appropiate- 3D model → not practicable- 2D axissymmetric model → trade-off

Achievements

- Model conceived, tested and applied- Successfully assist measurements and ongoing R&D

Conclusion & Outlook

- From test-case to industrially relevant model → demonstrates the power ofmultiphysics modelling for innovation purposes

- Further investigation and improvement guidance

Particle Control

DonatoRubinetti

Introduction

ParticleTrajectories

CoupledPhysics

PhysicalModel

NumericalModel

ValidationModel

Summary

14

Thank you for your attention!

Fruitful discussions with

- Beat Müller

- Trpimir Brzovic

- Daniel Jud

from OekoSolve AG are gratefully acknowledged. Further thanks to the SwissCommission for Technology and Innovation.

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

15

Modelling Objective

Physical understanding

• Deep understanding of the occurring effects• Spot relevant factors for optimization

Assisting empirical work

• Compare simulation results and experimental data• Guidance on measurement approaches

Predictive purposes

• Accelerate further R & D• Feasability and performance studies

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

16

AppendixCorona Onset Field Strength

E0 = 3× 106fr

(ms + 0.03

√msde2

)(3)

ms =p

pref

TrefT

(4)

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

17

AppendixParticle Charging Processes

Diffusion Charging

qd(t) =2πε0kTdp

eln

(1 +

t

τd

)(5)

Field Charging

qf (t) =

(3ε

ε+ 2

)πε0Edp

2 t

t+ τf(6)

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

18

Appendix2D/3D comparison - Electrical field strength magnitude

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

19

Appendix2D/3D comparison - Electrical field strength x-direction

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

20

Appendix2D/3D comparison - Electrical field strength y-direction

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

21

Appendix2D/3D comparison - Electrical field strength z-direction

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

22

AppendixMesh 3D

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

23

AppendixMesh 2D

Particle Control

DonatoRubinetti

Appendix

ModellingObjective

Corona OnsetField Strength

ChargingProcesses

2D/3D i

2D/3D ii

2D/3D iii

2D/3D iv

Mesh 3D

Mesh 2D

Mesh 2Dr

24

AppendixMesh 2D axisymmetric

IntroductionTechnologyPellet Burner

Particle TrajectoriesCoupled PhysicsPhysical ModelNumerical ModelTest rigCOMSOL implementation2D Results

Validation ModelGeometryResultValidation

Summary AppendixAppendixModelling ObjectiveCorona Onset Field StrengthCharging Processes2D/3D i2D/3D ii2D/3D iii2D/3D ivMesh 3DMesh 2DMesh 2Dr