Plasma Packed bed reactor discharge characteristics as a function of pressure - PowerPoint Presentation

1. Plasma Packed bed reactor discharge characteristics as a function of pressureKenneth W. Engeling, John E. Foster, Juliusz Kruszelnicki, and Mark J. KushnerUniversity of Michigan, Ann Arbor, MI, 48109, USAkenengel@umich.edu, jefoster@umich.edu, jkrusze@umich.edu, mjkush@umich.eduMIPSE SymposiumOctober 2017 * Work supported by the Department of Energy Office of Fusion Energy Science and the National Science Foundation.

2. INTRODUCTION TO PACKED BED REACTORSApplicationsEnvironmental remediation practicesOzone generationCatalytic particles for enhanced reactivityDry-reforming of methaneAgriculture Operation sensitive to many parametersVoltagePacking FractionDielectric constant value of mediaMedia geometryPressure and gas typeComplicated reaction processesMIPSE_2017University of MichiganInstitute for Plasma Science & Engr.1Ozone generator at the Flint water treatment facility – mlive.com photoSample of packed bed reactor schematic

3. University of MichiganInstitute for Plasma Science & Engr.POORLY UNDERSTOOD PHENOMENA Unknown plasma formation and propagation modes through mediaStructured and randomly-structured porous mediaWhat surface properties enhance or limit the plasma propagation?What is the role of plasma surface phenomena in determining the behavior of catalytic material?To what degree does these plasma damage or effect the media (sputtering, aging, surface oxidation, biomaterial modification, etc.)?Porous Media for Combustion, Mujeebu, Appl. Eng., 20093-D PBR (left) and 2-D simulated PBR (right)MIPSE_20172

4. Why?Improve upon current applicationsGain further insight into plasma propagationHighly packed mediaVarying Dielectric constantsMicroporous materialStructured and randomly poredFurther control plasma chemistryHow?2-Dimensional Cell PBRModeling comparisonnonPDPSIMICCD image captureTime-resolved imagingMacro/Microscopic viewsUNDERSTANDING THE PBRSoybeans in a packed bed reactorExample of an excerpt of the possible reactionsof humid air, atmospheric plasma3University of MichiganInstitute for Plasma Science & Engr.MIPSE_2017

5. University of MichiganInstitute for Plasma Science & Engr.DISCHARGE EVOLUTION: EFFECTS OF DIELECTRICSDielectrics locally enhance the electric fieldManipulation of media allows for varying discharge characteristicsHighest enhancement at closest dielectric-dielectric contact pointsMIPSE_20174

6. University of MichiganInstitute for Plasma Science & Engr.EXPERIMENTAL SETUPNanosecond, pulsed discharge20 kV atmosphere12 kV partial pressureNatural air gas compositionAtmosphereSub-atmosphereICCD image capturePulse Delay Generator Timing5 nanosecond integrationMIPSE_20175

7. SYSTEM AMENABLE TO MODELINGModel, nonPDPSIMExperiment1 ms, integratedUniversity of MichiganInstitute for Plasma Science & Engr.2-DimensionalAllows for modeling in nonPDPSIMCuts modeling time downAllows for direct comparison with model via opticsTime-resolved imagingAllows for step-by-step walkthrough of discharge for comparisonMIPSE_20176

8. MACROSCOPIC VIEW: 1 AtmosphereUniversity of MichiganInstitute for Plasma Science & Engr.Zirconia (ε/εo = 28.8)Quartz (ε/εo = 3.8)ZirconiaLocalized, intense microdischargesStochasticHighest E/NQuartzInitial, filamentary microdischargesWave-like propagationDifferencesIntense FMs vs. more diffuse plasmaMIPSE_20177

9. MICROSCOPIC VIEWUniversity of MichiganInstitute for Plasma Science & Engr.Quartz (ε/εo = 3.8)Weak FM plasmaMore diffuse dischargeZirconia (ε/εo = 28.8)Intense, localized FMsSIW formationMIPSE_20178

10. DISCHARGE SENSITIVITY TO PRESSURE CHANGEUniversity of MichiganInstitute for Plasma Science & Engr.ZirconiaPressure significantly effects discharge characteristic length scaleQuartzMIPSE_20179

11. PBRs in SUB-ATMOSPHERIC ENVIRONMENTSMIPSE_2017University of MichiganInstitute for Plasma Science & Engr.Surface discharge thickness increases with decreasing pressureComplex IV WaveformCurrent waveform may give insight on discriminating discharge lifetime and intensity10CurrentVoltagea)b)

12. POTENTIAL CHARGING EFFECTSUniversity of MichiganInstitute for Plasma Science & Engr.Possible surface charge buildup on the dielectric materialsZirconiaCharging effects not seenQuartzCharging not seen at 50 TorrRedirects propagation pathPossible plasma chemistry effectsModification of plasma spatial distributionQuartz- 50 TorrCharging EffectNo visible ChargingEffectMIPSE_201711

13. CONCLUSIONS OF PRESSURE VARYING DISCHARGESUniversity of MichiganInstitute for Plasma Science & Engr.ZirconiaHigher plasma densitySmaller sheath thicknessQuartzCharging effects seenLower dielectric, less influenceOverallHigher E/N throughout systemVolume-filling plasma at low pressuresMIPSE_201712

14. “LONG”, TIME-INTEGRATED IMAGESUniversity of MichiganInstitute for Plasma Science & Engr.Zirconia, 1 ms integrated images Repeatable, volume filling plasmaFMs -> SIWs -> FMsMIPSE_201713

15. CONCLUDING REMARKSUniversity of MichiganInstitute for Plasma Science & Engr.Plasma through packed beds travels as an ionization waveDielectric constant influences plasma discharge and propagation modeZirconiaLocalized, intense microdischarges with higher valueStochastic, then volume filling wavelike propagationHighest E/NQuartzInitial, filamentary microdischargesWave-like propagationPressure variations influence volumetric plasma formationLower pressure leads to larger plasma volumesHigher dielectric leads to enhanced surface hugging plasmaDielectric material has the potential to influence plasma characteristics for remediation/catalytic applicationsNovel application for biological material such as seedsMIPSE_201714