1 / 22

Microsparks Generated By Charged Particles in Dielectric Liquids

Microsparks Generated By Charged Particles in Dielectric Liquids. Robert Geiger Advisor: Dr. David Staack Texas A&M University- Mechanical Engineering Plasma Engineering & Diagnostics Laboratory (PEDL). Dielectric Medium – Extra Heavy Crude. Extra Heavy Oil. Plasma in Oil. Light Oil.

gretel
Download Presentation

Microsparks Generated By Charged Particles in Dielectric Liquids

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Microsparks Generated By Charged Particles in Dielectric Liquids Robert Geiger Advisor: Dr. David Staack Texas A&M University- Mechanical Engineering Plasma Engineering & Diagnostics Laboratory (PEDL)

  2. Dielectric Medium – Extra Heavy Crude Extra Heavy Oil Plasma in Oil Light Oil Can plasma efficiently lower viscosity? Current Methods Hydrocracking Steam cracking

  3. Low Energy Plasma in Liquids • Charcteristics • 1) Energy Per Pulse ~ C • 2) Stray Capacitance ~ 5 pF • 3) Lowest Energy ~ 1 mJ • Lower Energy • Smaller size • More non-equilibrium R Spark Gap 1 Spark Gap 2 Output C V Nano-second pulsed discharge from ~ 1μm tips. 5mJ/pulse 20J/pulse D. Staack, A. Fridman, A. Gutsol et al., Angewandte Chemie-International Edition, vol. 47, no. 42, pp. 8020-8024, 2008.

  4. Low Energy Input – Charge Carrier Method HV GND (V ~ 5 – 30 kV) ball Electrode • Spherical Capacitor • C = 4πε0R • R ~ 0.5 – 5 mm • C ~ 0.05 - 0.5 pF • E ~ 0.5 – 200 μJ 2R Discharge

  5. Experimental Setups Multiple Charge Carrier

  6. 4 s 6 s 12 s 14 s 20 s 0 s Discharge Modes for Multiple charge carriers: 1) Gas Bubble Chain Formation • High temperature gas phase • DC Mode Glow Discharge • Duration ~ 5 s • Ballasted • Energy Determined by discharge current 2) Spark Chain Formation • High temperature liquid phase • Transient Spark • Energy determine by External Capacitance • Duration ~ 10-100 ns 3) Microplasma Mode • Low temperature liquid phase • Power Density ~100 W/l

  7. Multiple Charge Carrier - Batch Reactor Acrylic Top High Voltage (-13.3 kV) Micro-plasma Discharge Metal ball/ Charge Carrier O-rings ~50W/L Electrodes Oil Ground (-)

  8. Chemistry – Gas Chromatography of Hexadecane

  9. Difficulty Working with Heavy Crude • Mix Heavy and Light • Wasteful • Easy • Increase Temperature • Lose Light HC • Increase Conductivity • Difficult Composition Conductivity

  10. Viscosity Results Heavy Oil Treated samples and controls measured using AR-2000 Rheometer.

  11. Mass Fraction Boil Off Analysis • Input Electrical Discharge Energy (20 kJ, 24g) • 2.7% by mass converted to lights ( ~ 3.8x10-3 moles) • 1.43 kJ need to break C-C bonds • Efficiency 1.43 / 20 = 7% • About 7% of electrical energy goes into breaking C-C bonds • System has not been optimized Heavy Oil Decrease in Heavy HCs Increase in Light HCs

  12. Summary • Interesting way to initiate nanosecond microsparks • Great control over discharge energy • Spark Gaps (mJ  J) • Charge Carriers (uJ  mJ ) • Control of plasma properties in liquids • Scaling is possible • Viscosity decreases were observed • Cracking to lighter hydrocarbons Future Work • High Temperature and Pressure • Effect of energy per pulse on chemistry

  13. References Question? References: • Alyssa Wilson et al 2008 Plasma Sources Sci. Technol. 17 045001 • Ayato Kawashima et al, J. Appl. Phys. • D. Staack, A. Fridman, A. Gutsol et al., Angewandte Chemie-International Edition, vol. 47, no. 42, pp. 8020-8024, 2008. Acknowledgements: This material is based upon work suppoerted by the National Science Foundation Grant #1057175

  14. Microsparks – Emission Spectra Hα

  15. Particle Dynamics – Contact Charging Field Enhancement Factor Lift off Voltage mg = qE g = qαV/d q = α CV α = (mgd/CV2)1/2 α ~ 1/β Experimental α ≈ 0.3 Charge relaxation τ = ε/σ For Mineral Oil ~ 0.5 s Liu, T. M.-C. (2010). The Design of a Micro/Nano-Particle Electrostatic Propulsion System.

  16. Mixing Heavy and Light Oils Pure Heavy Crude ~ 188.4 Pa . s 70/30 mixture ~ 38.2 Pa . s Pure Light Oil ~ 0.0196 Pa . s

  17. Change of Mass

  18. Discharge in Liquids - Process • Initiation  Low Density Region • Electrolysis • Boiling (Joule Heating) • Electrostatic Cavitations • Breakdown • Primary Streamer • Secondary Streamer • Spark • Thermalization • Relaxation 1950s- present thoroughly studied breakdown process in transformer oils and DI water. Plasma’s properties less studied. Cathode (-) Anode (+) Gap ~ 6 cm

  19. Discharges in Liquids - Initiation Assumptions: All initiation mechanism achieve a low density reduction  n Const (I) and (V) δ – initial pertubation size r Local Low Density Region (n) Boiling Analysis (Energy Balance) Electrolysis Analysis ( Faradays law of electrolysis) Y = (Yeild of Fluid) Electrostatic Cavitation Analysis (Force Balance) Cavitation Electrode should be larger Fluid

  20. Bubble Formation Time Estimates Microbubble can be generated most quickly by cavitation and even by other methods as conditions similar to experiments. V = 10 kV Rtip = 1 μm ne = 1012 cm-3 I= 10 nA V = 10 kV Rtip = 5 μm ne = 1016 cm-3 I= 350 mA

  21. Experimental Setups Single Charge Carrier Resistor Dielectric Liquid Power Supply Multiple Charge Carrier

More Related