Van Ortega Cayetano

Shama Karu

Sean McKeown

Themistoklis Zacharatos

Advisor: Dr. Woo Lee

Plasma Specialist: Dr. Kurt Becker Powered by:

Project NTP

Why Fuel Cells?• Environmental Effects

– Reduction of automobile greenhouse gas emissions by 50%

– Cut down on smog and acid rain– Reduce noise pollution

• Social Ramifications– Reduction of energy imports– Lower energy costs

• Applications– Batteries– Transportation– Power Plants

Introduction to Plasma:

• Plasmas are an equilibrium of ions and electrons within a confined space.

• Different characteristics of plasmas are produced with various means of energy applications.

Categories of Plasmas:

Various plasmas:– Homogeneous Plasma

– Arc Discharge (lightning)

– Thermal Plasma

– Non-Thermal Plasma (NTP) (fluorescent tubes)

Few variations among plasmas:– Electron density

– Thermal energy

– Energy consumption

Cause of Variations:• Pressure• Voltage• Material of electrodes• Type of gas• Means of plasma production

(plasma source)

Goals:

• Obtain a clear understanding of plasma

• Breakdown Methane at a lower temperature than the current conventional methods using NTP

• Improve on previous year

Production of Plasma:• A commonly used method of generating and

sustaining NTP is through an electric field. – Two parallel electrodes are applied with voltage to form a

capacitive discharge

Breakdown of Methane:

Methane steam reforming:

CH4 + 2H2O CO2 + 4H2

CH4 + H2O CO + 3H2Temperature: 600–1300K with Ni/Ca/Carbon – based catalyst

Methane plasma reforming: x CH4 + e- C2H2 + 3H2 + e-

C2H4 + 2H2 + e-

C2H6 + H2 + e-

C2H2 + H2 + e-

Temperature ~ 300K C2H4 + H2 + e-

Plasma Reformation of Methane:

Reference: Yu. Gerasimov, T.A. Graecheva, Yu. Lebedev:Chim. Vys. Energii, vol. 17, pp 270 (1983)

• Reaction occurs largely by free radical pathways.

•Endothermic reaction shows diminishing returns: high efficiency at low energies, but very little benefit at higher energy.

• Several competing pathways for reaction (some with similar energies) means more analysis will be required.

Initiation: CH4 + e- CH3 · + H· + e-

Propagation: CH3· + CH4

C2H6 + H·

H· + CH4 CH3 · + H2

Termination: H· + H· H2

CH3· + H· CH4

CH3· + CH3

· C2H6 Temperature ~ 300K

Glass PipetteAnode

Cathode

AC HV +

Network

Plasma Region

Gas FlowSpectroscopy, Gas

ChromatographyPure He or Ar

He/N2 or Ar/N2

He/Ar + N2 + CH3OH

1 kV, 50 W 250 kHz

Reference: Prof. Becker

The Plasma Reactor: Dielectric Barrier Discharge at/above Atmospheric Pressure

Design Considerations:Explanation of previous design:• Constriction of gas flow through the plasma source.

• The constriction can also take the form of a wide slit -- or a straight row of holes.

Gas Flow

Current designs are being modeled from this perspective.

Gas Flow

• Constricts gas flow• Narrow space conducive for plasma discharge

• Requires sealant for joints• Assembly needs stability (brace)• Requires interface with mass flow meter

“Hourglass” Design

Multi-tube Design

• Rigid• Narrow space necessary for plasma discharge

• Requires interface with mass flow meter

Capillary tubes

Quartz tubing

Current design focus: (Planar Design)

Gas Chromatograph:

• Problem– We are detecting 100-

1000 ppm of hydrogen– Previous Column

detected methane not H2

• Solution– New Column can detect

in 100s of ppm of H2

– Gas sampler will prevent loss of material

MassFlowController

MassFlowController

MassFlowController

NH3

Ar

CH4 PlasmaSource-SD

PlasmaSource-Grad

Schematic Diagram of Gas Flow:

GC

• Construct a new source

• Experiment with ratio of methane to argon flow

• Experiment with pressure and flow rate of gas mixture

• Work with RF generator to optimize H2 output– Tune frequency

– May not need carrier gas

• Elemental analysis by Gas Chromatography (GC)– GC automation

Future Plasma Research:

Gantt Chart:

Expenses: Equipment Cost

Gas Chromatogram Column 140.00$ Automated Sampler 400.00$ Total 540.00$

MaterialsElectrodes Molybdenum Foil 169.00$ Tungsten Foil 148.00$ Silver Foil 131.00$ Dielectric Polyamide - Nylon 6 89.00$ Alumina Sheet 286.00$ Total 823.00$

TOTAL 1,363.00$

Summary of Experimental Results with Cold Plasma:

Physics Department:•Experiments with He/Ar+N2+CH3OH

–Gas temperature between 350 – 380 K range–Increase in CO, OH, and CH emissions, indicating a (partial) plasma-induced break-up of CH3OH

–Very weak H emission –Needs improvement for controlling methanol content–May require more energetic electrons Reference: Prof. Becker

Summer CVD Lab experiment:• Total flow-rate of Ar/MeOH mixture was 151.8cc/min

• Methanol concentration before entering plasma to be 1.29%

Conclusion:• GC detector not sensitive enough to detect such a small concentration

• Agrees with experiments done by the Physics Department

Summary of Experiment Attempting to Crack Methanol from Pipette Design:

• Flow-rate of pure Argon was 140cc/min

• Flow-rate of Ar/MeOH was 11.8cc/min

• Total flow-rate was 151.8cc/min

• Power in was approximately 150W

• Methanol concentration before entering plasma to be 1.29%Conclusion:• GC detector not sensitive enough to pick up such a

small concentration• Agrees with experiments done by the Physics depart.