Bulletin of the American Physical Society
72nd Annual Gaseous Electronics Conference
Volume 64, Number 10
Monday–Friday, October 28–November 1 2019; College Station, Texas
Session TF2: Green Plasma Technologies II: Environmental and Energy Applications |
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Chair: Olivier Guiatella, LPP Polytechnique, France Room: Century II |
Friday, November 1, 2019 8:00AM - 8:15AM |
TF2.00001: Comparison of Thomson scattering measurements and kinetic modeling of electron recombination in nanosecond pulsed discharges with CO$_{\mathrm{2}}$ and O$_{\mathrm{2}}$ diluted in Ar. Yue Wu, Christopher Limbach, Andrey Starikovskiy, Richard Miles Accurate prediction of electron recombination rates in complex gas mixtures critically influences the development and operational conditions of repetitively pulsed and continuous running low temperature plasma sources. Time and space-resolved recombination in Ar with additions of CO$_{\mathrm{2}}$ and O$_{\mathrm{2}}$ is studied through combined experimental measurements by Thomson scattering and kinetic modeling. Single nanosecond pulsed discharges are produced in a pin-to-sphere discharge geometry at a pressure of 80 Torr. Subsequent to pulsed excitation at 20 kV, spatiotemporal Thomson scattering measurements of electron density and electron temperature are obtained. Relative to a pure argon discharge, addition of 0.75{\%} CO$_{\mathrm{2}}$ suppresses the initial plasma density by nearly a factor of two, while O$_{\mathrm{2}}$ dilution of 1.0{\%} slightly decreases both the initial electron density and electron temperature. These results are compared to a kinetic model of the discharge afterglow developed to study recombination processes and plasma chemistry. The model results clarify that the presence of molecular ions accelerates the plasma decay through dissociative recombination and the molecular gas admixture accelerates the relaxation of the electron temperature at low electron energies, especially in the case of CO$_{\mathrm{2}}$ addition. [Preview Abstract] |
Friday, November 1, 2019 8:15AM - 8:30AM |
TF2.00002: Optimal conditions for nitric oxide synthesis by a plasma process Miles Turner, Cezar Gaman, Gary J. Lanigan Nitrogen is an important element in plant growth, and consequently access to nitrogen in chemically active forms is essential to modern agriculture. Molecular nitrogen, however, is practically inert. Conversion of molecular nitrogen to biologically useful forms, known as fixation, is an energetically intensive process that is at dominantly effected by consuming fossil fuels and emitting carbon dioxide via the Haber-Bosch process. This makes a large contribution to greenhouse gas emission, and consequently to anthropogenic climate change. A plasma process might prevent these emissions, by replacing fossil fuels with renewable energy sources, and thus contribute to addressing one of the most important challenges of the present century. The energy efficiency of the plasma process is an important consideration. We show than an analytic model can describe the most salient processes involved in plasma nitrogen fixation, and that this model implies that the energy efficiency of such a plasma process could be as much as 20~\%. However, there is an apparently unavoidable compromise between yield (or molar conversion efficiency) and energy efficiency, which suggests that a practical expectation is around 10%. This is somewhat larger than is presently achieved by Haber-Bosch. [Preview Abstract] |
Friday, November 1, 2019 8:30AM - 9:00AM |
TF2.00003: Plasma Chemistry of Synthesis and Conversion of Energetic Materials Invited Speaker: Alexander Fridman Presentation reviews latest results obtained in Nyheim Plasma Institute of Drexel University on plasma-chemical processes of fuel conversion and synthesis of energetic materials in non-thermal discharges. Major discharges in focus are: \begin{enumerate} \item Non-equilibrium gliding arcs stabilized in reverse vortex Tornado flow \item Micro- and nanosecond pulsed dielectric barrier discharges \item Cold and transitional discharges in liquids \end{enumerate} Major specific plasma-chemical processes in focus are: \begin{enumerate} \item Methane conversion in mixture with different gases \item Methane (natural gas) direct liquefaction process \item Liquid-phase synthesis of polymeric nitrogen compounds \end{enumerate} Mechanisms of the plasma-chemical processes are discussed as well as physical and chemical kinetics of the processes in strongly non-equilibrium conditions [Preview Abstract] |
Friday, November 1, 2019 9:00AM - 9:15AM |
TF2.00004: Submerged Electrical Discharge for Heavy Oil Upgrading and Conversion Kunpeng Wang, Shariful Bhuiyan, Md. Abdullah Baky, Christopher Campbell, Howard Jemison, David Staack We investigated a submerged spark discharge under liquids, characterized by nanosecond pulse duration and low energy per pulse, to generate reactive species at the gas liquid interface to convert heavy hydrocarbons to light hydrocarbons. High purity (\textgreater 99{\%}) n-hexadecane was tested in this spark gap reactor. Discharge gas composition was changed between methane, hydrogen and inert gas. Pulsing energy was controlled by changing the capacitor size which varied between 20, 50 and 100 pF. SEI was controlled for each test and remained at 500kJ/kg. Breakdown voltage, spark gap power and total number of pulses were estimated in real time based on the total voltage and current measured. Total solid formation in processed samples was estimated. Solids production predominately depend on pulsing energy and carrier gas. Increasing the pulsing energy also increased the solids formation. Discharges with 100 pF capacitor yields more than 5{\%} total solids, while discharges with 20 pF capacitor only generates 1{\%} total solids. Analysis by GC-FID and TGA showed that more than 10{\%} hexadecane compound in each sample were converted to new compounds assisted by the plasma discharge process. GC-MS was further used to identify the new compounds. Inert gas discharges in hexadecane seem to produce more reactive species based on GC-MS signals because they strongly interact with the GC column. Methane and hydrogen produced more stable species due to their high reactivity of plasma species. [Preview Abstract] |
Friday, November 1, 2019 9:15AM - 9:30AM |
TF2.00005: Plasma pulse rock drilling to induce micro-cracks for reduced cutting energy and increased rate of penetration Mirza Akhter, Jacob Mallams, Xin Tang, Aamer Kazi, Yi-Tang Kao, Sanat Kumar, Bruce Tai, Dion Antao, Alan Palazollo, David Staack Underwater plasma can generate intense shock waves, which when impacted on a brittle surface induce microcracks. The effect of the plasma discharge on the surface depends on plasma pulse energy, electrode gap spacing, and electrode substrate spacing. The microcracks generated on the surface can reduce the strength of the material. This could be useful in rock drilling applications where there is a need of higher rate of penetration and reduced operational downtime. Preliminary results with shockwave plasma pulse drilling under atmospheric conditions were promising. Nano-second plasma pulses in liquid were used to induce microcracks on rock surface. A parametric study on plasma energy per pulse vs number of discharges and induced cracks on surface was carried out. Effects of electrode gap spacing and electrode substrate spacing were studied at atmospheric conditions. To simulate downhole pressure conditions a pressure vessel capable of 5000 psi was built. Initial tests show that an increasingly smaller electrode gap is required for a plasma discharge to occur at elevated pressures. The reduction in cutting energy due to microcracks is yet to be explored but overall results show that plasma pulse drilling may be beneficial in the drilling process. [Preview Abstract] |
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