Bulletin of the American Physical Society
66th Annual Gaseous Electronics Conference
Volume 58, Number 8
Monday–Friday, September 30–October 4 2013; Princeton, New Jersey
Session KW3: Green Plasma Technologies II |
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Chair: Biswa Ganguly, Air Force Research Laboratory Room: Nassau Room |
Wednesday, October 2, 2013 1:30PM - 2:00PM |
KW3.00001: Developments in Power efficient dissociation of CO2 using non-equilibrium plasma activation Invited Speaker: Richard van de Sanden Sustainable energy generation by means of, either photovoltaic conversion, concentrated solar power or wind, will certainly form a significant part of the energy mix in 2025. The intermittency as well as the temporal variation and the regional spread of this energy source, however, requires a means to store and transport energy on a large scale. In this presentation the means of storage will be addressed of sustainable energy transformed into fuels and the prominent role plasma science and technology can play in this great challenge. The storage of sustainable energy in these so called solar fuels, e.g. hydrocarbons and alcohols, by means of artificial photosynthesis from the feedstock CO2 and H2O, will enable a CO2 neutral power generation infrastructure, which is close to the present infrastructure based on fossil fuels. The challenge will be to achieve power efficient dissociation of CO2 or H2O or both, after which traditional chemical conversion (Fisher-Tropsch, Sabatier, etc.) towards fuels can take place. A promising route is the dissociation or activation of CO2 by means of plasma, possible combined with catalysis. Taking advantage of non-equilibrium plasma conditions to reach optimal energy efficiency we have started a solar fuels program at the beginning of 2012 focusing on CO2 plasma dissociation into CO and O2. The plasma is generated in a low loss microwave cavity with microwave powers up to 10 kW using a supersonic expansion to quench the plasma and prevent vibrational-translational relaxation losses. New ideas on the design of the facility and results on power efficient conversion (more then 50\%) of large CO2 flows (up to 75 standard liter per minute with 11\% conversion) at low gas temperatures will be presented. [Preview Abstract] |
Wednesday, October 2, 2013 2:00PM - 2:15PM |
KW3.00002: Production of Nano-composite Si-M powders by plasma spraying for next generation lithium ion batteries Makoto Kambara, Naren Gerile, Mashiro Kaga, Tasuku Hideshima We have attempted plasma spraying to produce nano Si powders for lithium ion batteries at the industrial compatible throughputs. Several 100 nm nano-composite powders are typically produced from metallurgical grade Si powders, and its improved battery capacity has been revealed. When doped with \textgreater 10 mol{\%}Ni, several SiNix alloy particles, that are the congruent phases with relatively high melting temperature in the Si-Ni binary system, were produced. The battery performance of these powders was not as good as that with Si powders only. In contrast, at 5 mol{\%}Ni addition, NiSi$_{2}$ phase was only detected apart from Si. Importantly, the battery performance was improved. Since NiSi$_{2}$ is an incongruent phase that forms through peritectic reaction, it plausibly nucleates heterogeneously on surface of Si particles that nucleate in advance. In fact, TEM analysis revealed that NiSi$_2$ was present on Si surface not as individual particles. Therefore, such a composite structure, not a simple mixture of foreign particles, is considered to improve the battery performance possibly by increasing the particle mechanical integrity as well as the electric conductivity of the electrode. [Preview Abstract] |
Wednesday, October 2, 2013 2:15PM - 2:30PM |
KW3.00003: Planar NO LIF measurement of point-to-plane discharge in a premixed propane/air flame Jacob Schmidt, Biswa Ganguly The effect of a point-to-plane pulsed discharge induced radical production in a pre-mixed propane/air flame has been investigated by phase-locked Planar Laser-Induced-Fluorescence (PLIF) measurements of NO radical. NO fluorescence images were acquired by exciting transitions within the A2$\Sigma +$ $\leftarrow$ X2$\Pi $ (v'$=$0,v"$=$0) $\gamma $ -band, near 226 nm. Phase locked NO PLIF measurements with the variation of pulsed plasma energy, equivalence ratio, applied voltage rise time have been performed. A fast rise time (20 ns) and a slower rise time (250 ns), 8-10 kV high voltage pulsers are used to produce NO radical densities 10-100 times greater than the ambient flame produced NO radicals in both lean, balanced and rich pre-mixed flames with $\le $ 2.5 mJ deposited pulsed energy per pulse. The excess NO radical densities were found to decay to 50{\%} level with time constants $\ge $250 $\mu$s in the burnt gas regions with gas temperatures greater than 1000 K. The super-equilibrium NO populations were dependent on the deposited energy and overall equivalence ratio, but independent of pulse rise time for similar energy deposition per pulse. Due to long decay lifetimes, super-equilibrium NO populations are convected away with the ambient flow from plasma production regions in the flame and observed in downstream exhaust gas regions. [Preview Abstract] |
Wednesday, October 2, 2013 2:30PM - 2:45PM |
KW3.00004: Measurement of OH radical density in DBD-enhanced premixed burner flame by laser-induced fluorescence Kazunori Zaima, Koichi Sasaki We examined OH density in DBD-enhanced premixed burner flame by laser-induced fluorescence (LIF). We ignited a premixed flame with ${\rm CH_4/O_2/Ar}$ mixture using a burner which worked as the ground electrode. The upper part of the flame was covered with a quartz tube, and we attached an aluminum electrode on the outside of the quartz tube. DBD inside the quartz tube was obtained between the aluminum electrode and the burner nozzle. The planar beam from a pulsed tunable laser excited OH in ${\rm X^2\Pi(v"=0)~to~A^2\Sigma^+(v'=0)}$, and we captured two-dimensional distribution of the LIF intensity using an ICCD camera. We employed three pump lines of $Q_1$(J=4, 8 and 10), and the rotational temperature of OH(X) was deduced from the ratio of the LIF intensities. The total density of OH was obtained from the LIF intensities and the rotational temperature. A principal experimental result was that no remarkable increase was observed in the OH density by the superposition of DBD. The correlation between the pulsed discharge current and the temporal variation of the OH density was not clear, suggesting that the oscillation of the OH density with a small amplitude is related to the transittion time constant between equilibrium and nonequilibrium combustion chemistries. [Preview Abstract] |
Wednesday, October 2, 2013 2:45PM - 3:00PM |
KW3.00005: Microwave plasma jet assisted combustion of premixed methane-air: Roles of OH(A) and OH(X) radicals Chuji Wang, Wei Wu Plasma assisted combustion (PAC) technology can enhance combustion performance by pre-heating combustion fuels, shortening ignition delay time, enhancing flame holding, or increasing flame volume and flame speed. PAC can also increase fuel efficiency by extending fuel lean flammability limit (LFL) and help reduce combustion pollutant emissions. Experiment results have shown that microwave plasma could modify flame structure, increase flame volume, flame speed, flame temperature, and flame stability, and could also extend the fuel lean flammability limit. We report on a novel microwave PAC system that allows us to study PAC using complicated yet well-controlled combinations of operating parameters, such as fuel equivalence ratio ($\varphi )$, fuel mixture flow rate, plasma gas flow rate, plasma gases, plasma jet configurations, symmetric or asymmetric fuel-oxidant injection patterns, etc. We have investigated the roles of the stated-resolved OH(A, X) radicals in plasma assisted ignition and combustion of premixed methane-air fuel mixtures. Results suggest that that both the electronically excited state OH(A) and the electronic ground state OH(X) enhance the methane-air ignition process, i.e. extending the fuel LFL, but the flame stabilization and flame holding is primarily determined by the electronic ground state OH(X) as compared to the role of the OH(A). E-mail: \underline {cw175@msstate.edu}. [Preview Abstract] |
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