Bulletin of the American Physical Society
63rd Annual Gaseous Electronics Conference and 7th International Conference on Reactive Plasmas
Volume 55, Number 7
Monday–Friday, October 4–8, 2010; Paris, France
Session PR3: Green Plasma Technologies: Environmental and Energy Applications |
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Chair: Hisataka Hayashi, Toshiba Corporation Room: Petit Amphitheatre |
Thursday, October 7, 2010 2:00PM - 2:15PM |
PR3.00001: Pulsed corona oxidation of low NO and NO$_{2}$ concentrations: semi-industrial tests and model simulations to illustrate the process E.A. Filimonova, F.J.C.M. Beckers, E.J.M. van Heesch, W.F.L.M. Hoeben, A.J.M. Pemen Conventional NO$_{x }$removal technologies are complex and require high temperature and large quantities of additives or absorbents. The plasma driven process is less complex, runs at ambient temperature, needs no additives and handles large flows. However, plasma technology has not yet been developed to industrial scale due to challenges of reliable pulsed power generation and efficient reactor technology. We present results of tests at semi-industrial scale accompanied by computer simulations, to illustrate the analysis of the reactor process. The pollutant source is a diluted exhaust flow of a 15 kW Diesel engine. NO$_{x}$ input to the reactor is 30 ppm. The reactor is a 500 liter multiple-plate saw-blade structure fed by a 100 ns pulse source of 5 kW maximum average power. The computer model of removal process takes into account processes of chemical kinetics, diffusion outside and inside of streamer traces during multi-pulsed treatment and continued conversion in the inactive volume between reactor and point of gas sampling. Results show fair agreement between measured and simulated data of NO, NO$_{2}$ and O$_{3}$. HNO$_{2}$, HNO$_{3}$ production is shown as the completion of the process. [Preview Abstract] |
Thursday, October 7, 2010 2:15PM - 2:30PM |
PR3.00002: Mechanism of flame stabilization by Nanosecond Repetitively Pulsed Discharges Christophe Laux, Gabi Stancu, Farah Kaddouri, David Pai, Guillaume Pilla, Deanna Lacoste The stabilization of lean combustible mixtures, which burn at lower flame temperatures than stoichiometric mixtures and thus produce lesser amounts of thermal nitric oxides, is a crucial issue for the design of the next generation of internal combustion and aircraft engines. In recent years, nanosecond repetitively pulsed discharges have been shown to be highly effective, energy efficient techniques for these applications. Stabilization has been attributed to a combination of thermal and chemical effects produced by the discharge. However, the mechanisms for heat or active species production have not been fully understood. To this end, we have performed time-resolved measurements of temperature and species concentrations in an atmospheric pressure air plasma discharge produced by nanosecond repetitive pulses, using advanced techniques such as Cavity Ring-Down Spectroscopy (CRDS), Two-Photon Laser Induced Fluorescence (TALIF) or quantitative emission spectroscopy. The results show that nanosecond discharges at atmospheric pressure can dissociate up to 50{\%} of molecular oxygen in less than 50 ns. Time-resolved electric measurements are also presented to estimate the efficiency of energy deposition by this process. This ultrafast mechanism has many potential applications, from plasma assisted combustion to materials synthesis. [Preview Abstract] |
Thursday, October 7, 2010 2:30PM - 2:45PM |
PR3.00003: One-step methanol synthesis via methane partial oxidation induced by microreactor integrated DBD Tomohiro Nozaki, Shuhei Yuzawa, Anil Agiral, Shohei Moriyama, Ken Okazaki Direct conversion of natural gas into synthetic fuels such as methanol attracts broad attention because direct process can reduce capital and operating costs of high temperature, energy intensive, multi-step methane conversion processes. This paper presents a direct and selective synthesis of organic oxygenates such as methanol, formaldehyde, and formic acid via methane partial oxidation at room temperature induced by non-thermal discharge in microreactor. Production of active oxygen species by dielectric barrier discharge is essential to initiate oxidative chain reaction of methane. Heat generated by methane partial oxidation is removed efficiently in the microreactor configuration: liquid components are condensed on the reactor wall and separated from oxygen-rich reactive plasma, enabling selective synthesis of oxygenates while high methane conversion is achieved in a single reactor. As a result, organic oxygenates were synthesized with one-pass yield of 5-20 percent with 70-30 percent selectivity. In addition to oxygenates, syngas was produced with selectivity of 40 percent and H2/CO = 1. Assuming one step catalytic DME synthesis as a post discharge process, one-pass liquid yield of 30 with 80 percent selectivity is feasible. [Preview Abstract] |
Thursday, October 7, 2010 2:45PM - 3:00PM |
PR3.00004: Plasma-assisted reduction of NiO/Al$_{2}$O$_{3}$ catalyst in atmospheric dielectric barrier discharge Xin Tu, Helen J. Gallon, Martyn V. Twigg, J. Christopher Whitehead The activation of a NiO/Al$_{2}$O$_{3}$ catalyst has been carried out using a CH$_{4}$ plasma in an atmospheric dielectric barrier discharge reactor. The catalyst was reduced from NiO to the active Ni form, which showed high selectivity for the conversion of CH$_{4}$ into H$_{2}$ and solid carbon. Characterisation of the reduced catalyst by SEM analysis revealed the presence of significant amounts of carbon nanofibres on the catalyst surface. The machanism for the NiO/Al$_{2}$O$_{3}$ catalyst reduction in non-thermal plasma was proposed. In addition, the reduced Ni/Al$_{2}$O$_{3}$ catalyst has been tested for dry reforming of CH$_{4}$. The presence of the catalyst in the discharge greatly decreased the breakdown voltage due to the distortion effect of local electric field around pellets. The plasma reduced catalyst significantly improved the H$_{2}$ selectivity (45.2 {\%}), in comparison to the reaction with no catalyst, resulting in an increase in the H$_{2}$/CO ratio from 0.84 to 2.53. [Preview Abstract] |
Thursday, October 7, 2010 3:00PM - 3:15PM |
PR3.00005: Characterization of high-performance PEMFC electrodes produced using an industrial plasma process Marjorie Cavarroc, Matthieu Vogt, Aboubakr Ennajdaoui Development and production of high performance fuel cell components is a major concern in the actual context of energetic challenge. Plasma processes have already demonstrated their potential as methods to produce PEMFC electrodes and membranes [1, 2, 3]. The main difficulty encountered in generally the platinum amount in the fuel cell, due to the price of this material (34~750 euros/kg in February 2010). Reducing Pt amount in the electrodes while increasing the fuel cell performance is an actual challenge both scientific and economic. The work we present here has been performed in this frame. It has been realized on the PuMa plasma equipment located in Dreux -- France. Electrodes are made of a catalytic layer of platinum deposited on conventional uncatalyzed E-Tek{\textregistered} gas diffusion layer. The deposition is performed using magnetron sputtering, assisted by a second plasma source. Electrodes are tested together with Nafion{\textregistered} 212 membrane under pure O$_{2}$ and pure H$_{2}$. Electrodes manufactured using this plasma process exhibit high performances, up to 0.9 W/cm$^{2}$ for a Pt loading lower than 0.04 mg/cm$^{2}$. [1] A.Ennajdaoui, et al., Eur. Phys. J. Appl. Phys. 42 (2008) 9-16 [2] M. Cavarroc, et al., Electrochem. Com. 11 (2009) 859--861 [3]~A. Ennajdaoui, et al., J. Power Sources, 195 (2010) 232--238 [Preview Abstract] |
Thursday, October 7, 2010 3:15PM - 3:30PM |
PR3.00006: Hydrophilic finishing of LDPE films using plasma treatment Dieter F. Ihrig, Jens Eggemann, Richard Schuhmacher, Michael Licht To harvest atmospheric water (dew) we use polymer films (LDPE/LLDPE) which allows cooling down a device just by looking through the atmospheric window at 8 to 13 micron into the cold upper atmosphere. First results from such tools are published in [1]. Problems are resulting of the very high hydrophobic properties of PE. Conventional plasma based procedures are able to generate polar groups on the surface of polymers, but they are not stable. To stabilize this groups we coated the films with an organic layer or a plasma polymerization process.. By this we are able to generate a contact angle on the film of 55 to 60 degr. stable over several month. Such a technique is also interesting as a pretreatment for printing on films with water based lacque. It will be given an introduction in winning water using radiation exchange and results of field-tests. The changing contact-angle over the time on plasma treated and films with organic layer including XPS will be shown. First results of a structure with hydrophobic and hydrophilic areas present the capability of a surface like the desert beatle stenocara. The project was funded by the German Federal Ministry of Education and Research (FKZ 02WD0458).\\[4pt] [1] Jour. Phys. Chem. of the Earth, Elsevier 33, 86 - 91 (2008) [Preview Abstract] |
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