J.O. Chae

Reduction of the particulate and nitric oxide from the diesel engine using a plasma chemical hybrid system

A new plasma/catalyst continuously regenerative hybrid system (PCRHS) is introduced to reduce diesel particulate matter (DPM), NOx, CO, etc., contained in diesel exhaust gas. The catalyst temperature, plasma energy density, and exhaust gas characteristics were investigated with a passenger diesel car (2500cc) at the dynamometer test bed and chassis dynamometer with CVS-75 test mode. It was reported that the smoke removal efficiency was around 70% at the dynamometer test bed with 80 W energy consumption, and that PM removal efficiency was 68% at the chassis dynamometer. The NOx was reduced up to 20% according to the electrode types and temperature, respectively. The hybrid system test shows that DPM and CO were almost removed and NOx reduced to 30% simultaneously by the system. Considering these results, PCRHS could be a promising method to regenerate diesel particulate.

Plasma Discharge Initiation of Explosives in Rock Blasting Application: A Case Study

A plasma discharge initiation system for the explosive volumetric combustion charge was designed, investigated and developed for practical application. Laboratory scale experiments were carried out before conducting the large scale field tests. The resultant explosions gave rise to less noise, insignificant seismic vibrations and good specific explosive consumption for rock blasting. Importantly, the technique was found to be safe and environmentally friendly.

Kinetics of carbon dioxide reforming of methane via nonequilibrium plasma reactions

Summary form only given. CO2 reforming of CH4 not only eliminates two greenhouse gases but also yields syngas which is preferable feedback for synthetic fuel. The conversions of reactants realized via corona plasma reactions were obviously higher than the equilibrium conversions at atmospheric pressure, and the plasma reactions were always rapid. Experimental results reflect the unique kinetics of nonequilibrium plasma reactions. Within nonequilibrium plasma, the temperature of energetic electrons (Te) is far higher than the temperature of other particles (T). The dissociation reactions of energetic electrons with molecules, e + A rarr products, play an important role, so the kinetics of nonequilibrium plasma reactions should be different with that of gas reactions usually explained by the classical collision theory. According to the collision theory, the rate for gas reaction, A + B rarr products, is given by (-d CA/d t) = K1middotCAmiddotCB, and the rate constant Kc is calculated by K1 = (8RTe/pime)0.5middotsigma0 middot(1+E1/RT)middotexp(-E1/RT) where T is the reaction temperature, sigma is the collision cross section, and E1 is the threshold energy. mAB = (mA+m B)/(mAmiddotmB), mA and m B are the molar masses of A and B. We deduced the rate constant K2 of the dissociation reaction in non-equilibrium plasma which may be expressed as K2 = (8RTe/pim e)0.5middotsigma0middot(1+E0 /RTe)middotexp(-E0/RTe). Due to Te being far higher than T and the molar mass of electron m e being far lower than mAB, K2 is far larger than K1 even if sigma0, the collision cross section for the dissociation reaction, is some less than sigma. So the dissociation reactions are very prompt, and the CO2 reforming via nonequilibrium can be rapid and may realize higher conversions. Using our experimental data resulted from CO2 reforming via AC corona plasma reactions, we drew a macroscopic kinetics model expressed as -d CCH4/d t = 0.10 exp (-11.72/W)CCH4 0.53CCO2 1.1 where the W is the input power during the plasma reactions

Application of a plasma-catalytic system for removal organic pollutants

Publisher Summary This chapter presents the experimental studies for indoor air control as well as for an industrial application of a plasma-catalytic system for removal of organic pollutants. The basic characteristics of the plasma-catalytic decomposition of toluene, butyl acetate, and isopropyl alcohol are investigated. The different kinds of plasmas—such as, corona, dielectric barrier, and surface discharges—are investigated. Nonthermal plasma alone cannot solve the problem of VOC removal because of the formation of byproducts—such as, CO, ozone, and aerosols. Several catalysts for the VOC decomposition are introduced in a combination with plasma treatment. The plasma treatment significantly increases the catalytic decomposition rate and the Pt-based catalyst completely removes the CO produced by plasma reactor. To improve and increase the combustion of VOCs, an innovative technology is proposed where plasma reactor is coupled with a catalytic reactor.

Experimental study for production of h2/co synthesis gas using steam plasma

Summary form only given. The use of synthesis gas offers the opportunity to furnish a broad range of environmentally clean fuels and high value chemicals. However, synthesis gas manufacturing systems based on waste oil are capital intensive, and hence, there is great interest in technologies for cost effective synthesis gas production. Direct production of synthesis gas with flexible H2/CO ratio, which is in agreement with the stoichiometric ratios required by major synthesis gas based petrochemicals, can decrease the capital investment as well as the operation cost. Although CO2 reforming and catalytic partial oxidation can directly produce desirable H2/CO synthesis gas can be obtained by optimizing the process schemes based on steam reforming and autothermal reforming as well as partial oxidation. In this work, the possibility of using the electric arc plasmatron for the work on the water vapor as the basic heat-transfer agent - as the plasma-forming gas. The theoretical calculation is carried out and the practical results of the work of the plasmatron using the water vapor are obtained. Process of the decomposition of waste oil for increasing the efficiency of heat exchange in technological process is investigated

Characteristics and thermodynamics of carbon nanotubes synthesized via corona plasma deposition

Summary form only given. Carbon nanotubes were synthesized via a cooperating technology of low-temperature plasma deposition and template-controlled growth at atmospheric pressure. The as-grown multiwall carbon nanotubes with outer diameter of about 40 nm were restrictedly synthesized in the channels of anodic aluminum oxide template from a methane/hydrogen gas mixture, whose molar ratio is 1/10, by AC corona plasma deposition. The innermost diameter of the carbon nanotubes is about 1.3 nm. Differing from the well-crystallized graphitic nanotubes synthesized via high-temperature DC arc plasma, the carbon nanotubes synthesized via low-temperature plasma deposition generally consist of carbon crystallites whose basal planes roughly arrange along the tubular axes. So there raise questions about the formation mechanism of the tubular structure and the innermost diameter of the nanotubes. Previous report in energetics predicted the smallest graphitic nanotube being 0.4 nm, and carbon nanotube with such size was indeed synthesized via DC arc plasma. But the energetics of crystalline carbon nanotube is complicated because there is considerable internal surface energy among the carbon crystallites. We calculated the Gibbs free energies of tubular crystallitic carbon nanotube and solid crystallitic nanowire. It was found that the carbon nanotubes consisting of crystallites with their basal planes arranging along the tubular axes have the lower Gibbs free energy, indicating a possible thermodynamic preference for their tubular structures

Atmospheric pressure plasma regeneration of diesel particulate filter

Summary form only given. Atmospheric pressure electric discharge plasma is being widely studied for its applications in environmental remediation. At present, diesel engine emissions pose a severe threat to environment by releasing oxides of nitrogen and particulate matter. To control these particulate emissions directly, plasma has been studied. However, energy consumptions and operational stability are causes of concern. Diesel particulate filter (DPF) is the most widely used method to control particulate emissions these days. However, DPF needs continuous regeneration because of soot deposition. Without regeneration, DPF becomes inefficient and increases the back pressure to the engine due to soot clogging. Electric discharge plasma, with its strong oxidation characteristics can be utilized in the DPF regeneration process even at lower exhaust temperatures. Plasma oxidizes NO in the exhaust to NO2 and NO2 in turn oxidizes soot in presence of oxygen to release CO and CO2. The advantage with plasma regeneration is that it proceeds at a lower temperature at which no damage to DPF can happen. The reaction path way is: NO2 + C rarr CO + NO; 2NO2 + C rarr CO2 + 2NO. In the present study, a dielectric barrier discharge reactor operated at room temperature is employed to oxidize NO to NO2. A high voltage power supply is utilized to energize the plasma reactor. A digital oscilloscope (TDS 744A, 500 MHz, 2 GS/s) and voltage divider are used for waveform analysis and measurements of voltage and current. A small DPF made of SiC (34.2times34.2times150.4 mm3) filled with carbon soot of known weight is utilized for the regeneration purposes. NO (500 ppm in N2) and O2 gases are supplied to the reactor from standard cylinders at flow rates of 9 lpm and 1 lpm respectively. NOx is measured using Horiba MEXA-554JK analyzer and GasTec tubes. Particulate emission is measured using a diesel opacimeter (OP-100). Initial experiments are conducted to optimize NO oxidation to NO2 using plasma reactor. In the next step, regeneration of DPF is carried out. Different parameters such as gas total gas flow rate and gas temperature are studied

Plasma Assisted Selective Catalytic Reduction of Nitrogen Oxides

Publisher Summary This chapter investigates the effect of plasma pretreatment for NO x control on a Selective Catalytic Reduction (SCR) catalyst. Reduction of nitrogen oxides (NO x ) is considered as a great challenge in the overall task of keeping the environment clean. Presently, various industries employ selective catalytic reduction process to control NO x emissions. The limitation of SCR process is that it cannot efficiently remove NO x from low-temperature emissions. Pretreatment of the exhaust gas by electric discharge plasma has been found to be helpful in enhancing the catalytic activity. This chapter presents a pulsed corona reactor, which has been used in combination with industry supplied SCR catalyst to control NO x from a simulated flue gas mixture. The role of plasma in the combined system at different operating temperatures is discussed, the effect of water on the combined system is studied, and the effect of plasma pretreatment for NO x control on a SCR catalyst is investigated. A wire-cylinder plasma reactor is energized by short-rising high-voltage pulses. A SCR catalytic reactor is placed ahead of the plasma reactor. The significance of the plasma reactor is found to be the conversion of NO to NO 2 . Plasma effect results in 35% increase in NO x removal efficiency on the catalyst at 180°C for an energy density of 47 J/l. The effect of plasma decreases with temperature.

Experimental study for control of VOCs using plasma-catalyst hybrid system

Summary form only given, as follows. In this study, a new plasma-catalyst continuously regenerative hybrid system is introduced for neutralization of odors and reduction of specific volatile organic compounds (VOCs) in the indoor air environment.

Experimental study for hydrogen assisted system for diesel engine for the reduction of exhaust pollutions

Summary form only given, as follows. In this study, a new plasma system is introduced to for generation of rich gas for diesel aftertreatment and other applications. The designed plasma system allows one to reform diesel fuel into hydrogen rich gas (H/sub 2/ + CO). The plasma boosts a partial oxidation reaction that reforms hydrocarbon fuels into a hydrogen-rich gas partial oxidation (at an oxygen/carbon ratio of 1, exothermic reaction).