Kazuhiko Madokoro

Daihatsu Motor Co., Ltd., Ōsaka, Ōsaka, Japan

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Publications (13)15.66 Total impact

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    ABSTRACT: An uneven dielectric barrier discharge (DBD) reactor of 21 electrode pairs that can improve the energy efficiency for the removal of particulate matter (PM) from a diesel engine is characterized. Ninety percent of PM (about 0.48 g/h) is removed by plasma discharges at an energy injection of 90 W into an exhaust gas (40 Nm3/h with PM emission rate 0.53 g/h). The discharge properties and relations of PM removal and energy efficiency with energy injection are given. The fuel penalty due to the use of the uneven DBD reactor is estimated. Comparison with other types of DBD reactors is carried out. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
    Asia-Pacific Journal of Chemical Engineering 08/2009; 5(5):701 - 707. · 0.80 Impact Factor
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    ABSTRACT: The scale-up of an uneven type of dielectric barrier discharge (DBD) reactor driven by a positive-negative pulse power supply for the removal of particulate matter (PM) from a diesel engine has been carried out. The scale of the uneven DBD reactor was changed by using three kinds of reactors consisting of 20, 30, or 50 pairs of uneven alumina and stainless steel plates. In this study, relations of energy injection into the above DBD reactors, PM removals, PM removal efficiencies with pair numbers have been investigated. The parameters in the kinetic model used to describe the PM removal are given.
    International Journal of Chemical Reactor Engineering 01/2009; · 0.79 Impact Factor
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    ABSTRACT: The influence of polarity and rise time of the pulse voltage on the removal of particulate matter (PM) emitted from a diesel engine was investigated using a dielectric barrier discharge reactor. Four kinds of pulse voltage waveforms (positive, negative, positive–negative and negative–positive) were used. It was found that the energy efficiency for PM removal is just a function of energy injection and that there are no obvious influences on PM removal and energy efficiency within the voltage waveforms except the negative pulse voltage of a peak voltage below 8kV. A comparison of PM removals using various kinds of pulse voltage waveforms and different types of plasma reactors is given.
    Plasma Chemistry and Plasma Processing 07/2008; 28(4):511-522. · 1.73 Impact Factor
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    ABSTRACT: The removal properties of diesel exhaust particles (DEP) were investigated using an engine exhaust particle size spectrometer (EEPS), field emission-type scanning electron microscopy (FE-SEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). DEP were treated using a dielectric barrier discharge (DBD) reactor installed in the tail pipe of a diesel engine, and a model DBD reactor fed with DEP in the mixture of N(2) and O(2). When changing the experimental parameters of both the plasma conditions and the engine load conditions, we obtained characteristic information of DEP treated with plasma discharges from the particle diameter and the composition. In evaluating the model DBD reactor, it became clear that there were two types of plasma processes (reactions with active oxygen species to yield CO(2) and reactions with active nitrogen species to yield nitrogen containing compounds). Moreover, from the result of a TOF-SIMS analysis, the characteristic secondary ions, such as C(2)H(6)N(+), C(4)H(12)N(+), and C(10)H(20)N(2)(+), were strongly detected from the DEP surfaces during the plasma discharges. This indicates that the nitrogen contained hydrocarbons were generated by plasma reactions.
    Analytical Sciences 03/2008; 24(2):253-6. · 1.57 Impact Factor
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    ABSTRACT: Recently, a great deal of attention has been paid to the innovative plasma technology for the removal of diesel particulate matter (PM). The authors have developed a plasma PM removal system. In order to estimate the contribution of active oxygen species to PM oxidation,
    International Journal of Automotive Technology 01/2008; 39(2):387-392. · 0.69 Impact Factor
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    ABSTRACT: The removal of diesel particulate matter (PM) is experimentally carried out using two types of uneven dielectric barrier discharge (DBD) reactors driven by positive–negative pulse voltage power supplies. One uneven DBD reactor is fed with exhaust gases from a diesel engine at the exhaust gas temperature and another uneven DBD reactor is fed with PM dispersed in a gas mixture of oxygen and nitrogen at room temperature, where PM was collected from the exhaust gases of the diesel engine. PM emission rates, PM sizes, and PM oxidation products are measured using a PM emission rate monitor, a particle size spectrometer, and a gas chromatograph at various discharge energy densities. It has been found that most of PM is oxidized completely into gaseous products of CO and CO2 under plasma discharge conditions. © 2007 American Institute of Chemical Engineers AIChE J, 2007
    AIChE Journal 06/2007; 53(7):1891 - 1897. · 2.58 Impact Factor
  • S. Yao, C. Fushimi, K. Madokoro, Y. Fujioka
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    ABSTRACT: Recently, the authors have developed a non-thermal plasma system for the removal of harmful particulate matter from diesel engines. In this paper, the characterization of such a non-thermal plasma system (typically including a dielectric barrier discharge (DBD) reactor and a pulse power supply) is carried out electrically and optically using a discharge waveform measurement system of a voltage probe, two current transformers, and an oscilloscope, a high dynamic range streak camera combined with a spectroscope, and a high speed camera. The pulse voltage is applied to the DBD reactor at a fixed value and a frequency of 100 Hz. The rise time, positive width, and peak value of the pulse voltage are, respectively, 3.5 μs, 6 μs, and 13.2 kV. The discharge time duration is 14 μs. The optical emission from the discharge gap lasts for 14 μs. The emission lines are found within 300 - 410 nm and 620- 770 nm. The discharges are generally of an individual micro-discharge property as reported elsewhere.
    10/2006;
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    S. Yao, C. Fushimi, K. Madokoro, K. Yamada
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    ABSTRACT: Uneven dielectric barrier discharge (DBD) reactors driven by positive–negative pulse plasma discharges were investigated for particulate matter (PM) removal from a diesel engine. Two kinds of uneven alumina plates and three kinds of uneven stainless steel plates were used to assemble six kinds of uneven DBD reactors of discharge gaps 0.4–1.0mm. The experimental results show that PM from diesel engines can be removed using the uneven DBD reactors. The maximum PM removal was 67% at 300W energy injections using the DBD reactor of 0.4mm gap distance. PM removal increased with decreasing gap distance. The energy efficiency using the uneven DBD reactor of a shorter gap distance was higher than that using the uneven DBD reactor of a longer gap distance as the uneven DBD reactor of a shorter gap distance has a higher PM deposition rate. The energy efficiency was typically in a range of 3–10.6g/kWh at an energy density of 2–16J/L. A comparison of this study with reports given by other research groups is given.
    Plasma Chemistry and Plasma Processing 09/2006; 26(5):481-493. · 1.73 Impact Factor
  • S. Yao, K. Madokoro, C. Fushimi, K. Yamada
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    ABSTRACT: A new DBD reactor made of uneven alumina and stainless steel plates has been developed for particulate matter (PM) removal from a diesel engine using pulsed plasma discharges. PM removal using 24 pairs of uneven alumina and stainless steel plates is the same as that using 32 pairs of flat alumina plates and mesh metal electrodes that we previously reported. A disturbed discharge uniformly has been obtained in spaces between the uneven alumina plates and stainless steel plates; however, it is difficult to get a uniform discharge using flat alumina plates and mesh metal electrodes. The discharge energy efficiency is 3.6 g/kWh at maximum, which is under improvement for an actual application. © 2005 American Institute of Physics
    AIP Conference Proceedings. 10/2005; 799(1):209-212.
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    ABSTRACT: A dielectric barrier discharge (DBD) reactor, driven by a pulsed corona surface discharge (PCSD), was developed for the removal of particulate matter (PM) in an undiluted exhaust gas of a diesel engine. The DBD reactor consisted mainly of alumina (Al2O3) plates and metal meshes covered on the surfaces of Al2O3 plates. The PCSD was carried out with a pulse power supply at atmospheric pressure and the temperature of exhaust gases. The energy efficiency for PM removal was 26.5 μg/J at maximum and 1 μg/J with 42% PM removal. The construction of the DBD reactor that promoted PM deposition on Al2O3 surfaces improved energy efficiency. The constants in PM removal model were given. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1901–1907, 2004
    AIChE Journal 07/2004; 50(8):1901 - 1907. · 2.58 Impact Factor
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    ABSTRACT: A pulsed corona surface discharge (PCSD) system was established for particulate matter (PM) and NOx removals from a diesel engine. The PCSD was carried out with a dielectric barrier discharge (DBD) reactor and a pulse power supply at atmospheric pressure and room temperature. The DBD reactor consisted mainly of an alumina (Al2O3) tube and a stainless steel rod (cathode) inserted in the alumina tube, and an aluminum coil (anode) wound on the outside surface of the Al2O3 tube. Pulse voltage was applied to the outside Al coil and stainless steel rod. PM was removed at a rate of 89% at maximum with 40% NOx removal. Relations of pulse voltage and frequency to PM and NOx removals were investigated. PM was oxidized by NO2 and other kinds of active oxygen species, such as O and O3 from plasma discharges. A surface adsorption/desorption and PM oxidation model of PM removal was established. The kinetic equations and their constants were given. © 2004 American Institute of Chemical Engineers AIChE J, 50:715–721, 2004
    AIChE Journal 03/2004; 50(3):715 - 721. · 2.58 Impact Factor
  • Journal of chemical engineering of Japan 01/2003; 36(4):435-440. · 0.62 Impact Factor
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    ABSTRACT: Worldwide emission regulations on diesel particulate matter (PM) into the atmosphere have become more stringent. In Japan a new vehicular emission regulation, so called "post new long term regulation", will be introduced since 2009. In this regulation, PM emission rate is should be less than 0.005 g/km. We have developed an uneven type of dielectric barrier discharge (DBD) reactor, which consists of uneven alumina plates and uneven stainless steel plates, to comply with the regulation. PM emitted from a diesel engine (4-cycle, direct Injection, 2 liter) was oxidized by some active oxygen species produced by the corona discharges. The PM emission rate under conditions with or without corona discharges was measured. The pressure drop in the DBD reactor was measured at the inlet of the DBD reactor. The energy efficiency and pressure drop are very important. In this study, we investigated the effect of the number of pairs of the alumina plate and stainless steel plate on the performance of the reactor because the rise in the number of the pairs of the uneven alumina and stainless steel plates can be generally considered to increase the energy efficiency and decrease the pressure drop. When the engine output was 3.0 kW, PM removal ratio and energy efficiency using 20 pairs were 47-84% and 2.9-0.85 g-PM/kWh, respectively, in the range of injection energy of 84-340 W. When 50 pairs were used, the energy efficiency was greatly increased to 13.7-3.6 g-PM/kWh. PM removal ratio was 86% at the injection energy of 87 W and reached 94% at 250 W. The rise in the number of pairs from 20 to 30 or 50 increases the opening space and discharge (reaction) area of the reactor. Thus, the increase in PM removal ratio and energy efficiency is due to the increase in the discharge area. The pressure drop was 6.8 and 4.3 kPa when 20 or 30 pairs were used. The pressure drop was reduced to 2.3 kPa, which corresponds to the 2.9% energy loss, by using 50 pairs by the increase of opening space of the reactor. It was found that the energy efficiency of PM removal is inversely proportional to the approximately 1.6 power of the space velocity and that the pressure drop is proportional to the 1.2 power of the space velocity. Based on the regression curve, it was found that 56 pairs of the uneven alumina and stainless plates can provide an energy loss due to pressure drop smaller than 2 %.