Takuya Kuwahara

Diesel NOx aftertreatment by combined process using temperature swing adsorption, NOx reduction by nonthermal plasma, and NOx recirculation: Improvement of the recirculation process

NO(x) emitted from a stationary diesel engine generator was treated with a hybrid system comprising NO(x) reduction by nonthermal plasma (NTP) and temperature swing adsorption (TSA) driven by engine waste heat. TSA produces a low-volume gas mixture of N(2) and highly concentrated NO(x), which is effectively reduced by NTP treatment. Improved treatment performance and efficiency are achieved by re-injecting the NTP-treated gas mixture into the engine intake. The system comprises two switchable adsorption chambers; the operation of this system was simulated by using a one-chamber system. The maximum energy efficiency for NO(x) treatment is 200 g(NO(2))/kWh. The respective contributions of NTP and injection of N(2) and NO(x) to the performance were theoretically analyzed. The analysis predicts that high energy efficiency and high NO(x)-removal efficiency can be simultaneously achieved with this system but miniaturization of the adsorption chambers will be a challenge.

Improvement of

Atmospheric-pressure nonequilibrium nonthermal plasma hybrid exhaust gas aftertreatment systems that do not utilize precious metal catalysts, harmful ammonia, etc., have been developed by the authors. Two types of new environmental protection systems (a dry system and a wet system), which enable the production of ultralow , particulate matter and emissions as well as reduced fuel consumption and low cost, are investigated for diesel engines, marine engines, and combustion boiler applications. This paper reports the principles of the dry system and some recent experimental results of laboratory tests. The reduction comprises three flow processes: 1) adsorption, 2) heating, and 3) cooling processes. The heating process corresponds to the regeneration process. These processes are repeated in the following order: 1), 2), and 3). This dry system demonstrates excellent energy efficiencies that meet the most recent Japanese national regulations regarding automobile diesel engine exhaust gas. In this study, approximately 60% of the of the exhaust (: 240 325 ppm, , N: standard state) can be treated for 35 h. An improved system energy efficiency of 143 , which is the highest yet, is achieved for reduction.

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Odor control has gained importance for ensuring a comfortable living environment. In this paper, the authors report the experimental results of a study on the detailed characteristics of a laminated film-electrode and a laminated film-electrode packed-bed nonthermal plasma reactor, which are types of dielectric barrier discharge (DBD) reactor used for odor control. These plasma reactors can be potentially used for the decomposition of volatile organic compounds (VOCs) and reduction of NOx. The reactor is driven by a low-cost 60-Hz neon transformer. Removal efficiencies under various experimental conditions are studied. The complete decomposition of the main odor component, namely, NH3, is achieved in a dry environment. The retention times are investigated for the complete removal of NH3 in the case of the film-electrode plasma reactor and the film-electrode packed-bed plasma reactor. The removal efficiency of the former reactor is lower than that of the latter reactor. Mixing another odor component such as CH3CHO in the gas stream has no significant effect on NH3 removal efficiency.

Reduction Efficiency in Diesel Emission Control Using Nonthermal Plasma Combined Exhaust Gas Recirculation Process

Thispaperdescribesanewmeasuringtechniqueofvoidfractionusingmagnetic fluid.Theproposedmeasurement can be realized with simple devices. The present study consists of two appropriate experiments termed “static experiment” (“calibration test”) and “flow experiment” (“actual flow test”). In the present study, the experiments have been performed with fully diluted magnetic fluid for the purpose of applying to common two-phase flow situations such as air–water. Results of the experiments have concluded that the proposed measuring technique of voidfractioncanmeasurevoidfractioninair–watertwo-phase flowsituationsbyaddingasmallamountofmagnetic fluid to fluids of interest. The present method has promise for other fluids. Nomenclature A = area of cross section of pipe, m 2 B = magnetic flux density, T for tesla H = magnetic field, A=m for ampere=m H = magnitude of magnetic field, A=m j = volumetric flux, m=s k = Boltzmann constant, J=K M = magnetization, A=m

Odor Removal Characteristics of a Laminated Film-Electrode Packed-Bed Nonthermal Plasma Reactor

In this article, a supercritical CO2-based solar Rankine cycle system (SRCS) with a novel-concept thermally driven pump is studied. The thermally driven pump is a refrigerant-circulating pump composed of two expansion tanks and having merits of low power consumption and high reliability in comparison with conventional mechanical pump. The application of the present thermally driven pump in the supercritical CO2-based SRCS shows that an oscillatory flow is realized in the system and the system thermal efficiency is enhanced compared to the SRCS using the mechanical feed pump.

Void Fraction Measurement of Gas-Liquid Two-Phase Flow Using Magnetic Fluid

As the regulations governing diesel engine emissions become more stringent, it is difficult to fulfill these new requirements using only techniques that improve combustion. More effective aftertreatment technology is thus needed particularly for particulate matter (PM). Although the use of ceramic diesel particulate filters (DPF) is a leading technology in automobiles, it still presents a problem in terms of soot removal or regeneration for marine diesel engine operated with marine diesel oil (A-heavy fuel oil) including the sulfur. In the present study, to establish a nonthermal plasma DPF regeneration method for marine diesel engines, laboratory-scale and pilot-scale experiments are carried out. The pressure difference decreased only when the plasma is turned on and that regeneration is realized at 320°C. The amount of ozone required for regeneration is determined under various engine-operating conditions, and basic characteristics of regeneration are clarified. The required plasma energy is approximately 5% of the generated power of the marine engine.

Performance study of supercritical CO2-based solar Rankine cycle system with a novel-concept thermally driven pump

Since it is difficult to fulfill the recent stringent regulations governing marine diesel engine emission by means of combustion improvement alone, an effective aftertreatment technology is needed to achieve efficient NOx and particulate matter (PM) simultaneous removal. In the present study, we design and investigate an effective aftertreatment system that employs a combination of ozone injection and nonthermal plasma (NTP) reduction for a marine diesel engine. The proposed technology offers the advantage of the useless of precious-metal catalysts, urea solution, and harmful heavy-metal catalysts. In the aftertreatment system, PM in the exhaust gas is first captured by a ceramic diesel particulate filter (DPF). Subsequently, the deposited PM is oxidized and removed by NTP-induced ozone injection. After the treatment, NOx in the exhaust gas is treated by the following two flow processes using NTP combined with NOx adsorbents: (a) adsorption and (b) desorption processes. These processes are repeated periodically and total emission control is achieved. Because the deposited PM and the desorbed NOx are treated at high-concentration state by ozone and oxygen-lean NTP, the higher performance for total marine diesel emission control is recorded. The maximum efficiencies of NOx and PM reduction were 94% and 95%, respectively.

Pilot-scale experiments of continuous regeneration of ceramic particulate filter in marine diesel engine using nonthermal plasma-induced radicals

Due to the fact that it is difficult to fulfill the recent stringent regulations governing marine diesel engine emission by means of combustion improvement alone, an effective aftertreatment technology is required to achieve the efficient simultaneous removal of NOx and particulate matter (PM). In the present study, we designed and investigated an effective aftertreatment system that employs a combination of ozone injection and nonthermal plasma (NTP) reduction for a marine diesel engine. The proposed technology offers the advantage of not requiring precious-metal catalysts and harmful heavy-metal catalysts as well as urea solution. In this aftertreatment system, PM in the exhaust gas is first captured by a ceramic diesel particulate filter. Subsequently, the deposited PM is oxidized and removed by NTP-induced ozone injection. After the PM treatment, NOx in the exhaust gas is treated by adsorption followed by NTP-combined desorption and reduction processes. These processes are repeated periodically, and total emission control is achieved. Since the deposited PM and the desorbed NOx are treated at a high-concentration state by ozone and oxygen-lean NTP, a higher performance for total marine diesel emission control is recorded. The maximum efficiencies of NOx and PM reduction were 94% and 95%, respectively.

A Pilot-Scale Experiment for Total Marine Diesel Emission Control Using Ozone Injection and Nonthermal Plasma Reduction

Because the regulations governing diesel engine emissions are becoming more stringent, effective aftertreatment is needed for particulate matter. Although diesel particulate filters (DPFs) are a leading technology used in automobiles, there remains a problem with DPF regeneration for marine diesel engines that use heavy oil fuel. In the present study, pilot-scale experiments were conducted to develop a particulate oxidation technology for marine diesel engine emissions using DPF regeneration by nonthermal-plasma-induced ozone injection. It has been shown that particulate oxidation depends on the exhaust gas temperature, and regeneration can be performed most effectively at a temperature of approximately 300 °C.

Pilot-scale experiment of total marine diesel emission control using ozone injection and nonthermal plasma reduction

Microfabrication by photolithography and nickel plating of fluoropolymer film, exposed to atmospheric-pressure nonthermal-plasma (NTP) graft polymerization, are investigated. Electroless nickel plating on the NTP-graft-polymerizationtreated polytetrafluoroethylene (PTFE) film is successfully achieved. Highly adhesive nickel plating is obtained by reverse bend test. Furthermore, photolithographic patterns are formed on the plated PTFE film. This process is expected to be applied to flexible printed substrates and millimeter-wave antenna.