Study of NOx removal characteristics under dielectric barrier discharge field

学位記番号:工博甲44

Plasma Processes for Renewable Energy Technologies

The use of renewable energy is an effective solution for the prevention of global warming. On the other hand, environmental plasmas are one of powerful means to solve global environmental problems on nitrogen oxides, (NOx), sulfur oxides (SOx), particulate matter (PM), volatile organic compounds (VOC), and carbon dioxides (CO2) in the atmosphere. By combining both technologies, we can develop an extremely effective environmental improvement technology. Based on this background, a Special Issue of the journal Energies on plasma processes for renewable energy technologies is planned. On the issue, we focus on environment plasma technologies that can effectively utilize renewable electric energy sources, such as photovoltaic power generation, biofuel power generation, wind turbine power generation, etc. However, any latest research results on plasma environmental improvement processes are welcome for submission. We are looking, among others, for papers on the following technical subjects in which either plasma can use renewable energy sources or can be used for renewable energy technologies: Plasma decomposition technology of harmful gases, such as the plasma denitrification method; Plasma removal technology of harmful particles, such as electrostatic precipitation; Plasma decomposition technology of harmful substances in liquid, such as gas–liquid interfacial plasma; Plasma-enhanced flow induction and heat transfer enhancement technologies, such as ionic wind device and plasma actuator; Plasma-enhanced combustion and fuel reforming; Other environment plasma technologies

Optimisation of autoselective plasma regeneration of wall-flow diesel particulate filters

The increase in number of diesel powered vehicles has led to greater concern for the effects of their exhaust emissions. Engine manufacturers must now consider using diesel particulate filters to make their engines meet the legislated limits. Diesel particulate filters can remove more than 95% of the particulates from the exhaust flow but require cleaning, known as regeneration. This thesis describes the research and optimisation of the Autoselective regeneration system for cordierite wall flow diesel particulate filters. The novel Autoselective technology uses an atmospheric pressure glow discharge plasma to selectively oxidise particulate matter (soot) trapped within the filter. The aim of this research was to produce a regeneration system that can operate under all exhaust conditions with a low energy demand and no precious metal dependence to compete with the numerous pre-existing technologies. The effect of discharge electrode type and position on regeneration performance has been investigated in terms of regeneration uniformity, power requirement and regeneration rate. The results showed that the electrode orientation had a large effect on regeneration distribution and energy demand. The electrode capacitance and breakdown voltage was shown to affect the choice of power supply circuit because not all power supply topologies were suitable for powering electrodes with >100 pF capacitance. A number of power supplies were designed and tested, a voltage driven resonant transformer type supply was shown to be optimal when used in conjunction with a swept frequency. The current and frequency ranges of electrical discharges were continuously variable, and their effect on discharge regeneration performance was studied. The results showed that the discharge frequency had no effect on the regeneration process but did affect spatial distribution. An optimised resonant transformer power supply was designed that was ideally suited for the electrodes used. A novel power modulation strategy, which used a switching frequency phase locked to the ~ iii ~ modulating frequency, was employed which extended the operating range of the discharge to below 10 mA for electrode separations > 7.5 mm. The heat flows within the filter and discharge during regeneration were analysed and the filter damage process was linked to the heat released by the discharge inside the filter wall. Other filter materials were compared based on the findings and Mullite ceramic was identified as a potentially better filter material for Autoselective regeneration. The filtration efficiency is important and was observed to be affected by the Autoselective process. The effect of the discharge on filtration efficiency was studied and the mechanism of particulate re-entrainment was identified as a combination of electrostatic and electro-acoustic forces. The Autoselective technology was successfully implemented in both flow-rig and on-engine tests. Results showed significant reduction in back-pressure for power inputs of ~ 500 W. The understanding of the Autoselective regeneration system has been improved and the research resulted in a novel method of filter regeneration

A Self regenerating diesel emissions particulate trap using a non-thermal plasma

There is great concern about the adverse effects associated with exposure to diesel exhaust. There is increasing evidence that diesel exhaust particulate matter (PM) is carcinogenic and may cause cancer. Non-cancerous lung damage and respiratory problems are also associated with exposure to diesel exhaust as well as acid rain and smog. Diesel exhaust PM is very easily respirable once emitted into the atmosphere and therefore poses a significant health problem. A diesel engine emissions particle removal system which utilizes Electrostatic Precipitation (ESP) and Non Thermal Plasma (NTP) technologies was studied for trapping and oxidizing micron sized particles (0.01 to 10 microns) in the exhaust. Particles are first charged in a mono polar manner in a NTP in the diesel exhaust stream, and then collected on an electrically grounded precipitation surface. Gaseous radicals produced in the NTP oxidize the precipitated particles to provide a continuously regenerating system. This device is targeted to help meet recently instituted US Environmental Protection Agency (EPA) Tier II as well as upcoming European (Euro 4, 5) and Japanese diesel particulate emissions standards. This system can be coupled with a suitable catalyst or other emissions treatment technologies to produce a complete exhaust aftertreatment system. Analytical and empirical methods were used to model the proposed Self Regenerating Diesel Emissions Particulate Trap. The analysis showed that a total particle precipitation efficiency of greater than 95% could be obtained using less than 0.5% of total engine energy output at a vehicle speed of 120 km/hr for a compact diesel powered vehicle. It was determined that the energy requirement for producing gaseous radicals in the exhaust stream is higher than is needed for particle charging and precipitation. It was also determined that the conversion of radicals can be accomplished using less than 2% of the total engine output. The results of the model developed shows that the proposed device would be effective reducing diesel PM emissions on a heavy-duty vehicle

Low power auto selective regeneration of monolithic wall flow diesel particulate filters

This paper presents research into a novel autoselective electric discharge method for regenerating monolithic wall flow diesel particulate filters using low power over the entire range of temperatures and oxygen concentrations experienced within the exhaust systems of modern diesel engines. The ability to regenerate the filter independently of exhaust gas temperature and composition significantly reduces system complexity compared to other systems. In addition, the system does not require catalyst loading and uses only massproduced electronic and electrical components, thus reducing the cost of the after-treatment package. Purpose built exhaust gas simulation test rigs were used to evaluate, develop and optimise the autoselective regeneration system. On-engine testing demonstrated the performance of the autoselective regeneration process under real engine conditions. Typical regeneration performance is presented and discussed with the aid of visual observations, particulate mass measurements, back pressure measurements and energy consumption. The research demonstrates the potential of the novel autoselective method for diesel particulate filter regeneration. The autoselective process does not require an exhaust by-pass and enables the system to be low power, catalyst-free and exhaust temperature independent

Exhaust Gas Cleaning Systems: A Maritime Study

This project\u27s goal is to provide supplementary information on compliance options for MARPOL Annex VI, specifically exhaust gas cleaning systems. The report covers the adverse effects of sulfur oxides, nitrogen oxides, and particulate matter; as well as the social and legal actions made to reduce the pollutants emitted from maritime vessels. The technical details of various compliance options are explained; emphasis is placed on open-loop, closed-loop, and dry exhaust gas cleaning systems. Finally this report details the guidelines and methods for monitoring emissions. This report is supplementary to a study being conducted by the U.S. Department of Transportation from January 2016 through May 2016