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

Solid oxide fuel cell electrode characterization and improvement for fuel flexibility and supplemental power production

Solid oxide fuel cells (SOFC) were fabricated and the electrodes tested for their individual catalytic effectiveness in various fuels by exposing each electrode to mixed gas while the opposite electrode was exposed to its respective pure gas. Mixed hydrogen and oxygen gas was successfully utilized as fuel in a single chamber SOFC (SC-SOFC). The conditions at which the porous nickel-yttria-stabilized zirconia (Ni-YSZ) cermet anode performed well did not significantly overlap the conditions at which the La₀.₈Sr₀.₂Fe₀.₈Co₀.₂ oxide (LSCF) cathode performed well, but there was significant catalytic activity at both electrodes which increased the open circuit voltage (OCV) beyond that predicted by the Nernst equation. The results of these tests, and future tests of similar format, could be useful in the development of SC-SOFC electrode catalysts. Pyrolytic carbon was used as fuel in a SOFC with a YSZ electrolyte and a bi-layer anode composed of nickel gadolinia-doped ceria (Ni-GDC) and Ni-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous Ni-YSZ as a buffer anode layer between the electrolyte and the Ni-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided. A cell of similar construction was used with externally applied acetylene flame soot as fuel so that soot captured at the exhaust of a diesel engine could be utilized for secondary power generation in a SOFC while decreasing particulate pollution without the need for filter regeneration --Abstract, page iii

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

Autoselective regeneration of gelcast ceramic foam

This thesis describes the development and application of an electric discharge for regenerating gelcast ceramic foam diesel particulate filters (DPF) for effective and efficient reduction of particulate matter (PM) emissions from diesel fuelled IC engines. The combustion in diesel compression ignition engines generates a number of unwanted by-products including PM. The PM from diesel engines is believed to be potentially carcinogenic when inhaled into the lungs and, therefore, needs to be controlled. Emission legislation has made it increasingly difficult for engineers to reduce PM emissions whilst meeting NOx targets by combustion optimisation alone, leading to the requirement for exhaust gas aftertreatment, most notably exhaust gas filtration. Filtration and regeneration (filter cleaning) technology must be robust, filter high amounts of PM, be compact, energy efficient and cost effective. A large number of published solutions do not meet all of these criteria. This research has developed a compact, efficient, robust and cost effective solution: The Autoselective regeneration of gelcast ceramic foam DPFs. Gelcast ceramic foam geometry can be optimised on a microscopic and macroscopic scale with a large number of material characteristics. This thesis develops and applies new methodology for rapid optimisation of gelcast ceramic foam DPFs. The optimum foam geometry is found to be highly application-dependent. Filters with >95% filtration efficiency and a low filtration volume have been demonstrated, although are limited in their PM mass holding capacity. It was found that filters with higher PM mass holding capacity require larger pore sizes and filtration volume. Design maps were produced to allow rapid optimisation of gel cast ceramic foams with a novel methodology that can be applied to all forms of deep bed filtration, saving both time and cost in future filter development. Investigation and optimisation of Autoselective regeneration demonstrated that the regeneration system is most effective when the electric discharge is active within the filter volume. Using modelling and novel methods for measuring heat flux from electrical discharges, thermal optimisation of the heat flows in the system were achieved. Rig tests increased the robustness of the regeneration system and developed profiled mesh electrodes to maximise the effective regeneration volume. An engine test programme demonstrated regeneration effectiveness of -12 g kW·1 h-I which is equivalent to -333 W for a typical 56 kW heavy duty diesel engine. Alternatives such as fuel burners and electrical resistance heaters typically consume between I and 5 kW of fuel energy for filter regeneration. Multiple electrode prototypes are presented and evaluated for efficient and effective on-engine and on-vehicle PM control.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Current Air Quality Issues

Air pollution is thus far one of the key environmental issues in urban areas. Comprehensive air quality plans are required to manage air pollution for a particular area. Consequently, air should be continuously sampled, monitored, and modeled to examine different action plans. Reviews and research papers describe air pollution in five main contexts: Monitoring, Modeling, Risk Assessment, Health, and Indoor Air Pollution. The book is recommended to experts interested in health and air pollution issues

NOx ADSORPTION AND NTP DESORPTION-REDUCTION

NOx emissions have multi-fold hazards for both environment and human health, due to their role in the formation of fine particles, ozone smog, acid rain and eutrophication. The increasing level of emissions and the improved comprehension of NOx toxicity have led to a progressive reduction of allowed emissions from stationary and mobile anthropic sources. NOx emissions can be controlled by altering the combustion process (e.g. Selective Non-Catalytic Reduction) or by post-combustion treatment of the flue gases (e.g. Selective Catalytic Reduction). These two technologies are the most commonly used for industrial processes in a wide range of applications. SCR has a higher capital cost than SNCR but allows a superior reduction of NOx concentration and it is the preferred technique in many industrial applications when high-quality standards are required. Due to the recent stricter European regulations for NOx emissions, SNCR is almost inadequate for the new standards, and cost-effective and alternative methods to SCR are under investigation. The NOx adsorption and non-thermal plasma desorption/reduction strategy was proposed and it is investigated in this thesis. The process consists of the adsorption of NOx on a sorbent material followed by the sorbent regeneration using non-thermal plasma in N2 flushing. The presence of the plasma has the double effect of promoting the NOx desorption from the sorbent surface and reducing the NOx desorbed to N2 and O2. A further reduction of NOx can be performed in a DBD plasma reactor. The desorption and reduction are promoted by the high reactive nitrogen gas discharge particles that react with NOx. A granular activated carbon (GAC) was investigated for NOx adsorption from simulated flue gases. The adsorption capacity for NOx was negligible (less than 4mg/g) if a mixture of NO diluted in N2 was considered; however, it was possible to calculate the adsorption isotherms at 30 and 120°C. A great improvement in the adsorption capacity was calculated as oxygen was fed (up to 66mg/g). The tests demonstrated that part of the NO was catalytically oxidized to NO2 in the presence of oxygen, with a consequent improvement in NOx adsorption. Even the adsorbent impregnation with copper (GAC-Cu) played a positive role in the NO oxidation, hence improving the capacity to remove NOx from the gas stream. Dielectric Barrier Discharge reactors demonstrated a high efficiency (up to 100%) in NOx reduction. The configurations with one and two dielectrics were investigated, highlighting the high performance of the one dielectric barrier discharge reactor and the high flexibility of the two dielectric barriers discharge. A numerical analysis was performed to model the plasma condition promoted in the realistic reactors. The results in terms of electric parameters were consistent with those estimated in the gas discharge, e.g. electric field, electron density and electron temperature. Cyclic tests of adsorption and sorbent regeneration plasma-assisted demonstrated the effectiveness of the process by using GAC-Cu for NOx removal. The amount of NOx adsorbed during the adsorption stage was desorbed and converted during the desorption plasma-assisted process. Higher effectiveness (≈100%) was estimated in the case of GAC-Cu of commercial size (1.5-3mm), while the effectiveness decreased in the case of lower granular size (0.3-0.6mm). The possibility to perform the process at low temperature makes this technology suitable for those gas treatment plants that require a retrofit to accomplish the new regulations. The gas would be treated with the designed reactor to obtain further NOx reduction, without risks of ammonia slip that represents the main problem of high-efficiency conventional technologies

Energy Materials Coordinating Committee (EMaCC): Fiscal year 1996. Annual technical report

The DOE Energy Materials Coordinating Committee (EMaCC) serves primarily to enhance coordination among the Department`s materials programs and to further effective use of materials expertise within the Department. These functions are accomplished through the exchange of budgetary and planning information among program managers and through technical meetings/workshops on selected topics involving both DOE and major contractors. In addition, EMaCC assists in obtaining materials-related inputs for both intra- and interagency compilations. The EMaCC reports to the Director of the Office of Energy Research in his or her capacity as overseer of the technical programs of the Department. This annual technical report is mandated by the EMaCC terms of reference. This report summarizes EMaCC activities for FY 1996 and describes the materials research programs of various offices and divisions within the Department