• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Laboratory and field trials of the ability of vegetated porous paving to remediate pollutants

Mayer, M. January 2013 (has links)
Flooding is impossible to prevent completely, consequences of excess water can however, be reduced and often avoided via flood risk management. With the increase in impermeable surfaces, approaches that have the intention of imitating natural drainage to manage storm-water are known as Sustainable (Urban) Drainage Systems (SUDS). Pollutants from vehicles have been identified as a concern in the urban environment, with origins including exhaust emissions, engine oil leakage and erosion of vehicle components. Investigation of vegetated parking surfaces (VPS) to limit the impact of pollutants are scarce, therefore this study aims to determine pollution tolerance of grass species for use in VPSs, prior to investigating the effects that vehicles have on a vegetated surfaces and alternative methods in which to analyse them. A pot trial investigated effects of increasing oil concentrations on the growth of four grass species. F. rubra L. was found to tolerate contamination to a higher degree than the other species and L. perenne L. produced more cumulative biomass throughout the investigation. A parallel study determined that Ca, Cu, K, Mg, Mo, P and Zn accumulated in grass shoots, indicating that F. rubra L. and L. perenne L. may be suitable for further analysis. field trial focused on a regularly-used L. perenne L.-covered VPS at a local school, analysing the influence of vehicles on vegetated parking bays. Compaction and mean element concentrations increased across the VPS, with distance from the roadside. Use of mineral magnetism as a proxy for geochemical detection did not prove successful as no significant correlation was identified between magnetic susceptibility (χ) and element concentration. Use of GIS provided this study with an alternative method for data presentation. Usually covering large scale analyses, an interactive geovisual map of geochemical dispersal and compaction across the VPS provided a novel method of visualising results from an investigation of this scale.
2

Towards Achieving Better NOx Removal In Discharge Plasma Treatment Of Diesel Engine Exhaust

Sinha, Dipanwita 12 1900 (has links)
In India, the expansion of industries and two-fold increase in motor vehicles over the last decade are posing a serious environmental crisis in the form of urban air pollution. Common pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs), and nitrogen oxides produced by industry and motor vehicles. Air pollution results from a variety of sources. The natural sources include volcanoes, forest fire, scattering soil, biological decay, lightning strikes, dust storms etc. and man-made sources include thermal power plants, vehicular exhausts, incinerators and various other industrial emissions. More than 60% of the air pollution is contributed by these man-made sources. Amongst the gaseous pollutants, the major concern and a challenging task is to control oxides of nitrogen, commonly referred to as NOx. In case of diesel engines, despite the modification in engine design and improvement in after treatment technologies, large amount of NOx continues is get emitted and attempts to develop new catalyst to reduce NOx have so far been less successful. Further, with the emission standards becoming more stringent, estimates are that NOx and particulate matter emission must be reduced by as much as 90%. In this context, the emergence of electrical discharge plasma technique in combination with the few existing technologies is providing to be economically viable and efficient technology. In this thesis emphasis has been laid on the discharge based non-thermal plasma for NOx removal. NOx from simulated gas mixture and actual diesel engine exhaust has been treated. The thesis mainly addresses the following issues. . • Performance evaluation of pipe-cylinder and wire-cylinder reactor for NOx removal . • Study of effect of plasma assisted adsorbent reactor on NOx removal . • Study of effect of adsorption and plasma based desorption using different adsorbent material and electrode configuration The first chapter provides introduction about the air pollutants and the existing NOx control technologies, a brief history of electric discharge plasma, a detailed literature survey and scope of the work. A detailed experimental setup consisting of voltage sources, gas system (simulated flue gas and diesel exhaust), gas analyzers, adsorbent materials are discussed in the second chapter. In the third chapter, NOx is treated by three different methods and are described in separate parts. In first part we have done a comparative study of NO/NOx removal using two different types of dielectric barrier discharge electrodes: a) wire-cylinder reactor, b) pipe-cylinder reactor. Investigations were first carried out with synthetic gases to obtain the baseline information on the NO/NOx removal with respect to the two geometries studied. Further, experiments were carried out with raw diesel exhaust under loaded condition. A high NOx removal efficiency 90% was observed for pipe-cylinder reactor when compared to that with wire-cylinder reactor, where it was 53.4%. In second part an analysis has been made on discharge plasma coupled with an adsorbent system. The cascaded plasma-adsorbent system may be perceived as a better alternative for the existing adsorbent based abatement system in the industry. During this study the exhaust is sourced from a diesel generator set. It was observed that better NO removal in a plasma reactor can be made possible by achieving higher average fields and subsequent NO2 removal can be improved using an adsorbent system connected in cascade with the plasma system. This part describes the various findings pertaining to these comparative analyses. The third and last part of chapter 3 consists of gas desorption from an adsorbent by non-thermal plasma, which is an alternative to conventional thermal desorption, has been studied in relation to diesel engine exhaust. In this process saturated adsorbent material is regenerated using high energetic electrons and excited molecules produced by non thermal plasma. The last Chapter lists out the major inferences drawn from this study.

Page generated in 0.0842 seconds