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  • 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

Effects of ozonation on cooling water systems

Mosugelo, Keneetswe Lilian 26 July 2010 (has links)
Cooling water systems are needed to dissipate heat. The mist from open system cooling towers has been implicated as a source of infections of Legionella pneumophila. As a result biocide is added to cooling water systems, but the addition of biocide worsens biofouling, scaling and corrosion. Increasing environmental pressure has resulted in a move away from biocides which are usually chlorine based chemicals, so that the use of ozone instead has recently been reported as a way of controlling microbiological growth. This study aims to compare the corrosion rates (using calculated and measured surface areas) of different metals exposed to chemically treated and ozone treated cooling water in an industrial cooling water system. The types of corrosion were also observed and recorded. The scales from different components of the cooling systems as well as scale from chemically and ozone treated D tower water were characterized qualitatively using X-ray diffraction (XRD), Thermo gravimetric Analysis (TGA) and Atomic Absorption Spectroscopy. The D tower is a cooling water circuit in which the cooling water is from the Vaal River. As expected, the stainless steel has the lowest corrosion rate of 0.000 milli inches/year followed by brass with 1.531 milli inches/year and lastly mild steel (2.098 milli inches/year). Water quality rather than the presence or absence of ozone determines the corrosion rate. This confirms the findings reported in the literature. Scale from chemically treated water contains many different compounds while scale from ozone treated contains only different polymorphs of CaCO3, which is present in the water source and magnesium calcite.
2

Problematik der Keimbelastung wasserführender Dentaleinheiten in der Universitätsmedizin Göttingen unter besonderer Berücksichtigung von Legionella pneumophila - Bestandsaufnahme und Möglichkeiten der Keimreduzierung / Problems of the germ load of water-leading dental units in the university medicine Goettingen under special consideration of Legionella pneumophila - stock taking and possibilities of the germ reduction

Muschinsky, Niklas 28 October 2014 (has links)
No description available.
3

Avaliação de um sistema industrial de resfriamento de água. / Evaluation of an industrial system of cooling water.

Oikawa, Eduardo Hiroshi 19 March 2012 (has links)
Neste trabalho, foi estudado o desempenho de um sistema constituído de torres de resfriamento e a sua integração em uma planta industrial de hidrogenação de butadieno. Caracterizou-se o desempenho das torres de resfriamento com base em um modelo fenomenológico, cujos parâmetros foram obtidos a partir da medição de variáveis operacionais reais. O processo de hidrogenação foi configurado em um simulador de processos, sendo o caso base estabelecido nas condições de projeto. Elaborou-se um módulo específico referente às torres de resfriamento, que foi integrado ao processo configurado no simulador. Em seguida, analisaram-se as interações das condições operacionais da torre de resfriamento no desempenho do processo industrial. / In the present work, the performance of a system composed of a cooling tower integrated in butadiene hydrogenation plant was studied. An experimental investigation was made to characterize the cooling towers based on a phenomenological model and in real process conditions. The hydrogenation process was configured on a process simulator and design specifications were considered as base case. A cooling tower module was developed and integrated to the process simulator. The interaction of the cooling tower system and the plant operation was investigated.
4

Avaliação de um sistema industrial de resfriamento de água. / Evaluation of an industrial system of cooling water.

Eduardo Hiroshi Oikawa 19 March 2012 (has links)
Neste trabalho, foi estudado o desempenho de um sistema constituído de torres de resfriamento e a sua integração em uma planta industrial de hidrogenação de butadieno. Caracterizou-se o desempenho das torres de resfriamento com base em um modelo fenomenológico, cujos parâmetros foram obtidos a partir da medição de variáveis operacionais reais. O processo de hidrogenação foi configurado em um simulador de processos, sendo o caso base estabelecido nas condições de projeto. Elaborou-se um módulo específico referente às torres de resfriamento, que foi integrado ao processo configurado no simulador. Em seguida, analisaram-se as interações das condições operacionais da torre de resfriamento no desempenho do processo industrial. / In the present work, the performance of a system composed of a cooling tower integrated in butadiene hydrogenation plant was studied. An experimental investigation was made to characterize the cooling towers based on a phenomenological model and in real process conditions. The hydrogenation process was configured on a process simulator and design specifications were considered as base case. A cooling tower module was developed and integrated to the process simulator. The interaction of the cooling tower system and the plant operation was investigated.
5

Trigenerace a její využití v praxi / Trigeneration and its use in practice

Čupera, Pavel January 2009 (has links)
e master's thesis clarifies the concept of trigeneration and the principle of absorbing cooling. Compare the advantages and disadvantages of this method of manufacture cool with compressor cooling. It presents an overview of the implementation of a developing cold absorption and performance. Acquainted with the types of absorption chillers of the two leading suppliers, their characteristics and existing applications of these refrigeration units in operation in the Czech Republic and abroad. It also assesses the possibility of using these units in conjunction with a cogeneration unit powered by internal combustion engine. It follows from the economic assessment of costs and income of the absorption chillers and compressor chillers and on concrete examples and an assessment of the effectiveness of the various options.

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