1. Modeliranje posledic izlitja raztopin vodikovega fluorida in natrijevega hidroksida : diplomsko delo univerzitetnega študijskega programa I. stopnjeUrška Brence, 2020, undergraduate thesis Abstract: V diplomskem delu je opisana uporaba prostodostopnih računalniških programov Evaporation Calculator in ALOHA. Računalniški program Evaporation Calculator smo uporabili za analizo masnega pretoka izhlapevanja vodikovega fluorida. Ugotovili smo, da se masni pretok izhlapevanja vodikovega fluorida povečuje s hitrostjo vetra, koncentracijo raztopine in temperaturo ozračja. Z uporabo računalniškega programa ALOHA smo modelirali kemijsko nesrečo izlitja 70 % fluorovodikove kisline v treh letnih časih. Rezultati so pokazali, da bi bile najhujše posledice kemijske nesreče razlitja HF v poletnem času. Takrat bi bili v smrtni nevarnosti vsi, ki bi bili od mesta nesreče oddaljeni 395 metrov ali manj in bi se tam zadrževali vsaj 60 minut. Ugotovili smo tudi, da se pri 10 minutnem zadrževanju na mestu v bližini kemijske nesreče območje nevarnosti zmanjša na 193 metrov. Negativne učinke na zdravje bi občutili vsi ljudje, ki bi bili od mesta nesreče oddaljeni 2600 metrov ali manj, ne glede na čas zadrževanja na nevarnem območju. Za izdelavo diplomskega dela smo uporabili tudi računalniški program Microsoft Excel, s katerim smo modelirali iztekanje raztopine natrijevega hidroksida iz rezervoarja skozi majhno odprtino. Rezultati so pokazali, da bi se hranilnik izpraznil v 18 minutah in 27 sekundah. Prav tako smo z omenjenim programom modelirali potek nevtralizacije 70 % raztopine vodikovega fluorida s 50 % raztopino natrijevega hidroksida ter izračunali spremembo temperature zmesi, ki je posledica eksotermne reakcije med izbranima kemikalijama.
Keywords: ALOHA, Evaporation Calculator, izlitje vodikovega fluorida, modeliranje iztekanja, nevtralizacija, eksotermna reakcija
Published in DKUM: 24.09.2020; Views: 1022; Downloads: 119
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2. Multiple-effect evaporation in aluminosilicate technologyDušan Klinar, Janvit Golob, 2001, professional article Abstract: The article presents an engineering approach to the development of an alternative production with the existing equipment. Zeolite production is becoming an alternative to the old »Bayer« process for aluminum hydrate production. By applying appropriate know-how old equipment was used for an economically as well as ecologically acceptable production. In this equipment adaptation among other production steps the multistage evaporation battery was the most critical part of the process. We applied semi empirical approach on the basis of Z. Rant ideas to find heat transfer coefficients and to determine which equipment elements are more relevant for efficient performance and need serious maintenance.
Keywords: chemical engineering, evaporation in silicate technology, bauxite alumina production, evaporators, process optimization, heat transfer, heat flow, empirical equations, heat transfer coefficients, zeolites
Published in DKUM: 24.08.2017; Views: 1618; Downloads: 112
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3. Monitoring the evaporation of fluids from fiber-optic micro-cell cavitiesEyal Preter, Borut Preložnik, Vlada Artel, Chaim Sukenik, Denis Đonlagić, Avi Zadok, 2013, original scientific article Abstract: Fiber-optic sensors provide remote access, are readily embedded within structures, and can operate in harsh environments. Nevertheless, fiber-optic sensing of liquids has been largely restricted to measurements of refractive index and absorption spectroscopy. The temporal dynamics of fluid evaporation have potential applications in monitoring the quality of water, identificationof fuel dilutions, mobile point-of-care diagnostics, climatography and more. In this work, the fiber-optic monitoring of fluids evaporation is proposed and demonstrated. Sub-nano-liter volumes of a liquid are applied to inline fiber-optic micro-cavities. As the liquid evaporates, light is refracted out of the cavity at the receding index boundary between the fluid and the ambient surroundings. A sharp transient attenuation in the transmission of light through the cavity, by as much as 50 dB and on a sub-second time scale, is observed. Numerical models for the transmission dynamics in terms of ray-tracing and wavefront propagation are provided. Experiments show that the temporal transmission profile can distinguish between different liquids.
Keywords: fiber-optic sensors, opto-fluidics, evaporation monitoring, optical micro-cells, fiber cavities, droplet analysis
Published in DKUM: 22.06.2017; Views: 1239; Downloads: 336
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4. Influence of temperature on the surface enhanced Raman scattering spectra of 2, 4, 6 - trinitrotolueneSimon Hamler, 2015, master's thesis Abstract: The detection of trace amounts of explosive like trinitrotoluene (TNT) is an important issue in the prevention of terrorist attacks. Surface enhanced Raman scattering (SERS) spectroscopy has become a powerful detection technique for identification of minute amounts of analytes. This thesis presents data of TNT in solution, deposited on a nanostructured gold surface, which is heated up to 60 °C. The observed changes in the microscopy images and in the SERS spectra are explained by evaporation, phase transition and decomposition of the TNT molecules. The impact of temperature dependence of SERS effect is studied on a chemisorbed 4-Nitrothiophenol monolayer. To minimize the evaporation of TNT molecules, a self-assembled monolayer of mercaptohexanol (MCH) was inserted between plasmonic surface and TNT.
Keywords: surface enhanced Raman spectroscopy, explosives, temperature dependence, microscopy, evaporation, phase transition, decomposition
Published in DKUM: 05.11.2015; Views: 2132; Downloads: 107
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5. Improving the economic and environmental performances of the beet sugar industry in Slovenia: increasing fuel efficiency and using by-products for ethanolDamjan Krajnc, Miro Mele, Peter Glavič, 2007, original scientific article Abstract: This paper investigates the possibilities of attaining zero-waste emissions inthe case of sugar production. The case-studied sugar plant located in Slovenia reflected a typical plant, using traditional sugar production from beet. An investigation of the possible use of waste and by-products from sugarprocessing was carried out, in order to approach zero-waste from beet sugar processing. The sugar production process was simulated and optimization was carried out concerning energy utilization. Consumption of energy in the chosen sugar plant was lowered by simultaneous optimization of the evaporationand crystallization process. Changing the fuel type used in the case-studied sugar plant (replacement of heavy fuel oil with natural gas) produced a significant decrease in air emission. Opportunities in the sugar industry have been discovered for adapting to new market conditions through the optimization of combined sugar-ethanol production. The two proposed options have been economically and environmentally evaluated and compared.
Keywords: kemična industrija, trajnostni razvoj, proizvodnja sladkorja, minimiranje porabe energije, evaporacija, etanol, chemical industries, sustainable development, sugar production, energy minimization, evaporation, ethanol, zero waste
Published in DKUM: 01.06.2012; Views: 2699; Downloads: 107
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