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1

Ractive pollutants dispersion modeling in a street canyon

Merah A., Noureddine A.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

91--103

EN

Reactive pollutant dispersion in a 3-D urban street canyon is numerically investigated using a computational fluid dynamics (CFD) code (Ansys-CFX), with the k–ε turbulence model and includes transport equations for NO, NO2, and O3 with simple photochemistry. An area emission source of NO and NO2 was considered in the presence of background O3 with an ambient wind perpendicular to the along-canyon direction. The results showed that the magnitude of NOx (NO+NO2) concentrations on the leeward side of the upstream buildings was much larger than the windward side of the downstream building, due to the entrainment and dispersion of traffic emissions by the primary vortex. The reverse is the case for ozone with higher concentrations on the windward side compared to the leeward side. The model has been validated against no-reactive pollutant experimental data of the wind tunnel experiments of Hoydysh and Dabberdt [1].

2

Influence of H2O2 and O3 on PGM Extraction from Used Car Catalysts

Fornalczyk A., Willner J., Gajda B., Sedlakova-Kadukova J.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

963--968

EN

Catalytic converters contain the catalytic substance in their structure, which is a mixture of Platinum Group Metals (PGMs). The prices of these metals and a growing demand for them in the market, make it necessary to recycle spent catalytic converters and recovery of PGMs. In the study, the effect of ozone and hydrogen peroxide application on the possibility of extracting PGM from used car catalysts was investigated. The catalytic carrier was milled, sieved and then the fractions with the desired grain size were treated with the appropriate HCl mixture and 3%, 5%, 10%, 15% and 30% H2O2, respectively, and the tests were also carried out at temperature 333 K. Ozone tests were conducted with the O3 flow in the range of 1,3,5 g/h. Samples for analysis were collected after 30 min, 1 h, 2 h, 3 h and after 4 h, respectively. The residue after the experiments and filtration process was also analysed. The obtained results confirmed the assumption that PGMs can be extracted using hydrochloric acid with the addition of H2O2 or ozone as oxidants. It allows to significantly intensify the carried out reactions and to improve the rate of PGMs transfer to the solution.

3

Ambient air quality for different weather conditions in two sites of observation

Olszowski T.

Ecological Chemistry and Engineering. A

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2017

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Vol. 24, nr 1

19--31

EN

This paper presents the results of a short-term study into the variability of air quality corresponding to a variety of weather conditions in two observation spots differing in terms of urban development and land use character. The project reported here was conducted in the areas of housing development in the rural and urban areas during the cold season. The analysis involved 384 independent, 60-minute registrations of core air pollutants (NO2, SO2, O3 and PM10). The research applied reference methodologies applied for measurements of physical parameters. The results of the registrations were compared by application of the Common Air Quality Index (CAQI) and the results were verified and analyzed by non-parametric tests (Spearman correlation and Wilcoxon ranked pair test). Consequently, it was stated that the comparison of air quality parameters by the application of the CAQI index provides an adequate solution. It was also observed that the short-term variability of the air quality parameters in the measurement spots is strictly related with the weather conditions in a given location. It was also concluded that during the cold season, the degree of urban development of the residential areas does not have a decisive effect on the course of the profiles of the core pollutants registered during one day. As a result, it was indicated that PM10 forms the source of pollution and determines the overall air quality. The study also revealed that air quality in the inhabited rural areas does not differ much from the more populated residential area in the town.

PL

Artykuł przedstawia wyniki krótkoterminowych badań nad zmiennością jakości powietrza dla odmiennych warunków pogodowych w dwóch, różniących się stopniem zurbanizowania i sposobem użytkowania, miejscach obserwacji. Projekt badawczy przeprowadzono na obszarze osiedli mieszkalnych w mieście i na wsi w sezonie chłodnym. Przeanalizowano 384 niezależnych, 60-minutowych rejestracji wartości stężenia podstawowych zanieczyszczeń powietrza (NO2, SO2, O3 i PM10). Wykorzystano referencyjne metodyki pomiarów wielkości fizycznych. Rezultaty rejestracji porównano przy wykorzystaniu ogólnego indeksu jakości powietrza (CAQI) a następnie przeanalizowano i zweryfikowano przy użyciu testów nieparametrycznych (korelacji Spearmana i testu Wilcoxona). Stwierdzono, że porównywanie jakościowych parametrów powietrza w różnych lokalizacjach przy użyciu CAQI jest dobrym rozwiązaniem. Wykazano, że krótkotrwała zmienność aerosanitarnej jakości powietrza jest ściśle związana z panującymi warunkami pogodowymi. Stwierdzono, że w sezonie zimowym, stopień zurbanizowania terenów zamieszkałych nie ma decydującego wpływu na dobowy kształt profili stężeń podstawowych zanieczyszczeń. Wykazano, że zanieczyszczeniem ustalającym ogólną jakość powietrza jest PM10. Znaleziono, że w okresie chłodnym, jakość powietrza na zamieszkałych obszarach wsi nie jest lepsza niż na znacznie bardziej ludnym osiedlu miejskim.

4

Numerical methods in understanding reaction pathways NOx oxidation

Jaroszyńska-Wolińska J., Malinowski S.

Budownictwo i Architektura

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2016

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Vol. 15, nr 3

75--81

EN

Different quantum chemical models were applied in energetic analysis of the process of oxidation of NO and NO2 through reaction with ozone generated by non-thermal equilibrium (low temperature), atmospheric pressure plasma. The potential energy surfaces of systems comprising NO and NO2 with ozone were characterized. The NOx oxidation processes well known, at the molecular level, were modelled by ab initio quantum chemistry methods to calculate the total reaction energy, Et, of each step in the reaction chain. Quantum chemistry was further applied in an attempt to detect the presence of any transition states and to calculate the activation energy, Ea, of reactions (1) NO + O3 and (2) NO2 + O3 using the MP2 level of theory with three different basis sets and fine potential energy scan resolution.