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Retail stores are understudied given the energy, occupant health, and potential sales impacts associated with poor indoor air quality (IAQ). There is also evidence of elevated pollutants in retail environments. This thesis is an exploration of the indoor air quality of retail stores. The first section of this thesis is a literature review on field investigations of the indoor air quality in retail buildings. Sixteen investigations report different measurements in 17 specific types of retail environments. Measurements vary depending on the specific investigation, but include VOCs, SVOCs, particles, microbiological species, and radon. When reported, indoor to outdoor ratios of almost all pollutants are greater than unity, suggesting the importance of indoor sources in retail environments. The second section of this thesis is an analysis of the whole store net emission factor for different retail environments. From the types of pollutants found in the retail store investigations, VOCs were the only pollutant group studied frequently enough to merit this analysis. The final section is an analysis of the potential for pollutant remediation strategies. Two methods, increasing air change rate and air cleaning, are considered with an analysis of the energy penalties associated with each. / text

To fill in this niche and to make the development of ecological biotechnologies more intense in Lithuania, a biofilter with the activated pine-bark charge has been designed at the Department of Environment Protection of Vilnius Gediminas Technical University; besides, complex research on biological air purification processes have been carried out with the help of this biofilter. Using biologically activated pine-bark charge in the developed filter, to carry out biological air purification research and to evaluate the efficiency of the theoretical and practical methods and its application. The fractionated charge of coniferous bark has been used in the special equipment with natural microflora cultivated for air purification from volatile organic compounds; and the potential of the employment of the developed equipment has been fully evaluated after theoretical and experimental researches and mathematical modelling. The experimental researches and their results prove that development and use of biofilters for air purification from volatile organic compounds at various production enterprises of Lithuania is promising. Its implementation is especially promoted by comparatively low capital and operation costs of air purification, high air purification efficiency and strict norms of pollutants emitted into the air set in the European Union.

To fill in this niche and to make the development of ecological biotechnologies more intense in Lithuania, a biofilter with the activated pine-bark charge has been designed at the Department of Environment Protection of Vilnius Gediminas Technical University; besides, complex research on biological air purification processes have been carried out with the help of this biofilter. Using biologically activated pine-bark charge in the developed filter, to carry out biological air purification research and to evaluate the efficiency of the theoretical and practical methods and its application. The fractionated charge of coniferous bark has been used in the special equipment with natural microflora cultivated for air purification from volatile organic compounds; and the potential of the employment of the developed equipment has been fully evaluated after theoretical and experimental researches and mathematical modelling. The experimental researches and their results prove that development and use of biofilters for air purification from volatile organic compounds at various production enterprises of Lithuania is promising. Its implementation is especially promoted by comparatively low capital and operation costs of air purification, high air purification efficiency and strict norms of pollutants emitted into the air set in the European Union.

Poor indoor air quality is a source of adverse health effects. TiO2 coatings deposited on well-illuminated surfaces, such as window panes, can be used to fully mineralize indoor air pollutants by photocatalysis. In such applications it is important to ensure stable photocatalytic activity for a wide range of operating conditions, such as relative humidity and temperature, and to avoid deactivation of the catalyst. In this thesis photocatalytic removal of the indoor-pollutant acetaldehyde (CH3CHO) on nanostructured TiO2 films is investigated, and in particular it is proposed how such films can be modified and operated for maximum performance. Catalyst deactivation can be reduced by purposefully changing the surface acidity of TiO2 by covalently attaching SO4 to the surface. Moreover, the overall photocatalytic activity on anatase TiO2 films can be improved by increasing the fraction of exposed reactive {001} surfaces, which otherwise are dominated by {101} surfaces. In the first part of the thesis mode-resolved in-situ FTIR is used to elucidate the reaction kinetics of CH3CHO adsorption and photo-oxidation on the TiO2 and SO4 – modified TiO2 surfaces. Surface concentrations of main products and corresponding reaction rates were determined. Formate is the major reaction product, whose further oxidation limits the complete oxidation to gaseous species, and is responsible for photocatalyst deactivation by site inhibition. The oxidation reaction is characterized by two reaction pathways, which are associated with two types of surface reaction sites. On the sulfate modified TiO2 catalyst fewer intermediates are accumulated, and this catalyst resists deactivation much better than pure TiO2. A hitherto unknown intermediate – surface-bound acetaldehyde dimer with an adsorption band at 1643 cm−1 was discovered, using interplay between FTIR spectroscopy and DFT calculations. The second part of the thesis treats the effect of increasing the relative abundance of exposed {001} facets on the photocatalytic activity of anatase TiO2 films prepared by DC magnetron sputtering. A positive effect was observed both for liquid-phase photo-oxidation of methylene blue, and for gas-phase photocatalytic removal of CH3CHO. In both cases it was found that the exposed {001} surfaces were an order of magnitude more reactive, compared to the {101} ones. Furthermore, it was found that the reactive films were more resilient towards deactivation, and exhibited almost unchanged activity under varying reaction conditions. Finally, a synergetic effect of SO4 – modification and high fraction of exposed {001} surfaces was found, yielding photocatalysts with sustained high activity. The results presented here for facet controlled and chemically modified TiO2 films are of interest for applications in the built environment for indoor air purification and as self-cleaning surfaces. / GRINDOOR

Master of Science / Department of Chemical Engineering / Larry E. Erickson / Photocatalytic oxidation (PCO) is a promising and emerging technique in controlling indoor air contaminants, including volatile organic compounds (VOCs). It has broad air cleaning and deodorization applications in indoor environments ranging from residential and office buildings to healthcare and nursing facilities as well as spacecrafts, aircraft cabins and clean rooms in the agricultural and food industry. Numerous studies have been conducted to improve the effectiveness and performance of this technology. These include development of new configurations, energy-efficient catalysts and other parameters to control the process. However, only limited research has been conducted under realistic indoor environmental conditions. One of the most recent developments in photocatalysis is the synthesis of 2% C- and V-doped TiO[subscript]2, which is active under both dark and visible light conditions. However, like most research conducted in photocatalysis, the study on the reactivity of this catalyst has been performed only under laboratory conditions. This study investigated the possible application of the novel C and V co-doped TiO[subscript]2 in cleaning indoor air. Mathematical modeling and simulation techniques were employed to assess the potential use of some of the promising systems that utilize the catalyst (i.e., packed bed and thin films) as well as the effect of mass transfer limitations in the degradation of acetaldehyde, one of the VOCs that can be found in offices, residential buildings and other facilities.

La qualité de l’air à l’intérieur des bâtiments basse consommation devient une problématique préoccupante dans le contexte actuel de règlementations thermiques de plus en plus exigeantes. Une des solutions envisagées pour concilier qualité de l’air intérieur et performance énergétique dans les bâtiments est l’intégration de systèmes d’épuration dans les réseaux de ventilation. Peu de retour d’expériences in situ permettent d’évaluer l’intérêt de ces systèmes pour répondre à la problématique. La solution envisagée dans ces travaux est l’évaluation par la simulation numérique. Ce choix a nécessité le développement d’un outil numérique capable de représenter de façon couplée les phénomènes thermiques, aérauliques et ceux liés à la qualité de l’air intérieur par une représentation multipolluant, à l’échelle d’un bâtiment ou d’une partie d’un bâtiment. Cet outil a été développé dans l’environnement Dymola sous le langage Modelica. Des expérimentations ont été menées dans ces travaux dans le but de compléter l’outil numérique par des lois empiriques caractérisant, d’une part les phénomènes de sorption des polluants gazeux par les matériaux de revêtement intérieur, d’autre part le comportement, à la fois énergétique et sanitaire, de six solutions d’épuration. Pour illustrer la capacité d’étude acquise grâce aux développements numériques et expérimentaux qui ont été réalisés dans le cadre des travaux de thèse, une zone de bureaux d’un bâtiment tertiaire a été simulée pour deux zones climatiques et pour deux types de pollution extérieure sur une année type complète. Les trois solutions d’épuration ayant montrées des performances tangibles lors de la phase expérimentale ont été simulées sous plusieurs conditions de fonctionnement puis comparées à deux cas de surventilation des locaux (sans épuration de l’air). Un indice global combinant performance sanitaire et énergétique a été ainsi défini dans le but de hiérarchiser les différentes stratégies simulées. Les résultats obtenus permettent de valider la méthodologie employée, notamment en montrant à la fois l’intérêt de contextualiser les solutions envisagées pour les évaluer, et l’importance de travailler, lors des expérimentations, à des conditions représentatives de la réalité des environnements intérieurs. Plusieurs voies d’amélioration de l’outil numérique développé sont également proposées en conclusion, ainsi que différents points de discussion qui méritent l’attention de travaux futurs dans le domaine. / Indoor air quality in low-energy buildings has become these recent years an important topic with the rigorous performance expectations in terms of envelope airtightness and energy consumption set by the RT2012 thermal building code. One possible solution to conciliate indoor air quality and energy performance is to integrate air-cleaning systems in the building ventilation system. Because of the lack of scientific results regarding the suitability of those systems to solve this problematic, an investigation using numerical simulation has been conducted in the present work. This choice led to the development of a numerical tool that resolves in a coupled way, the heat and mass transfers, considering a multi-pollutant representation at the scale of the building/rooms. This tool was developed in the Dymola environment, using the Modelica programming language. Several experiments were also performed in the present work to acquire complementary data about the sorption of gaseous pollutants by indoor covering materials and about the cleaning effectiveness and energy consumption of six air-cleaning systems. To illustrate the capabilities of the numerical tool, simulations have been performed for an office building zone. The building has been located in two climatic zones and submitted to two levels of outdoor pollution, for a whole year. Three of the tested solutions that have shown the best air-cleaning performances in the experimental phase have been simulated under various operating conditions. Two cases of higher amount of fresh air, i.e. without any air-cleaning system, have been also included to the study. One index has then been defined to compare the performance of the different solutions considering both the exposure reduction to eight pollutants and the induced energy consumption. The results obtained in the present study confirm the adequacy of the proposed methodology. In particular, the importance of evaluating the solutions in their real context and not simply relying on their intrinsic performances to judge their performances when applied to indoor environments has been demonstrated. Another important issue is the need to conduct experimental characterizations of sorption processes and air-cleaning system under environmental conditions representative of real indoor spaces, i.e. low pollutant concentration and adequate air temperature, humidity and velocity. Future developments needed to improve the capabilities of the numerical tool are presented in conclusion as well as some important issues that would need a careful attention for further works in the domain.

В работе проведено исследование двухфазного течения потока в инерционном пылеуловителе со штампованными решетками и батарейного циклона для газоперекачивающего агрегата ГПА-Ц-16 на базе конвертированного двигателя НК-16СТ. В результате исследований было определено гидравлическое сопротивление, глубина очистки, структура течения. Проведен анализ потерь давления и структуры течения в его элементах. / In work the research of a two-phase current of a stream in the inertial dust collector with stamped lattices and a battery cyclone for the gas-distributing GPA-С-16 unit on the basis of the converted NK-16ST engine is conducted. As a result of researches the hydraulic resistance, cleaning depth, structure of a current was determined. The analysis of pressure losses and structure of a current in its elements is carried out.