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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.
21

Building energy simulation of a Run-Around Membrane Energy Exchanger (RAMEE)

Rasouli, Mohammad 22 February 2011
<p>The main objective of this thesis is to investigate the energetic, economic and environmental impact of utilizing a novel Run-Around Membrane Energy Exchanger (RAMEE) in building HVAC systems. The RAMEE is an energy recovery ventilator that transfers heat and moisture between the exhaust air and the fresh outdoor ventilation air to reduce the energy required to condition the ventilation air. The RAMEE consists of two exchangers made of water vapor permeable membranes coupled with an aqueous salt solution.</p> <p>In order to examine the energy savings with the RAMEE, two different buildings (an office building and a health-care facility) were simulated using TRNSYS computer program in four different climatic conditions, i.e., cold-dry, cool-humid, hot-humid and hot-dry represented by Saskatoon, Chicago, Miami and Phoenix, respectively. It was found that the RAMEE significantly reduces the heating energy consumption in cold climates (Saskatoon and Chicago), especially in the hospital where the required ventilation rate is much higher than in the office building. On the other hand, the results showed that the RAMEE must be carefully controlled in summer to minimize the cooling energy consumption.</p> <p>The application of the RAMEE in an office building reduces the annual heating energy by 30% to 40% in cold climates (Saskatoon and Chicago) and the annual cooling energy by 8% to 15% in hot climates (Miami and Phoenix). It also reduces the size of heating equipment by 25% in cold climates, and the size of cooling equipment by 5% to 10% in hot climates. The payback period of the RAMEE depends on the air pressure drop across the exchangers. For a practical pressure drop of 2 cm of water across each exchanger, the payback of the RAMEE is 2 years in cold climates and 4 to 5 years in hot climates. The total annual energy saved with the RAMEE (including heating, cooling and fan energy) is found to be 30%, 28%, 5% and 10% in Saskatoon, Chicago, Miami and Phoenix, respectively.</p> <p>In the hospital, the RAMEE reduces the annual heating energy by 58% to 66% in cold climates, and the annual cooling energy by 10% to 18% in hot climates. When a RAMEE is used, the heating system can be downsized by 45% in cold climates and the cooling system can be downsized by 25% in hot climates. For a practical range of air pressure drop across the exchangers, the payback of the RAMEE is immediate in cold climates and 1 to 3 years in hot climates. The payback period in the hospital is, on average, 2 years faster than in the office building). The total annual energy saved with RAMEE is found to be 48%, 45%, 8% and 17% in Saskatoon, Chicago, Miami and Phoenix, respectively. The emission of greenhouse gases (in terms of CO<sub>2</sub>-equivalent) can be reduced by 25% in cold climates and 11% in hot climates due to the lower energy use when employing a RAMEE.</p>
22

Life Cycle Exergy Analysis of Wind Energy Systems : Assessing and improving life cycle analysis methodology

Davidsson, Simon January 2011 (has links)
Wind power capacity is currently growing fast around the world. At the same time different forms of life cycle analysis are becoming common for measuring the environmental impact of wind energy systems. This thesis identifies several problems with current methods for assessing the environmental impact of wind energy and suggests improvements that will make these assessments more robust. The use of the exergy concept combined with life cycle analysis has been proposed by several researchers over the years. One method that has been described theoretically is life cycle exergy analysis (LCEA). In this thesis, the method of LCEA is evaluated and further developed from earlier theoretical definitions. Both benefits and drawbacks with using exergy based life cycle analysis are found. For some applications the use of exergy can solve many of the issues with current life cycle analysis methods, while other problems still remain. The method of life cycle exergy analysis is used to evaluate the sustainability of an existing wind turbine. The wind turbine assessed appears to be sustainable in the way that it gives back many times more exergy than it uses during the life cycle.
23

Building energy simulation of a Run-Around Membrane Energy Exchanger (RAMEE)

Rasouli, Mohammad 22 February 2011 (has links)
<p>The main objective of this thesis is to investigate the energetic, economic and environmental impact of utilizing a novel Run-Around Membrane Energy Exchanger (RAMEE) in building HVAC systems. The RAMEE is an energy recovery ventilator that transfers heat and moisture between the exhaust air and the fresh outdoor ventilation air to reduce the energy required to condition the ventilation air. The RAMEE consists of two exchangers made of water vapor permeable membranes coupled with an aqueous salt solution.</p> <p>In order to examine the energy savings with the RAMEE, two different buildings (an office building and a health-care facility) were simulated using TRNSYS computer program in four different climatic conditions, i.e., cold-dry, cool-humid, hot-humid and hot-dry represented by Saskatoon, Chicago, Miami and Phoenix, respectively. It was found that the RAMEE significantly reduces the heating energy consumption in cold climates (Saskatoon and Chicago), especially in the hospital where the required ventilation rate is much higher than in the office building. On the other hand, the results showed that the RAMEE must be carefully controlled in summer to minimize the cooling energy consumption.</p> <p>The application of the RAMEE in an office building reduces the annual heating energy by 30% to 40% in cold climates (Saskatoon and Chicago) and the annual cooling energy by 8% to 15% in hot climates (Miami and Phoenix). It also reduces the size of heating equipment by 25% in cold climates, and the size of cooling equipment by 5% to 10% in hot climates. The payback period of the RAMEE depends on the air pressure drop across the exchangers. For a practical pressure drop of 2 cm of water across each exchanger, the payback of the RAMEE is 2 years in cold climates and 4 to 5 years in hot climates. The total annual energy saved with the RAMEE (including heating, cooling and fan energy) is found to be 30%, 28%, 5% and 10% in Saskatoon, Chicago, Miami and Phoenix, respectively.</p> <p>In the hospital, the RAMEE reduces the annual heating energy by 58% to 66% in cold climates, and the annual cooling energy by 10% to 18% in hot climates. When a RAMEE is used, the heating system can be downsized by 45% in cold climates and the cooling system can be downsized by 25% in hot climates. For a practical range of air pressure drop across the exchangers, the payback of the RAMEE is immediate in cold climates and 1 to 3 years in hot climates. The payback period in the hospital is, on average, 2 years faster than in the office building). The total annual energy saved with RAMEE is found to be 48%, 45%, 8% and 17% in Saskatoon, Chicago, Miami and Phoenix, respectively. The emission of greenhouse gases (in terms of CO<sub>2</sub>-equivalent) can be reduced by 25% in cold climates and 11% in hot climates due to the lower energy use when employing a RAMEE.</p>
24

Exploring the Environmental Impact of A Residential Life Cycle, Including Retrofits: Ecological Footprint Application to A Life Cycle Analysis Framework in Ontario

Bin, Guoshu January 2011 (has links)
The residential sector is recognized as a major energy consumer and thus a significant contributor to climate change. Rather than focus only on current energy consumption and the associated emissions, there is a need to broaden sustainability research to include full life cycle contributions and impacts. This thesis looks at houses from the perspective of the Ecological Footprint (EF), a well-known sustainability indicator. The research objective is to integrate EF and Life Cycle Analysis (LCA) measures to provide an enhanced tool to measure the sustainability implications of residential energy retrofit decisions. Exemplifying single-detached houses of the early 20th century, the century-old REEP House (downtown Kitchener, Canada), together with its high performance energy retrofits, is examined in detail. This research combines material, energy and carbon emission studies. Its scope covers the life cycle of the house, including the direct and indirect consumption of material and energy, and concomitant carbon emissions during its stages of material extraction, transportation, construction, operation, and demolition. The results show that the REEP House had a significant embodied impact on the environment when it was built and high operating energy and EF requirements because of the low levels of insulation. Even though the renovations to improve energy efficiency by 80% introduce additional embodied environmental impacts, they are environmentally sound activities because the environmental payback period is less than two years.
25

Environmental comparison of Michelin Tweel and pneumatic tire using life cycle analysis

Cobert, Austin 03 September 2009 (has links)
Recently Michelin has been developing a new airless, integrated tire and wheel combination called the Tweel. The Tweel promises performance levels beyond those possible with conventional pneumatic technology because of its shear band design, added suspension, and decreased rolling resistance. However, many questions remain as to what kind of environmental impact this radical new design will have. The environmental impact of the Tweel will be compared to a current radial tire used on BMWs, but because of the complexity in manufacturing, using, and disposing these tires it is somewhat difficult to compare environmental problems. Currently there are environmental issues all throughout a tire's lifespan from rubber manufacturing emissions to tire disposal, and the rapidly growing method to evaluate all of these points is Life Cycle Analysis (LCA). LCA is the essential tool required by businesses in order to understand the total environmental impact of their products - cradle-to-grave. By considering the entire life cycle of a Tweel from manufacturing, through use and disposal, and comparing it to knowledge of current tires, an accurate assessment of the entire environmental impact of the Tweel will be made. Since the Tweel is currently still in the research phase and is not currently manufactured and used however, there are uncertainties with respect to end-of-life scenarios and rolling resistance estimates that will affect the LCA. Thus, it will be important to consider a range of options to determine which one will have the most environmental benefits while still keeping the strengths of the Tweel design intact.
26

Evaluation of scrap tire-derived porous rubber tubing as a green membrane for sustainable water filtration (ECOL-Mem process)

Garcia, Ana Maria 01 June 2007 (has links)
Increasing population and extensive urbanization have strained resources around the world, promoting water scarcity and solid waste accumulation. Addressing the issues of access to safe drinking water and basic sanitation in developing countries is challenging due to limited technological and financial resources. Therefore, it is imperative that durable, low-cost, and sustainable technologies are developed to help alleviate these problems. At the same time, the production of solid waste has increased and includes waste tires, which pose a health and environmental hazard. Although efforts have been made to develop new markets for recycled scrap tires, a vast majority are still being stockpiled or landfiled. This study aims to evaluate a water treatment system that addresses the problem of access to safe drinking water and sanitation, while providing a new market for recycled scrap tires. The system, termed ECOL-Mem, utilizes commercially available porous rubber tubing (PRT), which is marketed for drip irrigation purposes. To our knowledge, this is the first time this product has been used in a water treatment system. The PRT is manufactured through a hot extrusion process and contains 65% recycled crumb rubber and a binder (e.g. polyethylene). The proposed configuration simulates a hollow fiber membrane filtration system driven by a vacuum that operates inside-out. The system was first tested using clean water to obtain intrinsic characteristics. It was then tested using bentonite and sludge solutions that simulated impaired source water. For the case of a bentonite solution containing 700 mg/L, 20L of permeate could be obtained in one hour while the total solids removal remained around 20%. In order to improve the water quality, a flocculation-enhanced filtration phase was explored. The flocculant is chitin, a biopolymer that can be derived from waste shellfish. Upon addition of the chitin, between 60% and 70% of total solids removal could be obtained for different feed waters. Although optimization is needed, the PRT system has shown promising results, while providing a technology that targets the needs of developing countries in the areas of safe drinking water, basic sanitation, and solid waste recycling.
27

Environmental impact and performance of transparent building envelope materials and systems

Robinson-Gayle, Syreeta January 2003 (has links)
Building envelopes are elements with a long lifetime, which provide a barrier between internal and external space and contribute to the internal environmental conditions provision. Their complex role ensures a large impact on the environmental and energy performance of a building and the occupant perception of a space. This study looks at the use of novel materials and processes to help reduce the environmental impact of buildings by improving facade and transparent roof design. There are three main strands to the work. First, novel building components, ETFE foil cushions were examined. Physical testing has shown that ETFE foil cushions compare favourably to double glazing in terms of thermal and daylighting performance which was also noted as one of the most likeable feature by occupants. Environmental impact analysis has indicated that ETFE foils can reduce the environmental impact of a building through reduced environmental burden of both the construction and operation of the building. Secondly, a cradle-to-gate Life Cycle Analysis (LCA) was carried out for float glass, which considered the environmental impacts of glass manufacture. The embodied energy was calculated to be 13.4 ± 0.5 GJ per tonne while the total number of eco-points 243 ± 11 per tonne. It is shown that float glass is comparable to the use of steel, and highly preferable to the use of aluminium as a cladding panel. Finally, a concept design tool (FACADE) was developed by defining a large number of office facade models and employing dynamic thermal, daylighting and environmental impact modelling to create a database which can be accessed through a user friendly interface application. A parametric analysis has indicated that using natural ventilation where possible can reduce the environmental impact of offices by up to 16%. Improving the standard of the facade and reducing the internal heat loads from lighting and equipment can reduce environmental impact up to 22%. This study makes a significant contribution to understanding the environmental impact of building envelope individual and integrated components.
28

Exploring the Environmental Impact of A Residential Life Cycle, Including Retrofits: Ecological Footprint Application to A Life Cycle Analysis Framework in Ontario

Bin, Guoshu January 2011 (has links)
The residential sector is recognized as a major energy consumer and thus a significant contributor to climate change. Rather than focus only on current energy consumption and the associated emissions, there is a need to broaden sustainability research to include full life cycle contributions and impacts. This thesis looks at houses from the perspective of the Ecological Footprint (EF), a well-known sustainability indicator. The research objective is to integrate EF and Life Cycle Analysis (LCA) measures to provide an enhanced tool to measure the sustainability implications of residential energy retrofit decisions. Exemplifying single-detached houses of the early 20th century, the century-old REEP House (downtown Kitchener, Canada), together with its high performance energy retrofits, is examined in detail. This research combines material, energy and carbon emission studies. Its scope covers the life cycle of the house, including the direct and indirect consumption of material and energy, and concomitant carbon emissions during its stages of material extraction, transportation, construction, operation, and demolition. The results show that the REEP House had a significant embodied impact on the environment when it was built and high operating energy and EF requirements because of the low levels of insulation. Even though the renovations to improve energy efficiency by 80% introduce additional embodied environmental impacts, they are environmentally sound activities because the environmental payback period is less than two years.
29

Vers l’éco-conception des piles à combustible : développement d'un procédé de recyclage des catalyseurs des systèmes de PEMFC à base de platine / Fuel cells eco-design

Duclos, Lucien 04 October 2016 (has links)
Les piles à combustible (PAC) de type PEMFC permettent d’assurer la conversion d’énergie chimique en énergie électrique en utilisant de l’hydrogène pouvant être produit à partir de sources renouvelables. La catalyse des réactions mises en jeu lors de cette conversion d’énergie nécessite l’utilisation de platine, dont les ressources sont faibles et la production (extraction et raffinage) complexe. De plus, du fait de son prix élevé, ce métal représente une part importante du coût de production des PEMFC. Aujourd’hui, le prix de cette technologie doit être réduit pour qu’elle soit économiquement compétitive et puisse être commercialisée à grande échelle. En outre, les charges en platine dans les électrodes de piles à combustible ne peuvent être réduites significativement sans altération de la performance et de la durabilité de ces systèmes. Donc, le développement d’une filière de recyclage pour assurer la récupération du Pt en fin de vie des PAC pourrait permettre une réduction du coût de production des PEMFC.Cette thèse a consisté à mettre en place une voie de recyclage du platine d’assemblages membrane-électrodes (AME) de PEMFC. Un procédé hydrométallurgique composé des étapes suivantes : (i) lixiviation, (ii) séparation et (iii) récupération du platine a été développé. Différentes alternatives de lixiviation (HCl/H2O2, HCl/HNO3), de séparation (par résine ou solvant), de récupération (sous forme de nanoparticules ou de sel) ont été testées. Le fonctionnement de ces processus de récupération du platine a alors été optimisé à partir de produits modèles (Pt/C et solutions synthétiques). Le choix de ces derniers a ensuite été orienté grâce à une étude d’analyse du cycle de vie (ACV) réalisée à l’échelle de l’AME.Enfin, 76% du platine contenu dans des AME composées de catalyseurs Pt-Co a pu être récupéré. Ce rendement a pu être obtenu après mise en place du procédé composé des étapes suivantes : (i) dissolution du Pt par lixiviation avec le mélange HCl/H2O2, (ii) séparation du cobalt sur résine échangeuse d’ions, (iii) récupération sous forme de nanoparticules par la voie polyol. Les résultats finaux d’ACV ont montré que le recyclage du platine permettrait une nette réduction des impacts environnementaux du cycle de vie d’AME de PEMFC. / The proton exchange membrane fuel cells (PEMFC) can be used to convert chemical energy into electrical energy using hydrogen which can be produced from renewable sources. Platinum (Pt) is the best catalyst used to perform PEMFC electrochemical reaction catalysis. However Pt resources are low and his production (extraction and refining) is complex. Moreover the platinum price represents an important part of the PEMFC stack cost. Nowadays this technology is too expensive to be competitive with conventional energy conversion systems, and cannot be commercialized at a large scale. In addition, PEMFC electrode platinum loading could not be reduced without affecting the system performance and durability. Thus PEMFC production cost could be reduced by recovering platinum from used fuel cells.The main goal of this thesis was to develop a platinum recovery way from fuel cells membrane electrodes-assemblies (MEAs). In order to achieve this objective the following steps were combined in a hydrometallurgical process: (i) leaching, (ii) separation, (iii) recovery. Several alternatives were tested for each step: leaching (HCl/H2O2, HCl/HNO3), separation (resin or solvent), and platinum recovery (as nanoparticles or as a complex). These platinum recovery steps were optimized using Pt/C catalysts and synthetic solutions. Then life-cycle analysis (LCA) methodology has been used to help with the process selection.Finally, about 76% of the platinum contained in multi-metallic catalysts (PtCo/C) MEAs has been recovered. The following path has been followed in this case: (i) dissolution in HCl/H2O2 solution, (ii) separation from cobalt with an ion exchange resin, (iii) recovery has nanoparticles using the polyol process. The LCA study final results showed that a significant reduction of PEMFC MEA life-cycle environmental impact could be achieved by recycling Pt at these systems end-of-life.
30

Hur kan hållbarheten utökas för Storsjö Strand?

Olsson, Caroline, Rudeklint, Hanna January 2017 (has links)
Det här   examensarbetet har Östersunds kommuns nya stadsdel Storsjö Strand i fokus,   där arbetet går ut på att utvärdera hur kommunens hållbarhetsprogram har   fallit ut för de två första husen på Storsjö Strand och varför, samt att   undersöka vilka drivande faktorer som finns bakom byggnadernas miljöbelastning.   Hållbarhetsutvärderingen görs genom intervjuer med berörda byggherrar samt   Östersunds kommun, och drivande faktorer till miljöbelastning undersöks genom   att utföra en livscykelanalys där ingående material kopplas till en   resulterande miljöbelastning för respektive hus. Då   hållbarhetsutvärderingen utgår från intervjuer finns risk att   intervjuobjekten kan försköna fakta, vilket är en viktig begränsning vid   utläsning av resultatet. Resultatet från hållbarhetsutvärderingen   visar att trots att Östersunds kommun helt släppt sin egen utvärdering av   byggherrarna har byggherrarna ändå följt hållbarhetsprogrammet till stor del.   Slutsatserna avseende hållbarhetsprogrammet gäller främst kommunen, där dessa   hade gagnats av att förtydliga krav och mål, och kontraktera dessa krav i   markanvisningsavtal för att ge önskad effekt. För livscykelanalysen begränsas   denna främst av att alla steg i en livscykel inte är inkluderade, utan   primärt analyseras de inledande stegen. Resultatet visar för båda husen att   det till allra största del är metaller och legeringar som driver   miljöbelastning i störst grad per kubikmeter material, medan de   material som driver minst miljöbelastning är rena icke processade   naturmaterial såsom skiffer, grus och kalksten. Därutöver resulterar   konstruktionsmaterialen i den största miljöbelastningen   när hela mängden tas hänsyn till, vilket hade kunnat undersökas djupare med   snävare livscykelanalyser. / This thesis revolves around the district Storsjö   Strand, an area in Östersund which is developing to a new residential area   with high sustainability visions. The work consist of two parts; one where   the outcome of the municipality’s sustainability program is evaluated and one   where the two first buildings in the area is investigated regarding what   causes their environmental impact. The evaluation of the sustainability   program is made by interviews with the constructors and representatives from   the municipality, and the two buildings environmental impact is investigated   by performing a life cycle analysis where building material is connected to a   resulting environmental impact for each house. Since the evaluation of the   municipality’s sustainability program is based on interviews, there could be a risk for bias. The results from the   evaluation shows that both constructors have followed the sustainability   program to great extent, even though the municipality itself have dropped all planned follow-up. The conclusions   from the evaluation is that the municipality would be benefit from clarifying   goals and demands in the sustainability program, and transfer the clarified   demands to their land agreements. The limitations for the life cycle analysis is   mainly that all steps in the life cycle of a building is not included in the   analysis – only the initial steps are included. The   results for both buildings show that it is mainly metals and alloys that   drives environmental impact per cubic meter of material. The materials that   causes the smallest environmental impact per cubic meter is natural materials   that have not been processed, i.e. shale, limestone and gravel. The   construction materials will always result in the largest environmental impact   for the total quantity, simply because these materials are the largest   quantities represented in the building, and alternations of these   construction materials should be further investigated. / <p>Betyg 170707, H14.</p>

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