Browsing by Subject "Energy consumption"
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Item Analysis of Improved Fenestration for Code-Compliant Residential Buildings in Hot and Humid Climates(Texas A&M University, 2006-10-30) Mukhopadhyay, JayaThis thesis presents an analysis of energy efficient residential windows in hot and humid climates. To accomplish this analysis, the use of accurate simulation tools such as DOE-2.1e is required, which incorporates the results from the WINDOW-5.2 simulation program to assess accurate fenestration performance. The thesis also investigates the use of optimal glazing types, which, for future applications, could be specified in the code to reduce annual net energy consumption to zero. Results show that combinations of low-E and double pane, clear-glazed windows, which are optimally shaded according to orientation are the best solution for lowering both annual energy consumption and peak electricity loads. The study also concludes that the method used to model fenestration in the simulation program plays an important role in accurately determining the effectiveness of the glazing option used. In this particular study, the use of the WINDOW-5.2 program is highly recommended especially for high performance windows (i.e., low-E glazing). Finally, a discussion on the incorporation of super high performance windows (i.e., super low-E, ultra low-E and dynamic / switchable glazing) into the IECC code concludes that these types of glazing strategies can reduce annual net energy use of the window to zero. Future work identified by this thesis includes a more extensive examination of the passive solar potential of high performance fenestration, and an examination of the appropriate methods for specifying these properties in future versions of the IECC code. This implies that future specifications for fenestration in the IECC code could aim for zero net annual energy consumption levels from residential fenestration.Item Climate action strategies for the University of Texas at Austin(2010-05) Hernandez, Marinoelle; Eaton, David J.; Walker, Jim H.This report analyzes the current greenhouse gas emissions inventory for The University of Texas at Austin (UT-Austin), reviews the carbon reduction strategies being implemented at UT-Austin and other peer institutions, and offers recommendations for strategies that could reduce greenhouse gas emissions at UT-Austin in the future.Item Modeling energy consumption in the mining and milling of uranium(2010-12) Tavrides, Emily Loree; Schneider, Erich A.; Biegalski, SteveA family of top-down statistical models describing energy consumption in the mining, milling, and refining of uranium are formulated. The purpose of the models is to estimate the energy-to-grade dependence for uranium extraction, while defining a minimum grade that can be feasibly mined and produced. The results serve as a basis for understanding the factors governing energy consumption in the production of U3O8. The models are applied to a considerably larger data set of operating mines than in any previous effort. In addition, the validity of the modeling approach is established by modeling energy for two other commodities, gold and copper, thereby showing it can be applied to other metals. Statistical measures of explanatory power show that the models the energy-to-grade relationship is well-described for both uranium and gold. For copper, there was insufficient data over a broad range of ore grades to obtain a model that passed statistical confidence measures. The results show that mining of lower-grade deposits of uranium is likely to be less energy-intensive than previous investigators concluded. It is shown that the uncertainty in the results is dominated by the contribution of the grade-independent component of energy consumption.Item Pollutant control strategies for acceptable indoor air quality and energy efficiency in retail buildings(2013-12) Zaatari, Marwa; Novoselac, Atila; Siegel, Jeffrey A.Indoor air is associated with substantial health risks and is estimated to be responsible for the loss of over 4.7 million healthy life years (years lost due to morbidity and mortality) annually in the U.S. The highest indoor air-related health benefits can be expected from policies and strategies that efficiently target pollutants having the greatest contribution to the burden of disease. This burden is caused by indoor sources as well as by outdoor pollutants transported to the indoors. The diversity of pollutants, pollutant sources, and the resulting health effects challenge the comparison of the impacts of different control strategies on energy consumption and indoor air quality. To address this challenge, this work presents a quantitative framework for reaching the optimal energy cost for the maximum achieved exposure benefits, specifically for retail buildings and their understudied energy, economic, and health risk influence. The main objectives of this dissertation are to 1) determine pollutants of concern in retail buildings that contribute the greatest to the burden of disease, and 2) determine energy-efficient, exposure-based control strategies for different retail types and locations. The research in this dissertation is divided into four specific aims that fulfill these two objectives. The first specific aim (Specific aim 1.a) addresses Objective 1 by applying available disease impact models on pollutant concentrations taken from 15 literature studies (150 stores, a total of 34 pollutants). Of those pollutants, there was little data reported on particulate matter (PM) concentrations and none on emission rates for PM, limiting our understanding of exposure to this pollutant. The second specific aim (Specific aim 1.b) also addresses Objective 1 by characterizing particulate matter (PM) concentrations, emission rates, and fate of ambient and indoor-generated particles in retail buildings. The tasks of this specific aim consisted of particulate matter and ventilation measurements in 14 retail buildings. Among the findings of Objective 1, PM2.5 and acrolein are the main contaminants of concern for which control methods should be prioritized, contributing to 160 disability-adjusted life years (DALYs; years lost due to premature mortality and disability) per 100,000 persons annually. Employees in grocery stores mainly drove this burden. An efficient indoor exposure reduction strategy should take into account all mechanisms that influence pollutant concentrations: indoor and outdoor sources (highlighting the importance of retail type and location), infiltration, ventilation, and filtration. The remaining specific aims address Objective 2 by investigating the energy and air quality impact of two commonly used exposure control scenarios, ventilation (Specific aim 2.a) and filtration (Specific aim 2.b). The tasks of Specific aim 2.a consisted of modeling the impact of multiple ventilation strategies on contaminants of concern for six major U.S. cities and two retail types. The tasks for Specific aim 2.b consisted of conducting field measurements on 15 rooftop units to determine the fan energy impacts of filter pressure drop. These results are used in combination with a large dataset of 75 filters commonly installed in commercial buildings to estimate the energy consequences of filtration. Results for Objective 2 are presented from the quantitative comparison of the impact on energy usage and DALYs lost of three main approaches: (1) adjusting ventilation only; (2) adjusting filtration only; and (3) adjusting ventilation and filtration together. All approaches were able to provide substantial reductions in the health risks (19-26% decrease in DALYs lost); the magnitude of the reductions depended on the ventilation/filtration scenario, the retail type, and the city. The magnitude of energy cost to achieve the maximum health benefits depended on the city and the retail type (for example for a 10,000 m2 grocery store, the energy cost ranged from $1,100 for the annual cost of filtration energy in Los Angeles to $24,000 for the annual cost of ventilation in Austin). The uncertainties of the estimates driving these findings are discussed throughout the results section. The finding that emerges from this analysis is the pollutant exposure control ventilation (PECV) strategy. This strategy is superior to the ventilation rate procedure (VRP; ASHRAE Standard 62.1-2010) and the indoor air quality procedure (IAQP; ASHRAE Standard 62.1-2010) as it decides on a range of ventilation rates by weighing the exposures of contaminants of concern found in retail buildings. Then, among the range of ventilation rates identified, the PECV recommends the optimal ventilation rate that leads to energy usage savings in the climate considered. Overall, the work presented here prioritizes specific contaminants of concern in retail buildings and proposes an exposure-based, energy-efficient control strategy for different retail types and locations. Policy makers, engineers, and building owners can use these results to decide amongst appropriate control strategies that will lead to minimum energy consumption and, at the same time, will not compromise occupant health. This work can be repeated for different types of buildings, notably for residences, schools, and offices where abundant information is available on both pollutant concentrations and ventilation rates, but where information is lacking on how to optimize the control strategies for better indoor air quality.Item Synthesis of portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance(2009-12) Chen, Irvin Allen; Juenger, Maria C.G.Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, Portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, 1.) incorporation of waste materials in portland cement synthesis, and 2.) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S–C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate-belite cement that contained medium C4A3 S and C2S contents showed good dimensional stability, sulfate resistance, and compressive strength development and was considered the optimum phase composition for calcium sulfoaluminate-belite cement in terms of comparable performance characteristics to portland cement. Furthermore, two calcium sulfoaluminate-belite cement clinkers were successfully synthesized from natural and waste materials such as limestone, bauxite, flue gas desulfurization sludge, Class C fly ash, and fluidized bed ash proportioned to the optimum calcium sulfoaluminate-belite cement synthesized from reagent-grade chemicals. Waste materials composed 30% and 41% of the raw ingredients. The two calcium sulfoaluminate-belite cements synthesized from natural and waste materials showed good dimensional stability, sulfate resistance, and compressive strength development, comparable to commercial portland cement.Item Thermodynamic analysis and sustainability improvement of nanoparticles synthesis processes with application to titanium dioxide(2012-05) Li, Bingbing; Zhang, Hong-Chao; Fan, Zhaoyang; Rivero, Iris V.; Tate, Derrick; Wang, ShirenIncreasing world population, dwindling resources, and the degradation of natural ecosystems make thermodynamics and sustainability improvement of manufacturing processes a prominent goal for the engineering community for the foreseeable future. Although nanomanufacturing is expected to generate major economic impacts estimated in the billions of dollars, little is known about the energy consumption, potential environmental health and safety risks associated with public exposure of nanoparticles synthesis processes. The overarching objective of this research is to present a complete thermodynamic (including energy consumption and exergy losses) analysis and sustainability improvement for the nanoparticles synthesis processes. Firstly, the introductions of sustainable manufacturing, industrial ecology, energy consumption and nanotechnology are introduced briefly in Chapter 1. Then problem statement, research objective and contribution are clearly stated. Secondly, the literature review on data collection (top-down and bottom-up), thermodynamic model, mechanical model, finite element analysis and manufacturing processes are summarized in Chapter 2. Thirdly, the energy consumption and exergy losses general model for nanoparticles synthesis processes (divided into two main processes: precursor transport and chemical reaction) based on thermodynamics and kinetics is created in Chapter 3, which includes all the assumptions, boundaries, conditions and equations of model. Both first law and second law of thermodynamics were used for energy consumption and exergy losses of nanoparticles synthesis processes which are considered as steady state, steady flow open system. A simplified exergy model was also created for nanoparticles synthesis process. A two dimensional kinetic differential equations describing the conservation of mass, momentum and energy with appropriate boundary conditions was modeled for precursor transport process (convection and diffusion). The NPs chemical reaction process was modeled by thermodynamic model. Fourthly, the created model was applied to titanium dioxide nanoparticles (TiO2 NPs) synthesis processes. Background, crystal structure and route of TiO2 NPs are introduced in first section. Then the experimental setup, calculation and analysis for electrochemical annodization process (including five main processes: formation of oxide layer, chemical diffusion, physical diffusion, infiltration and crystallization) of TiO2 NPs are placed in detail. Based on results from experimental data and discussions, the energy consumption and exergy losses for the specific electrochemical annodization process are clearly demonstrated and the identification of sustainability improvement potential is also given. The thermodynamic model about size dependence of nanoparticles on electrical voltage is also discussed and validated by both experimental data and literature data. Fifthly, conclusion is given that the created model is validated by the electrochemical annodization process of TiO2 NPs and can also be applied to other nanoparticles synthesis processes, which is really essential and fundamental for sustainability development and life cycle assessment of manufacturing process. Future work is indicated in the end.