Engineering Commons^™

Enabling A Sustainable Economy Through Energy Systems Modeling: Solar-Centric, Efficient, Integrated And Continuous Process Synthesis And Optimization, Emre Gencer

Open Access Dissertations

The expected increase in food, energy and water demand due to increase in population and change in consumption habits in conjunction with diminishing fossil fuel reserves and increasing greenhouse gas emissions urge the development and implementation of alternative energy conversion techniques using renewable energy for a sustainable economy. Among renewable energy sources, solar energy is prominent due to its abundance. A sustainable economy can be created by producing building blocks foundational to meeting all basic human needs of daily existence. However, intermittencies and limitations on land area dedicated to harness solar energy are the major obstacles on widespread implementation of …

Electric Machine Differential For Vehicle Traction Control And Stability Control, Sandun Shivantha Kuruppu

Open Access Dissertations

Evolving requirements in energy efficiency and tightening regulations for reliable electric drivetrains drive the advancement of the hybrid electric (HEV) and full electric vehicle (EV) technology. Different configurations of EV and HEV architectures are evaluated for their performance. The future technology is trending towards utilizing distinctive properties in electric machines to not only to improve efficiency but also to realize advanced road adhesion controls and vehicle stability controls. Electric machine differential (EMD) is such a concept under current investigation for applications in the near future. Reliability of a power train is critical. Therefore, sophisticated fault detection schemes are essential in …

Redefining The Operation And Design Considerations Of Organic Solar Cells: Role Of Morphology And Defect States, Biswajit Ray

Open Access Dissertations

Organic photovoltaic (OPV) technology is currently a topic of great interest for potentially low cost solar energy conversion and possibility of many novel PV applications (e.g., building-integrated PV, portable solar cells). Successful commercialization of this technology, however, will require significant improvement in efficiency and lifetime. In the last few years, innovation in novel polymer synthesis has raised the efficiency of OPV above 10%, at par with a-Si and earth-abundant solar cells. Further improvement in performance relies on breakthroughs in device design, which requires profound understanding of the physics of device operation. A major challenge in the design of the state …

Solar Cell Temperature Dependent Efficiency And Very High Temperature Efficiency Limits, John Robert Wilcox

Open Access Dissertations

Clean renewable solar energy is and will continue to be a critically important source of electrical energy. Solar energy has the potential of meeting all of the world's energy needs, and has seen substantial growth in recent years. Solar cells can convert sun light directly into electrical energy, and much progress has been made in making them less expensive and more efficient. Solar cells are often characterized and modeled at 25 °C, which is significantly lower than their peak operating temperature. In some thermal concentrating systems, solar cells operate above 300 °C. Since increasing the temperature drastically affects the terminal …

Energy Systems Analysis For A Solar Economy, Dharik Sanchan Mallapragada

Open Access Dissertations

The use of solar energy for human needs faces challenges owing to its relatively low energy intensity and intermittent availability, coupled with the constrained availability of renewable carbon and land resources. This study uses systems analysis tools to identify carbon and energy efficient transformations of solar energy for different purposes, including transportation fuels and grid-scale energy storage. These efforts have been complemented with a feasibility analysis of existing fossil-energy and other hybrid pathways.

In an era of limited fossil resources, liquid fuels from sustainably available (SA) biomass could meet the energy needs of the transportation sector. We present a method …

An Experimental Investigation Of Wind Turbine Aerodynamic Interaction, Brandon Lee Ennis

Open Access Dissertations

Wind turbines have become a viable component in the overall energy makeup of the United States due to improved economics where energy prices have risen and production costs dropped. For a fixed cost, the effectiveness of a wind turbine financially is highly related to its performance. Considering the size of current wind farms, a minor performance improvement will result in large additional sums of revenue. A problem that has received attention with wind farms is that while the fixed costs of the development do get spread out further to reduce the installed cost of each wind turbine, the wind turbines …

An Analysis Of The Impact Of Storage Temperature, Moisture Content & Duration Upon The Chemical Components & Bioprocessing Of Lignocellulosic Biomass, Arun Athmanathan

Open Access Dissertations

The successful utilization of lignocellulosic biomass as a feedstock for fuels and chemicals necessitates storage for 2-6 months. It is correspondingly important to understand the impact of storage parameters - moisture concentration, temperature and duration - on biomass quality.

As aerobic storage is the most viable large-scale solution, aerobic storage experiments were carried out with three projected bioenergy feedstocks - sweet sorghum (Sorghum bicolor) bagasse, corn (Zea mays) stover and switchgrass (Panicum virgatum). Stored samples of each were examined for dry matter loss and composition change to develop a material balance around carbohydrates and lignin.

A mean dry matter loss …

Technology Agnostic Analysis And Design For Improved Performance, Variability, And Reliability In Thin Film Photovoltaics, Sourabh Dongaonkar

Open Access Dissertations

Thin film photovoltaics (TFPV) offer low cost alternatives to conventional crystalline Silicon (c-Si) PV, and can enable novel applications of PV technology. Their large scale adoption however, requires significant improvements in process yield, and operational reliability. In order to address these challenges, comprehensive understanding of factors affecting panel yield, and predictive models of performance reliability are needed. This has proved to be especially challenging for TFPV for two reasons in particular. First, TFPV technologies encompass a wide variety of materials, processes, and structures, which fragments the research effort. Moreover, the monolithic manufacturing of TFPV modules differs significantly from that of …