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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.
1

Model-based design of hybrid electric marine propulsion system using modified low-order ship hull resistance and propeller thrust models

Liu, Siyang 05 January 2021 (has links)
Transportation is a primary pollution source contributing to 14 percent of global greenhouse gas emissions, and 12 percent of transportation emissions came from maritime activities. Emissions from the ferry industry, which carries roughly 2.1 billion passengers and 250 million vehicles annually, is a major concern for the general public due to their near-shore operations. Compared to the rapidly advancing clean automotive propulsion, fuel efficiency and emissions improvements for marine vessels are more urgent and beneficial due to the significantly higher petroleum fuel consumption and heavy pollutants and the relatively slow adoption of clean propulsion technology by the marine industry. Hybrid electric propulsion, proven to be effective for ground vehicles, presents a promising solution for more efficient clean marine transportation. Due to the diversified hull/propulsor design and operation cycle, the development of a hybrid electric marine propulsion system demands model-based design and control optimization for each unique and small batch production vessel. The integrated design and control optimization further require accurate and computation efficient hull resistance and propulsor thrust calculation methods that can be used to predict needed propulsion power and gauge vessel performance, energy efficiency, and emissions. This research focuses on improving the low-order empirical hull resistance and propulsor thrust models in the longitudinal direction by extracting model parameters from one-pass computational fluid dynamics (CFD) simulation and testing the acquired models in integrated design optimization of the marine propulsion system. The model is implemented in MATLAB/Simulink and ANSYS Aqwa and validated using operation data from BC Ferries’ ship Tachek. The modified low-order model (M-LOM) is then used in the integrated optimizations of propulsion system component sizes and operation control strategies for another BC Ferries’ ship, Skeena Queen. The performance, energy efficiency, and emissions of various propulsion options, including nature gas-mechanical and natural gas-electric benchmarks, and hybrid electric alternatives of series hybrid, parallel hybrid, and battery/pure electric are compared to demonstrate the benefits of the new method in completing these complex tasks and hybrid electric marine propulsion. The research forms the foundation for further studies to achieve more accurate propulsion demand prediction and a more comprehensive lifecycle cost assessment of clean marine propulsion solutions. / Graduate
2

Electric Propulsion System for Exceptionally Short Takeoff and Landing Electric Air Vehicles

Mahvelatishamsabadi, Parisa January 2019 (has links)
Over the past few years, electric propulsion systems have been widely used in automotive applications. The next decade is likely to see the electrification of aerial vehicles. In the past 20 years, the passengers demand in the aviation industry has increased by roughly 5% annually. Drastic increment in the passengers demand leads to many problems such as emission, noise pollution, airports capacity shortage, and high fuel consumption. An electric airplane that can take off and land in an extremely short runway can solve all the mentioned problems. Also, an airplane that is smaller and lighter with the ability to take off and land from an extremely short runway can be used as a new transportation system in congested cities and solve the urban road traffic and compensate for people’s time wasted in traffic. With this in mind, in this thesis, the feasibility of converting a conventional fixed-wing direct-drive propeller airplane to an electric extremely short takeoff and landing airplane has been examined. An overview of the history of electric aerial vehicles and flying cars is conducted where some of these vehicles are still under development phase. The main aim of this thesis is to address the effect of takeoff and landing runway length on the electric motor main specifications, including power, torque, and speed. Also, the effect of cruising speed on the motor specifications are investigated, and it is observed that there is a considerable difference between the amount of required power for the cruising mode and takeoff mode. In the end, the impact of the braking system and airplane weight on the landing distance are examined, and It is found that for an airplane with a cruise-efficient propeller, usage of thrust reverser is not practical and hence it is not recommended. Although if the propeller is designed to have high efficiency at takeoff and landing, the thrust reverser can be a good solution to make the landing runway shorter. / Thesis / Master of Applied Science (MASc)
3

Performance Assessment of Electrical Motor for Electric Aircraft Propulsion Applications : Evaluation of the Permanent Magnet Motor and its Limitations in Aircraft Propulsion

Beckman, Mathias, Christy Gerald Volden, Alex January 2019 (has links)
This thesis project will evaluate which kind of electrical motor is best suited for aircraft propulsion and which parameters effect the efficiency. An economic analysis was conducted, comparing the fuel price (Jet A1) for a gas turbine and the electricity price for an electric motor of 1MW. The study was conducted by using analytical methods in MATLAB. Excel was used to compile and present the data. The data used in this thesis project were assumed with regards to similar studies or pre-determined values. The main losses for the Permanent Magnet Synchronous Motor (PMSM) were calculated to achieve a deeper understanding of the most important parameters and how these parameters need to improve to allow for future electric propulsion systems. The crucial parameters for the losses were concluded to be the temperature, voltage level, electrical frequency, magnetic flux density, size of the rotor and rotational speed. The three main losses of a PMSM was illustrated through the analytical equations used in MATLAB. The calculations present how the ohmic losses depend on the temperature (0-230°C) at different voltages (700V and 1000V), how the core losses depend on frequency (0-1000Hz) at different magnetic flux densities and how the windage losses depend on rotational speed (7000-10000 rpm). It could be concluded that at 8500 rpm an efficiency of 91,26% could be achieved at 700V, 1.5T and 90.4% at 1000V, 1.65T. The decrease in efficiency is a result of the increase in magnetic flux density. When looking at the economic viability of electrical integration the power to weight ratio and energy price was compared for the gas turbine and electrical motor including an inverter and battery. This resulted in a conclusion that a pure electrical system may not compete with a gas turbine in 30 years of time due to the low energy density of the battery. It was also concluded that the emissions during cruise could be lowered significantly. If the batteries were charged in Sweden the emissions would decrease from ~937 kg CO2 to ~31 kg CO2. If the batteries were charged in the Nordic region the emissions would decrease to ~119kg CO2. However, if the batteries were to be charged in the US the carbon dioxide emission would be ~1084 kg CO2, which is an increase in CO2 emission compared to the gas turbine.
4

Mission Design Considerations of the Propulsion System Demonstration as part of the Hugin Space Exploration Technology Satellite Mission

Romil, Barkarmo January 2022 (has links)
Beyond Atlas is a Swedish private company with the goal of exploring the solar system with cheap and reliable spacecraft. Part of their maiden mission, Hugin, aims to demonstrate navigation, propulsion, and communication technology on a 3U CubeSat. This thesis aims to investigate the feasibility of using the Enpulsion NANO electric propulsion (EP) system for deep-space applications and how to best demonstrate its capabilities in low-Earth orbit. Literature reviews of scientific papers and software simulations were conducted to gain an understanding of the underlying processes involved in EP in-orbit operations. Analyses were made on orbital maneuvers, momentum unloading, power and thermal restrictions. The results suggest that the EP system's capabilities is mainly limited by the saturation time of the reaction wheels restricting longer duration orbital maneuvers. Orbital maneuvers for demonstrating the capabilities are proposed based on the limitations imposed on the EP system by the rest of the spacecraft. On the basis of the results of this research, it can be concluded that the Enpulsion NANO thruster's operational range can be utilized both as a low thrust efficient main drive and as a high thrust maneuvering thruster for deep-space applications but is limited by the high power consumption and low thrust-to-power ratio.
5

Viability of Power-Split Hybrid-Electric Aircraft under Robust Control Co-Design

Bandukwala, Mustafa January 2021 (has links)
No description available.
6

Measurement of Static and Dynamic Performance Characteristics of Electric Propulsion Systems

Brezina, Aron Jon 21 June 2012 (has links)
No description available.

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