• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 548
  • 70
  • 62
  • 47
  • 43
  • 24
  • 21
  • 16
  • 8
  • 6
  • 5
  • 5
  • 3
  • 2
  • 2
  • Tagged with
  • 1078
  • 1078
  • 324
  • 258
  • 216
  • 210
  • 199
  • 173
  • 124
  • 115
  • 111
  • 106
  • 105
  • 104
  • 103
  • 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.
201

Distributed Energy Storage Systems: Microgrid Application, Market-Based Optimal Operation and Harmonic Analysis

Arghandeh Jouneghani, Reza 03 May 2013 (has links)
The need for modern electricity infrastructures and more capable grid components brings attention to distributed energy storage systems because of their bidirectional power flow capability. This dissertation focuses on three different aspects of distributed energy storage system applications in distribution networks. It starts with flywheel energy storage system modeling and analysis for application in microgrid facilities. Then, a market-based optimal controller is proposed to enhance the operational profit of distributed energy storage devices in distribution networks. Finally, impact of multiple distributed energy storage devices on harmonic propagation in distribution networks is investigated. This dissertation provides a comparison between batteries and flywheels for the ride-through application in critical microgrid facilities like data centers. In comparison with batteries, the application of FES for power security is new. This limits the availability of experimental data. The software tool developed in this dissertation enables analysis of short-term, ride-through applications of FES during an islanded operation of a facility microgrid. As a result, it can provide a guideline for facility engineers in data centers or other types of facility microgrids to design backup power systems based on FES technology. This dissertation also presents a real-time control scheme that maximizes the revenue attainable by distributed energy storage systems without sacrificing the benefits related to improvements in reliability and reduction in peak feeder loading. This optimal control algorithm provides a means for realizing additional benefits by utilities by taking advantage of the fluctuating cost of energy in competitive energy markets. The key drivers of the economic optimization problem for distributed energy storage systems are discussed. In this dissertation, the impact of distribution network topology on harmonic propagation due to the interaction of multiple harmonic sources is investigated. Understanding how multiple harmonic sources interact to increase or decrease the harmonic distortion is crucial in distribution networks with a large number of Distributed Energy Resources. A new index, Index of Phasor Harmonics (IPH), is proposed for harmonic quantization in multiple harmonic source cases. The proposed IPH index presents more information than commonly used indices. With the help of the detailed distribution network model, topological impacts of harmonic propagation are investigated. In particular, effects of mutual coupling, phase balance, three phase harmonic sources, and single phase harmonic sources are considered. / Ph. D.
202

Analysis of a Hybrid Energy Storage System and Electri ed Turbocharger in a Performance Vehicle

Stiene, Tyler January 2017 (has links)
This research investigates the effects of both a Hybrid Energy Storage System and an Electrified Turbocharger in a consumer performance vehicle. This research also attempts to support the development of a prototype vehicle containing a Hybrid Energy Storage System currently being developed at McMaster University. Using a custom simulation tool developed in Matlab Simulink, Simulink models of each of the technologies were developed to predict the behavior of these subsystems across multiple physical domains. Control modeling, optimization and testing was completed for both systems. In addition, controls modeling for the Hybrid Energy Storage System was integrated with the development effort for a prototype vehicle considering the specifics of real world components. To assess the impact of these technologies on a performance vehicle platform, the simulation tool tested each technology using multiple vehicle variations. Three vehicle variants were developed, representing: a conventional performance hybrid design, a hybrid vehicle containing an electrified turbocharger, and a vehicle containing a Hybrid Energy Storage System. Electrical system peak output power was the vehicle specification held constant between each vehicle variant. Each vehicle variant was simulated against a number of traditional drive cycles representing everyday driving scenarios in an attempt to compare fuel economy while identifying each technologies individual impact on the vehicles performance. Finally, each vehicle variant was simulated using a custom performance drive cycle in a virtual race. Both technologies as assessed and in comparison to a larger battery variant, did not result in improved fuel economies during conventional vehicle driving. Both the Hybrid Energy Storage System and electrified turbocharger demonstrated improved vehicle performance in particular scenarios. / Thesis / Master of Applied Science (MASc) / Electrified vehicles have not typically been viewed as performance vehicles. A recent trend has seen a growing number of manufacturers turn to hybrid and electric powertrains to produce high performing vehicles. However, a performance vehicle's electrical power is conventionally limited by the size and power of its battery, adding weight and cost. Two technologies offer the ability to increase the power of these electrified components without the need for a large battery. First, Hybrid Energy Storage System combines ultra-capacitors and batteries to increase the power density of the system. Second, an Electrified Turbocharger improves the turbo lag of a turbocharged engine and also recovers waste heat energy from the exhaust gases which is then used to propel the vehicle. This research identifies and demonstrates the potential impact these two technologies have when included in an American Muscle Car.
203

<strong>Organic redox-active materials design for redox flow batteries</strong>

Xiaoting Fang (15442055) 30 May 2023 (has links)
<p>  </p> <p>Nowadays, clean and renewable energy sources like wind and solar power have been rapidly growing for the goal of phasing out traditional fossil fuels, achieving carbon neutrality, and realizing sustainable development. Long-duration and large-scale energy storage is needed to address the intermittent nature of these sources. Especially, redox flow battery (RFB) is an attractive energy storage device for large scale applications because of its high scalability, design flexibility, and intrinsic safety. The all vanadium redox flow battery stands for the state-of-the-art system, but the high vanadium cost and limited energy density are among the limiting factors for wide commercialization. Therefore, it is necessary to develop new RFB materials that are cost-effective and highly soluble. Organic redox-active molecules (redoxmers) hold great potential to satisfy these requirements due to structural diversity, tunable chemical and electrochemical properties, and earth-abundant sources. With rational structural design, organic redoxmers can show favorable properties such as high solubility, suitable redox potential, and good chemical stability. However, current efforts are mainly on the development of anolyte redoxmers, e.g. phenazine, anthraquinone and viologen. Only limited types of catholyte candidates have been reported such as ferrocene and TEMPO. The major reason for such slow-paced progress is the limited chemical stability of these catholyte redoxmers. To bridge this critical gap, my efforts are focused mainly on the design and development of promising catholyte redoxmers for both aqueous organic (AORFBs) and non-aqueous organic redox flow batteries (NRFBs).</p> <p>Phenoxazine functionalized with a hydrophilic tetraalkylammonium group demonstrates good water solubility and suitable redox potential. Cyclic voltammograms (CV) and flow cell testing were used to evaluate the electrochemical properties and battery performance, respectively. Besides, the battery fading mechanism was systematically investigated by CV, liquid chromatography mass spectra (LC-MS) and electron paramagnetic resonance (EPR) spectroscopy. The redoxmer decomposition mechanism analysis will benefit future redoxmer development by guiding the molecular design of more stable structure candidates. </p> <p>A structural design strategy for the development of novel TMPD-based (tetramethyl-<em>p</em>-phenylenediamine) catholyte redoxmers for NORFBs is presented. Two categories of functional groups, including oligo(ethylene glycol) (EG) either chains and phenyl rings, were incorporated into the TMPD core to improve solubility and stability in non-aqueous electrolytes, respectively. EPR characterization and bulk electrolyte (BE) analysis were carried out to evaluate the redoxmers stability. In addition, DFT studies were conducted to understand the impacts of functional groups on redox potential and chemical stability. The present work demonstrates the feasibility of constructing promising redoxmers from TMPD and provides insights into molecular designing of catholytes to achieve high solubility and excellent stability for non-aqueous redox flow batteries.</p>
204

A Novel, Elastically-Based, Regenerative Brake and Launch Assist Mechanism

Nieman, Joshua E. 17 June 2014 (has links)
No description available.
205

Testing of Carbon Foam with a Phase Change Material for Thermal Energy Storage

Irwin, Matthew A. 24 September 2014 (has links)
No description available.
206

Iron-Ligand Electrokinetics towards an all-Iron Hybrid Redox Flow Battery

Hawthorne, Krista Leigh 02 September 2014 (has links)
No description available.
207

Experimental Testing and Mathematical Modeling of a Thermoelectric Based Hydronic Cooling and Heating Device with Transient Charging of Sensible Thermal Energy Storage Water Tank

Krishnamoorthy, Sreenidhi January 2008 (has links)
No description available.
208

Modeling and Analysis of Hydraulic Energy Storage System for Hybrid Locomotives

Zhang, Boya January 2010 (has links)
No description available.
209

STUDY OF FULLY-MIXED HYBRID THERMAL ENERGY STORAGE WITH PHASE CHANGE MATERIALS FOR SOLAR HEATING APPLICATIONS

Abdelsalam, Mohamed 11 1900 (has links)
A novel design of hybrid thermal energy storage (HTES) using Phase Change Material (PCM) was evaluated using a mathematical model. Both single and multi-tank (cascaded) storage were explored to span small to large-scale applications (200-1600 litres). The storage element was based on the concept of a fully-mixed modular tank which is charged and discharged indirectly using two immersed coil heat exchangers situated at the bottom and top of the tank. A three-node model was developed to simulate different thermal behaviors during the operation of the storage element. Experiments were conducted on full-scale 200-l single-tank sensible heat storage (SHS) and hybrid thermal energy storage (HTES) to provide validation for the mathematical model. The HTES incorporated rectangular PCM modules submerged in the water tank. Satisfactory agreement was found between the numerical results and the experimental results obtained by Mather (2000) on single and multi-tank SHS. In addition, good agreement was noticed with the experiments performed by the author on single-tank SHS and HTES at McMaster University. The developed model was found to provide high levels of accuracy in simulating different operation conditions of the proposed design of storage element as well as computational efficiency. A parametric study was undertaken to investigate the potential benefits of the HTES over the SHS, operating under idealistic conditions. The HTES can perform at least two times better than the SHS with the same volume. The PCM volume fraction, melting temperature and properties were found to have critical impact on the storage gains of the HTES. All the parameters must be adjusted such that: (1) the thermal resistance of the storage element is minimized, and (2) most of the energy exchange with the storage element takes place in the latent heat form. The performance of the single-tank HTES was evaluated numerically while operating in a solar thermal domestic hot water (DHW) system for a single-family residence. The PCM parameters were selected to maximize the solar fraction during the operation on a typical spring day in Toronto. The use of the HTES can reduce the tank volume by 50% compared to the matched size of the SHS tank. However, the HTES was found to underperform the SHS when the system was operated in different days with different solar irradiation intensities. The effect of different draw patterns was also investigated. The results indicated that thermal storage is needed only when the energy demand is out-of-phase with the energy supply. For the same daily hot water demand, different consumption profiles; ex. dominant morning, dominant evening, dominant night and dispersed consumptions, showed slight impact on the performance of the system. The concept of multi-tank (cascaded) HTES storage was explored for medium/large scale solar heating applications such as for restaurants, motels, and multi-family residences. The design was based on the series connection of modular tanks through the bottom and top heat exchangers. Each individual tank had a PCM with different melting temperature. The results showed that the cascaded storage system outperformed the single-tank system with the same total volume as a result of the high levels of sequential or tank-to-tank stratification. The use of the cascaded HTES resulted in slight improvement in the solar fraction of the system. / Thesis / Doctor of Philosophy (PhD)
210

EXPERIMENTAL ANALYSIS OF ELECTRIC DOUBLE LAYER AND LITHIUM-ION CAPACITORS FOR ENERGY STORAGE SYSTEMS AND THEIR APPLICATION IN A SIMULATED DC METRO RAILWAY SYSTEM

Wootton, Mackenzie January 2018 (has links)
This works begins by providing motivation for additional research and political interest in the use of passenger railway systems as a method of ‘green’ transportation. Additional motivation for the adoption of energy saving methods within new and existing railway systems is also provided. This motivation stems from the relatively small carbon dioxide emissions per passenger kilometer and large quantity of electrical energy used in association with passenger railway systems. In specific cases, both theoretical analyses and experimental implementations of energy storage in railway systems have shown a reduction in electrical energy use and/or vehicle performance gains. Current railway energy storage systems (ESS) commonly make use of battery or electric double layer capacitor (EDLC) cells. A review of select energy storage technologies and their application in railway systems is provided. For example, the developing Qatar Education City People Mover system makes use of energy dense batteries and power dense EDLCs to provide the range and power needed to operate without a conventional railway power source between stations, formally called catenary free operation. As an alternative to combining two distinct energy storage technologies, this work looks at experimentally characterizing the performance of commercially available lithium ion capacitors (LiCs); a relatively new energy storage cell that combines characteristics of batteries and EDLCs into one cell. The custom cell testing apparatus and lab safety systems used by this work, and others, is discussed. A series of five tests were performed on two EDLC cells and five LiC cells to evaluate their characteristics under various electrical load conditions at multiple temperatures. The general conclusion is that, in comparison to the EDLC cells tested, the LiC cells tested offer a superior energy density however, their power capabilities are relatively limited, especially in cold environments, due to larger equivalent series resistance values. The second topic explored in this work is the development of a MATLAB based DC powered passenger vehicle railway simulation tool. The simulation tool is connected to the experimental analysis of EDLC and LiC cells by comparing the volume and mass of an energy storage system needed for catenary free (no conventional DC power supply) operation between train stations using either energy storage technology. A backward facing modelling approach is used to quantify the drive cycle electrical power demands as a function of multiple vehicle parameters and driving parameters (eg. acceleration rate, travel distance and time). Additional modelling methods are provided as a resource to further develop the simulation tool to include multiple vehicles and their interactions with the DC power supply. Completion of the multi-vehicle simulation tool with energy storage systems remains a task for future work. / Thesis / Master of Applied Science (MASc)

Page generated in 0.0344 seconds