The thesis is focused on the design of a self-powered sensor for measurement of water flow rate and temperature in water pipelines. The key block of this thesis is the construction of an electric generator powered by excitation with turbulent flow. The generated voltage should power the sensor's circuits and allow water flow rate measurements. Throughout the development, three prototypes of generators powered by turbulent flow were created. Turbulences were not created by an insertion of a bluff body but by inner geometry of the pipeline elements. Maximum power of 10,66 uW was generated at flow rate of 8 m3/h. Afterwards, a prototype of water flow rate and temperature sensor was assembled. Energy self-sufficiency of the device at common flow rates was not achieved using the chosen procedure. The designed flow rate measurement method is suitable for an approximate flow rate estimation.

This thesis will focus on creating electromagnetic vibration generator for a project ESPOSA. This generator will be used in aeronautical application. There it will be powering required electronics. Electronics is thought a part, which will be sensing, writing and sending required data.

<p>  </p> <p>This masters thesis presents a literature review of widely used ink-based manufacturing techniques, ink-based materials used in energy harvesting. their preparation and applications in human-integrated energy harvesting devices. In addition, the challenges, and opportunities in this area of study is discussed. Lastly, the experimental methodology and results of a stencil printed PVA-gelatin composite ink based flexible triboelectric nanogenerator used for human-integrated energy harvesting is summarized.</p>

<p>Contact electrification of solids in a gas medium involves two stages, i.e., surface charge deposition immediately at separation, and dissipation due to dielectric breakdown of the medium as the gap increases. The presumption that such gas breakdown obeys Paschen's law, which is conventionally determined for gas between electrodes with constant charge supply, is widely accepted yet unverified. The present work experimentally validates such dependence of the breakdown voltage of air between charged dielectric surfaces on both its pressure and the gap distance. Sample surfaces are brought to cycles of contact electrification in a vacuum chamber and charge relaxation due to air breakdown is monitored with measurements of the Coulomb attraction by fixing either the air pressure or gap distance and varying the other. The results indicate thresholds of pressure and distance to facilitate investigations of the raw amount of charge transfer prior to any breakdown discharge, which is adopted to examine the saturation trend of surface charge density in the contact electrification of multiple material combinations using the same test apparatus. Comparatively consistent results are obtained in repeated tests for a variety of contact pairs, while a reduction of saturated surface charge density is observed for PTFE against PDMS after breakdown discharge in low-pressure air, which is preliminarily attributed to alternations of PTFE surfaces caused by accelerated cation strikes during air breakdown, based on SEM images and estimations of particle energy in Townsend avalanches. Conclusions on both the general raw level of surface charge density and the air breakdown during separation in contact electrification are applied to complement models of vibro-impact triboelectric energy harvesters for predicting their performance under various air pressures and physical dimensions in order to either prevent or exploit air breakdown to enhance the power output.</p>

The objective of this dissertation is to develop a mechanical model of a nonlinear piezoelectric energy harvesting system induced by Duffing oscillator and predict the periodic motions of such a nonlinear dynamical system under different excitation frequency. In this dissertation, analytical distributed-parameter electromechanical modeling of a piezoelectric energy harvester will be presented. The electromechanically coupled circuit equation excited by infinitely many vibration modes is derived. The governing electromechanical equations are reduced to ordinary differential equations in modal coordinates and eventually an infinite set of algebraic equations is obtained for the complex modal vibration response and the complex voltage response of the energy harvester beam. One single vibration mode is chosen and discussed. The periodic motions are obtained through an implicit mapping method with high accuracy, stability and bifurcations of periodic motions are determined by the eigenvalue analysis. Frequency-amplitude characteristics of periodic motions are achieved by the Fourier transform

No description available.

Cal Poly’s Recreation Center expansion project provides an opportunity to implement Energy Harvesting From Exercise Machines (EHFEM). Part of this implementation is a system that reports the exercise machines’ energy production. Although products capable of reporting exercise machine energy harvesting statistics exist, they have limited capabilities. This thesis project defends a system capable of reporting exercise machine power statistics in near real-time. The system consists of display, database, and power measurement modules. The display module presents statistics in an interactive, graphical, and widely-accessible way. The database module provides an efficient way of organizing and accessing stored statistics. Multiple power measurement module types gather power and energy generation measurements from multiple exercise machine types and transmit those measurements to the database module over the computer network.

Phase change material (PCM)-based ocean thermal energy harvesting is a relatively new method, which extracts the thermal energy from the temperature gradient in the ocean thermocline. Its basic idea is to utilize the temperature variation along the ocean water depth to cyclically freeze and melt a specific kind of PCM. The volume expansion, which happens in the melting process, is used to do useful work (e.g., drive a turbine generator), thereby converting a fraction of the absorbed thermal energy into mechanical energy or electrical energy. Compared to other ocean energy technologies (e.g., wave energy converters, tidal current turbines, and ocean thermal energy conversion), the proposed PCM-based approach can be easily implemented at a small scale with a relatively simple structural system, which makes it a promising method to extend the range and service life of battery-powered devices, e.g, autonomous underwater vehicles (AUVs). This dissertation presents a combined theoretical and experimental study of the PCM-based ocean thermal energy harvesting approach, which aims at demonstrating the feasibility of the proposed approach and investigating possible methods to improve the overall performance of prototypical systems. First, a solid/liquid phase change thermodynamic model is developed, based on which a specific upperbound of the thermal efficiency is derived for the PCM-based approach. Next, a prototypical PCM-based ocean thermal energy harvesting system is designed, fabricated, and tested. To predict the performance of specific systems, a thermo-mechanical model, which couples the thermodynamic behaviors of the fluid materials and the elastic behavior of the structural system, is developed and validated based on the comparison with the experimental measurement. For the purpose of design optimization, the validated thermo-mechanical model is employed to conduct a parametric study. Based on the results of the parametric study, a new scalable and portable PCM-based ocean thermal energy harvesting system is developed and tested. In addition, the thermo-mechanical model is modified to account for the design changes. However, a combined analysis of the results from both the prototypical system and the model reveals that achieving a good performance requires maintaining a high internal pressure, which will complicate the structural design. To mitigate this issue, the idea of using a hydraulic accumulator to regulate the internal pressure is proposed, and experimentally and theoretically examined. Finally, a spatial-varying Robin transmission condition for fluid-structure coupled problems with strong added-mass effect is proposed and investigated using fluid structure interaction (FSI) model problems. This can be a potential method for the future research on the fluid-structure coupled numerical analysis of AUVs, which are integrated with and powered by the PCM-based thermal energy harvesting devices. / Doctor of Philosophy / The global ocean, which covers about 71% of the Earth’s surface, absorbs a great amount of heat from the sunshine everyday, making it a reliable and renewable source of thermal energy. Also, the temperature of the ocean water varies with depth, which provides a necessary condition (i.e, a temperature gradient) to extract the thermal energy. If harvested and converted into electrical energy using small scale portable devices, the ocean thermal energy can be a potential energy resource to provide power for autonomous underwater vehicles (AUVs), which are conventionally powered by on-board rechargeable batteries. To this end, this dissertation presents a study of using solid/liquid phase change materials (PCMs) to extract thermal energy from the temperature gradient in the ocean. The basic idea is to use the warm surface water and deep cold water to melt and freeze the PCM cyclically. In the meantime, the volume of PCM will expand and contract accordingly. Therefore, a turbine generator can be driven by the volume expansion in the melting process, thereby converting a fraction of the absorbed thermal energy into electrical energy. This study includes four key aspects. First, to evaluate the theoretical full potential of the PCM-based approach, a solid/liquid phase change thermodynamic model – which represents an idealized energy harvester – is developed. Based on the thermodynamic model, an upperbound of the thermal efficiency is derived. Secondly, two prototypical systems, as well as a thermo-mechanical model which can predict the performance of specific designs, are developed. Third, for the purposes of performance improvement and pressure regulation, the latter of which is associated with the structural safety, a hydraulic accumulator is added to the existing system and its effects are examined using both experimental and theoretical methods. Finally, a computational method is proposed and demonstrated, which can be a potential tool for the design of PCM-based ocean thermal energy harvesting systems when they are integrated with exiting AUVs.

Demand for compact, easily deployable, energy-efficient computers has driven the development of general-purpose transiently powered computers (TPCs) that lack both batteries and wired power, operating exclusively on energy harvested from their surroundings. TPCs' dependence solely on transient, harvested power offers several important design-time benefits. For example, omitting batteries saves board space and weight while obviating the need to make devices physically accessible for maintenance. However, transient power may provide an unpredictable supply of energy that makes operation difficult. A predictable energy supply is a key abstraction underlying most electronic designs. TPCs discard this abstraction in favor of opportunistic computation that takes advantage of available resources. A crucial question is how should a software-controlled computing device operate if it depends completely on external entities for power and other resources? The question poses challenges for computation, communication, storage, and other aspects of TPC design. The main idea of this work is that software techniques can make energy harvesting a practicable form of power supply for electronic devices. Its overarching goal is to facilitate the design and operation of usable TPCs. This thesis poses a set of challenges that are fundamental to TPCs, then pairs these challenges with approaches that use software techniques to address them. To address the challenge of computing steadily on harvested power, it describes Mementos, an energy-aware state-checkpointing system for TPCs. To address the dependence of opportunistic RF-harvesting TPCs on potentially untrustworthy RFID readers, it describes CCCP, a protocol and system for safely outsourcing data storage to RFID readers that may attempt to tamper with data. Additionally, it describes a simulator that facilitates experimentation with the TPC model, and a prototype computational RFID that implements the TPC model. To show that TPCs can improve existing electronic devices, this thesis describes applications of TPCs to implantable medical devices (IMDs), a challenging design space in which some battery-constrained devices completely lack protection against radio-based attacks. TPCs can provide security and privacy benefits to IMDs by, for instance, cryptographically authenticating other devices that want to communicate with the IMD before allowing the IMD to use any of its battery power. This thesis describes a simplified IMD that lacks its own radio, saving precious battery energy and therefore size. The simplified IMD instead depends on an RFID-scale TPC for all of its communication functions. TPCs are a natural area of exploration for future electronic design, given the parallel trends of energy harvesting and miniaturization. This work aims to establish and evaluate basic principles by which TPCs can operate,

As the Internet-of-everything continues diversifying, wireless nods sensors, wearables, and smart-objects will require mature technologies to harvest energy from the environment in which they are installed. Out of the many energy forms, solar and artificial light are constantly present and the utilization solar technologies including organic photovoltaics can provide advantages including flexibility, semitransparency, and lightweight. Additionally, the incredibly low environmental footprint and reduced manufacturing costs associated with solution processing can provide an edge for entry into the industrial and consumer markets. While the utilization of conjugated polymers and nonfullerenes elevated the efficiencies of organic photovoltaic for commercialization, increasing the technological readiness level requires the development of protocols to translate lab performance of state-the-art-materials to scalable manufacturing techniques that can be adapted for roll-to-roll processing. This dissertation demonstrates the full fabrication of high-performance OPV devices through techniques such as inkjet printing and slot-die coating. The development of ink formulation frameworks based on solvent engineering, rheological and interface properties, and solubility parameters sets the base for standardized high-yield processes with reduced environmental footprint in line with circular carbon initiatives. Moreover, the utilization of engineering strategies involving intrinsic properties of materials, device architectures, and integration enables the development of complex energy harvesting and sensing devices for potential utilization in agrivoltaics and biosensing.