Onset of Self-Excited Oscillations of Traveling Wave Thermo-Acoustic-Piezoelectric Energy Harvester Using Root-Locus Analysis

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
O. Aldraihem ◽  
A. Baz
Keyword(s):  
Temperature Gradient ◽  
Thermal Energy ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Feedback Loop ◽  
Energy Harvester ◽  
Waste Heat ◽  
Electrical Energy ◽  
Acoustic Resonator ◽  
Piezoelectric Energy

The onset of self-excited oscillations is developed theoretically for a traveling wave thermo-acoustic-piezoelectric (TAP) energy harvester. The harvester is intended for converting thermal energy, such as solar or waste heat energy, directly into electrical energy without the need for any moving components. The thermal energy is utilized to generate a steep temperature gradient along a porous regenerator. At a specific threshold of the temperature gradient, self-sustained acoustic waves are generated inside an acoustic resonator. The resulting pressure fluctuations excite a piezoelectric diaphragm, placed at the end of the resonator, which converts the acoustic energy directly into electrical energy. The pressure pulsations are amplified by using an acoustic feedback loop which introduces appropriate phasing that make the pulsations take the form of traveling waves. Such traveling waves render the engine to be inherently reversible and thus highly efficient. The behavior of this class of harvesters is modeled using the lumped-parameter approach. The developed model is a multifield model which combines the descriptions of the acoustic resonator, feedback loop, and the regenerator with the characteristics of the piezoelectric diaphragm. A new method is proposed here to analyze the onset of self-sustained oscillations of the traveling wave engine using the classical control theory. The predictions of the developed models are validated against published results. Such models present invaluable tools for the design of efficient TAP energy harvesters and engines.

Onset of Self-Excited Oscillations of Traveling Wave Thermo-Acoustic-Piezoelectric Energy Harvester

2010 ◽  
Author(s):  
O. Aldraihem ◽  
A. Baz
Keyword(s):  
Temperature Gradient ◽  
Thermal Energy ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Feedback Loop ◽  
Energy Harvester ◽  
Waste Heat ◽  
Electrical Energy ◽  
Acoustic Resonator ◽  
Piezoelectric Energy

The onset of self-excited oscillations is developed theoretically for a traveling wave thermo-acoustic-piezoelectric (TAP) energy harvester. The harvester is intended for converting thermal energy, such as solar or waste heat energy, directly into electrical energy without the need for any moving components. The thermal energy is utilized to generate a steep temperature gradient along a porous stack. At a specific threshold of the temperature gradient, self-sustained acoustic waves are generated inside an acoustic resonator. The resulting pressure fluctuations excite a piezoelectric diaphragm, placed at the end of the resonator, which converts the acoustic energy directly into electrical energy. The pressure pulsations are amplified by using an acoustic feedback loop which introduces appropriate phasing that make the pulsations take the form of traveling waves. Such traveling waves render the harvester to be inherently reversible and thus highly efficient. The behavior of this class of harvesters is modeled using the lumped-parameter approach. The developed model is a multi-field model which combines the descriptions of the acoustic resonator, feedback loop, and the stack with the characteristics of the piezoelectric diaphragm. A new method is proposed here to analyze the onset of self-sustained oscillations of the traveling wave engine using the classical control theory. The predictions of the developed models are validated against published results. Such models present invaluable tools for the design of efficient thermo-acoustic-piezoelectric (TAP) energy harvesters and engines.

Onset of Oscillations in Traveling Wave Thermo-Acoustic-Piezo-Electric Harvesters Using Circuit Analogy and SPICE Modeling

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
M. Nouh ◽  
O. Aldraihem ◽  
A. Baz
Keyword(s):  
Temperature Gradient ◽  
Thermal Energy ◽  
Traveling Wave ◽  
Acoustic Waves ◽  
Feedback Loop ◽  
Waste Heat ◽  
Acoustic Resonator ◽  
Critical Threshold ◽  
Circuit Analogy ◽  
Piezo Electric

Equations governing different physical fields such as mechanical, acoustical, and electrical are inherently similar. This enables mechanical, thermal, and acoustical networks to be fully described with analogous electric networks. For thermo-acoustic-piezo-electric (TAP) harvesters, such a modeling approach allows the whole system to be characterized in the electrical domain and facilitates the understanding of the underlying physics. In this paper, a traveling wave thermo-acoustic-piezoelectric (TWTAP) energy harvester is considered which converts thermal energy, such as solar or waste heat energy, directly into electrical energy without the need for any moving components. The input thermal energy generates a steep temperature gradient along a porous regenerator. At a critical threshold of the temperature gradient, self-sustained acoustic waves are developed inside an acoustic resonator. The associated pressure fluctuations impinge on a piezo-electric diaphragm, placed at the end of the resonator, to generate electricity. The acoustic pressure oscillations are amplified by a specially designed acoustic feedback loop that introduces appropriate phasing to make the pulsations take the form of traveling waves. The behavior of this TWTAP is modeled using electrical circuit analogy. The developed model combines the descriptions of the acoustic resonator, feedback loop, and the regenerator with the characteristics of the piezo-electric diaphragm. With the help of a simulation program with integrated circuit emphasis (SPICE) code, the developed electric circuit is used to analyze the system’s stability with regard to the input heat and hence predict the necessary temperature ratio required to establish the onset of self-sustained oscillations inside the harvester’s resonator. The predictions are compared with published results obtained using root locus and numerical methods and validated against experiments. This approach provides a very practical approach to the design of TAP energy harvesters both in the time and frequency domain. Such capabilities do not exist presently in the well-known design tool design environment for low-amplitude thermo-acoustic energy conversion (DeltaEC) developed at Los Almos National Laboratory which is limited to steady-state analysis. This is in contrast to the present approach which can be applicable to both steady as well as transient analysis.

Experimental Investigation of Thermoacoustic-Piezoelectric Energy Harvesters and Refrigerators With Dynamic Magnifiers

2013 ◽  
Author(s):  
M. Nouh ◽  
O. Aldraihem ◽  
A. Baz
Keyword(s):  
Temperature Gradient ◽  
Thermal Energy ◽  
Acoustic Waves ◽  
Waste Heat ◽  
Mechanical Impedance ◽  
Acoustic Resonator ◽  
Critical Threshold ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Theoretical Results

Conventional Thermoacoustic-Piezoelectric (TAP) energy harvesters convert thermal energy, such as solar or waste heat energy, directly into electrical energy without the need for any moving components. The input thermal energy generates a steep temperature gradient along a porous medium. At a critical threshold of the temperature gradient, self-sustained acoustic waves are developed inside an acoustic resonator. The associated pressure fluctuations impinge on a piezoelectric diaphragm, placed at the end of the resonator. The reverse phenomenon results in piezo-driven thermoacoustic refrigerators (PDTARs). A pressure wave driven by a piezo-speaker induces a temperature gradient across the porous body. In this study, the TAP harvester and the PDTAR are coupled with auxiliary elastic structures in the form of simple spring-mass systems to enhance their performance. The proposed addition is referred to as a dynamic magnifier and has been shown in different areas to amplify significantly the deflection of vibrating structures. A comprehensive model of the dynamically magnified thermoacoustic-piezoelectric (DMTAP) system has been developed earlier that includes equations of motions of the system’s mechanical components, the harvested voltage, the mechanical impedance of the coupled structure at the resonator end as well as the equations necessary to compute the self-excited frequencies of oscillations inside the acoustic resonator. Theoretical results confirmed significant amplification of the harvested power is feasible if the magnifier’s parameters are properly chosen. The performance of experimental prototypes of a DMTAP harvester and a PDTAR with a dynamic magnifier are examined here. The obtained experimental findings are validated against the theoretical results. Dynamic magnifiers serve as a novel approach to enhance the effectiveness of thermoacoustic energy harvesting and refrigeration.

Spray-on thermoelectric energy harvester

MRS Advances ◽  
2018 ◽  
Vol 4 (15) ◽  
pp. 851-855 ◽  
Author(s):  
Robert E. Peale ◽  
Seth Calhoun ◽  
Nagendra Dhakal ◽  
Isaiah O. Oladeji ◽  
Francisco J. González
Keyword(s):  
Thin Films ◽  
Power Generation ◽  
Energy Harvester ◽  
Waste Heat ◽  
Spray Deposition ◽  
Electrical Energy ◽  
Seebeck Coefficients ◽  
Thermoelectric Energy ◽  
P Type ◽  
Energy From Waste

AbstractThermoelectric (TE) thin films have promise for harvesting electrical energy from waste heat. We demonstrate TE materials and thermocouples deposited by aqueous spray deposition on glass. The n-type material was CdO doped with Mn and Sn. Two p-type materials were investigated, namely PbS with co-growth of CdS and doped with Na and Na2CoO4. Seebeck coefficients, resistivity, and power generation for thermocouples were characterized.

A Complete System Modelling of Piezoelectric Energy Harvester (PEH) with Silicon Carbide (SiC) Used as Cantilever Base

2014 ◽  
Vol 69 (8) ◽  
Author(s):  
Mohd Nor Fakhzan Mohd Kazim ◽  
Selvanayakan Raman ◽  
Muhammad Hafiz Shafie ◽  
Nashrul Fazli Mohd Nasir ◽  
Asan Gani Abdul Muthalif
Keyword(s):  
Silicon Carbide ◽  
Output Power ◽  
Energy Harvester ◽  
Damping Ratio ◽  
Electrical Energy ◽  
System Modelling ◽  
Electronic Circuitry ◽  
Piezo Element ◽  
Piezoelectric Energy ◽  
Sic Wafer

Silicon carbide (SiC) is a material that possesses hardness and robustness to operate under high temperature condition. This work is a pilot in exploring the feasibility of cubic piezo element on the SiC wafer with integrated proof mass as horizontal cantilever with perpendicular displacement with respect to the normal plane. With the advance of electronic circuitry, the power consumption is reduced to nano-watts. Therefore, harvesting ambient energy and converting into electrical energy through piezoelectric material will be useful for powering low power devices. Resonance is a property which able to optimize the generated output power by tuning the proof masses. The damping ratio is a considerable parameter for optimization. From analytical study, small damping ratio will enhance the output power of the piezoelectric energy harvester (PEH). This paper will present mathematical modelling approach, simulation verification and the conditional circuit named versatile precision full wave rectifier.  

scholarly journals Study of Hybrid PVA/MA/TEOS Pervaporation Membrane and Evaluation of Energy Requirement for Desalination by Pervaporation

2018 ◽  
Vol 15 (9) ◽  
pp. 1913 ◽  
Author(s):  
Zongli Xie ◽  
Derrick Ng ◽  
Manh Hoang ◽  
Jianhua Zhang ◽  
Stephen Gray
Keyword(s):  
Thermal Energy ◽  
Waste Heat ◽  
Energy Requirement ◽  
Electrical Power ◽  
Electrical Energy ◽  
Commercial Application ◽  
Heating And Cooling ◽  
Pervaporation Membrane ◽  
Multi Stage ◽  
Multiple Effect Distillation

Desalination by pervaporation is a membrane process that is yet to be realized for commercial application. To investigate the feasibility and viability of scaling up, a process engineering model was developed to evaluate the energy requirement based on the experimental study of a hybrid polyvinyl alcohol/maleic acid/tetraethyl orthosilicate (PVA/MA/TEOS) Pervaporation Membrane. The energy consumption includes the external heating and cooling required for the feed and permeate streams, as well as the electrical power associated with pumps for re-circulating feed and maintaining vacuum. The thermal energy requirement is significant (e.g., up to 2609 MJ/m3 of thermal energy) and is required to maintain the feed stream at 65 °C in recirculation mode. The electrical energy requirement is very small (<0.2 kWh/m3 of required at 65 °C feed temperature at steady state) with the vacuum pump contributing to the majority of the electrical energy. The energy required for the pervaporation process was also compared to other desalination processes such as Reverse Osmosis (RO), Multi-stage Flash (MSF), and Multiple Effect Distillation (MED). The electrical energy requirement for pervaporation is the lowest among these desalination technologies. However, the thermal energy needed for pervaporation is significant. Pervaporation may be attractive when the process is integrated with waste heat and heat recovery option and used in niche applications such as RO brine concentration or salt recovery.

Modeling and optimization of a wide-band piezoelectric energy harvester for smart building structures

2020 ◽  
Vol 11 (02) ◽  
pp. 2050009
Author(s):  
Prateek Asthana ◽  
Gargi Khanna
Keyword(s):  
Resonant Frequency ◽  
Energy Harvester ◽  
Proof Mass ◽  
Mechanical Energy ◽  
Wide Band ◽  
Electrical Energy ◽  
Sensor Nodes ◽  
Ambient Vibrations ◽  
Band Energy ◽  
Piezoelectric Energy

Piezoelectric energy harvesting refers to conversion of mechanical energy into usable electrical energy. In the modern connected world, wireless sensor nodes are scattered around the environment. These nodes are powered by batteries. Batteries require regular replacement, hence energy harvesters providing continuous autonomous power are used to power these sensor nodes. This work provides two different fixation modes for the resonant frequency for the two modes. Variation in geometric parameter and their effect on resonant frequency and output power have been analyzed. These harvesters capture a wide-band of ambient vibrations and convert them into usable electrical energy. To capture random ambient vibrations, the harvester used is a wide-band energy harvester based on conventional seesaw mechanism. The proposed structure operates on first two resonant frequencies in comparison to the conventional cantilever system working on first resonant frequency. Resonance frequency, as well as response to a varying input vibration frequency, is carried out, showing better performance of seesaw cantilever design. In this work, modeling of wide-band energy harvester with proof mass is being performed. Position of proof mass plays a key role in determining the resonant frequency of the harvester. Placing the proof mass near or away from fixed end results in increase and decrease in stress on the piezoelectric layer. Hence, to avoid the breaking of cantilever, the position of proof mass has been analyzed.

A Novel Multi-Directional Nonlinear Piezoelectric Energy Harvester Coupled With Nonlinear Conditioning Circuits

2015 ◽  
Author(s):  
Zhengbao Yang ◽  
Jean Zu
Keyword(s):  
Energy Harvester ◽  
Piezoelectric Materials ◽  
Electrical Energy ◽  
Elastic Rods ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
High Power Output ◽  
Transduction Mechanisms ◽  
Self Powered ◽  
Aluminum Plates

Energy harvesting from vibrations has become, in recent years, a recurring target of a quantity of research to achieve self-powered operation of low-power electronic devices. However, most of energy harvesters developed to date, regardless of different transduction mechanisms and various structures, are designed to capture vibration energy from single predetermined direction. To overcome the problem of the unidirectional sensitivity, we proposed a novel multi-directional nonlinear energy harvester using piezoelectric materials. The harvester consists of a flexural center (one PZT plate sandwiched by two bow-shaped aluminum plates) and a pair of elastic rods. Base vibration is amplified and transferred to the flexural center by the elastic rods and then converted to electrical energy via the piezoelectric effect. A prototype was fabricated and experimentally compared with traditional cantilevered piezoelectric energy harvester. Following that, a nonlinear conditioning circuit (self-powered SSHI) was analyzed and adopted to improve the performance. Experimental results shows that the proposed energy harvester has the capability of generating power constantly when the excitation direction is changed in 360. It also exhibits a wide frequency bandwidth and a high power output which is further improved by the nonlinear circuit.

Energy Conservation and Storage Systems

2002 ◽  
Vol 20 (5) ◽  
pp. 391-399 ◽  
Author(s):  
Ayhan Demirbaş
Keyword(s):  
Energy Management ◽  
Thermal Energy ◽  
Waste Heat ◽  
Storage Systems ◽  
Electrical Energy ◽  
Thermal Storage ◽  
Energy Costs ◽  
Thermal Battery ◽  
Storage Technology ◽  
And Storage

In response to increasing electrical energy costs and the desire for better lad management, thermal storage technology has recently been developed. Storage of thermal energy in the form of sensible and latent heat has become an important aspect of energy management with the emphasis on efficient use and conservation of the waste heat and solar energy in industry and buildings. Thermal storage has been characterized as a kind of thermal battery.

Direct Thermoelectric Microgeneration Using Residual Heat of Photovoltaic System

2012 ◽  
Vol 608-609 ◽  
pp. 97-113 ◽  
Author(s):  
José Rui Camargo ◽  
Jamir Machado da Silva ◽  
Ederaldo Godoy Junior ◽  
Renan Eduardo da Silva ◽  
Luiz Eduardo Nicolini do Patrocínio Nunes ◽  
...  
Keyword(s):  
Thermal Energy ◽  
Waste Heat ◽  
Electrical Power ◽  
Thermoelectric Module ◽  
Electrical Energy ◽  
Photovoltaic System ◽  
Prototype System ◽  
Theoretical Evaluation ◽  
Photovoltaic Panel ◽  
Influence Of Temperature

All photovoltaic panel heats up when exposed to sunlight and this heating reduces the electrical power output of the same. This work presents the use of this unwanted waste heat, converting it into thermal energy directly by means of the Seebeck effect, which is the direct conversion of thermal energy into electrical energy by means of an arrangement of semiconductor materials that when exposed to temperature gradients generate electric current. In this work emphasis was placed on the influence of temperature on generation processes involved. Thus, the theoretical evaluation, it presents the mathematical models of thermoelectric and photovoltaic systems by raising the curves of voltage, current and electric power generated, and analyses the influence of temperature in each model. To obtain the simulation curves it uses MATLAB ® 5.3, taking into account the parameters of thermoelectric modules and real photovoltaic cells. In practical evaluation, a prototype was assembled containing thermoelectric module attached to the bottom of a photovoltaic panel in order to use the heat energy absorbed by the panel. The data were stored and analyzed, where we observed the influence of temperature in both systems, validating the mathematical modeling. It is the applicability of the mathematical model given the results obtained with the prototype system.

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