SPATIAL SPICE MODEL OF A WIRELESS SENSOR NETWORK NODE BASED ON A THERMOELECTRIC GENERATOR

This paper presents a spatial SPICE model of a wireless sensor network node that enables simulation of performances in the steady-state and time-domain. The model includes constructive non-electrical parts of the node and a thermoelectric generator employing the thermoelectric effects. The simulation results are compared with the experiment to validate the proposed model. It enabled the characterization of WSN nodes comprising different thermoelectric generators and heatsinks in terms of energy conversion efficiency

FINITE ELEMENT AND IMAGING APPROACHES TO ANALYZE MULTISCALE ELECTROTHERMAL PHENOMENA

Electrothermal effects are crucial in the design and optimization of electronic devices. Thermoreflectance (TR) imaging enables transient thermal characterization at submicron to centimeter scales. Typically, finite element methods (FEM) are used to calculate the temperature profile in devices and ICs with complex geometry. By comparing theory and experiment, important material parameters and device characteristics are extracted. In this work we combine TR and FEM with image blurring/reconstruction techniques to improve electrothermal characterization of micron and nanoscale devices

Application of MEMS technology in the field of thermoelectric generators

Práce je zaměřena na moderní oblast využití MEMS technologií v oblasti termoelektrických generátorů. Úvodem jsou diskutovány základní principy konstrukce a výroby MEMS TEG modulů. Praktická část práce sestává z ověření parametrů komerčního MEMS TEG modulu měřením a jeho simulace. Simulace je provedena pomocí MATLAB/Simulink i analytických metod. V závěru práce je na základě získaných poznatků provedeno zhodnocení využití metod „thermal energy harvesting” v oblasti letecké techniky.This thesis is focused on the modern field of application of MEMS technology in the field of thermoelectric generators. The introductory part deals with fundamental principles of MEMS TEG construction and manufacturing. The practical part of this thesis consists of verification of commercial MEMS TEG parameters and its simulation. Simulation is carried out using MATLAB/Simulink as well as analytical methods. The conclusion deals with evaluation of use of thermal energy harvesting methods in aircraft-specific field.

Range extension of a bimorph varifocal micromirror through actuation by a Peltier element

A bimorph varifocal micromirror actuated thermoelectrically by a Peltier element is reported. The single crystal silicon micromirror is 1.2 mm in diameter with a centered 1 mm diameter gold coating for broadband reflection. The actuation principle is capable of varying the micromirror temperature above and below the ambient temperature, which contributed to a 57% improvement in the addressable curvature range in comparison to previously reported electrothermal and optothermal actuation techniques for the device. Altering the device temperature from 10 C to 100 C provided a mirror surface radius of curvature variation from 19.2 mm to 30.9 mm respectively. The experimental characterization of the micromirror was used as a basis for accurate finite element modeling of the device and its actuation. Negligible optical aberrations are observed over the operating range, enabling effectively aberration-free imaging. Demonstration in an optical imaging system illustrated sharp imaging of objects over a focal plane variation of 212 mm

Thermoelectric generators

As the world is changing and developing with every passing day, the requirements of power are also increasing. There is a shift in utilizing the electrical energy as much as possible and for this reason, many countries have already made policies for completely ruling out the machines which don’t run on electricity. Apart from electricity, there are other forms of energy that can be used to convert that form into a more desirable form. For example, in a plant where the smoke comes out of the chimneys or in a car, the smoke carries a large amount of thermal energy with it. This energy is nothing but a waste and reduction in the efficiency of the systems. If somehow, this energy could be recovered, the efficiency can be increased. Thermoelectric generators serve for this purpose. Thermos electric generators get the heat and using the principle of heat conduction and p and n type materials, the heat can be directly converted into the electricity. There are many materials available in the market for p and n type but in our case, we chose silicon germanium which is also one of the most commonly used. First of all, a single module of thermoelectric generator will be made using p and n type material, as well as using conductive material and some ceramic substance. Then, the entire assembly will be made and this assembly will be exported to Ansys where custom materials will be added and applied on to the geometry. After performing analysis on full model, a comparative study will be presented in which the effect of material of conductive plate on to the voltage difference will be studie

SUSTAINABLE ENERGY HARVESTING TECHNOLOGIES – PAST, PRESENT AND FUTURE

Chapter 8: Energy Harvesting Technologies: Thick-Film Piezoelectric Microgenerato

Generalized Scharfetter--Gummel schemes for electro-thermal transport in degenerate semiconductors using the Kelvin formula for the Seebeck coefficient

Many challenges faced in today's semiconductor devices are related to self-heating phenomena. The optimization of device designs can be assisted by numerical simulations using the non-isothermal drift-diffusion system, where the magnitude of the thermoelectric cross effects is controlled by the Seebeck coefficient. We show that the model equations take a remarkably simple form when assuming the so-called Kelvin formula for the Seebeck coefficient. The corresponding heat generation rate involves exactly the three classically known self-heating effects, namely Joule, recombination and Thomson--Peltier heating, without any further (transient) contributions. Moreover, the thermal driving force in the electrical current density expressions can be entirely absorbed in the (nonlinear) diffusion coefficient via a generalized Einstein relation. The efficient numerical simulation relies on an accurate and robust discretization technique for the fluxes (finite volume Scharfetter--Gummel method), which allows to cope with the typically stiff solutions of the semiconductor device equations. We derive two non-isothermal generalizations of the Scharfetter--Gummel scheme for degenerate semiconductors (Fermi--Dirac statistics) obeying the Kelvin formula. The approaches differ in the treatment of degeneration effects: The first is based on an approximation of the discrete generalized Einstein relation implying a specifically modified thermal voltage, whereas the second scheme follows the conventionally used approach employing a modified electric field. We present a detailed analysis and comparison of both schemes, indicating a superior performance of the modified thermal voltage scheme

Generalized Scharfetter-Gummel schemes for electro-thermal transport in degenerate semiconductors using the Kelvin formula for the Seebeck coefficient

Many challenges faced in today's semiconductor devices are related to self-heating phenomena. The optimization of device designs can be assisted by numerical simulations using the non-isothermal drift-diffusion system, where the magnitude of the thermoelectric cross effects is controlled by the Seebeck coefficient. We show that the model equations take a remarkably simple form when assuming the so-called Kelvin formula for the Seebeck coefficient. The corresponding heat generation rate involves exactly the three classically known self-heating effects, namely Joule, recombination and Thomson-Peltier heating, without any further (transient) contributions. Moreover, the thermal driving force in the electrical current density expressions can be entirely absorbed in the diffusion coefficient via a generalized Einstein relation. The efficient numerical simulation relies on an accurate and robust discretization technique for the fluxes (finite volume Scharfetter-Gummel method), which allows to cope with the typically stiff solutions of the semiconductor device equations. We derive two non-isothermal generalizations of the Scharfetter-Gummel scheme for degenerate semiconductors (Fermi-Dirac statistics) obeying the Kelvin formula. The approaches differ in the treatment of degeneration effects: The first is based on an approximation of the discrete generalized Einstein relation implying a specifically modified thermal voltage, whereas the second scheme follows the conventionally used approach employing a modified electric field. We present a detailed analysis and comparison of both schemes, indicating a superior performance of the modified thermal voltage scheme.Comment: 26 pages, 7 figure