Thermoelectric Generator Elements Research Articles

Fabrication of Thin TEG (Bi-Ni) Using Magnetron Sputtering Technology and Investigations

As the industry develops more and more, heat is produced during fabrication processes, resulting in an excess of heat. One of the ways to solve the problem can be the conversion of excess heat into electricity using a thermoelectric generator (TEG). The authors of this paper propose a method of using thin-film TEGs for electricity generation, a procedure that has been given little attention to in the literature. In this study, thin TEGs (about 50–100 nm thick) were obtained from Bi-Ni, using magnetron sputtering technology. This type of TEG can be used not only as a device that generates electricity, but also as a protective layer for various systems, protecting them from environmental influences. In addition, such TEGs can be formed on a complex, uneven surface, with various details changing their geometric shape. As shown from XRD studies, the obtained Bi-Ni layer is polycrystalline. XRD studies help to determine whether the layer obtained is composed of pure layers of Bi and Ni metals or whether metal oxides have formed (metal oxides have a negative effect on electrical conductivity). An increase in the temperature from 80 to 120 K, respectively, increases the voltage generated by the TEG from 0.01 to 0.03 V. Meanwhile, the efficiency of such TEG element changes from 1 to 4.5% when the temperature change increases from 30 to 119 K.

Convection-effect-enhanced micro thermoelectric module directly heated by catalytic combustion

A novel micro thermoelectric power generation module directly heated with localized catalytic combustion has been proposed. Arrays of high-temperature plate-type thermoelectric generator (TEG) elements, of which the hot junction is directly heated by exothermic catalytic oxidation of hydrocarbon fuel, are designed. Heat losses caused by heat conduction through the TEG element are recovered by the convection effect with unburned mixture flows. Catalyst layers were prepared by impregnating Pd or Pt catalyst on porous Al2O3 supports coated by using the suspension plasma spray. A series of one-dimensional numerical analyses considering the catalytic combustion in addition to the conductive and convective heat transfer were made to examine the temperature field of the TEG module and to investigate how various parameters affect the convection effect. A model combustor using quartz plates was developed, which mimics the temperature fields of the SiGe TEG module. It is found that, with the aid of the convection effect, temperature differences over 700 °C between the hot/cold junctions can be achieved, while the unreacted fuel concentration is less than 10%. Finally, 40 mm-long Ni-based alloy TEG elements have been fabricated using laser cutting and spot welding techniques, which ensure high operating temperatures and reliability. In a power generation demonstration using butane as a fuel, an open circuit voltage of 0.64 V has been obtained from a single TEG module with a peak output power and a power generation density as high as 10.1 mW and 10.8 kW/m3, respectively.

PEMANFAATAN THERMO ELECTRIC GENERATOR DARI KONVERSI ENERGI PANAS MENJADI LISTRIK UNTUK CHARGER PONSEL

Thermo Electric generator element is a conversion system that converts heat into electricity by utilizing heat energy. This tool is designed which comes from wood fuel as a heat source, which can be converted by a Thermo Electric Generator (TEG) into electricity, because not all rural areas have electricity, so researchers use it as a back up for cellphone chargers. This research is a small scale only used for cellphone chargers, the results show that the temperature difference is a very influential factor in producing voltage output and electric current, the greater the temperature gradient (ΔT) produced, the greater the voltage output on the thermo electric. The working principle of the TEG element is that there is a temperature difference on each side, so the TEG will generate electricity. The TEG output is stabilized by an LM317 regulator to a constant 5V DC, the voltage does not fluctuate and does not cause damage to the cellphone. This element is packaged in the form of thin strips with two-sided cross sections, with one side absorbing heat and one side absorbing cold. The tool is designed to consist of 4 TEG with type TEG 12706 arranged in series to increase tension. The results of the research on the hot temperature side of at least 40.1 0C with a voltage of 0.70V DC and a maximum heat temperature of 187 0C with a voltage of 8.55V DC and on the cold side of a minimum of 0 0C a maximum of 26 0C with (P) power 0.105 W, (V) 8V DC voltage and (I) 0.013 mA current.

Using the constant properties model for accurate performance estimation of thermoelectric generator elements

Thermoelectric devices convert thermal energy directly into electrical energy or vice versa. Analytically, the performance (efficiency and power output) of a thermoelectric generator can be quickly estimated using a Constant Properties Model (CPM) suggested by Ioffe. However, material properties in general are temperature dependent and the CPM can yield meaningful estimates only if the constant values of the TE properties used in the formulations are physically appropriate. In this study, a comparison of different averaging modes shows that a combination of integral averaging over the temperature scale for the Seebeck coefficient and spatial averages for the electrical and thermal resistivities proves to be the best among the considered approximations to represent the constant property values. However, averaging spatially requires the knowledge of the exact temperature distribution along the length of the thermoelectric leg (temperature profile), which is usually obtained by Finite Element Method (FEM) calculations. Since FEM is costly and time consuming, a fast and easy way of obtaining a well approximated self-consistent temperature profile is used in this study. The relevance, magnitude and the physical origin of the non-linearity of the temperature profile are visualised by separately plotting the individual contributions to the bending of the temperature profile (Joule, Thomson and Fourier heat contributions). On analyzing the temperature profiles for different highly efficient thermoelectric materials, it is found that the non-constancy of the temperature dependence of the thermal conductivity significantly contributes to the deflection of real temperature profiles from a linear one. This mainly explains the considerable discrepancy of CPM results from exact calculations whereas, so far, the neglect of Thomson heat has been assumed to be the main source of discrepancy and several models with Thomson correction factors have been proposed. With our current view, such models cannot completely remove the discrepancy to CPM unless the T profile is taken into account and can lead to unpredictable error for different material cases and temperatures.

Numerical Simulation and Validation of Thermoeletric Generator Based Self-Cooling System with Airflow

In this paper, a general numerical methodology is developed and validated for the simulation of steady as well as transient thermal and electrical behaviors of thermoelectric generator (TEG)-based air flow self-cooling systems. The present model provides a comprehensive framework to advance the study of self-cooling applications by combining fluid flow, heat transfer and electric circuit simulations. The methodology is implemented by equation-based coupled modeling capabilities from multidisciplinary fields to capture the dynamic thermos-electric interaction in TEG elements, enabling the simulation of overall heating/cooling/power characteristics as well as spatially distributed thermal and flow fields in the entire device. Experiments have been conducted on two types of self-cooling arrangements to measure the device temperature, voltage and power produced by TEG modules. It was found that the computational model was able to predict the experimental results within 5% error. A parametric study was carried out using the validated model to study the effect of heat sink geometry and TEG arrangements on device temperature and power produced by the device. It was found that the power for self-cooling could be maximized by proper matching of the TEG modules to the fluid mover. Although an increase in fin density results in a rise in fan power consumption, a marked increase in net power and decreases in thermal resistance are observed.

The Importance of Considering Parasitic Heat Losses When Modeling TEG Performance for High-Temperature Applications

For a thermoelectric generator (TEG) with nonideal heat exchangers, the electrical power output can be maximized by matching the thermal resistances of the TEG Rteg and heat exchangers Rhx. Due to the fact that TEG elements are not thermally isolated from the surroundings, this study shows that inner heat losses are significant for proper thermal resistance matching—particularly for TEG systems for high-temperature applications. The inner heat losses are here defined as parasitic heat transfer mechanisms within the space between the thermoelectric (TE) couple legs. Analytical modeling is carried out using a thermal resistance network and applied to determine the performance of a TE system comprising a finned heat sink as well as a TEG with base area of A = 6 × 6 × 10−4 m2 and leg width of a = 3 × 10−3 m. The performance of different TEG designs is evaluated, and the optimum thermal resistance ratio, i.e., Rhx/Rteg, obtained for different values of leg length and built-in TE couple leg number. Finally, the developed analytical model is employed in a multiobjective TEG design optimization scheme, based on the theory of Pareto efficiency, to maximize the power output while minimizing the amount of TE material required. The results obtained from the multiobjective optimization reveal that the amount of TE material required in a module can be reduced by 6.63% without any power output loss in comparison with the results of one-parameter optimization.

Modeling of various heat adapter plate 4 and 6 array for optimization of thermoelectric generator element using modified diffusion equation

The use of waste heat from exhaust gas and converting it to electricity is now an alternative to harvest a cheap and clean energy. Thermoelectric generator (TEG) has the ability to directly recover such waste heat and generate electricity. The aim of this study is to simulate the heat transfer on the aluminum adapter plate for homogeneity temperature distribution coupled with hot side of TEG type 40-40-10/100 from Firma Eureka and adjust their high temperatures to the TEG operating temperature to avoid the element damage. Modelling was carried out using MATLAB modified diffusion equation with Dirichlet boundary conditions at defined temperature which has been set at the ends of the heat source at 463K and 373K ± 10% on the hot side of the TEG element. The use of nylon insulated material is modeled after Neumann boundary condition in which the temperature gradient is ∂T/∂n = 0 out of boundary. Realization of the modelling is done by designing a heat conductive plate using software ACAD 2015 and converted into a binary file format of Mathlab to form a finite element mesh with geometry variations of solid model. The solid cubic model of aluminum adapter plate has a dimension of 40mm length, 40mm width and also 20mm, 30mm and 40mm thickness arranged in two arrays of 2×2 and 2×3 of TEG elements. Results showed a temperature decrease about 40.95% and 50.02% respectively from the initial source and appropriate with TEG temperature tolerance.

A thermoelectric-based energy harvesting module with extended operational temperature range for powering autonomous wireless sensor nodes in aircraft

This paper describes the performance improvement of an energy harvesting device for aircraft by increasing its operational temperature range. The thermoelectric energy harvesting device consists of two cavities each containing a different phase change material, acting as thermal mass. Thermoelectric generator elements (TEGs) are attached to the inner part of the fuselage and to the thermal mass. Therefore, an artificially enhanced temperature difference between the bottom and the top surface of the TEGs is created during take-off and landing. Different temperature profiles mimicking short/mid-range European flights are investigated. The performance in terms of efficiency, power-to-weight ratio and energy harvested is studied in detail, both by simulations and experimental data.

Examination of a Thermally Viable Structure for an Unconventional Uni-Leg Mg2Si Thermoelectric Power Generator

We have fabricated an unconventional uni-leg structure thermoelectric generator (TEG) element using quad thermoelectric (TE) chips of Sb-doped n-Mg2Si, which were prepared by a plasma-activated sintering process. The power curve characteristics, the effect of aging up to 500 h, and the thermal gradients at several points on the module were investigated. The observed maximum output power with the heat source at 975 K and the heat sink at 345 K was 341 mW, from which the ΔT for the TE chip was calculated to be about 333 K. In aging testing in air ambient, a remarkable feature of the results was that there was no notable change from the initial resistance of the TEG module for as long as 500 h. The thermal distribution for the fabricated uni-leg TEG element was analyzed by finite-element modeling using ANSYS software. To tune the calculation parameters of ANSYS, such as the thermal conductance properties of the corresponding coupled materials in the module, precise measurements of the temperature at various probe points on the module were made. Then, meticulous verification between the measured temperature values and the results calculated by ANSYS was carried out to optimize the parameters.

Performance optimization of a thermoelectric generator element with linear, spatial material profiles in a one-dimensional setup

Abstract