Making Thermoelectric Materials SnxGa1−xNx Alloys by Magnetron Sputtering Technology

2015 ◽  
Vol 1120-1121 ◽  
pp. 490-492
Author(s):  
Xing Long Guo
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Magnetron Sputtering ◽  
Thermoelectric Materials ◽  
Power Plants ◽  
Waste Heat ◽  
Heat Pumps ◽  
High Mechanical Strength ◽  
Power Generators ◽  
Device Operation

Thermoelectric materials are of interest for applications as heat pumps and power generators. Thermoelectric properties of SnxGa1−xN alloys have been investigated. It was found that as Sn concentration increases, the thermal conductivity decreases and power factor increases, which leads to an increase in the TE figure of ZT. The valuge of ZT was found to be 0.07 at 300 K for Sn0.38Ga0.64N alloy. The results indicate that SnGaN alloys could be potentially important TE materials for many applications, especially for prolonged TE device operation at high temperatures, such as for recovery of waste heat from automobile, aircrafts, and power plants due to their superior physical properties, including the ability of operating at high temperature/high power conditions, high mechanical strength and stability, and radiation hardness.

Topology Optimization of Multimaterial Thermoelectric Structures

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen
Keyword(s):  
Topology Optimization ◽  
Thermoelectric Materials ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Oil Refining ◽  
Numerical Verification ◽  
Temperature Range ◽  
Multiple Materials ◽  
P Type

Abstract A large amount of energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. The thermoelectric generator (TEG) provides a way to reutilize this portion of energy by converting temperature differences into electricity using Seebeck phenomenon. Because the figures of merit zT of the thermoelectric materials are temperature-dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, the authors propose a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The multimaterial TEG is optimized using the solid isotropic material with penalization (SIMP) method. Instead of dummy materials, both the P-type and N-type electric conductors are optimally distributed with two different practical thermoelectric materials. Specifically, Bi2Te3 and Zn4Sb3 are selected for the P-type element while Bi2Te3 and CoSb3 are employed for the N-type element. Two optimization scenarios with relatively regular domains are first considered with one optimizing on both the P-type and N-type elements simultaneously, and the other one only on single P-type element. The maximum conversion efficiency could reach 9.61% and 12.34% respectively in the temperature range from 25 °C to 400 °C. CAD models are reconstructed based on the optimization results for numerical verification. A good agreement between the performance of the CAD model and optimization result is achieved, which demonstrates the effectiveness of the proposed method.

Multimaterial Topology Optimization of Thermoelectric Generators

2019 ◽  
Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen
Keyword(s):  
Topology Optimization ◽  
Conversion Efficiency ◽  
Thermoelectric Materials ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Computational Simulation ◽  
Oil Refining ◽  
Temperature Range ◽  
Multiple Materials

Abstract Over 50% of the energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. As an attempt to deal with the growing energy crisis, the solid-state thermoelectric generator (TEG), which converts the waste heat into electricity using Seebeck phenomenon, has gained increasing popularity. Since the figures of merit of the thermoelectric materials are temperature dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, this paper proposes a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The objective of the optimization problem is to maximize the output power and conversion efficiency as well. The proposed method is implemented using the Solid Isotropic Material with Penalization (SIMP) method. The proposed method can make the most of the potential of different thermoelectric materials by distributing each material into its optimal working temperature interval. Instead of dummy materials, both the P and N-type electric conductors are optimally distributed with two different practical thermoelectric materials, namely Bi2Te3 & PbTe for P-type, and Bi2Te3 & CoSb3 for N-type respectively, with the yielding conversion efficiency around 12.5% in the temperature range Tc = 25°C and Th = 400°C. In the 2.5D computational simulation, however, the conversion efficiency shows a significant drop. This could be attributed to the mismatch of the external load and internal TEG resistance as well as the grey region from the topology optimization results as discussed in this paper.

Anderson Localization of Phonons in Random Multilayer Thin Films

2012 ◽  
Vol 1404 ◽  
Author(s):  
Anthony Frachioni ◽  
Bruce White
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Anderson Localization ◽  
Lattice Thermal Conductivity ◽  
Waste Heat ◽  
Mean Free Path ◽  
The United States ◽  
Energy Scavenging ◽  
Multilayer Thin Films

ABSTRACT1020 Joules of energy are generated by the United States each year; 60% of this energy is lost to waste heat [1]. Thermoelectric based energy scavenging has tremendous potential for the recovery of significant quantities of this waste heat. However, utilization of thermoelectric devices is limited due to relatively low energy conversion efficiency and the utilization of relatively scarce materials. This work focuses on generating sustainable and efficient thermoelectric materials through modifications to the lattice vibrations of materials with excellent thermoelectric electronic properties (Seebeck coefficients larger than 500 μV/K). In particular, Anderson localization of phonons in random multilayer thin films has been explored as a means for reducing lattice thermal conductivity to values approaching that of aerogels (∼10 mW/m-K). Silicon has been a sample of choice due to its high crust abundance and Seebeck coefficient. Reverse non-equilibrium molecular dynamics simulations have been utilized to determine the thermal conductivity of structures of interest. Simulations with pure Lennard-Jones argon solids have been performed to establish a methodology and to characterize the effect of different kinds of disorder prior to the examination of silicon. The simulation results indicate that mass disorder confined to randomly selected planes to be an effective way in which to reduce lattice thermal conductivity with the lattice thermal conductivity decreasing by a factor of thirty (to 4 mW/m-K) in the argon case and a factor of over ten thousand (to 15 mW/m-K) for silicon. Based on models in which the charge carrier mean free path is limited by scattering from the planes with mass disorder, the mobility of silicon is expected to reach values of 10 cm2/V-s. At this mobility the thermoelectric figure of merit, ZT, (utilizing the Wiedeman-Franz law to calculate the electronic thermal conductivity) varies between 4.5 and 11 as the mass ratio of the disordered planes is varied from 4 to 10 in 20% of the lattice planes. These results indicate that the pursuit of nanostructured thermoelectric materials in the form of random multilayers may provide a path to efficient and sustainable thermoelectric materials.

Effect of TiO2 additive on thermoelectric properties of SrTiO3

2019 ◽  
Vol 13 (02) ◽  
pp. 2051001
Author(s):  
Wei-Ying Yang ◽  
Ke-Xian Wang ◽  
Zheng Cao ◽  
Hao-Yang Yu ◽  
Xiao-Bo Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Strontium Titanate ◽  
Thermoelectric Properties ◽  
Waste Heat ◽  
Molar Ratio ◽  
Composite Powders ◽  
The Impact

Strontium titanate ([Formula: see text] has the advantages of being non-toxic, environmentally friendly and high-temperature stable, and has potential application in waste heat power generation at medium and high temperature. To explore the impact of TiO2 on the thermoelectric properties of SrTiO3, we synthesized TiO2/La10Nbb10-STO composite powders by hydrothermal method using precursor solution of 10[Formula: see text]mol.% La and 10[Formula: see text]mol.% Nb co-doped STO (La10Nb10-STO) containing TiO2 nanopowders with different molar ratio. After cold pressing and sintering, composite bulk materials were obtained, and their microstructure and thermoelectric transport properties were analyzed. With the increasing TiO2, although the thermal conductivity of TiO2/La10Nb10-STO composite decreased and the Seebeck coefficient increased, the minimum thermal conductivity and the maximum Seebeck coefficient were 2.54[Formula: see text][Formula: see text][Formula: see text] and 215[Formula: see text][Formula: see text]V[Formula: see text][Formula: see text], respectively, at 1000[Formula: see text]K, but the power factor decreased at high temperature due to the apparent decrease of electrical conductivity, resulting in the ZT values being lower than that of La0Nb10-STO without TiO2 addition at high temperature. Significantly, the addition of TiO2 can improve the thermoelectric performance of strontium titanate at low temperature. This approach is expected to improve the ZT of SrTiO3-based thermoelectric material through additional controlling of electrical conductivity.

scholarly journals Heat Transfer in Thermoelectric Materials and Devices

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Zhiting Tian ◽  
Sangyeop Lee ◽  
Gang Chen
Keyword(s):  
Heat Transfer ◽  
Energy Conversion ◽  
Thermoelectric Materials ◽  
Waste Heat ◽  
Co2 Reduction ◽  
Potential Candidate ◽  
Power Generators ◽  
Air Conditioners ◽  
Thermoelectric Energy Conversion ◽  
Thermoelectric Energy

Solid-state thermoelectric devices are currently used in applications ranging from thermocouple sensors to power generators in space missions, to portable air-conditioners and refrigerators. With the ever-rising demand throughout the world for energy consumption and CO2 reduction, thermoelectric energy conversion has been receiving intensified attention as a potential candidate for waste-heat harvesting as well as for power generation from renewable sources. Efficient thermoelectric energy conversion critically depends on the performance of thermoelectric materials and devices. In this review, we discuss heat transfer in thermoelectric materials and devices, especially phonon engineering to reduce the lattice thermal conductivity of thermoelectric materials, which requires a fundamental understanding of nanoscale heat conduction physics.

scholarly journals Analysis of Different Strategies for Lowering the Operation Temperature in Existing District Heating Networks

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 321 ◽  
Author(s):  
Francesco Neirotti ◽  
Michel Noussan ◽  
Stefano Riverso ◽  
Giorgio Manganini
Keyword(s):  
Energy Efficiency ◽  
Power Plants ◽  
Waste Heat ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
District Heating ◽  
Heating System ◽  
Heat Pumps ◽  
Critical Parameters ◽  
District Heating System

District heating systems have an important role in increasing the efficiency of the heating and cooling sector, especially when coupled to combined heat and power plants. However, in the transition towards decarbonization, current systems show some challenges for the integration of Renewable Energy Sources and Waste Heat. In particular, a crucial aspect is represented by the operating temperatures of the network. This paper analyzes two different approaches for the decrease of operation temperatures of existing networks, which are often supplying old buildings with a low degree of insulation. A simulation model was applied to some case studies to evaluate how a low-temperature operation of an existing district heating system performs compared to the standard operation, by considering two different approaches: (1) a different control strategy involving nighttime operation to avoid the morning peak demand; and (2) the partial insulation of the buildings to decrease operation temperatures without the need of modifying the heating system of the users. Different temperatures were considered to evaluate a threshold based on the characteristics of the buildings supplied by the network. The results highlight an interesting potential for optimization of existing systems by tuning the control strategies and performing some energy efficiency operation. The network temperature can be decreased with a continuous operation of the system, or with energy efficiency intervention in buildings, and distributed heat pumps used as integration could provide significant advantages. Each solution has its own limitations and critical parameters, which are discussed in detail.

scholarly journals Evaluation of the Environmental Sustainability of a Stirling Cycle-Based Heat Pump Using LCA

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4469
Author(s):  
Umara Khan ◽  
Ron Zevenhoven ◽  
Tor-Martin Tveit
Keyword(s):  
High Temperature ◽  
Heat Pump ◽  
Waste Heat ◽  
Heat Pumps ◽  
Heat Output ◽  
Environmental Footprint ◽  
Stirling Cycle ◽  
Impact Reduction ◽  
Temperature Heat ◽  
Very High

Heat pumps are increasingly seen as efficient and cost-effective heating systems also in industrial applications. They can drastically reduce the carbon footprint of heating by utilizing waste heat and renewable electricity. Recent research on Stirling cycle-based very high temperature heat pumps is motivated by their promising role in addressing global environmental and energy-related challenges. Evaluating the environmental footprint of a heat pump is not easy, and the impacts of Stirling cycle-based heat pumps, with a relatively high temperature lift have received little attention. In this work, the environmental footprint of a Stirling cycle-based very high temperature heat pump is evaluated using a “cradle to grave” LCA approach. The results for 15 years of use (including manufacturing phase, operation phase, and decommissioning) of a 500-kW heat output rate system are compared with those of natural gas- and oil-fired boilers. It is found that, for the Stirling cycle-based HP, the global warming potential after of 15 years of use is nearly −5000 kg CO2 equivalent. The Stirling cycle-based HP offers an environmental impact reduction of at least 10% up to over 40% in the categories climate change, photochemical ozone formation, and ozone depletion when compared to gas- and oil-fired boilers, respectively.

scholarly journals Computationally Modelling the Use of Nanotechnology to Enhance the Performance of Thermoelectric Materials

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5096
Author(s):  
Peter Spriggs ◽  
Qing Wang
Keyword(s):  
High Temperature ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Waste Heat ◽  
Global Climate ◽  
Computational Simulation ◽  
Electrical Energy ◽  
Maximum Efficiency ◽  
Temperature Range ◽  
Band Engineering

The increased focus on global climate change has meant that the thermoelectric market has received considerably more attention. There are many processes producing large amounts of waste heat that can be utilised to generate electrical energy. Thermoelectric devices have long suffered with low efficiencies, but this can be addressed in principle by improving the performance of the thermoelectric materials these devices are manufactured with. This paper investigates the thermoelectric performance of market standard thermoelectric materials before analysing how this performance can be improved through the adoption of various nanotechnology techniques. This analysis is carried out through the computational simulation of the materials over low-, mid- and high-temperature ranges. In the low-temperature range, through the use of nanopores and full frequency phonon scattering, Mg0.97Zn0.03Ag0.9Sb0.95 performed best with a ZT value of 1.45 at 433 K. Across the mid-temperature range a potentially industry leading ZT value of 2.08 was reached by AgSbTe1.85Se0.15. This was carried out by simulating the effect of band engineering and the introduction of dense stacking faults due to the addition of Se into AgSbTe2. AgSbTe1.85Se0.15 cannot be implemented in devices operating above 673 K because it degrades too quickly. Therefore, for the top 200 K of the mid-temperature range a PbBi0.002Te–15% Ag2Te nanocomposite performed best with a maximum ZT of 2.04 at 753 K and maximum efficiency of 23.27 at 813 K. In the high-temperature range, through the doping of hafnium (Hf) the nanostructured FeNb0.88Hf0.12Sb recorded the highest ZT value of 1.49 at 1273 K. This was closely followed by Fe1.05Nb0.75Ti0.25Sb, which recorded a ZT value of 1.31 at 1133 K. This makes Fe1.05Nb0.75Ti0.25Sb an attractive substitute for FeNb0.88Hf0.12Sb due to the much lower cost and far greater abundance of titanium (Ti) compared with hafnium.

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