Special Issue "Development and Application of Thermoelectric Power Generators, Energy Harvesters and Refrigerators"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy".

Deadline for manuscript submissions: closed (31 October 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Min-Wook OH

Department of Advanced Materials Engineering, Hanbat National University, 125, Dongseo-daero, Yuseong-gu, Daejeon, Korea
E-Mail
Interests: thermoelectric materials and modules; electrical and thermal transport properties; thermal conducting materials; waste heat recovery; energy harvesting; computational simulations; First-Principles Calculations; molecular dynamics simulations
Guest Editor
Prof. Dr. Byung Jin Cho

Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea
Website | E-Mail
Interests: thermoelectric materials and modules; electrical and thermal transport properties; thermal conducting materials; waste heat recovery; energy harvesting; computational simulations; First-Principles Calculations; molecular dynamics simulations

Special Issue Information

Dear Colleagues,

Thermal energy is one of the most abundant forms of energy, but is the most challenging energy to be converted into a useful form, such as electrical energy. Due to the great range in temperatures of thermal energy, various energy-conversion technologies can be adapted for conversion. Among them, thermoelectric technologies have attracted a great deal of interest due to their usefulness in wide temperature ranges, and scalability from micro devices with micro-watt output powers to container-sized systems measured in kilowatts. Thermoelectric conversion includes power generation and refrigeration, which include heating, ventilation, and air conditioning (HVAC). Thermoelectric power generation with body heat, waste heat, geothermal, or solar power as thermal sources is an attractive and environmentally clean way to generate electrical power. Thermoelectric cooling has the advantages of precise temperature control, fast response times, and multiformity in system sizes.

Even though thermoelectric principles have been known for about two hundred years, and representative materials, such Bi2Te3 compounds, were developed in the mid-twentieth century, a new era for this technology is beginning due to the dramatic improvements in thermoelectric materials. In addition, due to global demands, with respect to recovering waste heat for electricity and a great interest in energy harvesting, thermoelectric modules and system technologies have been rapidly developed. New functionalities, such as flexibility being added to thermoelectric modules, the applications and markets for thermoelectric modules are also expanding.

In this Special Issue, we invite investigators to contribute original articles, as well as review articles, that will contribute to the ongoing efforts to develop thermoelectric modules and systems for power generation, refrigeration, and energy harvesting. Potential topics include, but are not limited to:

  • Inorganic thermoelectric modules
  • Organic thermoelectric modules
  • Thermoelectric cooling systems
  • Flexible thermoelectric generators
  • Thermoelectric power generation systems
  • Photovoltaic-thermoelectric hybrid generators
  • Piezoelectric-thermoelectric hybrid generators
  • Joining method for thermoelectric module fabrication
  • Thermoelectric energy harvesting technologies
  • Thermoelectric materials, diffusion barriers, and filler metals for soldering and brazing

Prof. Dr. Min-Wook OH
Prof. Dr. Byung Jin Cho
Guest Editors

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Keywords

  • Thermoelectric power generation
  • Thermoelectric cooling and refrigeration
  • Thermoelectric devices and modules
  • Thermoelectric materials
  • Energy harvesting
  • Brazing and Soldering

Published Papers (7 papers)

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Research

Open AccessFeature PaperArticle Control of Carrier Concentration by Ag Doping in N-Type Bi2Te3 Based Compounds
Appl. Sci. 2018, 8(5), 735; https://doi.org/10.3390/app8050735
Received: 30 March 2018 / Revised: 23 April 2018 / Accepted: 3 May 2018 / Published: 6 May 2018
Cited by 1 | PDF Full-text (1943 KB) | HTML Full-text | XML Full-text
Abstract
Many elements have been used as dopants to enhance the thermoelectric performance of Bi2Te3-related materials. Among them, Ag’s effect on thermoelectric properties, where Ag acts as a donor or acceptor, remains unclear. To elucidate the role of Ag in [...] Read more.
Many elements have been used as dopants to enhance the thermoelectric performance of Bi2Te3-related materials. Among them, Ag’s effect on thermoelectric properties, where Ag acts as a donor or acceptor, remains unclear. To elucidate the role of Ag in n-type Bi2Te3 based compounds, Ag was added to n-type (Bi0.9Sb0.1)2(Te0.85Se0.15)3. As the amount of Ag was increased, the electron concentration decreased, which means Ag acted as an acceptor. The added Ag atoms were found to occupy interstitial sites in the hexagonal lattices, as confirmed by X-ray analysis and first principles calculations. The reduction in electron concentration was attributed to the interaction between the interstitial Ag and intrinsic defects. Full article
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Open AccessArticle Power Control Optimization of an Underwater Piezoelectric Energy Harvester
Appl. Sci. 2018, 8(3), 389; https://doi.org/10.3390/app8030389
Received: 29 December 2017 / Revised: 25 February 2018 / Accepted: 2 March 2018 / Published: 7 March 2018
Cited by 1 | PDF Full-text (4318 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Over the past few years, it has been established that vibration energy harvesters with intentionally designed components can be used for frequency bandwidth enhancement under excitation for sufficiently high vibration amplitudes. Pipelines are often necessary means of transporting important resources such as water, [...] Read more.
Over the past few years, it has been established that vibration energy harvesters with intentionally designed components can be used for frequency bandwidth enhancement under excitation for sufficiently high vibration amplitudes. Pipelines are often necessary means of transporting important resources such as water, gas, and oil. A self-powered wireless sensor network could be a sustainable alternative for in-pipe monitoring applications. A new control algorithm has been developed and implemented into an underwater energy harvester. Firstly, a computational study of a piezoelectric energy harvester for underwater applications has been studied for using the kinetic energy of water flow at four different Reynolds numbers Re = 3000, 6000, 9000, and 12,000. The device consists of a piezoelectric beam assembled to an oscillating cylinder inside the water of pipes from 2 to 5 inches in diameter. Therefore, unsteady simulations have been performed to study the dynamic forces under different water speeds. Secondly, a new control law strategy based on the computational results has been developed to extract as much energy as possible from the energy harvester. The results show that the harvester can efficiently extract the power from the kinetic energy of the fluid. The maximum power output is 996.25 µW and corresponds to the case with Re = 12,000. Full article
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Open AccessArticle Na-Doping Effects on Thermoelectric Properties of Cu2−xSe Nanoplates
Appl. Sci. 2018, 8(1), 12; https://doi.org/10.3390/app8010012
Received: 23 November 2017 / Revised: 15 December 2017 / Accepted: 20 December 2017 / Published: 22 December 2017
Cited by 5 | PDF Full-text (2489 KB) | HTML Full-text | XML Full-text
Abstract
For this work, a β-phase Cu2−xSe nanowire and nanoplate, and a Na-doped Cu2−xSe nanoplate were successfully synthesized using solution syntheses. The morphologies of the Cu2−xSe nanowire and nanoplate could be easily controlled by changing the synthetic condition. [...] Read more.
For this work, a β-phase Cu2−xSe nanowire and nanoplate, and a Na-doped Cu2−xSe nanoplate were successfully synthesized using solution syntheses. The morphologies of the Cu2−xSe nanowire and nanoplate could be easily controlled by changing the synthetic condition. The Na-doped Cu2−xSe nanoplate was prepared by a simple treatment of the Cu2−xSe nanoplate with a sodium hydroxide-ethylene glycol solution. The nanopowders were then consolidated to bulk materials using spark plasma sintering (SPS). The phase structure and the microstructure of all of the samples were checked using X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), and scanning electron microscope (SEM) analyses. The thermoelectric transport properties, such as the electrical conductivity, Seebeck coefficient, carrier concentration, carrier mobility, and thermal conductivity, were measured at temperature ranges from 323 to 673 K. The results show that Na played two important roles: one is reducing the carrier concentration, thereby improving the Seebeck coefficient, the other is reducing the thermal conductivity. Overall, the maximum thermoelectric figure of merit (ZT) of 0.24 was achieved at 673 K in the Na-doped Cu2−xSe nanoplate. Full article
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Open AccessFeature PaperArticle Multi-Layer Metallization Structure Development for Highly Efficient Polycrystalline SnSe Thermoelectric Devices
Appl. Sci. 2017, 7(11), 1116; https://doi.org/10.3390/app7111116
Received: 19 September 2017 / Revised: 13 October 2017 / Accepted: 23 October 2017 / Published: 28 October 2017
Cited by 1 | PDF Full-text (3391 KB) | HTML Full-text | XML Full-text
Abstract
Recently, SnSe material with an outstanding high ZT (Figure of merit) of 2.6 has attracted much attention due to its strong applicability for highly efficient thermoelectric devices. Many studies following the first journal publication have been focused on SnSe materials, not on thermoelectric [...] Read more.
Recently, SnSe material with an outstanding high ZT (Figure of merit) of 2.6 has attracted much attention due to its strong applicability for highly efficient thermoelectric devices. Many studies following the first journal publication have been focused on SnSe materials, not on thermoelectric devices. Particularly, to realize highly efficient intermediate-temperature (600~1000 K) thermoelectric modules with this promising thermoelectric material, a more thermally and electrically reliable interface bonding technology needs to be developed so that the modules can stably perform their power generation in this temperature range. In this work, we demonstrate several approaches to develop metallization layers on SnSe thermoelectric legs. The single-layer metallization shows limitations in their electrical contact resistances and elemental diffusions. The Ag/Co/Ti multi-layer metallization results in lowering their electrical contact resistances, in addition to providing more robust interfaces. Moreover, it is found to maintain the interfacial characteristics without any significant degradation, even after heat treatment at 723 K for 20 h. These results can be effectively applied in the fabrication of thermoelectric devices or modules that are made of the SnSe thermoelectric materials. Full article
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Open AccessFeature PaperArticle Material Optimization for a High Power Thermoelectric Generator in Wearable Applications
Appl. Sci. 2017, 7(10), 1015; https://doi.org/10.3390/app7101015
Received: 13 September 2017 / Revised: 26 September 2017 / Accepted: 26 September 2017 / Published: 30 September 2017
Cited by 1 | PDF Full-text (2019 KB) | HTML Full-text | XML Full-text
Abstract
Thermoelectric power generation using human body heat can be applied to wearable sensors, and various applications are possible. Because the thermoelectric generator (TEG) is highly dependent on the thermoelectric material, research on improving the performance of the thermoelectric material has been conducted. Thus [...] Read more.
Thermoelectric power generation using human body heat can be applied to wearable sensors, and various applications are possible. Because the thermoelectric generator (TEG) is highly dependent on the thermoelectric material, research on improving the performance of the thermoelectric material has been conducted. Thus far, in developing thermoelectric materials, the researchers have focused on improving the figure of merit, ZT. For a TEG placed on the human body, however, the power density does not always increase as the material ZT increases. In this study, the material properties and ZT of P-type BiSbTe3 were simulated for carrier concentration ranging from 3 × 1017 to 3 × 1020 cm−3, and the power density of a TEG fabricated from the material dataset was calculated using a thermoelectric resistance model for human body application. The results revealed that the maximum ZT and the maximum power density were formed at different carrier concentrations. The material with maximum ZT showed 28.8% lower power density compared to the maximum obtainable power density. Further analysis confirmed that the mismatch in the optimum carrier concentration for the maximum ZT and maximum power density can be minimized when a material with lower thermal conductivity is used in a TEG. This study shows that the ZT enhancement of materials is not the highest priority in the production of a TEG for human body application, and material engineering to lower the thermal conductivity is required to reduce the optimum point mismatch problem. Full article
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Open AccessArticle Study on the High Temperature Interfacial Stability of Ti/Mo/Yb0.3Co4Sb12 Thermoelectric Joints
Appl. Sci. 2017, 7(9), 952; https://doi.org/10.3390/app7090952
Received: 31 August 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 15 September 2017
Cited by 2 | PDF Full-text (3840 KB) | HTML Full-text | XML Full-text
Abstract
To improve the interfacial stability at high temperatures, n-type skutterudite (SKD) thermoelectric joints with sandwich structures of Ti/Mo/Yb0.3Co4Sb12 were successfully designed and fabricated. In this structure, Mo and Ti were introduced as the barrier layer with the [...] Read more.
To improve the interfacial stability at high temperatures, n-type skutterudite (SKD) thermoelectric joints with sandwich structures of Ti/Mo/Yb0.3Co4Sb12 were successfully designed and fabricated. In this structure, Mo and Ti were introduced as the barrier layer with the goal of suppressing the interfacial diffusion and the buffer layer with the goal of enhancing the bonding strength, respectively. To evaluate the high temperature interfacial behavior of the Ti/Mo/Yb0.3Co4Sb12 joints, thermal shocking between 0 °C and 600 °C and isothermal aging at a temperature range of 550 °C to 650 °C were carried out in vacuum. During the isothermal aging process, Ti penetrates across the Mo layer, and finally diffuses into the Yb0.3Co4Sb12 matrix. By increasing the isothermal aging time, Ti continuously diffuses and reacts with the elements of Sb and Co in the matrix, consequently forming the multilayer-structured intermetallic compounds of Ti3Sb/Ti2Sb/TiCoSb. Diffusion kinetics was investigated and it was found that the interfacial evolution of the Ti/Mo/Yb0.3Co4Sb12 joints was a diffusion-controlling process. During the diffusion process, the formed Mo-Ti buffer layer acts as a damper, which greatly decelerates the diffusion of Ti towards the Yb0.3Co4Sb12 matrix at high temperatures. Meanwhile, it was found that the increase in the contact resistivity of the joints mainly derives from the inter-diffusion between Ti and Yb0.3Co4Sb12. As a result, the Ti/Mo/Yb0.3Co4Sb12 joint demonstrates the excellent stability of the interfacial contact resistivity. Service life prediction was made based on the stability of the contact resistivity, and it was found that the Ti/Mo/Yb0.3Co4Sb12 joint is qualified for practical applications at 550 °C. Full article
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Open AccessArticle Optimized Design of Thermoelectric Energy Harvesting Systems for Waste Heat Recovery from Exhaust Pipes
Appl. Sci. 2017, 7(6), 634; https://doi.org/10.3390/app7060634
Received: 1 June 2017 / Revised: 14 June 2017 / Accepted: 15 June 2017 / Published: 19 June 2017
Cited by 2 | PDF Full-text (5116 KB) | HTML Full-text | XML Full-text
Abstract
With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert [...] Read more.
With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert the waste heat from exhaust pipes, which are very often used to transport the heat, e.g., in automobiles, in industrial facilities or in heating systems. That is why a mockup of a heating is built-up, and the developed energy harvesting system is attached. To build-up this system, a model-based development process is used. The setup of the developed energy harvesting system is very flexible to test different variants and an optimized system can be found in order to increase the energy yield for concrete application examples. A corresponding simulation model is also presented, based on previously developed libraries in Modelica®/Dymola®. In the end, it can be shown—with measurement and simulation results—that a thermoelectric energy harvesting system on the exhaust pipe of a heating system delivers extra energy and thus delivers a contribution for a more efficient usage of the inserted primary energy carrier. Full article
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