scholarly journals High-Efficiency Skutterudite Modules at a Low Temperature Gradient

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4292 ◽  
Author(s):  
Wenjie Li ◽  
David Stokes ◽  
Bed Poudel ◽  
Udara Saparamadu ◽  
Amin Nozariasbmarz ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Conversion Efficiency ◽  
High Efficiency ◽  
Elevated Temperatures ◽  
Waste Heat ◽  
Thermal Interface Material ◽  
Module Design ◽  
Molybdenum Electrode

Thermoelectric skutterudite materials have been widely investigated for their potential application in mid-temperature waste heat recovery that has not been efficiently utilized A large amount of research has focused on developing materials with a high thermoelectric figure of merit (zT). However, the translation of material properties to device performance has limited success. Here, we demonstrate single-filling n-type Yb0.25Fe0.25Co3.75Sb12 and multi-filling La0.7Ti0.1Ga0.1Fe2.7Co1.3Sb12 skutterudites with a maximum zT of ~1.3 at 740 K and ~0.97 at 760 K. The peak zT of skutterudites usually occurs above 800 K, but, as shown here, the shift in peak zT to lower temperatures is beneficial for enhancing conversion efficiency at a lower hot-side temperature. In this work, we have demonstrated that the Fe-substitution significantly reduces the thermal conductivity of n-type skutterudite, closer to p-type skutterudite thermal conductivity, resulting in a module that is more compatible to operate at elevated temperatures. A uni-couple skutterudite module was fabricated using a molybdenum electrode and Ga–Sn liquid metal as the thermal interface material. A conversion efficiency of 7.27% at a low temperature gradient of 366 K was achieved, which is among the highest efficiencies reported in the literature at this temperature gradient. These results highlight that peak zT shift and optimized module design can improve conversion efficiency of thermoelectric modules at a low temperature gradient.

Sticky thermoelectric materials for flexible thermoelectric modules to capture low-temperature waste heat

MRS Advances ◽  
2020 ◽  
Vol 5 (10) ◽  
pp. 481-487 ◽  
Author(s):  
Norifusa Satoh ◽  
Masaji Otsuka ◽  
Yasuaki Sakurai ◽  
Takeshi Asami ◽  
Yoshitsugu Goto ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Waste Heat ◽  
Air Cooling ◽  
Conductive Adhesives ◽  
Hot Plate ◽  
Low Thermal Conductivity ◽  
Te Modules ◽  
P Type ◽  
Flexible Thermoelectric

ABSTRACTWe examined a working hypothesis of sticky thermoelectric (TE) materials, which is inversely designed to mass-produce flexible TE sheets with lamination or roll-to-roll processes without electric conductive adhesives. Herein, we prepared p-type and n-type sticky TE materials via mixing antimony and bismuth powders with low-volatilizable organic solvents to achieve a low thermal conductivity. Since the sticky TE materials are additionally injected into punched polymer sheets to contact with the upper and bottom electrodes in the fabrication process, the sticky TE modules of ca. 2.4 mm in thickness maintained temperature differences of ca. 10°C and 40°C on a hot plate of 40 °C and 120°C under a natural-air cooling condition with a fin. In the single-cell resistance analysis, we found that 75∼150-µm bismuth powder shows lower resistance than the smaller-sized one due to the fewer number of particle-particle interfaces in the electric pass between the upper and bottom electrodes. After adjusting the printed wiring pattern for the upper and bottom electrodes, we achieved 42 mV on a hot plate (120°C) with the 6 x 6 module having 212 Ω in the total resistance. In addition to the possibility of mass production at a reasonable cost, the sticky TE materials provide a low thermal conductivity for flexible TE modules to capture low-temperature waste heat under natural-air cooling conditions with fins for the purpose of energy harvesting.

scholarly journals Shape memory alloy engine for high efficiency low-temperature gradient thermal to electrical conversion

2019 ◽  
Vol 251 ◽  
pp. 113277 ◽  
Author(s):  
Prashant Kumar ◽  
Ravi Anant Kishore ◽  
Deepam Maurya ◽  
Colin J. Stewart ◽  
Reza Mirzaeifar ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Gradient ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Efficiency

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.

Heat Transport in Superlattices and Nanocomposites for Thermoelectric Applications

2006 ◽  
Vol 46 ◽  
pp. 104-110 ◽  
Author(s):  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Large Scale ◽  
Energy Transport ◽  
High Efficiency ◽  
Waste Heat ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure

Energy transport in nanostructures differs significantly from macrostructures because of classical and quantum size effects on energy carriers. Experimental results show that the thermal conductivity values of nanostructures such as superlattices are significantly lower than that of their bulk constituent materials. The reduction in thermal conductivity led to a large increase in the thermoelectric figure of merit in several superlattice systems. Materials with a large thermoelectric figure of merit can be used to develop efficient solid-state devices that convert waste heat into electricity. Superlattices grown by thin-film deposition techniques, however, are not suitable for large scale applications. Nanocomposites represent one approach that can lead to high thermoelectric figure merit. This paper reviews the current understanding of thermal conductivity reduction mechanisms in superlattices and presents theoretical studies on thermoelectric properties in semiconducting nanocomposites, aiming at developing high efficiency thermoelectric energy conversion materials.

scholarly journals Effect of Different Operating Conditions on Performance of Commercial Low-Temperature Thermoelectric Modules

2019 ◽  
Vol 9 (2) ◽  
pp. 1781-1791
Keyword(s):  
Low Temperature ◽  
Conversion Efficiency ◽  
Power Output ◽  
Waste Heat ◽  
Thermoelectric Module ◽  
Operating Conditions ◽  
Maximum Power ◽  
Thermoelectric Modules ◽  
Temperature Range ◽  
Maximum Power Output

In the field of waste heat recovery, thermoelectric generators (TEG) are used to convert waste heat to electric power. This system attracts the attention of researchers to make it more and more efficient. The performance of thermoelectric module (TEM) plays a crucial role for thermoelectric system. Appropriate selection of thermoelectric module is one of the important criteria for enhancing the power output and conversion efficiency of thermoelectric generator. In this work, the effect of various operating conditions on performance of thermoelectric modules was experimentally investigated. Three commercial bismuth telluride (Bi2Te3 ) thermoelectric modules (TEM1, TEM2, and TEM3) were experimentally tested to find the best performance module for low-temperature waste heat. The open-circuit voltage, power output, and conversion efficiency were measured at various operating conditions. Different operating parameters such as water mass flow rate, heater voltage, hot and cold side temperature of thermoelectric module, and external load resistance were considered for this work. An electric heater was used as a heat source and water used as a cooling fluid at heat sink side. It was observed that the TEM1 shows maximum power output of 0.31, 0.71 and 1.25W, for temperature ranges of 80-100, 100-150, and 150-200 oC respectively. TEM3 achieved maximum power output 0.81W for temperature range of 100-150 oC. TEM1, TEM2 and TEM3 have the maximum conversion efficiency of 1.37, 0.60, and 1.64 % respectively. The TEM2 having less power output and conversion efficiency for temperature range of 80-200 oC compare to TEM1 and TEM3. However, the TEM1 is more appropriate for temperature range of 80-200 oC and the TEM3 is also suitable for the temperature range of 80-150 oC.

scholarly journals The influence of pressure on the thermal conductivity of liquid He ll

1939 ◽  
Vol 171 (945) ◽  
pp. 242-250 ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Heat Flow ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Standard Method ◽  
The Other ◽  
Surface Films ◽  
Very High

The unusual characteristics of heat transfer in liquid He II have been reported in several recent papers. The very high thermal conductivity of the low-temperature modification of liquid helium was first noted by Keesom and Keesom (1935). It was then found by Allen, Peierls and Uddin (1937) and subsequently verified by Keesom, Keesom and Saris (1938) that the rate of transfer of heat varied with the temperature gradient. The discovery of the momentum transfer accompanying heat flow in He II which was made by Allen and Jones (1938) and the work on mobile surface films of the liquid done by Daunt and Mendelssohn (1938) show that a large part of the heat must be carried by some form of mass transfer. Several ideas and theories to explain the phenomena have been put forward by Kapitza (1938), Jones (1938), Michels, Bijl and de Boer (1938), Tisza (1938) and Keesom and Taconis (1938). The experimental evidence is as yet too meagre to prove or disprove any of the theories. It was with the intention of adding to the data already known concerning the properties of liquid He II that the present research was undertaken. The apparatus which was used is shown in fig. 1. The thermal conductivity was measured by a standard method. A constant supply of heat was supplied to one end of a long capillary containing liquid He II, and the other end was maintained at the constant temperature of the He II bath. Temperatures were observed at two points along the capillary.

scholarly journals Thermodynamic Performance of Adsorption Working Pairs for Low-Temperature Waste Heat Upgrading in Industrial Applications

2021 ◽  
Vol 11 (8) ◽  
pp. 3389
Author(s):  
Andrea Frazzica ◽  
Valeria Palomba ◽  
Belal Dawoud
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Heat Source ◽  
Specific Energy ◽  
Heat Recovery ◽  
Waste Heat ◽  
Internal Heat ◽  
Operating Cycle ◽  
Adsorbent Materials

The present work aims at the thermodynamic analysis of different working pairs in adsorption heat transformers (AdHT) for low-temperature waste heat upgrade in industrial processes. Two different AdHT configurations have been simulated, namely with and without heat recovery between the adsorbent beds. Ten working pairs, employing different adsorbent materials and four different refrigerants, have been compared at varying working boundary conditions. The effects of heat recovery and the presence of a temperature gradient for heat transfer between sinks/sources and the AdHT components have been analyzed. The achieved results demonstrate the possibility of increasing the overall performance when internal heat recovery is implemented. They also highlight the relevant role played by the existing temperature gradient between heat transfer fluids and components, that strongly affect the real operating cycle of the AdHT and thus its expected performance. Both extremely low, i.e., 40–50 °C, and low (i.e., 80 °C) waste heat source temperatures were investigated at variable ambient temperatures, evaluating the achievable COP and specific energy. The main results demonstrate that optimal performance can be achieved when 40–50 K of temperature difference between waste heat source and ambient temperature are guaranteed. Furthermore, composite sorbents demonstrated to be the most promising adsorbent materials for this application, given their high sorption capacity compared to pure adsorbents, which is reflected in much higher achievable specific energy.

Research on Waste Heat Recovery and Utilization of Hydrogen Production Industry Based on Heat Pipe Heat Exchanger Technology

2014 ◽  
Vol 1033-1034 ◽  
pp. 1362-1365
Author(s):  
Guang Wu ◽  
Jia Hui Song ◽  
Jun Feng Chen ◽  
Chao Qun Deng
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Hydrogen Production ◽  
Heat Pipe ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Technology Improvement ◽  
Pipe Heat

For the low temperature waste heat recovery problem, waste heat recycling system was designed based on the heat pipe heat transfer technology of hydrogen in industry. The system is mainly in the process of hydrogen production by methanol steam reforming, using heat pipe excellent thermal conductivity, isothermal and thermal response characteristics, it will be in the low temperature waste heat of flue gas as heat source, in the heat pipe under the action of high efficiency heat transfer, through technology improvement, structure optimization design, achieved high efficiency, energy saved heat transfer to the methanol in the reaction system of hydrogen production, achieved the goal of remaining heat to be recycled.

scholarly journals Organic Rankine-Cycle Turbine Power Plant Utilizing Low Temperature Heat Sources

1980 ◽  
Author(s):  
V. Maizza
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
High Efficiency ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heat Sources ◽  
Operational Parameters ◽  
Working Fluids ◽  
Waste Energy

Utilizing and converting of existing low temperature and waste heat sources by the use of a high efficiency bottoming cycle is attractive and should be possible for many locations. This paper presents a theoretical study on possible combination of an organic Rankine-cycle turbine power plant with the heat pump supplied by waste energy sources. Energy requirements and system performances are analyzed using realistic design operating condition for a middle town. Some conversion systems employing working fluids other than water are being studied for the purpose of proposed application. Thermodynamic efficiencies, with respect to available resource, have been calculated by varying some system operating parameters at various reference temperature. With reference to proposed application equations and graphs are presented which interrelate the turbine operational parameters for some possible working fluids with computation results.

Properties and Performance of Quantum Well Thermoelectric Materials

2010 ◽  
Author(s):  
Velimir Jovanovic ◽  
Saeid Ghamaty ◽  
Norbert B. Elsner ◽  
Daniel Krommenhoek
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Quantum Wells ◽  
Air Conditioning ◽  
High Efficiency ◽  
Waste Heat ◽  
Test Technique ◽  
And Performance ◽  
Te Modules ◽  
Conversion Efficiencies

New and more efficient thermoelectric (TE) materials that make use of nanotechnology have been developed. These new materials, called quantum wells (QW), are composed of alternating layers of 10 nm thick silicon and SiGe films. They can be deposited by various techniques and magnetron sputtering was used to obtain uniform layered structures that exhibited no degradation of the TE properties or microstructure after thermal aging. For QW thin films, the heat and current flow are “in plane” and in this orientation all of the thermoelectric properties (the Seebeck coefficient, electrical resistivty, and the thermal conductivity) are improved to increase the TE Figure of Merit, ZT (see equation 3, p. 4, for the definition of Z). From the most recent QW test data, ZTs greater than 3 at room temperature have been obtained which constitutes a significant improvement over the state-of-the-art (SOTA) bulk thermoelectrics which have ZTs less than 1. QW materials have the best measured TE power factor (Seebeck coefficient squared divided by electrical resistivity) and, combined with low thermal conductivity substrates, should provide very high efficiency TE modules. The QW TE materials with ZTs greater than 3 lead to conversion efficiencies greater than 20 percent, which allows for much wider commercial applications, particularly in the applications such as the waste-heat recovery from truck engines, refrigeration, and air conditioning, where the SOTA bulk TE modules were shown to be technically feasible but economically unjustified due to low conversion efficiencies. With higher efficiency QW materials, these applications become economically attractive. For the refrigeration and air conditioning applications, the QW TE materials are predicted to have higher coefficients of performance (COP) than the SOTA vapor compression systems, with the additional advantages of having no compressors, no moving parts, no refrigerants, no vibrations, no noise, and practically no maintenance. With such significant advantages, it is very important to have independent confirmation of the QW TE properties that lead to such improved performance. Three independent researchers have confirmed the previously measured QW TE properties using conventional test techniques, and a totally new test technique was developed to measure the TE properties and performance and the results provided yet another confirmation of the superior TE performance of the QW materials versus the SOTA bulk thermoelectrics. The temperature range for the applications is anticipated to be as low as −150C to the upper temperature of 1000C, with the power generation capacity ranging from milliwatts to kilowatts and cooling capacity ranging from watts to several tons of refrigeration.

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