Enhancement of high temperature thermoelectric performance of cobaltite based materials for automotive exhaust thermoelectric generators

2021 ◽  
Author(s):  
FATMA BAYATA
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Heat Recovery ◽  
Waste Heat ◽  
Sol Gel ◽  
Thermoelectric Performance ◽  
Thermoelectric Generators ◽  
Potential Candidate ◽  
Automotive Exhaust ◽  
Co Doped

Abstract Thermoelectric (TE) generators can directly convert exhaust waste heat into electricity in vehicles. However, the low conversion efficiency of TE generators is the main obstacle to their commercialization in automotive. Their efficiency mainly depends on the performance of the used materials which is quantified by the figure of merit (ZT value). In the present study, single- and co-doped calcium cobaltites(CCO) with rare-earth (Tb) and transition metals (Cu, Fe, Ni, Mn, Cr) were produced using sol-gel technique in order to improve their high temperature thermoelectric properties for heat recovery in exhaust manifold applications. By the combined effect of doping approach and the production technique used in this study, a remarkable decrease in the grain size of CCO was obtained, and thus its thermal conductivity dramatically decreased. Besides, thermopower values were improved significantly. The reduction in thermal conductivity and the increase in thermopower led to an enhancement in ZT value of CCO ceramics. Among all the co-doped samples, Tb-Cu co-doped CCO displayed the maximum ZT value of 0.116 at 873 K which is 2.5 times larger than that of pure CCO. The high thermal stability and the enhanced thermoelectric performance make Tb-Cu co-doped CCO material a potential candidate for heat recovery in automotive exhaust thermoelectric generators.

High efficiency GeTe-based materials and modules for thermoelectric power generation

2021 ◽  
Author(s):  
Tong Xing ◽  
Qingfeng Song ◽  
Pengfei Qiu ◽  
Qihao Zhang ◽  
Ming Gu ◽  
...  
Keyword(s):  
Power Generation ◽  
Thermoelectric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Thermoelectric Performance ◽  
Thermoelectric Generators ◽  
Thermoelectric Power Generation

GeTe-based materials have a great potential to be used in thermoelectric generators for waste heat recovery due to their excellent thermoelectric performance, but their module research is greatly lagging behind...

scholarly journals Numerical simulation of segmented ratio in bismuth telluride and skutterudites for waste heat recovery

2021 ◽  
Vol 2120 (1) ◽  
pp. 012007
Author(s):  
K W Cheong ◽  
J H Lim
Keyword(s):  
Output Power ◽  
Bismuth Telluride ◽  
Heat Recovery ◽  
Output Voltage ◽  
Waste Heat Recovery ◽  
Thermoelectric Generator ◽  
Waste Heat ◽  
Thermoelectric Performance ◽  
Length Ratio ◽  
Thermoelectric Generators

Abstract The thermoelectric performance of the segmented annular thermoelectric generators with the bismuth telluride and skutterudites has been investigated. The effect of the length ratio of the hot-segment leg to total length leg on the thermoelectric performance of the segmented annular thermoelectric generators is analysed and discussed and the optimization design of the annular thermoelectric generator with bismuth telluride and skutterudites as the materials with high thermoelectric performance is obtained. The result of the thermoelectric performance with the manipulated variable of the increase of length ratio, the output power, output voltage and efficiency of the segmented annular thermoelectric generators increase at the beginning then decrease afterwards. Additionally, to compare with the single bismuth telluride and skutterudites annular thermoelectric generators, the output voltage, output power and the conversion efficiency of the segmented annular thermoelectric generators can be improved twice. Lastly, the thermoelectric performance of the segmented annular thermoelectric generators operating in the changes of the temperature. The result has proved that as the temperature increase, the thermoelectric performance of the annular thermoelectric generator will also increase. Hence, the acquired results may be given some useful applications of the bismuth telluride and skutterudites on the segmented annular thermoelectric generators for waste heat recovery.

scholarly journals Approximate models for the lattice thermal conductivity of alloy thermoelectrics

2021 ◽  
Author(s):  
Jonathan Skelton
Keyword(s):  
Thermal Conductivity ◽  
Energy Efficiency ◽  
Lattice Thermal Conductivity ◽  
Waste Heat ◽  
Seebeck Effect ◽  
Thermoelectric Generators ◽  
Approximate Models

Thermoelectric generators (TEGs) convert waste heat to electricity and are a leading contender for improving energy efficiency at a range of scales. Ideal TE materials show a large Seebeck effect,...

scholarly journals High thermoelectric performance enabled by convergence of nested conduction bands in Pb7Bi4Se13 with low thermal conductivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lei Hu ◽  
Yue-Wen Fang ◽  
Feiyu Qin ◽  
Xun Cao ◽  
Xiaoxu Zhao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Waste Heat ◽  
Low Frequency ◽  
Thermoelectric Performance ◽  
Environmental Crisis ◽  
Quality Factors ◽  
Thermoelectric Efficiency ◽  
Low Thermal Conductivity ◽  
Conduction Bands ◽  
Thermoelectric Energy

AbstractThermoelectrics enable waste heat recovery, holding promises in relieving energy and environmental crisis. Lillianite materials have been long-term ignored due to low thermoelectric efficiency. Herein we report the discovery of superior thermoelectric performance in Pb7Bi4Se13 based lillianites, with a peak figure of merit, zT of 1.35 at 800 K and a high average zT of 0.92 (450–800 K). A unique quality factor is established to predict and evaluate thermoelectric performances. It considers both band nonparabolicity and band gaps, commonly negligible in conventional quality factors. Such appealing performance is attributed to the convergence of effectively nested conduction bands, providing a high number of valley degeneracy, and a low thermal conductivity, stemming from large lattice anharmonicity, low-frequency localized Einstein modes and the coexistence of high-density moiré fringes and nanoscale defects. This work rekindles the vision that Pb7Bi4Se13 based lillianites are promising candidates for highly efficient thermoelectric energy conversion.

High-Temperature PbTe Thin Films for Use in Cascade Thermoelectric Power Generation

2003 ◽  
Vol 793 ◽  
Author(s):  
J.B. Posthill ◽  
J.C. Caylor ◽  
P.D. Crocco ◽  
T.S. Colpitts ◽  
R. Venkatasubramanian
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Power Generation ◽  
High Temperature ◽  
Ambient Temperature ◽  
Thermoelectric Power ◽  
Thermal Evaporation ◽  
Potential Candidate ◽  
Substrate Orientation ◽  
Subtle Effect

ABSTRACTPbTe-based thin films were deposited by thermal evaporation at temperatures ranging from ambient temperature to 430°C on different vicinal GaAs (100) substrates and BaF2 (111). This materials system is being evaluated as a potential candidate thermoelectric material for a mid-temperature stage in a cascade power generation module. Pure PbTe, PbSe, and multilayer PbTe/PbSe films were investigated. All films deposited on different vicinal GaAs (100) substrates were found to be polycrystalline when deposited at 250°C or lower. A subtle effect of substrate orientation and multilayer periodicity appears to contribute to the more randomly oriented polycrystallinity, which also lowers the thermal conductivity. These results are compared with PbTe epitaxial results on BaF2 (111).

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