scholarly journals Thermoelectric Efficiency of Silicon–Germanium Alloys in Finite-Time Thermodynamics

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1116 ◽  
Author(s):  
Patrizia Rogolino ◽  
Vito Antonio Cimmelli
Keyword(s):  
Thermal Conductivity ◽  
Finite Time ◽  
Silicon Germanium ◽  
Finite Time Thermodynamics ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Energy ◽  
Different Temperatures ◽  
Nonlinear Regression Method ◽  
Relationship Of ◽  
The Relationship

We analyze the efficiency in terms of a thermoelectric system of a one-dimensional Silicon–Germanium alloy. The dependency of thermal conductivity on the stoichiometry is pointed out, and the best fit of the experimental data is determined by a nonlinear regression method (NLRM). The thermoelectric efficiency of that system as function of the composition and of the effective temperature gradient is calculated as well. For three different temperatures (T=300 K, T=400 K, T=500 K), we determine the values of composition and thermal conductivity corresponding to the optimal thermoelectric energy conversion. The relationship of our approach with Finite-Time Thermodynamics is pointed out.

Thermal Conductivity of One-Dimensional Silicon-Germanium Alloy Nanowires

2009 ◽  
Author(s):  
Yunki Gwak ◽  
Vinay Narayanunni ◽  
Sang-Won Jee ◽  
Anastassios A. Mavrokefalos ◽  
Michael T. Pettes ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Conversion ◽  
Silicon Germanium ◽  
Figure Of Merit ◽  
Mean Free Path ◽  
Thermoelectric Efficiency ◽  
One Dimensional ◽  
Thermoelectric Energy ◽  
Germanium Alloy ◽  
Alloy Nanowires

Thermal properties of one dimensional nanostructures are of interest for thermoelectric energy conversion. Thermoelectric efficiency is related to non dimensional thermoelectric figure of merit, ZT = (S^2 σT)/k where S, σ, k are the Seebeck coefficient, electrical conductivity and thermal conductivity respectively. These physical properties are interdependent, and hence making ZT of a material high is very challenging work. However, when the size of nanostructure is comparable to the wavelength and mean free path of energy carriers, it is feasible to avoid such interdependence to enhance ZT energy conversion. [1–3]

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.

scholarly journals Optimal temperatures and maximum power output of a complex system with linear phenomenological heat transfer law

2009 ◽  
Vol 13 (4) ◽  
pp. 33-40 ◽  
Author(s):  
Lingen Chen ◽  
Jun Li ◽  
Fengrui Sun
Keyword(s):  
Complex System ◽  
Heat Transfer ◽  
Power Output ◽  
Finite Time ◽  
Heat Engine ◽  
Thermal Capacity ◽  
Maximum Power ◽  
Finite Time Thermodynamics ◽  
Maximum Power Output ◽  
Different Temperatures

A complex system including several heat reservoirs, finite thermal capacity subsystems with different temperatures and a transformer (heat engine or refrigerator) with linear phenomenological heat transfer law [q ? ?(T -1)] is studied by using finite time thermodynamics. The optimal temperatures of the subsystems and the transformer and the maximum power output (or the minimum power needed) of the system are obtained.

NiTi Shape Memory Alloy Wire’s Constitutive Describe at Different Temperatures

2017 ◽  
Vol 729 ◽  
pp. 13-17
Author(s):  
Guang Yong Yang ◽  
Yang Zhong ◽  
Zhi Fei Qiu ◽  
Jun Wang ◽  
Wei Na Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Thermal And Mechanical Properties ◽  
Restoring Force ◽  
Intelligent Material ◽  
Different Temperatures ◽  
Relationship Of ◽  
The Relationship

NiTi shape memory alloy is an intelligent drive and awareness materials which develop very rapidly and is used in many fields in recent years, whose mechanical properties are not only related to chemical composition, but also closely related to the temperature. This article aims to study the NiTi shape memory alloy wire’s constitutive behavior coupled thermal and mechanical properties at different temperatures. By analyzing the results, the relationship of NiTi shape memory alloy between deformation and the restoring force at elevated temperature is obtained, thus providing a basis for the engineering design and simulation process of NiTi intelligent material.

The Relationship of the Main Properties of Desulphurization Gypsum Based Inorganic Thermal Insulation Mortar

2013 ◽  
Vol 357-360 ◽  
pp. 1120-1123
Author(s):  
Yong Lai ◽  
Yan Liu ◽  
Zhi Gang Luo
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Water Absorption ◽  
Bulk Density ◽  
Thermal Insulation ◽  
Relationship Of ◽  
The Relationship ◽  
Linear Correlations

This paper studies the relationship of the main properties of desulphurization gypsum based inorganic thermal insulation mortar. The results show that there are different linear correlations between fresh bulk density, hardened bulk density, compressive strength, volume water absorption, thermal conductivity and dry bulk density that is from 240 kg·m-3 to 500 kg·m-3. The linear correlations can provide some useful reference for the research and application of desulphurization gypsum based inorganic thermal insulation mortar.

Effect of High Temperature Annealing on the Thermoelectric Properties of GaP Doped SiGe

1987 ◽  
Vol 97 ◽  
Author(s):  
Jan W. Vandersande ◽  
Charles Wood ◽  
Susan Draper
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Power Factor ◽  
Silicon Germanium ◽  
Figure Of Merit ◽  
Annealing Temperature ◽  
High Temperature Annealing ◽  
Rich Phase ◽  
Temperature Range ◽  
Thermoelectric Energy

ABSTRACTSilicon-germanium alloys doped with GaP are used for thermoelectric energy conversion in the temperature range 300°C - 1000°C. The conversion efficiency depends on Z - S2/ρΛ, a material's parameter (the figure of merit), where S is the Seebeck coefficient, ρ is the electrical resistivity and Λ is the thermal conductivity. The annealing of several samples in the temperature range of 1100°C - 1300°C resulted in the power factor P (=S2/ρ) increasing with increased annealing temperature. This increase in P was due to a decrease in ρ which was not completely offset by a drop in S2 suggesting that other changes besides that in the carrier concentration took place. SEM and EDX analysis of the samples indicated the formation of a Ca- P-Ge rich phase as a result of the annealing. It is speculated that this phase is associated with the improved properties. Several reasons which could account for the improvement in the Power factor of annealed GaP doped SiGe are given.

The Effective Thermal Conductivity of Porous Polymethacrylimide Foams

2014 ◽  
Vol 609-610 ◽  
pp. 196-200 ◽  
Author(s):  
Peng Yue ◽  
Lin Qiu ◽  
Xing Hua Zheng ◽  
Da Wei Tang
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Formation Mechanism ◽  
3Ω Method ◽  
Temperature Range ◽  
Different Temperatures ◽  
The Relationship

A freestanding sensor-based 3ω method was employed to measure the effective thermal conductivity of porous polymethacrylimide (PMI) foams with different densities at different temperatures. Experimental data showed that within the measuring temperature range, the effective thermal conductivity increased with temperature. Moreover, the formation mechanism of the relationship between the effective thermal conductivity and temperature was analyzed in this paper.

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