Seebeck Scanning Microprobe for Thermoelectric FGM

2005 ◽  
Vol 492-493 ◽  
pp. 587-592 ◽  
Author(s):  
D. Platzek ◽  
G. Karpinski ◽  
Cestmir Drasar ◽  
Eckhard Müller
Keyword(s):  
Seebeck Coefficient ◽  
Conversion Efficiency ◽  
Temperature Difference ◽  
Current Flow ◽  
Electrical Potential ◽  
Large Temperature ◽  
Voltage Response ◽  
Temperature Dependent ◽  
Temperature Range ◽  
Additional Option

The FGM principle plays an important role in enhancing the efficiency of thermoelectric devices. While a thermoelectric generator (TEG) is typically operating in a large temperature difference, attractive conversion efficiency of a particular semiconductor is restricted to a small temperature range. Hence, when employing a semiconductor with its highest possible efficiency at the respective temperature in the internal temperature field along a stacked TEG, the overall conversion efficiency of the device may be considerably enhanced. Similarly, the FGM principle can be employed for linearization of thermal sensors. The output voltage (response) of the sensor is proportional to the Seebeck coefficient of the material the sensor is made of. Since the Seebeck coefficient is strongly temperature-dependent, the sensor response is not linear with temperature. However, combining in a stack two or more semiconductors which temperature dependence of the Seebeck coefficient are complementary to each other, results in a sensor with linear response (i.e. its output is proportional to the temperature difference, or heat flux, respectively.) Stacking of several materials to each other or grading a semiconducting sample requires a technique which can scan the Seebeck coefficient profiles S(x) along the stack. Accordingly a Seebeck micro-probe technique has been developed for scanning the surface of a sample monitoring S with a resolution of down to 10 µm within the temperature range from -15°C to 60°C. An additional option of such a device is the scanning of the electrical potential along the stack under current flow [1]. Thus, related experimental data on the local profiles of the electrical conductivity and Seebeck coefficient along the stack (or continuously graded FGM) will be available. The apparatus has been automated so that extended areas may be scanned providing two-dimensional images. Additionally, several samples can be scanned in one automatic run.

Synthesis and characterization of a quaternary copolymer retarder for cementing in a long sealing section with large temperature difference

2020 ◽  
Vol 44 (9) ◽  
pp. 3771-3776
Author(s):  
Zhigang Peng ◽  
Chen Chen ◽  
Qian Feng ◽  
Yong Zheng ◽  
Huan Liu ◽  
...  
Keyword(s):  
Temperature Difference ◽  
Synthesis And Characterization ◽  
Large Temperature ◽  
Temperature Range ◽  
Large Temperature Difference

We synthesized a retarder, which has excellent thickening performance in the temperature range of 90–150 °C.

scholarly journals Relationship between thermoelectric figure of merit and energy conversion efficiency

2015 ◽  
Vol 112 (27) ◽  
pp. 8205-8210 ◽  
Author(s):  
Hee Seok Kim ◽  
Weishu Liu ◽  
Gang Chen ◽  
Ching-Wu Chu ◽  
Zhifeng Ren
Keyword(s):  
Conversion Efficiency ◽  
Temperature Difference ◽  
Figure Of Merit ◽  
Energy Conversion Efficiency ◽  
Maximum Efficiency ◽  
Thermoelectric Device ◽  
Large Temperature ◽  
Thermoelectric Figure ◽  
Dimensionless Figure Of Merit ◽  
Temperature Dependences

The formula for maximum efficiency (ηmax) of heat conversion into electricity by a thermoelectric device in terms of the dimensionless figure of merit (ZT) has been widely used to assess the desirability of thermoelectric materials for devices. Unfortunately, the ηmax values vary greatly depending on how the average ZT values are used, raising questions about the applicability of ZT in the case of a large temperature difference between the hot and cold sides due to the neglect of the temperature dependences of the material properties that affect ZT. To avoid the complex numerical simulation that gives accurate efficiency, we have defined an engineering dimensionless figure of merit (ZT)eng and an engineering power factor (PF)eng as functions of the temperature difference between the cold and hot sides to predict reliably and accurately the practical conversion efficiency and output power, respectively, overcoming the reporting of unrealistic efficiency using average ZT values.

scholarly journals Inter-comparison of IASI and AATSR over an extended period

2015 ◽  
Vol 8 (9) ◽  
pp. 9785-9821
Author(s):  
M. Bali ◽  
J. Mittaz ◽  
E. Maturi ◽  
M. Goldberg
Keyword(s):  
Extended Period ◽  
Large Temperature ◽  
Calibration System ◽  
Temperature Dependent ◽  
Design Specification ◽  
Temperature Range ◽  
Global Space ◽  
Critical Issues ◽  
Highly Correlated ◽  
Stability And Accuracy

Abstract. The launch of ENVISAT in 2002 and the launch of MetTop-A in 2006 put two highly accurate instruments in space to measure Top of Atmosphere (TOA) radiances. These instruments are the AATSR and IASI. While the AATSR, by design is a climate accurate (i.e. accuracy within 0.1 K and stability within 0.05 K dec−1) instrument, the IASI is a hyperspectral instrument that has a stated accuracy of within 0.5 K. This accuracy and stability are used in producing climate CDR's from these instruments and also aids in using these instruments as benchmarks for inter-comparison studies that aim at measuring stability and accuracy of instruments that are concurrently flying with them. The GSICS (Global Space Based Inter-Calibration System) has extensively exploited the IASI by comparing its measurements with Polar as well as Geostationary satellite instruments and measuring the in-orbit stability and accuracy of these instruments. More recent re-calibration efforts, such as the NOAA CDR project that is aimed at recalibrating the AVHRR uses the IASI and the AATSR as references. However to trust the recalibrated radiances it is vital that the in-orbit accuracy of the reference sources is known and critical issues such as scan angle dependence, and temporal variation of the accuracy are fully evaluated across a large temperature range (200–300 K). In order to better understand the accuracy and asses the trustworthiness of these references we present here a comprehensive analysis of the AATSR–IASI bias derived from their collocated pixels, over the period January 2008 through March 2011. Our analysis indicates that generally the AATSR (Nadir View) and IASI can act as good reference instruments and IASI is much more accurate than its design specification. In fact, taking into account a small bias the AATSR–IASI bias is close to the AATSR pre-launch bias implying that IASI can get close to pre-launch levels of accuracy. We also examine temperature dependent bias in the AATSR at low (< 240 K) temperatures which seems to appear after orbit was lowered of the ENVISAT satellite and its inclination control was discontinued. In addition, a very small scan angular dependence of AATSR–IASI bias indicates that the AVHRR has a scan angle dependent bias. We also examine the bias problem with the 12 μm channel of the AATSR in detail. We show that this bias not only has a temperature dependence (it grows up to 0.4 K at low temperatures) but also has a seasonal dependence in the SST (265–300 K) temperature range and is highly correlated to instrument temperature in the cold temperature range. We then discuss a possible method to correct the 11 and the 12 μm bias so as to use the corrected radiances for re-calibration of AVHRR.

Unusually High Seebeck Coefficient Arisen from the Temperature-dependent Carrier Concentration in PbSe-AgSbSe2 Alloys

2021 ◽  
Author(s):  
Xuemei Wang ◽  
Gang Wu ◽  
Jianfeng Cai ◽  
Qiang Zhang ◽  
Junxuan Yang ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Wide Temperature Range ◽  
Induced Voltage ◽  
Temperature Dependent ◽  
Temperature Range ◽  
High Seebeck Coefficient

Seebeck coefficient describes the temperature gradient induced voltage in thermoelectrics. Usually, to obtain a high Seebeck coefficient within a wide temperature range is difficult, as it is limited by the...

Thermoelectric properties of In-filled and Te-doped CoSb3 prepared by high-pressure and high-temperature

2015 ◽  
Vol 29 (19) ◽  
pp. 1550095 ◽  
Author(s):  
Le Deng ◽  
Li Bin Wang ◽  
Jie Ming Qin ◽  
Tao Zheng ◽  
Jing Ni ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Pressure ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Temperature Dependent ◽  
Synthesis Time ◽  
Temperature Range

A novel chemical alloying method of high-pressure and high-temperature (HPHT) has been used for the synthesis of bulk-skutterudite [Formula: see text]. Through HPHT method, the synthesis time has been shortened from a few days to 30[Formula: see text]min. The samples of [Formula: see text] skutterudites were synthesized at 1.8–3.3[Formula: see text]GPa. We have studied the phase, the microstructure, and the temperature-dependent thermoelectric properties. The Seebeck coefficient, electrical conductivity and thermal conductivity were measured in the temperature range of 295–673[Formula: see text]K. As we expected, the thermal conductivity of sample [Formula: see text] decreased with the increase of the synthetic pressure. A maximal ZT of 0.64 was achieved for the [Formula: see text] synthesized at 1.8[Formula: see text]GPa at 673[Formula: see text]K. These results revealed that HPHT method may be helpful for optimizing electrical conductivity and thermal conductivity in a comparatively independent way.

scholarly journals Understanding the Seebeck coefficient of LaNiO3 compound in the temperature range 300-620 K

2021 ◽  
Author(s):  
Arzena Khatun ◽  
Shamim Sk ◽  
Sudhir Kumar Pandey
Keyword(s):  
Seebeck Coefficient ◽  
Transition Metal Oxides ◽  
Structural Parameters ◽  
Combustion Process ◽  
Rhombohedral Structure ◽  
Temperature Dependent ◽  
Solution Combustion ◽  
Temperature Range ◽  
Refinement Method ◽  
Type Character

Abstract Transition metal oxides have been attracted much attention in thermoelectric community from the last few decades. In the present work, we have synthesized LaNiO3 by a simple solution combustion process. To analyze the crystal structure and structural parameters we have used Rietveld refinement method wherein FullProf software is employed. The room temperature x-ray diffraction indicates the rhombohedral structure with space group R 3 c (No. 167). The refined values of lattice parameters are a = b = c = 5.4071 Å. Temperature dependent Seebeck coefficient (S) of this compound has been investigated by using experimental and computational tools. The measurement of S is conducted in the temperature range 300-620 K. The measured values of S in the entire temperature range have negative sign that indicates n-type character of the compound. The value of S is found to be ∼ -8 µV/K at 300 K and at 620 K this value is ∼ -12 µV/K. The electronic structure calculation is carried out using DFT+U method due to having strong correlation in LaNiO3. The calculation predicts the metallic ground state of the compound. Temperature dependent S is calculated using BoltzTraP package and compared with experiment. The best matching between experimental and calculated values of S is observed when self-interaction correction is employed as double counting correction in spin-polarized DFT + U (= 1 eV) calculation. Based on the computational results maximum power factors are also calculated for p-type and n-type doping of this compound.

scholarly journals A one-dimensional spot welding model

2006 ◽  
Vol 2006 ◽  
pp. 1-24 ◽  
Author(s):  
K. T. Andrews ◽  
L. Guessous ◽  
S. Nassar ◽  
S. V. Putta ◽  
M. Shillor
Keyword(s):  
Thermal Conductivity ◽  
Spot Welding ◽  
Electrical Potential ◽  
Dissimilar Materials ◽  
Electrical Heating ◽  
Large Temperature ◽  
Dimensional Model ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Welding Processes

A one-dimensional model is proposed for the simulations of resistance spot welding, which is a common industrial method used to join metallic plates by electrical heating. The model consists of the Stefan problem, in enthalpy form, coupled with the equation of charge conservation for the electrical potential. The temperature dependence of the density, thermal conductivity, specific heat, and electrical conductivity are taken into account, since the process generally involves a large temperature range, on the order of 1000 K. The model is general enough to allow for the welding of plates of different thicknesses or dissimilar materials and to account for variations in the Joule heating through the material thickness due to the dependence of electrical resistivity on the temperature. A novel feature in the model is the inclusion of the effects of interface resistance between the plates which is also assumed to be temperature dependent. In addition to constructing the model, a finite difference scheme for its numerical approximations is described, and representative computer simulations are depicted. These describe welding processes involving different interface resistances, different thicknesses, different materials, and different voltage forms. The differences in the process due to AC or DC currents are depicted as well.

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