Transient Needle Probe Technique for In-Pile Thermal Conductivity Measurements

2019 ◽  
Author(s):  
K. Davis ◽  
D. Estrada ◽  
A. Fleming ◽  
C. Hollar ◽  
C. Jensen
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurements ◽  
Probe Technique ◽  
Needle Probe

scholarly journals Thermal conductivity of snow measured by three independent methods and anisotropy considerations

2013 ◽  
Vol 7 (1) ◽  
pp. 217-227 ◽  
Author(s):  
F. Riche ◽  
M. Schneebeli
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Heat Flux ◽  
Direct Numerical Simulation ◽  
Heating Time ◽  
Conductivity Measurements ◽  
Needle Probe ◽  
The Difference ◽  
Steady State Heat ◽  
Snow Samples

Abstract. The thermal conductivity of snow determines the temperature gradient, and by this, it has a direct effect on the rate of snow metamorphism. It is therefore a key property of snow. However, thermal conductivities measured with the transient needle probe and the steady-state, heat flux plate differ. In addition, the anisotropy of thermal conductivity plays an important role in the accuracy of thermal conductivity measurements. In this study, we investigated three independent methods to measure snow thermal conductivity and its anisotropy: a needle probe with a long heating time, a guarded heat flux plate, and direct numerical simulation at the microstructural level of the pore and ice structure. The three methods were applied to identical snow samples. We analyzed the consistency and the difference between these methods. As already shown in former studies, we observed a distinct difference between the anisotropy of thermal conductivity in small rounded grains and in depth hoar. Indeed, the anisotropy between vertical and horizontal thermal conductivity components ranges between 0.5–2. This can cause a difference in thermal conductivity measurements carried out with needle probes of up to –25 % to +25 % if the thermal conductivity is calculated only from a horizontally inserted needle probe. Based on our measurements and the comparison of the three methods studied here, the direct numerical simulation is the most reliable method, as the tensorial components of the thermal conductivity can be calculated and the corresponding microstructure is precisely known.

Thermal-conductivity measurements of GaAs/AlAs superlattices using a picosecond optical pump-and-probe technique

1999 ◽  
Vol 59 (12) ◽  
pp. 8105-8113 ◽  
Author(s):  
W. S. Capinski ◽  
H. J. Maris ◽  
T. Ruf ◽  
M. Cardona ◽  
K. Ploog ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurements ◽  
Optical Pump ◽  
Probe Technique ◽  
Pump And Probe

scholarly journals Thermal Conductivity Measurements of Float Glass at High Temperatures by Needle Probe method.

2000 ◽  
Vol 108 (1256) ◽  
pp. 381-386 ◽  
Author(s):  
Hiroshi KIYOHASHI ◽  
Naoya HAYAKAWA ◽  
Shin'ichi ARATANI ◽  
Hidetoshi MASUDA
Keyword(s):  
Thermal Conductivity ◽  
High Temperatures ◽  
Float Glass ◽  
Probe Method ◽  
Conductivity Measurements ◽  
Needle Probe

scholarly journals Efficiency of the Needle Probe Test for Evaluation of Thermal Conductivity of Composite Materials: Two-Scale Analysis

2014 ◽  
Vol 36 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Dariusz Łydżba ◽  
Adrian Różański ◽  
Magdalena Rajczakowska ◽  
Damian Stefaniuk
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Numerical Simulations ◽  
Conductivity Measurement ◽  
Scale Analysis ◽  
Equivalent Conductivity ◽  
Inclusion Type ◽  
Two Phase ◽  
Needle Probe ◽  
Probe Test

Abstract The needle probe test, as a thermal conductivity measurement method, has become very popular in recent years. In the present study, the efficiency of this methodology, for the case of composite materials, is investigated based on the numerical simulations. The material under study is a two-phase composite with periodic microstructure of “matrix-inclusion” type. Two-scale analysis, incorporating micromechanics approach, is performed. First, the effective thermal conductivity of the composite considered is found by the solution of the appropriate boundary value problem stated for the single unit cell. Next, numerical simulations of the needle probe test are carried out. In this case, two different locations of the measuring sensor are considered. It is shown that the “equivalent” conductivity, derived from the probe test, is strongly affected by the location of the sensor. Moreover, comparing the results obtained for different scales, one can notice that the “equivalent” conductivity cannot be interpreted as the effective one for the composites considered. Hence, a crude approximation of the effective property is proposed based on the volume fractions of constituents and the equivalent conductivities derived from different sensor locations.

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