Measurement of thermal conductivity with the needle probe

2003 ◽  
Vol 35/36 (2) ◽  
pp. 127-138 ◽  
Author(s):  
Neil Lockmuller ◽  
John Redgrove ◽  
L'udovít Kubičár
Keyword(s):  
Thermal Conductivity ◽  
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.

Needle Probe for Measuring Thermal Conductivity of Molten Salts

2020 ◽  
Author(s):  
B. Merritt ◽  
K. Davisy ◽  
M. Wilkerson ◽  
T. Munro ◽  
P. Hartvigsen
Keyword(s):  
Thermal Conductivity ◽  
Molten Salts ◽  
Needle Probe

Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

2006 ◽  
Vol 77 (4) ◽  
pp. 044904 ◽  
Author(s):  
William F. Waite ◽  
Lauren Y. Gilbert ◽  
William J. Winters ◽  
David H. Mason
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Conductivity Data ◽  
Thermal Conductivity Data ◽  
Needle Probe

scholarly journals Evaluation of the influence of the degree of saturation, measuring time and use of a conductive paste on the determination of thermal conductivity of normal and lightweight concrete using the hot-wire method

2021 ◽  
Vol 71 (344) ◽  
pp. e260
Author(s):  
D. Revuelta ◽  
J.L. García-Calvo ◽  
P. Carballosa ◽  
F. Pedrosa
Keyword(s):  
Thermal Conductivity ◽  
Lightweight Concrete ◽  
Probe Method ◽  
Degree Of Saturation ◽  
Hot Wire ◽  
Measuring Time ◽  
Needle Probe ◽  
Cement Based Materials ◽  
Wire Method

The determination of thermal conductivity of cement-based materials is relevant from the perspective of buildings’ energy efficiency. The absence of unified tests for its measurement in mortars and concrete results in a heterogeneity of the data available in the literature. This work’s purpose is to determine the relevant influence from a a statistical viewpoint that three factors; degree of saturation, measuring time and use of a conductive paste, have in the measurement of the conductivity using the hot-wire needle probe method in two concretes with different thermal behavior: standard-weight concrete and lightweight concrete. The results obtained allow for the establishment of recommendations for future researchers on the minimum information to be included in their reports of thermal conductivity of cement-based materials by the needle probe method, the need to treat outliers, the most favorable saturation conditions and measuring times, as well as the possible benefits of using conductive pastes.

scholarly journals Measurements of Thermal Parameters in Antarctic Snow and Firn

1985 ◽  
Vol 6 ◽  
pp. 100-104 ◽  
Author(s):  
Manfred A. Lance
Keyword(s):  
Thermal Conductivity ◽  
Strong Dependence ◽  
Grain Structure ◽  
Ice Shelf ◽  
Governing Parameter ◽  
Needle Probe ◽  
Antarctic Snow ◽  
Data Yield ◽  
Image Position ◽  
Thermal Conductivities

Values Of Effective thermal conductivities of snow and firn were obtained at Filchner Ice Shelf (Antarctica). We employed a transient line source method (a needle probe with a diameter of 1.6 mm) for conductivity determination, which allows quick measurements with high spatial resolution. Our data yield a linear relationship between effective thermal conductivity (lg keff) and density (p) of snowwhich implies a strong dependence of thermal conductivity on density for 0.24≤p≤0.42, Comparison of thermal conductivities and other snow pit data suggests that density alone is a poor measure of effective thermal conductivities of snow and firn. We propose that grain structure is probably the governing parameter in determining heat transport in the upper firn layers.

Sign in / Sign up

Export Citation Format

Share Document