A simple method for the absolute measurement of thermal conductivity of drill cuttings

Geophysics ◽  
1986 ◽  
Vol 51 (8) ◽  
pp. 1580-1584 ◽  
Author(s):  
Tien‐Chang Lee ◽  
Thomas L. Henyey ◽  
Brian N. Damiata
Keyword(s):  
Thermal Conductivity ◽  
Thermal Contact ◽  
Absolute Measurement ◽  
Element Model ◽  
Simple Method ◽  
Drill Cuttings ◽  
Good Thermal Contact ◽  
Needle Probe ◽  
Radial Heat ◽  
Electric Heat

We present a method for absolute measurement of thermal conductivity of drill cuttings. The simplicity of the apparatus makes it suitable for nondestructive use of cuttings and for sample sizes too small to be measured with a needle probe. Because the measurement is absolute, no calibration standards are required. Samples are placed in a Plexiglas cup with a lid containing an electric heat source. The base of the cup is placed in good thermal contact with an aluminum‐block heat sink. Upward and radial heat losses are minimized with styrofoam insulation surrounding the cup. The accuracy of the method was estimated by cross‐measurement of selected samples with a well‐calibrated needle probe. Results indicate that errors in measurement are less than 5 percent for sample conductivities greater than 0.8 W/m ⋅ K if the heat loss through the styrofoam insulation is accounted for. Reproducibility is typically within 3 percent. An axisymmetric finite‐element model which simulates the temperature distribution of the measurement apparatus further demonstrates its viability.

Thermal Properties of Thin Metallic Layer Deposited on Insulators: Effect of the Interface on the Independent Determination of the Thermal Diffusivity and Conductivity of the Layer

2008 ◽  
Author(s):  
Danie`le Fournier ◽  
Jean Paul Roger ◽  
Christian Fretigny
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Thermal Resistance ◽  
Thermal Contact ◽  
Heat Diffusion ◽  
Metallic Layer ◽  
Good Thermal Contact ◽  
Lateral Heat

Lateral heat diffusion thermoreflectance is a very powerful tool for determining directly the thermal diffusivity of layered structures. To do that, experimental data are fitted with the help of a heat diffusion model in which the ratio between the thermal conductivity k and the thermal diffusivity D of each layer is fixed, and the thermal properties of the substrate are known. We have shown in a previous work that it is possible to determine independently the thermal diffusivity and the thermal conductivity of a metallic layer deposited on an insulator, by taking into consideration all the data obtained at different modulation frequencies. Moreover, it is well known that to prevent a lack of adhesion of a gold film deposited on substrates like silica, an intermediate very thin (Cr or Ti) layer is deposited to assure a good thermal contact. We extend our previous work: the asymptotic behaviour determination of the surface temperature wave at large distances from the modulated point heat source for one layer deposited on the substrate to the two layers model. In this case (very thin adhesion coating whose thermal properties and thickness are known), it can be establish that the thermal diffusivity and the thermal conductivity of the top layer can still be determined independently. It is interesting to underline that the calculus can also be extended to the case of a thermal contact resistance which has often to be taken into account between two solids. We call thermal resistance a very thin layer exhibiting a very low thermal conductivity. In this case, the three parameters we have to determine are the thermal conductivity and the thermal diffusivity of the layer and the thermal resistance. We will show that, in this case, the thermal conductivity of the layer is always obtained independently of a bound of the couple thermal resistance – thermal diffusivity, the thermal diffusivity being under bounded and the thermal resistance lower bounded. Experimental results on thin gold layers deposited on silica with and without adhesion layers are presented to illustrate the method. Discussions on the accuracy will also be presented.

Simple Measuring Method of Thermal Conductivity of Silicone Grease and Effect of Carbon Nanomaterials on Its Thermal Conductivity

2007 ◽  
Author(s):  
Toshio Tomimura ◽  
Seiji Nomura ◽  
Masaaki Okuyama
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanomaterials ◽  
Cooling System ◽  
Thermal Contact ◽  
Conductivity Measurement ◽  
Measuring Method ◽  
Heat Fluxes ◽  
Quantitative Relation ◽  
Silicone Grease ◽  
Simple Method

In the electronic equipment like personal computers with high heat fluxes for instance, the thermal contact resistance plays an important role in its cooling system. To attain high cooling performance, some kind of grease is often introduced between a heat source and a heat sink. In the present study, a simple method for thermal conductivity measurement of grease has been proposed and confirmed its validity by using greases with known thermal conductivity. From a series of measurements, the validity of the present measuring method has been confirmed. Further, the effect of the addition of carbon nanomaterials on the thermal conductivity of silicone grease has been investigated, and its quantitative relation has been clarified.

scholarly journals On the use of heated needle probes for measuring snow thermal conductivity

2022 ◽  
pp. 1-15
Author(s):  
Kévin Fourteau ◽  
Pascal Hagenmuller ◽  
Jacques Roulle ◽  
Florent Domine
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulations ◽  
Convenient Method ◽  
Thermal Contact ◽  
Measurement Procedure ◽  
Lookup Table ◽  
Standard Measurement ◽  
The Poor ◽  
Needle Probe ◽  
Set Up

Abstract Heated needle probes provide the most convenient method to measure snow thermal conductivity. Recent studies have suggested that this method underestimates snow thermal conductivity; however the reasons for this discrepancy have not been elucidated. We show that it originates from the fact that, while the theory behind the method assumes that the measurements reach a logarithmic regime, this regime is not reached within the standard measurement procedure. Using the needle probe without this logarithmic regime leads to thermal conductivity underestimations of tens of percents. Moreover, we show that the poor thermal contact between the probe and the snow due to insertion damages results in a further underestimation. Thus, we encourage the use of fixed needle probes, set up before the snow season and buried under snowfalls, rather than hand-inserted probes. Finally, we propose a method to correct the measurements performed with such fixed needle probes buried in snow. This correction is based on a lookup table, derived specifically for the Hukseflux TP02 needle probe model, frequently used in snow studies. Comparison between corrected measurements and independent estimations of snow thermal conductivity obtained with numerical simulations shows an overall improvement of the needle probe values after application of the correction.

High‐Temperature Skin Softening Materials Overcoming the Trade‐Off between Thermal Conductivity and Thermal Contact Resistance

Small ◽  
2021 ◽  
pp. 2102128
Author(s):  
Taehun Kim ◽  
Seongkyun Kim ◽  
Eungchul Kim ◽  
Taesung Kim ◽  
Jungwan Cho ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Trade Off

scholarly journals Microstructure Dependence of Effective Thermal Conductivity of EB-PVD TBCs

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1838
Author(s):  
Shi-Yi Qiu ◽  
Chen-Wu Wu ◽  
Chen-Guang Huang ◽  
Yue Ma ◽  
Hong-Bo Guo
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Stress ◽  
Effective Thermal Conductivity ◽  
Thermal Insulation ◽  
Inclination Angle ◽  
Physical Vapor Deposition ◽  
Thermal Contact ◽  
Mathematic Model ◽  
Columnar Structure ◽  
Structural Parameter

Microstructure dependence of effective thermal conductivity of the coating was investigated to optimize the thermal insulation of columnar structure electron beam physical vapor deposition (EB-PVD coating), considering constraints by mechanical stress. First, a three-dimensional finite element model of multiple columnar structure was established to involve thermal contact resistance across the interfaces between the adjacent columnar structures. Then, the mathematical formula of each structural parameter was derived to demonstrate the numerical outcome and predict the effective thermal conductivity. After that, the heat conduction characteristics of the columnar structured coating was analyzed to reveal the dependence of the effective thermal conductivity of the thermal barrier coatings (TBCs) on its microstructure characteristics, including the column diameter, the thickness of coating, the ratio of the height of fine column to coarse column and the inclination angle of columns. Finally, the influence of each microstructural parameter on the mechanical stress of the TBCs was studied by a mathematic model, and the optimization of the inclination angle was proposed, considering the thermal insulation and mechanical stress of the coating.

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.

Through-Plane Thermal Conductivity of PEMFC Porous Transport Layers

2010 ◽  
Vol 8 (2) ◽  
Author(s):  
Odne S. Burheim ◽  
Jon G. Pharoah ◽  
Hannah Lampert ◽  
Preben J. S. Vie ◽  
Signe Kjelstrup
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Residual Water ◽  
Order Of Magnitude ◽  
Thermal Conductivities

We report the through-plane thermal conductivities of the several widely used carbon porous transport layers (PTLs) and their thermal contact resistance to an aluminum polarization plate. We report these values both for wet and dry samples and at different compaction pressures. We show that depending on the type of PTL and the existence of residual water, the thermal conductivity of the materials varies from 0.15 W K−1 m−1 to 1.6 W K−1 m−1, one order of magnitude. This behavior is the same for the contact resistance varying from 0.8 m2 K W−1 to 11×10−4 m2 K W−1. For dry PTLs, the thermal conductivity decreases with increasing polytetrafluorethylene (PTFE) content and increases with residual water. These effects are explained by the behavior of air, water, and PTFE in between the PTL fibers. It is also found that Toray papers of differing thickness exhibit different thermal conductivities.

Sign in / Sign up

Export Citation Format

Share Document