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A simple way of calculating the thermal conductivity coefficient k is picking temperatures T1 and T2 at times t1 and t2, respectively, from the temperature vs. times measurement curve:
ka(t) = q/4p4π[ln(t2) – ln(t1)]/(T2 – T1).
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All probes consist of a source (i.e., a metal needle with an embedded heating wire and a temperature sensor), a handle or body (depending on the probe type), and a connection cable.
Full-space probes (VLQ) are needle probes equipped with a handle at one end of the source. They are completely inserted into the sample.
Half-space probes (HLQ), or "Pucks", are placed on top of the sample. The source is embedded into the bottom side of a puck-like probe body and has on-site contact with the material/sample.
Name | Standard VLQ | Standard HLQ | Mini HLQ |
|---|---|---|---|
Probe type: | Full-space | Half-space | Half-space |
Dimension (source, mm): | L: 70 × diameter (D): 2 | L: 70 × D: 2 | L: 45 × D: 1.5 |
Dimension (handle/body, mm): | L: 90 × D: 16 | L: 30 × D: 88 | L: 30 × D: 50 |
Evaluation parameter set: | Standard VLQ (VLQ Source 70x2) | Standard HLQ (HLQ D88 Source 70x2) | Mini HLQ (HLQ D50 Source 45x1.5) |
Measuring range (W/m·K): | 0.1–10 | 0.3–10 | 0.3–3 |
Accuracy (%): | ±2 | ±2 | ±5 |
Duration of 1 measurement (s): | 80 | 80 | 60 |
Min. sample size (mm): | L: 75 × D: 30 | L: 15 × D: 80 | L: ~15 × D: 50 |
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Analytical process
The approximate amount of time needed per sample is as follows:
Process | Time (min) | Comments |
|---|---|---|
1. Obtain a whole-round core section from the core rack | 0.3 | See Preparing Sections & Samples |
2. Locate the appropriate probe for the sample type | 0.5 | |
3. Verify sample identification in software | 0.5 | See Set Measurement Parameters |
4. Configure measurement program | 0.3 | |
5. Perform drift control | 5 | See Making a Measurement |
6. Heat and measure sample | 2 | |
7. 10 minute pause between measurements | 10 | |
8. Repeat steps 5-7 for 2 additional measurements (3 total) | 34 | |
9. Upload results to LIMS | 0.2 | See Uploading Data to LIMS |
10. Check results in LIMS | 1 | |
11. Remove the section and deliver to splitting room | 0.2 | |
Total Time per sample: | 54 (max) |
II. Procedures
A. Preparing the Instrument
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- Prior to initial testing of received cores at a site, the TK04 system should be tested and calibrated to ensure that there are no potential mechanical or software issues. Additional tests using the Standards should be run as part of the troubleshooting process if you experience issues during actual testing (See Troubleshooting).
The Macor Standard for the Standard VLQ consists of its black holding shell, while the Macor Standard for both the Standard HLQ and Mini HLQ is a white disc. Calibration tests for any of the available probe types should provide results of TC=1.626-1.637±2%. The Macor standard drift calculations are based on a Macor standard (1.637 ± 0.033 W/mK) because its properties are closest to basalt cores (See Appendix: TK04 Recommended Heating Power for information).
Standard VLQ- MACOR Standard
Standard MACOR Disc
Probe Test TC Value Expected Results:
TC= 1.626±2% W/mKProbe Test TC Value Expected Results:
TC= 1.637±2% W/mKTo conduct a probe test, scan the STND MACOR disc TCON (H) label kept above the testing apparatus and ensure that the appropriate heating time and drift control (DCL) settings are input under the Configuration settings (See Configuring the Measurement Program).
Example 1: A Standard HLQ properly positioned on the Standard MACOR Disc.
- Once the proper settings are confirmed, you can test the probes on the standard as if it were a normal sample. For the Standard VLQ this consists of leaving the probe needle in the MACOR standard, while for the HLQ probes you will need to attach it to the Standard MACOR Disc with a rubber band (See Example 1).
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Each data set from the Thermoconductivity Station is written to a file by section. These reports are found under the Physical Properties heading. The expanded reports include the linked original data files and more detailed information regarding the measurement.
Analysis | Component | Unit | Definition |
TCON | Bottom_depth | m | Location of bottom of measurement, measured from the top of the hole |
Comment | None | Comment about the run | |
Contact_value | None | Measure of contact quality between probe and sample | |
End_time | s | Elapsed time for end of analysis window | |
Heating_power | W/m | Power applied to needle during heating | |
Length_of_time | s | Elapsed time, start to finish, of analysis | |
Log_extreme_time | s | LET, used in calculation algorithm | |
Method | None | Data reduction method: SAM or TCON | |
Needle_name | None | Full-space or half-space | |
Number_of_solutions | None | Number of solutions found by the software | |
Offset | cm | Location of measurement from top of section | |
Start_time | s | Elapsed time into experiment for start of analysis window | |
Therm_con_average | W/(m·K) | Mean thermal conductivity result | |
Therm_con_number | None | Number of measurements in the population | |
Therm_con_result | W/(m·K) | Individual thermal conductivity result | |
Therm_con_stdev | W/(m·K) | Standard deviation (n-1) of measurement population | |
Top_depth | m | Location of top of measurement from top of hole |
C. Retrieve Data from LIMS
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Note: for loose sediments, use a lower heating power to avoid convective heat transport of pore fluids.
Material | Thermal Conductivity (W/m·K) | Recommended Heating Power (W/m) | ||
|---|---|---|---|---|
Mean | Range | VLQ | HLQ | |
Wood | 0.21 | 0.1–0.35 | 0.15–1.3 | — |
Coal | 0.29 | 0.1–1.5 | 0.15–5.4 | — |
Concrete | 1.00 | 0.75–1.4 | 1.0–5.0 | 0.5–2.2 |
Fused silica | 1.40 | 1.33–1.46 | 1.8–5.2 | 0.8–2.3 |
Clay | 1.40 | 1.2–1.7 | 1.6–6.1 | 0.7–2.6 |
Silt | 1.60 | 1.4–2.1 | 1.9–7.5 | 0.8–3.2 |
Basalt | 1.95 | 1.4–5.4 | 1.9–19.0 | 0.8–7.6 |
Siltstone | 2.04 | 0.6–4.0 | 0.8–14.0 | 0.4–5.7 |
Limestone | 2.29 | 0.5–4.4 | 0.7–16.0 | 0.4–6.3 |
Syenite | 2.31 | 1.3–5.3 | 1.7–19.0 | 0.8–7.5 |
Amphibolite | 2.46 | 1.4–3.9 | 1.9–14.0 | 0.8–5.6 |
Claystone | 2.46 | 1.6–3.4 | 2.1–12.0 | 0.5–9.3 |
Lava | 2.47 | 0.2–4.5 | 0.3–16.0 | 0.2–6.4 |
Gabbro | 2.50 | 1.6–4.1 | 2.1–15.0 | 0.9–5.9 |
Dolerite (Diabase) | 2.64 | 1.6–4.4 | 2.1–16.0 | 0.5–6.3 |
Granodiorite | 2.65 | 1.3–3.5 | 1.7–13.0 | 0.8–5.0 |
Quartz sand (wet) | 2.70 | 2.4–3.1 | 3.2–11.0 | 1.3–4.5 |
Marble | 2.80 | 2.1–3.5 | 1.8–13.0 | 1.2–5.0 |
Porphyrite | 2.82 | 3.8–10.0 | 1.5–4.2 | |
Boulder clay | 2.90 | 2.5–3.3 | 3.4–12.0 | 1.4–4.8 |
Diorite | 2.91 | 1.7–4.2 | 2.3–15.0 | 1.0–6.0 |
Slate (perpendicular) | 2.91 | 1.5–3.9 | 2.0–14.0 | 0.9–5.6 |
Gneiss | 2.95 | 1.2–4.7 | 1.6–17.0 | 0.7–6.7 |
Granite | 3.05 | 1.2–4.5 | 1.6–16.0 | 0.7–6.4 |
Eclogite | 3.10 | 2.4–3.4 | 3.2–12.0 | 1.3–4.9 |
Andesite | 3.20 | 1.6–4.7 | 2.1–17.0 | 1.0–6.7 |
Dolomite | 3.62 | 1.6–6.6 | 2.1–20.0 | 1.0–9.3 |
Slate (parallel) | 3.80 | 2.2–5.2 | 3.0–19.0 | 1.2–7.4 |
Peridotite | 3.81 | 5.0–14.0 | 2.0–5.5 | |
Anhydrite | 4.05 | 1.0–6.0 | 1.3–20.0 | 0.6–8.5 |
Pyroxenite | 4.27 | 3.2–5.1 | 4.3–18.0 | 1.7–7.2 |
Dunite | 4.41 | 3.5–5.2 | 4.7–19.0 | 1.9–7.4 |
Quartzite | 4.55 | 3.1–>8 | 4.2–20.0 | 1.7–11.0 |
Quartz | 9.50 | 6.5–12.5 | 8.7–20.0 | 3.5–17.0 |
V. Credits
This document originated from 2009, TK04 UG v.,V378P | 372 (Revised: 372|V371T|no change 03/18 ), that had contributions from the authors Hastedt, Y.-G. Kim, M.A. Kominz, and the reviewers David Houpt, T. Gorgas, M. Vasilyev, R. Wilkens, K. Milliken, H. Barnes, S. Hermann; T. Cobb. Credits for subsequent changes to this document are given in the page history.
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