Automated thermal conductivity tester
A system may include a test chamber with an area to hold a sample of material (e.g., concrete, thermal backfill, or sand). The area may be subject to a variable desaturation vacuum to dry the sample. The test chamber may also have a precision scale to weigh the sample and a probe inside the sample to provide heat and measure temperature. A controller may automatically and repeatedly dry the sample by varying the desaturation vacuum. According to some embodiments, heat inside and/our outside the sample may also be applied to facilitate desaturation. The controller calculates a thermal resistivity based on heat input, temperature, and time data collected for different saturation levels. A test result data store may contain electronic records (with each record including thermal resistivity values over a range of moisture content values that represent a dryout curve for the material).
1 . A system, comprising:
a test chamber, including:
an area to hold a sample of material, wherein the area is subject to a variable desaturation vacuum to dry the sample,
a precision scale to weigh the sample,
pistons to automatically raise the sample off of the precision scale and lower the sample back onto the precision scale between measurements, and
a probe inside the sample to provide heat and measure temperature;
a controller to automatically and repeatedly dry the sample by varying the desaturation vacuum and calculate a thermal resistivity based on heat input, temperature, and time data collected for different saturation levels; and
a test result data store containing electronic records, each record including thermal resistivity values over a range of moisture content values that represent a dryout curve for the material sample.
2 . The system of claim 1 , wherein the material is associated with at least one of: (i) concrete, (ii) thermal backfill, and (iii) sand.
3 . The system of claim 1 , further comprising an analog or a digital Pound per Square Inch (“PSI”) pressure gauge.
4 . The system of claim 1 , further comprising a vacuum port/air intake with solenoid valves.
5 . The system of claim 1 , wherein the test chamber further includes electronics pass throughs.
6 . The system of claim 1 , further comprising at least one heat ring outside the sample to facilitate evaporation.
7 . The system of claim 1 , wherein the thermal resistivity calculation is associated with a temperature multiplied by a sample distance divided by a weight of the sample.
8 . A method, comprising:
placing a sample of material into an area of a test chamber, wherein the area is subject to a variable desaturation vacuum to dry the sample;
weighing the sample with a precision scale in the test chamber;
providing heat and measuring temperature using a probe inside the sample;
automatically calculating thermal resistivity based on heat input, temperature, and time data;
automatically removing moisture from the sample by varying desaturation vacuum;
monitoring internal temperature data using the probe and weight data using the precision scale;
automatically raising the sample off of the precision scale and lowering the sample back onto the precision scale between measurements using pistons;
automatically determining if the sample has achieved dryout; and
if the sample has achieved dryout, storing results of calculation in a test result data store containing electronic records, each record including thermal resistivity values over range of moisture content values that represent a dryout curve.
9 . The method of claim 8 , further comprising:
also removing moisture from the sample by applying internal heat using the probe and external heat using a heat ring.
10 . The method of claim 8 , further comprising:
monitoring pressure using an automated sensor.
11 . The method of claim 8 , wherein the material is associated with at least one of: (i) concrete, (ii) thermal backfill, and (iii) sand.
12 . The method of claim 8 , wherein the thermal resistivity calculation is associated with a temperature multiplied by a sample distance divided by a weight of the sample.
13 . The method of claim 8 , further comprising:
creating the sample; and
inserting the probe into the sample.
14 . The method of claim 8 , further comprising:
saturating the sample with water.
15 . The method of claim 8 , further comprising:
setting up a thermal properties analyzer.
16 . The method of claim 8 , further comprising:
retrieving test results from the test result data store; and
creating the dryout curve.
17 . The method of claim 8 , wherein the test chamber is associated with an analog or a digital Pound per Square Inch (“PSI”) pressure gauge, a vacuum port/air intake with solenoid valves, and electronics pass throughs.