The Measurement Platform-2 (MP-2) is an advanced meter with unique selection of transient thermal conductivity sensors for a variety of applications, with a focus on primary measurements. The transient thermal conductivity sensors share similar principles of operation. The sensor wire is heated using a constant current source (q) and the temperature rise is recorded by monitoring the change in electrical resistance of the wire (THW and EFF) or by resistance temperature detector device (TLS). For samples of high thermal conductivity, resistance increases more slowly over time; for samples of low thermal conductivity, resistance increases more quickly over time.
Thermal conductivity MP-2 users benefit from the convenience and accuracy gained when using primary testing methods. The MP-2 controller auto-detects the connected sensor and loads corresponding testing parameters. Measurements are easily performed with the smart on-board software and transferred to computer with an included Windows utility program.
The Thermtest Transient Line Source (TLS) meter adheres with an internationally recognized standard of testing by complying with ASTM D5334-14 (100mm and 50mm) and IEEE 442-1981 (100mm). The sensor needle consists of a thin heating wire and temperature sensor sealed in a steel tube. The sensor is completely inserted into the sample to be tested. Heat is delivered to the sample using a constant current source (q) and the temperature rise is recorded over a defined time period. The slope (a) from plot of temperature rise versus logarithm of time is used in the calculation of thermal conductivity (k).
The TLS 100mm sensor can be used to measure the thermal conductivity and thermal resistivity of a variety of samples, including soil, rocks, concrete, and polymers. Tests can be performed with the push of a button and results displayed instantly.
The 50 mm sensor was designed for testing hard samples, like rock and concrete. Drilling the required 4 mm diameter x 50 mm hole in rigid samples is easy with the provided masonry drill bit. When testing hard samples, a thermal contact paste is used to enhance contact between the sensor and sample.
In order to measure the thermal conductivity of the paste, a sample holder was filled with enough silicone 120 thermal paste to cover the entire length of the sensor. A sample holder with suitable diameter was chosen depending on the sensor.
Table 1: Measured thermal conductivity of silicone 120 thermal paste at room temperature with Thermtest TLS 50mm and TLS 100mm sensors.
|Sample||Sensor Type||Thermal Conductivity (W/m·K)||% RSD||TPS ISO22007-2 (W/mK)||Spec Sheet (W/mK)|
|Silicone 120 Thermal Paste||TLS 50mm||0.768||0.42||0.73||0.77||TLS 100mm||0.776||0.82|
Notes: n = 5, %RSD = Percent Relative Standard Deviation