Technique Overview :
Modified Transient Plane Source (MTPS)
Fast, easy and highly accurate. A single-sided, “plug & play” sensor suitable for testing solids, liquids, powders and pastes. Offers maximum sample versatility. Conforms to ASTM D7984
Modified Transient Plane Source (MTPS). Simple and Precise.
The MTPS method employs a single-sided sensor to directly measure thermal conductivity and effusivity of materials. The MTPS method has the highest precision, highest sensitivity, shortest test time, and is the easiest to use among all three techniques.
Principles of Operation
Trident’s primary sensor employs the Modified Transient Plane Source (MTPS) technique in characterizing the thermal conductivity and effusivity of materials. It employs a single-sided, interfacial heat reflectance sensor that applies a momentary constant heat source to the sample. Typically, the measurement pulse is between 1 to 3 seconds. Thermal conductivity and effusivity are measured directly, providing a detailed overview of the heat transfer properties of the sample material.
How it works
- A known current is applied to the sensor’s spiral heating element, providing a small amount of heat.
- A guard ring surrounds the sensor coil to support a one-dimensional heat transfer into the sample. The applied current results in a rise in temperature at the interface between the sensor and the sample, which induces a change in the voltage drop of the sensor element.
- The rate of increase in the sensor voltage is used to determine the thermal properties of the sample. The voltage is factory-calibrated to temperature. The thermal conductivity is inversely proportional to the rate of increase in the temperature at the point of contact between the sensor and the sample. The voltage is used as a proxy for temperature and will rise more steeply when lower thermal conductivity materials (e.g. foam) are tested. Conversely, the voltage slope will be flatter for higher thermal conductivity materials (e.g. metal). With the C-Therm Trident, tabular thermal conductivity results are reported in real-time making thermal conductivity measurement fast and easy. No regression analysis is required.
Transient Line Source (TLS) Needle
The TLS method employs a needle probe to characterize the thermal conductivity of viscous and granular materials. It is the most robust sensor for thermal conductivity testing.
Principles of Operation
The Transient Line Source (TLS) technique operates in accordance with ASTM D5334, D5930 and IEEE Std 442-1981. Commonly referred to as needle probes, The TLS sensors provide a robust and efficient solution for measuring the thermal conductivity of granular materials, powders, polymer melts, soils, slurries, gels, and pastes.
This technique involves placing an electrically heated needle into a material. The heat flows out radially from the needle into the sample. During heating, the temperature difference between a thermocouple (T1) positioned in the middle of the heating wire, and a second thermocouple (T2) located at the tip of the needle is measured. By plotting this temperature difference versus the logarithm of time, thermal conductivity can be calculated. Typically, the measurement is on the order of 2-10 minutes.
How it works
- An internal platinum wire is heated electrically – providing a known amount of heat per unit length.
- The temperatures are measured at locations T1 (located in the middle of heating wire) and T2 (located at the tip of the needle).
- The rate of increase in temperature as a f