Thermal Conductivity Testing & Measurement refers to the capacity of a material to transfer heat. Materials that consist of high thermal conductivity, such as metals, allow for fast heating flow. On the other hand, insulating materials, like foams, slow down the flow of heat. Testing and evaluating thermal conductivity is vital in industries like electronics, in which dissipation of heat should be allowed, and construction, where the most efficient insulation should be applied so energy consumption could be limited.
Instrumentation
There are different methods implemented to measure thermal conductivity. The guarded hot plate method is conventional for solid materials, where heat flow between a heated and a cooled plate is measured. Laser flash analysis is one of the noncontact measurement techniques employed to measure thermal diffusivity in high-performance materials. Temperature rises on the opposite side of the material after the laser pulse is analyzed to determine this property. The most common method is the Transient Plane Source (TPS) or Hot Disk, which involves a measurement of thermal conductivity and diffusivity by placing a sensor between two samples of the material.
Strengths
Thermal conductivity is measured in the right way to choose materials for effective management of heat. In electronics, that is crucial for dispersing heat to avoid overheating, and in buildings, high thermal insulation reduces consumption as the structural materials do not lose heat unnecessarily. The methods of testing outlined here give consistent results over the broad range of materials involved: metals to insulators.
Limitations
Tests for thermal conductivity are accurate, but often the conditions of natural settings-such as humidity and pressure- are discounted because they do interfere with the process of heat transfer. In some cases, a method does not apply to all kinds of materials, notably for those materials in which there is structure and complexity or for situations under extreme conditions.
Related Techniques to Thermal Conductivity Testing & Measurement
Additional techniques include determinations of weight loss over a specific temperature range for a material known as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) where one monitors the heat flow through phase transitions.
