Dynalene can measure thermal conductivities ranging from 0 to 500 W/m·K at temperature ranges from -50°C (-58°F) to 2,000°C (3,632°F). Depending on your sample type or preferred method, we can use our laser flash, transient hot wire, or hot-box to analyze your sample. We can also perform custom thermal conductivity testing if your sample requires it.
|MATERIALS||Solids, liquids, pastes, powders|
|THERMAL CONDUCTIVITY RANGE||Laser flash: 0 to 2,000 W/m·K
Hot wire: 0 to 4 W/m·K
|TEMPERATURE RANGE||-50°C to 2,000°C (-58°F to 3,632°F)|
|ACCURACY||± 5% (depends on material)|
|REPRODUCIBILITY||± 3% (depends on material)|
|SAMPLE DIMENSION||Laser flash: 12.7 mm, 25.4 mm round
12.7 mm x 12.7 mm square
Hot wire: min. 100 mL fluid
Variety of solid geometries
Hot box: 6”x 6” square
1/2” to 3” thickness
|ADDITIONAL ASTM TESTS PERFORMED||E1461
We encounter lots of unique samples that may have unconventional testing requirements or specifications. If you are unsure what type of test or instrument is required to analyze your sample, give us a call and we’ll make sure it’s tested the way you want it.
What is thermal conductivity?
Thermal conductivity is a property that describes how fast (or how much) heat can pass through a material. Heat always flows from hot to cold, so when one side of a material gets hot, heat will flow to the colder side at a certain rate. Some materials can transport heat very fast, such as copper or aluminum, and other materials transport heat very slow, such insulation or wood.
Understanding thermal conductivity of a material is very important in heat transfer applications. Product engineers might be working on developing new building insulation with very low thermal conductivity to save on home heating costs. Other engineers may be working on increasing thermal conductivity in metal-alloy computer chip heatsinks to remove heat faster for more powerful next-generation chips. Scientists at NASA are constantly looking for state-of-the-art insulating materials to use as heat shields when the space shuttle re-enters the atmosphere. The thermal conductivity of a material is a vital property to understand in engineering and science applications when heat gets involved.
Thermal conductivity, thermal diffusivity, and R-value
As mentioned above, thermal conductivity tells us how fast (or how much) heat can transfer through a given material. A more formal definition would be the quantity of heat (Q) transmitted through a stationary material with a unit thickness (L) in a direction normal to a unit surface area (A) due to a temperature gradient (ΔT).
Thermal diffusivity may seem similar to thermal conductivity, but they are quite different. While the thermal conductivity tells us how much heat can move through a material, diffusivity provides us with a relationship between the ability of the material to conduct thermal energy and how much thermal energy it can store.
Thermal diffusivity can be seen as a material’s thermal inertia. In a material with high thermal diffusivity, the heat will move through the material rapidly because the material conducts heat fast relative to its thermal bulk.
R-value is closely related to thermal conductivity with a slight twist. R-value is a measure of thermal resistance and is commonly used in the building industry to measure insulative properties of materials (like the insulation between the walls of your home). It is the ratio of the temperature difference across the material relative to the heat flux. We can measure this property using our hot box instrument.
Instrument theory and further reading
Our laser flash measurement is based on the well-known flash method. In this method, the front side of a plane-parallel sample is heated by a short light pulse. The resulting temperature rise on the rear surface is measured using an infrared detector. By analysis of the resulting temperature versus-time curve, the thermal diffusivity can be determined.
Our transient hot wire instrument applies heat to the sample in the form of a very quick pulse. The wire measures both the heat pulse and temperature of the material sample and applies a mathematical model to fit the temperature versus-time curve.
Our hot box instrument measures the R-value by creating a steady state temperature gradient across the material. We measure the heat flow through the sample using a heat flow meter and compare this to the temperature differential to generate the R-value.
We have different instruments that measure thermal conductivity in different ways. More in depth discussion about how they work can be found below: