| Thermal Conductivity |
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The heat dissipation or thermal insulation capability of a material determines its range of applications. The four common thermal properties are Thermal Conductivity, Thermal Diffusivity, Heat Capacity, and Specific Heat.
– Materials with low thermal conductivity are suitable for thermal insulation applications, such as building materials, insulating paints, thermal insulation coatings, insulation wool, thermal insulation materials, artificial stone, and PU insulation foam. These materials are generally developed with the goal of achieving very low thermal conductivity. They are commonly used for high-temperature insulation, energy-efficient refrigerators, thermal insulation systems, partition walls, and more. – Common applications of materials with high thermal conductivity include graphite heat-dissipation sheets, heat sinks, thermal pastes, ceramic heat sinks, and thermal conductive tapes. These products are primarily developed to provide high heat dissipation performance and are widely used in electronic components, laptops, televisions, precision instruments, the automotive industry, mobile phones, LEDs, GPS devices, and other high-tech industries. – Heat transfer mainly occurs through conduction, convection, and radiation. When the two ends of a material are at different temperatures, thermal energy is transferred from the higher-temperature region to the lower-temperature region. The heat transfer rate can be calculated as follows: Heat Transfer Rate dQ/dt = K·A*(TH-TL)/d A: Cross-sectional area TH-TL: Temperature difference d: Thickness Q: Thermal energy t: Time K: Thermal conductivity coefficient [W/m°C] – Depending on the measurement method, thermal conductivity analysis can be divided into two approaches: Steady State and Transient State. – Steady State: As the name suggests, the sample is placed in a sample holder with a controlled heat source. During the process of reaching thermal equilibrium, changes in temperature over time are recorded. The primary analytical instrument used is Guarded Hot Plate. – Transient State: A constant heat source is applied to the sample, and the temperature change of the sample over time is recorded. The relationship between time and temperature change can be used to determine the sample's Thermal Conductivity, Thermal Diffusivity, and Heat Capacity. The most commonly used analytical instrument is the Hot Disk Thermal Conductivity Analyzer. |
