Absolute Thermal Conductivity Methods

Here are the three most popular absolute methods for measuring thermal conductivity of reference materials:

1. Guarded Hot Plate – This method is ideal for measuring low thermal conductivity materials.
2. Transient Plane Source – This is a versatile method for testing low to high-thermal conductivity materials.
3. Laser Flash Apparatus – This is a well-known method for testing medium to high thermal diffusivity. If density and specific heat are known, thermal conductivity can be calculated.

Absolute thermal conductivity methods have various real-world applications, including in building materials, where accurate thermal conductivity measurements are crucial for optimizing energy efficiency. Scientific research and quality control processes depend on absolute methods. Another application is developing advanced materials for industries such as aerospace and electronics.

Using absolute methods for measuring thermal conductivity offers several benefits:

1. Since calibration is unnecessary, the measurement process is simplified and time efficient.
2. The lowest uncertainty is achieved, resulting in highly accurate results.
3. Absolute methods are more reliable and consistent compared to calibrated methods.

The field of absolute thermal conductivity measurement is constantly evolving, and more advanced measurement techniques are being developed to improve accuracy and reduce uncertainty further. This is leading to a growing focus on expanding the range of materials that can be accurately measured using absolute methods.

References:

1. Guarded Hot Plate (GHP):
   Paper: Salmon, D. (2001). Thermal conductivity of insulations using guarded hot plates, including recent developments and sources of reference materials. Measurement Science and Technology, 12(12): R89.
   Available at: http://iopscience.iop.org/article/10.1088/0957-0233/12/12/201/meta

   ASTM: ASTM C177-13, Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus, ASTM International, West Conshohocken, PA, 2013, www.astm.org

2. Transient Plane Source (TPS):
   Paper: S. E. Gustafsson. Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials. Review of Scientific Instruments, 62(3): 797-804 (1991).
   Available at: http://scitation.aip.org/content/aip/journal/rsi/62/3/10.1063/1.1142087

   ISO: ISO 22007-2, Plastics — Determination of thermal conductivity and thermal diffusivity — Part 2: Transient plane heat source (hot disc) method, 2015, www.iso.org

3. Laser Flash Apparatus:
   Paper: W. J. Parker, R. J. Jenkins, C. P. Butler and G. L. Abbott. Flash Method of Determining Thermal Diffusivity, Heat Capacity, and Thermal Conductivity. Journal of Applied Physics, 32: 1679, (1961).
   Available at: http://scitation.aip.org/content/aip/journal/jap/32/9/10.1063/1.1728417

   T. Baba and A. Ono. Improvement of the Laser Flash Method to Reduce Uncertainty in Thermal Diffusivity Measurements. Measurement Science and Technology, 12, (2001).
   Available at: http://iopscience.iop.org/article/10.1088/0957-0233/12/12/304/meta

   ASTM: ASTM E1461-13, Standard Test Method for Thermal Diffusivity by the Flash Method, ASTM International, West Conshohocken, PA, 2013, www.astm.org