Development of the Transient Plane Source Method for Measuring Thermal Conductivity and Diffusivity of Graphite Composite under Geometric Constraints

Kermani, Sahar; Dashti Gohari, Isar; Asghari, Saeed

doi:10.48311/mme.2025.117644.82889

Development of the Transient Plane Source Method for Measuring Thermal Conductivity and Diffusivity of Graphite Composite under Geometric Constraints

Document Type : Original Article

Authors

Sahar Kermani

Isar Dashti gohari

Saeed Asghari

Institute of Materials and Energy, Iranian Space Research Center, Isfahan, Iran

10.48311/mme.2025.117644.82889

Abstract

The Transient Plane Source (TPS) method is one of the most accurate techniques for analyzing the thermal properties of materials, including solids, liquids, and powders. This method enables the evaluation of thermal parameters of anisotropic materials in both radial and axial directions, providing precise and non-destructive measurements for conductive and insulating materials. Temperature control during experiments further improves measurement accuracy. However, a key limitation of this method is the requirement to satisfy specific conditions between the thermal penetration depth and the sensor radius, which can be challenging depending on specimen geometry. In this study, the TPS method was used to determine the thermal conductivity and thermal diffusivity of a graphite composite as an anisotropic material. Despite geometric limitations, the measurement requirements were fulfilled by connecting multiple specimens and eliminating additional thermal contact resistance. Owing to the anisotropic nature of the sample, accurate determination of the specific heat capacity of graphite was also necessary; therefore, a novel measurement approach with an error of less than 7% was proposed. The thermal conductivity of graphite was measured as 20.792 W·m⁻¹·K⁻¹ in the axial direction and 51.390 W·m⁻¹·K⁻¹ in the radial direction. To validate the methodology, aluminum was used as a reference material assuming isotropic behavior. The results confirm that the TPS method is a powerful tool for analyzing the thermal behavior of materials and can contribute to optimizing the design of engineering and energy systems to improve performance and durability

Keywords

Thermal Conductivity

Anisotropic Materials

Transient Plane Source Method

Specific heat Capacity

Subjects

Heat & Mass Transfer

[1] J. Yao, "Transient Plane and Line Source Methods for Soil Thermal Conductivity Measurement," Geotechnical Testing Journal, vol. 40, no. 5, pp. 858–868, 2017. DOI:10.1520/GTJ20160094

[2] M. Kövér, M. Behúlová, M. Drienovský, and P. Motyčka, "Determination of the specific heat using laser flash apparatus," J. Therm. Anal. Calorim., vol. 122, no. 1, pp. 151–156, 2015. DOI:10.1007/s10973-015-4748-0

[3] ISO 22007-2: Plastics—Determination of thermal conductivity and thermal diffusivity, Part 2: Transient plane heat source (hot disc) method, ISO, Geneva, 2008

[4] A. Palacios, L. Cong, M. E. Navarro, Y. Ding, and C. Barreneche, “Thermal conductivity measurement techniques for characterizing thermal energy storage materials–A review,” *Renewable and Sustainable Energy Reviews*, vol. 108, pp. 32–52, 2019, Doi: DOI: 10.1016/j.rser.2019.03.020

[5] B. Ma, N. Kumar, A. Kuchibhotla, and D. Banerjee, "Estimation of measurement uncertainties for thermal conductivity of nanofluids using transient plane source (TPS) technique," in *2018 17th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)*, May 2018, pp.178–186. DOI: 10.1109/ITHERM.2018.8419622

[6] S. Malinarič, "Measurement of the thermal conductivity and diffusivity of steel and glass using transient methods," *International Journal of Thermophysics*, vol. 46, no. 2, Article 64, 2025. DOI: 10.1007/s10765-025-03564-y

[7] S. Tarasovs and A. Aniskevich, “Identification of the anisotropic thermal conductivity by an inverse solution using the transient plane source method,” Measurement, vol. 206, Art. no. 112252, 2023. doi: DOI: 10.1016/j.measurement.2022.112252

[8] D. Landry and R. Flores, “Power Corrections in the Transient Plane Source Method,” J. Heat Mass Transfer, vol. 147, no. 5, Art. no. 051701, May 2025. DOI: 10.1115/1.4067604

[9] M. N. Ozisik, *Heat Transfer: A Basic Approach*, New York: McGraw-Hill, 1985.

[10] Zhang, H., Li, Y. M., & Tao, W. Q. (2017). Theoretical accuracy of anisotropic thermal conductivity determined by transient plane source method. International Journal of Heat and Mass Transfer, DOI: 10.1016/j.ijheatmasstransfer.2017.01.025..

[11] V. Boháč, M. Gustavsson, L. Kubicar, and S. Gustafsson, "Parameter estimations for measurements of thermal transport properties with the hot disk thermal constants analyzer," *Review of Scientific Instruments*, vol. 71, 2000. DOI: 10.1063/1.1150635

[12] The Engineering ToolBox. (2003). Specific Heat of Metals. [Online]. Available: https://www.engineeringtoolbox.com/specific-heat-metals-d_152.html. [Accessed: 28-Sep-2025]

[13] Entegris, Inc., "Pyrolytic Sealed Bipolar Plates — Data Sheet (POCO)," [Online]. Available: https://www.entegris.com/.../datasheet-pyrocell-bipolar-plates-11044.pdf. [Accessed: Oct. 6, 2025].

[14] Dow Silicones Corporation, DOWSIL™ 340 Heat Sink Compound – Product Information Sheet, Dow Silicones Corporation, 2021.

[15] J. Fox and S. Weisberg, An R Companion to Applied Regression, 3rd ed. Thousand Oaks, CA, USA: SAGE Publications, 2019