An improved transient plane source method for measuring thermal conductivity of thin films: Deconvoluting thermal contact resistance. (May 2016)

• Record Type: Journal Article
• Authors: Ahadi, Mohammad; Andisheh-Tadbir, Mehdi; Tam, Mickey; Bahrami, Majid
• Is Part Of: International journal of heat and mass transfer. Volume 96(2016:May)
• Page Start: 371
• Page End: 380
• Publication Date: 2016-05
• Subjects: Thermal conductivity -- Thin film -- Transient plane source (TPS) method -- Thermal contact resistance (TCR) -- Hot disk thermal constants analyzer -- Guarded hot plate method; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.01.037
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Effects of contact resistances in the TPS thin film measurements are deconvoluted. The proposed method eliminates the need for conducting any reference tests. Benchmark studies are performed for ETFE, Nafion, and GDL samples. The results of the guarded hot plate method validate the proposed method. Mechanical behavior of a sample should be considered for its thermal assessment. Abstract: The conventional transient plane source (TPS) method cannot accurately measure bulk thermal conductivity of thin films and coatings, because of the inclusion of thermal contact resistances in the results. In this study, a new modified TPS method is proposed that allows accurate measurement of bulk thermal conductivity of thin films and coatings. For this purpose, first, a hot disk testbed is used to measure the total thermal resistance for different thicknesses of a sample in the TPS test column. The bulk thermal conductivity is then deconvoluted from the results. Experiments have been performed on ethylene tetrafluoroethylene (ETFE) sheets, Nafion membranes, and gas diffusion layers (GDLs) with different thicknesses using the proposed method, and the results have been cross-checked with the data obtained from the guarded hot plate method, as per ASTM standard C177-13. The present modified TPS method yields thermal conductivity values of 0.174 ± 0.002 W·m −1 ·K −1 for ETFE and 0.243 ± 0.007 W·m −1 ·K −1 for Nafion, while the values measured by the guarded hot plate method are 0.177 ± 0.002 W·m −1 ·K −1 for ETFE and 0.214 ± 0.003 W·m −1 ·K −1 for Nafion. The GDL results, on the other hand, change with mechanical pressure, and about 15.7% difference is observed between the GDL results of the two methods. Overall, the developed method is proved to be highly reliable, quick, and accurate.