Trident™ Measuring the Through-Plane Thermal Conductivity of Gas Diffusion Layers

The following Application Highlight addresses the through-plane thermal conductivity measurement of two gas diffusion layer membranes on the C-Therm Trident FLEX Thin Films Module. Understanding the heat transfer mechanism through the gas diffusion layer (GDL) membranes is important in designing and utilizing proton exchange membrane (PEM) fuel cells, where applying an efficient cooling process is key to more durable and reliable PEM fuel cells. Accurate knowledge of the heat flux will help determine different key processes such as water/gas transport rates, reaction kinetics, and saturation pressure. One of the leading performance indicators is the effective thermal conductivity of GDLs under a compression load, which simulates the expected operating conditions. In this study, two GDL samples with variations in composition and structure were tested. One sample is a neat carbon paper (Sigracet 39AA, 89% porosity), and the other incorporates a microporous layer (MPL) and a 5wt% PTFE for wet-proofing the carbon paper (Sigracet 22BB, 72% porosity). The C-Therm Trident FLEX Transient Plane Source (TPS) method, using the Thin Films module, was used to measure the effective through-plane thermal conductivity of the GDLs at two compression states: 0 MPa and 1 MPa. The 13mmTPS sensor and stainless steel as bulk materials were used in this study as shown in Figure 1. The samples were prepared by cutting them to fit the sensor area (15mm diameter), minimizing any error due to anisotropy. The 1 MPa compression load was applied using the Compression Test Accessory (CTA).