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Research Papers

# Through-Plane Thermal Conductivity of PEMFC Porous Transport Layers

[+] Author and Article Information
Odne S. Burheim

Department of Chemistry, NTNU, 7491 Trondheim, Norwayburheim@gmail.com

Jon G. Pharoah1

Fuel Cell Research Centre, Queens University, Kingston, ON, Canada K7L 3N6pharoah@me.queensu.ca

Hannah Lampert

RWTH Aachen University, 52074 Aachen, GermanyHannah.Lampert@rwth-aachen.de

Preben J. S. Vie

IFE, 2027 Kjeller, Norwaypreben.vie@ife.no

Signe Kjelstrup

Department of Chemistry, NTNU, 7491 Trondheim, Norwaysigne.kjelstrup@chem.ntnu.no

From the tables reporting on the porosity of PTLs, one can see that the thickness appear to change significantly more than the porosity. Take, for instance, the TGP-H-120 in Table 2. While the thickness (correspondingly total volume) is lowered by approximately 6%, the porosity changes only by 3%. The volume of the graphite is given by the sample weight and the graphite density $(0.0593 g/2.1±0.1 g cm−3=27±1 mm3)$. The volumes of the entire disk of PTL are $119±2 mm3$, $115±1 mm3$, and $111±1 mm3$ at 4.6 bars, 9.3 bars, and 13.9 bars, respectively.

1

Corresponding author.

J. Fuel Cell Sci. Technol 8(2), 021013 (Dec 01, 2010) (11 pages) doi:10.1115/1.4002403 History: Received July 01, 2010; Revised August 06, 2010; Published December 01, 2010; Online December 01, 2010

## Abstract

We report the through-plane thermal conductivities of the several widely used carbon porous transport layers (PTLs) and their thermal contact resistance to an aluminum polarization plate. We report these values both for wet and dry samples and at different compaction pressures. We show that depending on the type of PTL and the existence of residual water, the thermal conductivity of the materials varies from $0.15 W K−1 m−1$ to $1.6 W K−1 m−1$, one order of magnitude. This behavior is the same for the contact resistance varying from $0.8 m2 K W−1$ to $11×10−4 m2 K W−1$. For dry PTLs, the thermal conductivity decreases with increasing polytetrafluorethylene (PTFE) content and increases with residual water. These effects are explained by the behavior of air, water, and PTFE in between the PTL fibers. It is also found that Toray papers of differing thickness exhibit different thermal conductivities.

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## Figures

Figure 1

(a) The left figure depicts the apparatus used for measuring the thermal properties reported, while (b) the setup to the right depicts how the PTLs were exposed to water. The apparatus to the left was reported previously (9).

Figure 2

The geometry used for the modeling in this report. The model is thoroughly described elsewhere (3).

Figure 3

(Dry) Variation in measured thermal conductivity with varying paper thickness. All materials had 5% PTFE.

Figure 4

SEM micrographs of PTLs. From left: Toray TGP-H-060, TGP-H-090, and TGP-H-120—all 5% wet proof.

Figure 5

(Wet) Variation in measured thermal conductivity in the presence of residual water saturation

Figure 6

(PTFE) Variation in measured thermal conductivity with PTFE loading. All substrates are TP-90.

Figure 7

SEM. Micrographs of, from the left, Toray TGP-H-090—5%, 10%, and 60% wet proof PTLs

Figure 8

SEM micrographs of the SIGRACET GDL AA (left) and BA (right) PTLs containing 0 wt % and 5 wt % PTFE, respectively

Figure 9

A SEM micrograph SolviCore PTL untreated carbon paper

Figure 10

A SEM micrograph of the E-TEK EC-CC1-060

Figure 11

A SEM micrograph of the Freudenberg FCCT H2315 carbon cloth

Figure 12

Thermal resistance and apparatus thermal contact resistance of Toray (upper) and SIGRACET (lower) PTLs treated PTFE both with and without residual water. Experiments obtained at approximately 295 K and 9.3 bar compaction pressure using stacks of 21 mm diameter disks. The dry samples are indicated with triangles, and those containing water are indicated using circles. The water content, s, is indicated next to the data points.

Figure 13

Thermal resistance and apparatus thermal contact resistance of stacked E-TEK EC-CC1-060 carbon cloth without PTFE. PTLs both with and without residual water. Experiments obtained at 295 K and 9.3 bar compaction pressure using stacks of 21 mm diameter disks. The dry samples are indicated with triangles, and those containing water are indicated using circles. The water content, s, is indicated next to the data points.

Figure 14

Thermal resistance and apparatus thermal contact resistance of stacked Freudenberg FCCT carbon felt without (upper) and with PTFE (lower). PTLs both with and without residual water. Experiments obtained at 295 K and 9.3 bar compaction pressure using stacks of 21 mm diameter disks. The dry samples are indicated with triangles, and those containing water are indicated using circles. The water content, s, is indicated next to the data points.

## Errata

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