Measurement of in-plane thermal conductivity of carbon paper diffusion media in the temperature range of −20°C to +120°C

Zamel, Nada; Litovsky, Efim; Shakhshir, Saher Al; Li, Xianguo; Kleiman, Jacob

doi:10.1016/j.apenergy.2011.02.037

Cited by 80 publications

(54 citation statements)

References 24 publications

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“…Sadeghi et al 27 observed a small increase in in-plane thermal conductivity from 17.39 W/m K to 17.81 W/m K with an increase in PTFE content from 5% to 30%, respectively. In contrast, Zamel et al 31 observed a sharp decrease of approximately 11 W/m K at 60 to 70…”

Section: In-plane Effective Thermal Conductivitymentioning

confidence: 86%

Material and Morphological Heat Transfer Properties of Fuel Cell Porous Transport Layers

Konduru

Allen

2017

J. Electrochem. Soc.

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The complex structure of the porous transport layer (PTLs), commonly referred to as gas diffusion layers (GDL), makes direct measurement of thermal transport properties difficult. Typically, effective thermal conductivity values are obtained experimentally and computational models are developed to replicate the measurements. This approach is sufficient for generalized one-dimensional models of fuel cell performance, but is not sufficient to predict reactant maldistribution due to the presence of liquid water in the PTL. Further, the anisotropy in the PTL structure results in dissimilar properties for through-plane and in-plane transport. In this work an analytical model is developed to extract material properties from effective thermal conductivity measurements. The model accounts for the change in the effective thermal conductivity as a function of compression. Geometric changes due to compression are separated from morphological changes using a compression modulation function; the shape of which is indicative of how fiber-to-fiber contact morphology changes with respect to strain. Material and morphological properties are determined using effective thermal conductivity data for three commercial PTLs. The properties also enable prediction of in-plane heat transfer using through-plane empirical data and also provide insight into morphological changes due to compression. A porous transport layer (PTL), more commonly referred to as a gas diffusion layer (GDL), has multiple purposes in a fuel cell including distribution of reactant gases to the catalyst layer, facilitation of product water removal from the catalyst layer, electronic and thermal conduction to/from the catalyst layer, and redistribution of compressive stresses across the membrane electrode assembly (MEA). A typical PTL consists of carbon fibers, either in fibrous or a non-woven morphology, along with binding agents and non-wetting agents such as polytetrafluoroethylene (PTFE). Examples of a non-woven and a fibrous PTL are shown in Figure 1. PTL designation is used herein because the transport phenomena of interest is not restricted to diffusion of reactant gases, but is focused heat transfer.Heat transfer across a dry PTL is primarily due to conduction. When liquid water is present, then additional heat may be transferred from the catalyst layer via evaporation and conduction via the liquid water occupying the void space. Either mode of heat transfer, conduction or evaporation, may be the dominant effect depending upon the operating conditions.1 The location of an evaporation front within a PTL depends upon the temperature and temperature gradient within the PTL. The same can be said for water condensation within the PTL as demonstrated by Caulk and Baker.2 A highly conductive PTL may increase the conduction of heat, but result in widely distributed condensation that can block reactant transport. A less conductive PTL may decrease the conduction of heat, but result in a sharp temperature gradient that generates a thin, uniform layer of water which al...

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Section: In-plane Effective Thermal Conductivitymentioning

confidence: 86%

Material and Morphological Heat Transfer Properties of Fuel Cell Porous Transport Layers

Konduru

Allen

2017

J. Electrochem. Soc.

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“…For the in-plane thermal conductivity it was found that for PTFE free PTLs the thermal conductivity is lowered by w50% when comparing values measured at room temperature to values from measurements undertaken at 60 C and higher [24]. For the PTFE treated samples, the in-plane thermal conductivity is nearly unaffected in the range of À20 to þ120 C, respectively [24].…”

Section: Thermal Conductivity Of Pefc Componentsmentioning

confidence: 89%

“…The impact on thermal conductivity introduced by changing the temperature both for in-and through-plane thermal conductivity was measured by Zamel et al [24,31] For through-plane thermal conductivity with controlled compression; it was found that at 16% compression (unknown compaction pressure) the thermal conductivity of the PTL, regardless of PTFE content, does not depend significantly on temperature [31]. For the in-plane thermal conductivity it was found that for PTFE free PTLs the thermal conductivity is lowered by w50% when comparing values measured at room temperature to values from measurements undertaken at 60 C and higher [24].…”

Section: Thermal Conductivity Of Pefc Componentsmentioning

confidence: 99%

Ageing and thermal conductivity of Porous Transport Layers used for PEM Fuel Cells

Burheim¹,

Ellila²,

Fairweather³

et al. 2013

Journal of Power Sources

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“…The thermal diffusivity for films of blank epoxy was 0.12 mm 2 /s. [26][27][28] In their work, these authors measured the thermal conductivities of free-standing networks of aligned and randomly oriented SWCNTs from 10 to 400 K. For the aligned networks, the thermal measurements were made in the direction of SWCNT orientation. For both the aligned and randomly oriented samples, thermal conductivity increased with increasing temperatures; however, they observed that the thermal conductivities for the aligned SWCNTs were ~10 times greater than for randomly oriented SWCNTs ( The effect of the mixing SWCNTs into a pre-preg composite was investigated by Yoo et al In their work, they air-sprayed SWCNT that had been functionalized with carboxylic acids on their surface onto IM7-977 prepreg composites.…”

Section: Thermal Diffusivitymentioning

confidence: 99%

Development and thermal properties of carbon nanotube-polymer composites

Jackson

2016

Composites Part B: Engineering

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Measurement of in-plane thermal conductivity of carbon paper diffusion media in the temperature range of −20°C to +120°C

Cited by 80 publications

References 24 publications

Material and Morphological Heat Transfer Properties of Fuel Cell Porous Transport Layers

Material and Morphological Heat Transfer Properties of Fuel Cell Porous Transport Layers

Ageing and thermal conductivity of Porous Transport Layers used for PEM Fuel Cells

Development and thermal properties of carbon nanotube-polymer composites

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