Modeling the Effective Thermal Conductivity of an Anisotropic and Heterogeneous Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer

In this thesis, two numerical modeling methods are used to investigate the thermal conductivity of the polymer electrolyte membrane (PEM) fuel cell gas diffusion layer (GDL). First, an analytical model is used to study the through-plane thermal conductivity from representative physical GDL models informed by microscale computed tomography imaging of four commercially available GDL materials. The effect of the heterogeneity of the through-plane porosity of the GDL and polytetrafluoroethylene (PTFE) treatment is studied and it is noted that the high porosity surface transition regions have a dominating effect over the addition of PTFE in impacting the overall thermal conductivity. Next, the lattice Boltzmann method (LBM) is employed to study both the in-plane and through-plane thermal conductivity of stochastic numerically generated GDL modeling domains. The effect of GDL compression, binder content, PTFE treatment, addition of a microporous layer (MPL), heterogeneous porosity distributions, and water saturation on the thermal conductivity are investigated.MAS

Modeling the Effective Thermal Conductivity of an Anisotropic and Heterogeneous Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer

In this thesis, two numerical modeling methods are used to investigate the thermal conductivity of the polymer electrolyte membrane (PEM) fuel cell gas diffusion layer (GDL). First, an analytical model is used to study the through-plane thermal conductivity from representative physical GDL models informed by microscale computed tomography imaging of four commercially available GDL materials. The effect of the heterogeneity of the through-plane porosity of the GDL and polytetrafluoroethylene (PTFE) treatment is studied and it is noted that the high porosity surface transition regions have a dominating effect over the addition of PTFE in impacting the overall thermal conductivity. Next, the lattice Boltzmann method (LBM) is employed to study both the in-plane and through-plane thermal conductivity of stochastic numerically generated GDL modeling domains. The effect of GDL compression, binder content, PTFE treatment, addition of a microporous layer (MPL), heterogeneous porosity distributions, and water saturation on the thermal conductivity are investigated.MAS

The desiring child: an examination of childhood queerness in the fiction of Carson McCullers

The main purpose of this thesis is to present and highlight the radical potential in the work of Carson McCullers, primarily through an examination of her representation of young, queer individuals. This thesis argues that McCullers forces her readers to re-think the categories of “child” and “adult” through her creation of ambiguously gendered, sexual child characters.February 201

Lattice Boltzmann Modeling of the Effective Thermal Conductivity of an Anisotropic PEMFC GDL with Residual Water

Abstract not Available.</jats:p

Lattice Boltzmann Modeling of the Effective Thermal Conductivity of an Anisotropic Gas Diffusion Layer

In the present work, the anisotropic and heterogeneous effective thermal conductivity of the gas diffusion layer (GDL) is determined using a thermal lattice Boltzmann model. A three-dimensional fifteen speed (D3Q15), two-phase (fibre and air) model with single relaxation time is presented to determine the effective thermal conductivity in the through-plane and in-plane directions. The model solves the energy transport equation through a reconstructed fibrous GDL geometry. The geometry of the GDL was reconstructed using microscale computed tomography imaging of commercially available GDL materials. Simulated thermal conductivities determined in this work can provide insight into the effect of heterogeneity and anisotropy of the GDL on the thermal management required for improved PEM fuel cell performance.</jats:p

Modeling the Effective Thermal Conductivity of an Anisotropic Gas Diffusion Layer in a Polymer Electrolyte Membrane Fuel Cell

The anisotropic and heterogeneous effective thermal conductivity of the gas diffusion layer (GDL) of the polymer electrolyte membrane fuel cell was determined in the through-plane direction using an analytical thermal resistance model. The geometry of the GDL was reconstructed using porosity profiles obtained through microscale computed tomography imaging of four commercially available GDL materials. The effective thermal conductivity increases almost linearly with increasing bipolar plate compaction pressure. The effective thermal conductivity was also seen to increase with increasing GDL thickness as bulk porosity remained almost constant. The effect of the heterogeneous through-plane porosity distribution on the effective thermal conductivity is discussed. The outcomes of this work will provide insight into the effect of heterogeneity and anisotropy of the GDL on the thermal management required for improved PEMFC performance.</jats:p

Lattice Boltzmann Modeling of the Effective Thermal Conductivity of an Anisotropic Gas Diffusion Layer in a Polymer Electrolyte Membrane Fuel Cell

Abstract not Available.</jats:p