Mustafa Koz

Abstract

Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electrochemical engines. The performance of a PEMFC is adversely affected by oxygen (O2) concentration loss from the air flow channel to the cathode catalyst layer (CL). Oxygen transport resistance at the gas diffusion layer (GDL) and air channel interface is a non-negligible component of the O2 concentration loss. Simplified PEMFC performance models in the available literature incorporate the O2 resistance at the GDL-channel interface as an input parameter. However, this parameter has been taken as a constant so far in the available literature and does not reflect variable PEMFC operating conditions and the effect of two-phase flow in the channels.

This study numerically calculates the O2 transport resistance at the GDL-air channel interface and expresses this resistance through the non-dimensional Sherwood number (Sh). Local Sh is investigated in an air channel with multiple droplets and films inside. These water features are represented as solid obstructions and only air flow is simulated. Local variations of Sh in the flow direction are obtained as a function of superficial air velocity, water feature size, and uniform spacing between water features. These variations are expressed with mathematical expressions for the PEMFC performance models to utilize and save computational resources.

The resulting mathematical correlations for Sh can be utilized in PEMFC performance models. These models can predict cell performance more accurately with the help of the results of this work. Moreover, PEMFC performance models do not need to use a look-up table since the results were expressed through correlations. Performance models can be kept simplified although their predictions will become more realistic. Since two-phase flow in channels is experienced mostly at lower temperatures, performance optimization at low temperatures can be done easier.

Library of Congress Subject Headings

Proton exchange membrane fuel cells--Mechanical properties; Two-phase flow--Mathematical models

Publication Date

3-18-2015

Document Type

Dissertation

Student Type

Graduate

Degree Name

Microsystems Engineering (Ph.D.)

Department, Program, or Center

Microsystems Engineering (KGCOE)

Advisor

Satish G. Kandlikar

Advisor/Committee Member

Blanca Lapizco-Encinas

Advisor/Committee Member

Jiandi Wan

Comments

Physical copy available from RIT's Wallace Library at TK2933.P76 K69 2015

Campus

RIT – Main Campus

Plan Codes

MCSE-PHD

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