The Effects of Membrane Properties and Structural Parameters on the Non-Minimum Phase Behavior of the PEM Fuel Cell Humidification System

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
John F. Hall ◽  
Christine A. Mecklenborg ◽  
Clay S. Hearn ◽  
Dongmei Chen
Keyword(s):  
Fuel Cell ◽  
Phase Behavior ◽  
Material Property ◽  
Coupling Effect ◽  
Structural Parameters ◽  
Pem Fuel Cell ◽  
Membrane Properties ◽  
Minimum Phase ◽  
Vapor Transfer ◽  
Channel Plate

The water vapor transfer across a Nafion® membrane exhibits an undesired non-minimum phase behavior. This paper will show that even in the disturbance-to-output loop, the non-minimum phase zero adversely affects the feedback controller design because of the coupling effect between the disturbance-to-output and the input-to-output loops. The non-minimum phase zero location is influenced by the channel plate structure and the membrane material property. The structural parameters examined in this research include channel plate dimensions and heat transfer coefficients. The membrane properties studied include membrane vapor transfer properties described in the Arrhenius’ equation. A governing equation to link the non-minimum phase zero and the parameters is developed in this paper. This equation shows that the non-minimum phase zero arises from the competing heat and mass transfer dynamics, and is determined by the structural parameters and membrane properties. A sensitivity study is presented and shows that structural and material property optimization can be used with the control system design to mitigate the non-minimum phase behavior in the PEM fuel cell humidification system.

Effect of Bolts Locking Sequence on Flow-Channel Plate in Micro-PEMFC

2008 ◽  
Author(s):  
Chi-Hui Chien ◽  
Shih-Chun Li ◽  
Wei-Tsung Hsu ◽  
Chih-Wei Lin
Keyword(s):  
Fuel Cell ◽  
Three Dimensional ◽  
Deformation Mode ◽  
Pem Fuel Cell ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Flow Channel ◽  
Membrane Electrode ◽  
Cell Assembly ◽  
Channel Plate

The design and method of cell assembly play important roles in assessing the performance of PEM fuel cell. The cell assembly will affect the contact behavior between the bipolar plates, flow-channel plates, gas diffusion layers (GDLs) and membrane electrode assembly (MEA). From the past studies, it is noted that the flow-channel plates in the cell will be deformed while the cell was assembled by locking with bolts. This phenomenon may lead to leakage of fuels, high contact resistance and malfunctioning of the cells. The main aim of this research is to study the variation of the deformation mode of the flow-channel plat in a micro-PEM fuel cell assembly subjected to different bolts locking sequences. The commercial FEM package, ANSYS, was adopted to model the three-dimensional single micro-PEMFC FEM model and the numerical simulation analyses were performed. The effect of the bolts locking sequence on the deformations of flow-channel plate in the micro-PEMFC was presented.

Design Properties That Affect Controller Gain and Available Bandwidth of Non-Minimum Phase Membrane Humidifiers

2010 ◽  
Author(s):  
John F. Hall ◽  
Christine A. Mecklenborg ◽  
Dongmei Chen
Keyword(s):  
Membrane Properties ◽  
Minimum Phase ◽  
Available Bandwidth ◽  
Vapor Transfer ◽  
Control Gain ◽  
Controller Gain ◽  
The Impact ◽  
Competing Dynamics ◽  
Water Vapor Transfer ◽  
Zero Location

The water vapor transfer across a membrane exhibits non-minimum phase behavior. This paper shows that the competing dynamics of heat and mass transfer cause the membrane humidifier to have a non-minimum phase zero. Even though the non-minimum phase zero exists in the disturbance-output loop, it will limit the feedback controller gain because the disturbance-output loop is coupled with the input-output loop. The membrane properties and heat transfer parameters affect the non-minimum phase zero location. The impact on available feedback control gain and system bandwidth is analyzed in relation to changes of the non-minimum phase zero during hardware design.

PEM Fuel Cell Models Validation and Accuracy Analysis

2005 ◽  
Author(s):  
Qingyun Liu ◽  
Qiangu Yan ◽  
Junxiao Wu
Keyword(s):  
Fuel Cell ◽  
Diffusion Layer ◽  
Catalyst Layer ◽  
Pem Fuel Cell ◽  
Cell Plate ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Membrane Properties ◽  
Parameter Study ◽  
Fuel Cell Performance

A multi-resolution method is developed for the polymer electrolyte membrane (PEM) fuel cell simulation. A full 3D modeling is employed for membrane and diffusion layer, 1D+2D model is applied to the catalyst layer, that is, at each location of the fuel cell plate, the governing equations are integrated only in the direction perpendicular to the fuel cell plate; and a quasi-1D method with high numerical efficiency and reasonable accuracy is employed for the flow channels. The simulation accuracy was assessed in terms of fuel cell polarization curves and membrane ohmic overpotential. Overall, the agreements between simulated results and experimental data are good. However, at large current densities, when high relative humidity reactant inputs are employed, the simulation under predicts the fuel cell performance due to a single-phase assumption. The method slightly over predicts the fuel cell performance for a dry cathode input, possibly due to the nonlinearity of the membrane properties in dehydration case. Further, a parameter study was performed for a fully humidified cell and a relative dry cell. These parameters include porosity and permeability of gas diffusion layer; porosity, effective oxygen permeability, ratio of thickness of surrounding Nafion layer to exposed agglomerate area density and cathodic transfer coefficient of catalyst layer. Some insight can be obtained by examining their effects on the cell performances in order to further improve the model accuracy.

Sign in / Sign up

Export Citation Format

Share Document