Novel Design of Fuel Cell Bipolar for Optimal Uniform Delivery of Reactant Gases and Efficient Water Removal

The flow plate (20) defines stems (76), branches (78), and sub-branches (80) for moving fluid between each of the openings (34, 36) and the active area (42). The openings (34, 36) are trifurcated into two branches (78) and one stem (76) for providing flow of fluid through each of the stems (76) equal to the combined flow through co-diverging of the branches (78). The stems (76) have a minimal cross-sectional flow area less than the combined minimal cross-sectional flow area of the co-diverging of the branches (78). The stems (76) are bifurcated into two branches (78). The branches (78) have a uni form branch width (W) and are bifurcated into two sub branches (80). The active area (42) includes manifolds (46. 48) and active channels (50, 52) extending therebetween. Each of the sub-branches (80) is in fluid communication with one of the manifolds (46, 48). Each of the manifolds (46. 48) is trifurcated into three active channels (50, 52) for evenly distributing fluid between the openings (34,36) and the channels

Experimental Evaluation of a Control Strategy for Real-Time Optimization of Low Temperature PEM Fuel Cell Stack

A robust control strategy which ensures optimum performance is crucial to proton exchange membrane (PEM) fuel cell development. In a PEM fuel cell stack, the primary control variables are the reactant’s stochiometric ratio, membrane’s relative humidity and operating pressure of the anode and cathode. In this study, a 5 kW (25-cell) PEM fuel cell stack is experimentally evaluated under various operating conditions. Using the extensive experimental data of voltage-current characteristics, a feed forward control strategy based on a 3D surface map of cathode pressure, current density and membrane humidity at different operating voltages is developed. The effectiveness of the feed forward control strategy is tested on the Green-light testing facility. To reduce the dependence on predetermined system parameters, real-time optimization based on extremum seeking algorithm is proposed to control the air flow rate into the cathode of the PEM fuel cell stack. The quantitative results obtained from the experiments show good potential towards achieving effective control of PEM fuel cell stack

Experimental Evaluation of a Control Strategy for Real-Time Optimization of Low Temperature PEM Fuel Cell Stack

A robust control strategy which ensures optimum performance is crucial to proton exchange membrane (PEM) fuel cell development. In a PEM fuel cell stack, the primary control variables are the reactant’s stochiometric ratio, membrane’s relative humidity and operating pressure of the anode and cathode. In this study, a 5 kW (25-cell) PEM fuel cell stack is experimentally evaluated under various operating conditions. Using the extensive experimental data of voltage-current characteristics, a feed forward control strategy based on a 3D surface map of cathode pressure, current density and membrane humidity at different operating voltages is developed. The effectiveness of the feed forward control strategy is tested on the Green-light testing facility. To reduce the dependence on predetermined system parameters, real-time optimization based on extremum seeking algorithm is proposed to control the air flow rate into the cathode of the PEM fuel cell stack. The quantitative results obtained from the experiments show good potential towards achieving effective control of PEM fuel cell stack

CFD Modeling of a Catalytic Flat Plate Fuel Reformer for Hydrogen Generation

In this study, steam reforming of methane coupled with methane catalytic combustion in a catalytic plate reactor is studied using a two-dimensional mathematical model for co-current flow arrangement. A two-dimensional approach makes the model more realistic by increasing its capability to capture the effect of parameters such as catalyst thickness, reaction rates, inlet temperature and velocity, and channel height, and eliminates the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. In our work, we simulate the entire flat plate reformer (both reforming side and combustion side) and carry out parametric studies related to channel height, inlet velocities, and catalyst layer thickness that can provide guidance for the practical implementation of such design. The operating conditions chosen make possible a comparison of the catalytic plate reactor and catalytic combustion analysis with the conventional steam reformer. The CFD results obtained in this study will be very helpful to understand the optimization of design parameters to build a first generation prototype

Synthesis and Characterization of a Composite Membrane for Polymer Electrolyte Fuel Cell

A new proton exchange membrane (PEM) has been fabricated using a novel patented polymer structure modification technology. It has been shown that the new membrane has a higher proton transfer rate and lower resistance as compared to Nafion (R). This paper discusses issues related to membrane fabrication and testing procedures. (i) A brief fabrication procedure of PEM is outlined. The fabrication technique used here separates the proton exchange and structural requirements of the PEM allowing greater flexibility in membrane design. The proton exchange material developed herein is a terpolymer composed of various ratios of acrylic acid, styrene, and vinylsulfonic acid. Following a patented polymer structure modification technology, these materials were bound to an ethylene-tetrafluoroethylene copolymer mesh that had been rendered adhesive by hydroxylation in a two-step water-borne process. (ii) A previously developed theoretical model is used to calculate the relative resistance and proton transfer rate. According to the model, a simple second order differential equation describes the entire process and established a relationship between the membrane resistance and the total time taken for a specific amount of protons to pass through it. Finally, (iii) a simple two-cell experimental procedure is developed to calculate the relative membrane resistance and proton transfer capacity. The results show that theoretical predictions are in excellent agreement with the experimental observations. The new membrane could transfer protons approximately 80% faster than Nafion (R) per unit area under the test conditions utilized. Membrane resistance is also 71% lower compared to Nafion (R). These results suggest that there is now a new route of fabricating cost effective proton exchange membranes for fuel cell applications wherein one may focus more on the proton exchange capacity of the membrane allowing the structural properties of the membrane to be considered separately