Fuel cell hardware

Single cells with active areas of 5 to 50 cm are often used to evaluate the performance and durability of MEAs. The result represents the average performance of the entire cell. For cells with active areas of around 5 cm, the flow rates of the reactants are very low at a given stoichiometry, and may not be easy to control accurately. Very often, a constant flow rate of a few times stoichiometry corresponding to the highest current density is used. In such cases, mass transport resistance is made artificially low and does not represent the situation in which a constant stoichiometry is used for the entire current density region. 

In any design, the flow and distribution of the reaetants should mimie those of non-segmented eells. The results can be used to guide the fine tuning of the flow-fields so that a more uniform performance among different regions is achieved. The results can also be used to validate or invalidate or to improve mathematical models. 

Since a single cell can generate only a voltage less than 1 V, many unit cells are typically electrically connected in series to form a stack. The number of cells in a stack will determine the output voltage and power from the stack. 

The number of unit cells in a stack can range from 2 to hundreds. The stack has inlet and outlet manifolds for the anode reactant, the cathode reactant, and the coolant. The inlet manifolds allow the reactant (or coolant) equal opportunity to get to the inlet region of each unit cell. This helps minimize flie uneven distribution of the reactant among different cells. 

Uneven distribution of reaetant among eells is often caused by the aeeumulation of water droplets within the flow-field channels. If water aeeumulates within the ehannels of a unit cell, it will pose a higher resistance to the flow of the reaetant. This eauses the cell to reeeive a smaller amount of the reactant, which in turn carries a smaller amount of water out of the channels. These two events reinforce each other, and eventually could result in the flow of the reactant into this cell being less flian the stoichiometric amount, and reactant starvation occurs. Starvation of the luel can quickly damage the cell. Once a single cell is damaged, flie entire stack may have to be replaced. 

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The schematic of the electrolyser system is shown in Figure 1. A 5-cm2 PEM fuel cell hardware (Electrochem Inc.) was employed as an electrolytic cell. To perform electrolysis, the aqueous solution of CuCl (0.2 M) mixed with aqueous HC1 (2 M) was supplied from Reservoir 1 to the anode of the electrolyser via Pump 1. The aqueous HC1 solution (2 M) was supplied from Reservoir 2 to the cathode of the electrolyser via Pump 2. The hydrogen-producing electrolysis reaction was driven by an external applied voltage in the range 0.35-0.9 V. 

Within the realm of BAM2G membranes, a series of partially fluorinated bisphenol A-type poly(arylether) sulfones were synthesized. As mentioned above, these materials initially exhibited acceptable, useful service-life performance, but were unable to provide more than 500 h of continuous running time. This led to the decision that a perfluorinated backbone would be most beneficial in achieving fuel cell longevity in performance and efficiency. Therefore, the a, 3,p-trifluorostyrene monomer was chosen as the most suitable platform on which to build BAM3G polymers [98]. The BAM3G has demonstrated over 100,000 h of cumulative performance in a wide variety of Ballard fuel cell hardware. The BAM3G membranes have... 

It is worth noting that the hot-pressing process is not necessary for some kinds of MEAs. For example, when a CCM is used in a fuel cell, the CCM can be put direetly between two pieces of GDL and assembled into the fuel cell hardware. 

Abstract Whereas much attention has been paid to the environmental aspects of the life cycle of fuel cell fuel production, emphasis is placed on fuel cell hardware and materials recovery, including component reuse, remanufacturing, materials recycling and energy recovery for fuel cell maintenance and retirement processes. Fuel cell hardware recycling is described and issues related to the recycling infrastructure and the compatibihty of fuel cell hardware and materials are discussed. The role of materials selection and recovery in the fuel cell hfe cycle is described. Future trends for fuel cells centered on voluntary and mandatory recovery and the movement of life cycle considerations from computational research laboratories to design complete the discussion. 

Fuel cell hardware recycling promises to be an important environmental aspect of mass-produced systems. In recovery, materials are collected and separated before being reused, remanufactured, recycled or used for energy recovery, as follows ... 

The relationship between cell voltage and current density can be measured using fuel cell hardware a typical schematic polarization curve is shown in Fig. 1.4. It can be seen that there are four losses in the whole current density range (1) the OCV loss caused by H2 crossover and cathode mixed potential. 

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