Mitigating Water Accumulation in Fuel Cells

Abstract The flow field in a proton exchange membrane fuel cell is essential for efficiently managing water removal, especially at high current densities. This study designs that facilitates removal and presents considerations its implementation. A 3-path serpentine channel has been adopted as the reference model. When contact resistance not considered, performance of check-pattern superior under all voltage conditions, with maximum increase 5.1 %. considering resistance, similar most conditions; however, densities, checked pattern exhibits performance, improving by 5 to 7.2 larger rib area hinders but reduces resistance. Therefore, should be designed both together.

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The air-cooled fuel cell is a promising energy conversion device. However, the characteristics of forced convection often rapidly expel water from gas diffusion layer (GDL) into flow field, which reduces humidity membrane electrode assembly (MEA). Under low-humidity conditions, proton conductivity exchange (PEM) decreases, thereby impairing performance and durability cell. Inspired by tortuous transport pathways in maze model, we designed GDL with maze-like structure (M-GDL) to extend path, increasing internal We evaporation test verify loss resistance GDL. M-GDL exhibits remarkable loss, rate 0.35 mg min-1 cm-2, significantly lower than 0.79 cm-2 observed for commercial This extended retention capability leads notable increase cell, peak power density 0.77 W more double that GDL, where only 0.4 cm-2. work presents strategy mitigate issue low cells.

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Cooling system for fuel cell systems that efficiently dissipates heat while humidifying the fuel cell gases. The system uses a gas separator to extract steam from the return line, feed it back into the fuel supply line, and a water feed device to compensate for the steam separation. This allows humidification without excessive water buildup. The steam extraction also reduces the amount of water needed in the supply line. The system can also condense exhaust steam and feed it back into the supply line.

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Fuel cell system with improved water management without separate blowers. It has a unique inlet area change part between the branch flow paths to the fuel cell stacks. This part allows selectively increasing/decreasing the inlet areas of the branch paths. By temporarily increasing the supply flow rate to the stacks, it mimics higher stoichiometric ratios to enhance water discharge. This reduces flooding and improves performance without separate blowers.

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Temperature gradients across the catalyst-coated membrane influence water accumulation in anode gas diffusion layer (GDL) of polymer electrolyte fuel cells, yet experimental investigations remain limited. This study systematically examines impact a through-plane temperature gradient on distribution using operando synchrotron X-ray radiography. Lowering relative to cathode causes increased saturation GDL. behavior is mainly due phase-transition effects, specifically enhanced condensation and suppressed evaporation. A 0.168 observed under-rib regions GDL, which relatively high compared commonly reported values. These findings support growing recognition that can occur under certain gradients, highlighting crucial role need for improved GDL designs effective management.

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Preventing water accumulation and freeze-ups between the internal and external airtight lines of a fuel cell stack by removing portions of the external airtight gasket around manifolds. This allows any water or gas that enters the closed space between the lines to drain out instead of stagnating. The internal gasket still seals the reactant flow paths. The cutouts in the external gasket prevent a closed space between the lines that can trap water and cause issues like corrosion, freezing, and inspection errors.

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Fuel cell system that maintains optimal humidity and temperature for stack operation by adjusting the humidity and airflow of external air supplied to the stack. The system has valves to control exhaust air recirculation, bypassing humidifier, and stack airflow based on sensed stack and external air conditions. It also compensates stack air pressure and adjusts recirculation based on stack and intake temperatures. This prevents flooding from over-humidified air and power loss from dry air while maintaining differential pressure.

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Abstract Efficient transport of liquid water within the cathode channel plays a pivotal role in enhancing management proton exchange membrane fuel cells (PEMFCs). Employing multiple relaxation time lattice Boltzmann method (MRT-LBM), simulations are carried out for droplet aggregation and emission processes on surface with polytetrafluoroethylene (PTFE) shedding ratios 0%, 20%, 40%. Through analysis temporal dynamic evolutions position, shape, as well resulting pressure difference flow channel, it is revealed that PTFE ratio increases, deformation droplets during process becomes smaller. However, discharge process, shape turns to be more unstable, leading smaller average greater resistance movement droplets. The cases 20% 40% increases by 33.758% 93.329%, respectively, compared case no shedding.

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The performance and durability of proton-exchange membrane fuel cells (PEMFCs) are dependent on flow, humidifying water, outgoing water management. Unlike conventional flow fields with linear channels, the complex 3D fieldfeaturing repeating baffles along channel, known as baffle designinduces a micro-scale interface flux between gas diffusion layer (GDL) fields. Thus, an intensive oxygen is created that removes excess from GDL, thereby improving cell efficiency. Another approach for channel design Turing field, which resembles organization fluid flows in natural objects such leaves, lungs, blood system. This enhances distribution inlet significantly compared traditional designs. present study aims to combine advantages both field designs provide model investigations influence mixed efficiency PEMFCs. It was established achieves highest electrode current density 1.2 A/cm2, outperforming other Specifically, it 20% improvement over design, reaching 1.0 A/cm2 generating three times more than delivers 0.4 A/cm2. In contrast, serpentine exhibit lowest density. provides better utiliz... Read More

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<div class="section abstract"><div class="htmlview paragraph">The utilization of hydrogen in low-temperature Proton Exchange Membrane Fuel Cells (PEMFCs) stands out as a compelling prospect for driving widespread shift towards green industry practices. Despite significant advancements, comprehensive understanding water behaviour and dynamics within PEMFCs remains crucial their extensive integration propulsion applications. Striking delicate balance between flooding drying conditions poses challenge achieving stable efficient PEMFC operation. In this study, preliminary experimental investigation was conducted focusing on carbon-paper Gas Diffusion Layer (GDL) gas channel walls. The static, advancing receding contact angles were measured utilized boundary simulations. influence membrane humidity also examined during the campaign. 3D CFD simulations performed straight portion with selected domain length 5 mm section 1x1 mm. Two classes droplets (0.05 mm<sup>3</sup> 0.075 mm<sup>3</sup>) deposited middle double GDL wall. To account difference angles, r... Read More

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Immersion cooling system with bellows to reduce volume and footprint while preventing liquid accumulation. The system has a tank with a headspace above the liquid. A bellows is gaseously coupled with the headspace below the bottom of the space. This bellows compresses/expands as the headspace pressure changes. It reduces the volume required for the headspace gas and condenses vapor to prevent liquid accumulation. A condenser removes heat from the bellows gas. A pump drains excess liquid. Heat sources heat the bellows. Insulation prevents condensation. Multiple bellows can be used inside/outside the tank.

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Cooling system for fuel cells in vehicles like aircraft that uses a two-phase coolant to reduce weight and size while providing more uniform cooling compared to air cooling. Water droplets are sprayed into the coolant airstream upstream of the fuel cell to absorb heat. The coolant then condenses water vapor downstream. This allows a smaller coolant flow rate since water's latent heat of vaporization absorbs more heat than air. The water can be recycled. The coolant circuit can have a PCM for evaporative cooling at lower pressures.

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Fire protection system and method for preventing condensation in fire suppression systems to avoid issues like mold, corrosion, or short circuits. The system uses a fuel cell to generate oxygen-reduced cathode exhaust gas. This gas is dried before entering the protected space. A control system checks the dew point and allows entry only if it's below a set threshold. This ensures the gas is dry enough for the protected space application.

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Fuel cell bipolar plate design with optimized flow channels to improve performance and reduce flooding. The plate has hybrid channels that combine parallel channels at the inlet and outlet with interwoven channels in the reaction region. The interwoven channels have primary and secondary channels that merge and have varying sizes. This flow pattern is optimized using topology optimization to balance flow resistance, uniformity, and water removal. The optimized channels facilitate clearance of water in the GDL under the ribs and force oxygen into the GDL.

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The accumulation of liquid water in the gas diffusion layer (GDL) and associated clogging reactant pathways are limiting factors for performance polymer electrolyte fuel cells (PEFC). design manufacturing GDLs with a deterministic pore space have potential to accelerate development next-generation PEFC an optimized balance between supply product removal. In this study, we explore tailored structures obtained from carbonization 3D-printed precursor. Three different GDL designs investigated by using operando X-ray radiography subsequent tomography track pathways. results confirm effectiveness designed features terms controlled percolation reveal trend toward vapor phase transport rather than away catalyst interface along strong convective flow within highly porous ordered structures.

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Proton Exchange Membrane Fuel Cells (PEMFCs) are considered a crucial technology for mitigating resource limitations and addressing environmental challenges. To improve the output power mass transfer characteristics of PEMFCs, this study developed three-dimensional (3D) model PEMFC with wedge-shaped flow field plate using computational fluid dynamics (CFD) methods. This focused on analyzing behavior thermal management reactants, as well investigating water removal capacity across different angular channel configurations. The results indicated that air intake modes combined channels affected within fuel cell. performance was most significantly when reaction gases flowed convectively. At tilt angle 18 voltage 0.25 V, maximum current density reached 1.9547 A/cm 2 , representing 24% increase compared to conventional parallel channel. Under these conditions, reactive were more uniformly distributed PEMFC. demonstrated new in generates high densities at larger angles lower voltages, improving oxygen distribution facilitating efficient liquid removal.

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Fuel production system that reduces water waste and prevents water vapor shortage in fuel cell electrolyzers. The system has gas-liquid separators before and after the electrolyzer. Water vapor from separated water and external sources is supplied to the electrolyzer along with the feed gas. This ensures sufficient water vapor for electrolysis even when feed water ratio varies. It also recycles water vapor instead of wasting it. The separator after the synthesizer further recycles water vapor.

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Method for operating a fuel cell system to precisely determine the optimal time to empty a water separator container without using a level sensor. The method involves recirculating anode gas, separating liquid water in a water separator, measuring hydrogen content downstream after purging, and detecting a delayed increase to indicate the container is full.

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<div class="section abstract"><div class="htmlview paragraph">The interplay of electrochemistry, two-phase flow, and heat transfer generates complex transport phenomena within the porous materials fuel cells that are not yet fully understood. This lack comprehensive understanding complicates modeling liquid water transport, which is critical because hydration polymer electrolyte membrane significantly impacts cell performance. The mechanisms in media can be explained by capillary force, hydraulic permeation gravity effects, as well condensation evaporation. In general, mainly driven while body forces, such gravity, do affect its momentum. Due to limited experimental data on pressure saturation gas diffusion media, Leverett approach has been widely used for PEMFCs. a polynomial fitting imbibition unconsolidated sand packs. nature, this may accurately predict media. Fuel GDM materials, naturally hydrophilic, typically coated with nonwetting like polytetrafluoroethylene create hydrophobic surfaces pores. resulting nature intermediate wettability due coexistence hydrophilic p... Read More

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Porous metal gas diffusion layer (GDL) for fuel cells with improved water management. The GDL has flow channels defined by walls with surfaces having the same porosity as the rest of the GDL. This prevents compression and porosity reduction during channel formation. The channels allow capillary water flow and film-wise condensation on superhydrophilic surfaces. This promotes uniform reactant distribution and water removal in fuel cells.

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