Mitigating Water Accumulation in Fuel Cells

As polymer electrolyte membrane (PEM) fuel cells progress toward widespread commercialization for automotive applications, achieving enhanced durability heavy-duty vehicle (HDV) use becomes a critical challenge. The urgency of this advancement arises from the increasing demand lightweight, material-efficient, and sustainable energy systems to support zero-emission transportation, where PEM present distinct advantages over traditional battery systems. Among technical hurdles, effective water management is paramount ensuring reliable prolonged operation cells, particularly under high-stress conditions characteristic HDV applications. electrode assembly (MEA), functional core cell, consists two electrodes (anode cathode) separated by Nafion-based ionomer sandwiched between gas diffusion layers (GDLs) on both sides. Key electrochemical processes, including hydrogen oxidation reaction (HOR) at anode oxygen reduction (ORR) cathode, produce as byproduct. To sustain performance prevent degradation, must be efficiently removed avoid accumulation flooding, which could otherwise compromise cell... Read More

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Method for preventing condensate buildup in fuel cell systems used in vehicles like utility vehicles. The method involves injecting dry compressed air from the vehicle's existing compressed air supply into the cathode flow path of the fuel cell system. This displaces any moisture, like condensate, in the air and cathode off-gas, preventing it from accumulating in components like expander stages, bearings, and condensate separators. The compressed air injection is done before starting or after stopping the fuel cell components to dry them out.

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Fuel cell vehicle cooling method that improves evaporative cooling efficiency using recovered condensed water. The method involves spraying condensed water from the fuel cell onto the radiator to cool it. The amount sprayed is initially set based on the fuel cell load. If recovery exceeds evaporation, the spray amount is reduced. If recovery is low, it is increased. This matches the spray to the evaporative efficiency based on recovery feedback. This prevents wasting water and maximizes evaporative cooling efficiency.

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Fuel cells, as one of the most promising alternatives to lithium-ion batteries for portable power systems, still face significant challenges. A critical issue is their substantial performance degradation under low-humidity conditions. To address this, researchers commonly add silica components. This study employs a control variable method systematically investigate impact four parametersgas stoichiometry, temperature, humidity, and contenton fuel cell performance. Initially, effects gas humidity on were examined. Subsequently, hydrophilic was incorporated into membrane electrode assembly (MEA) assess its potential improving in environments. Experimental results reveal that 100% humidification, addition had minimal performance, particularly at high temperatures where improved by only 2.5%. attributed increased water production elevated temperatures, whichwhen combined with silicas retention propertiesexacerbates flooding. However, when reduced 50%, incorporation significantly enhanced At resulted 126.2% improvement, demonstrating efficacy rational strategy

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Condensate water storage device for fuel cell systems in applications like construction vehicles where the condensate water discharge needs to be controlled to prevent contamination and accidents. The device has a storage container with a valve that can be selectively opened to discharge the condensate water. The valve is moved by a driving source outside the container. This allows controlling whether the condensate water is discharged or stays in the container. The valve can have seals and elastic members to prevent leaks. The container can also have overflow holes to prevent overfilling.

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Turbomachine for fuel cell systems with an expander wheel and an air bearing to support the rotor shaft. A flow generator is placed in the flow path between the expander wheel and the air bearing. It generates an air flow towards the expander wheel based on rotor shaft speed. This prevents water condensate from entering the air bearing. As the turbomachine speed increases, the flow generator pushes more air to the expander wheel to counteract the positive pressure there. This avoids water ingress into the bearing as it's already spinning fast enough to generate sufficient air flow.

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Abstract Polymer electrolyte fuel cells (PEFCs) face significant challenges during cold starts, where water phase transitions affect critically cell performance. While previous studies have primarily focused on ice formation and melting behavior, the impact of condensation after breaking through freezing point remains insufficiently understood. In this study, we apply operando synchrotron X-ray computed tomography to visualize transient behavior in a PEFC under three different relative humidity (RH) conditions heating/cooling cycle simulating real-world cold-start conditions. The results revealed localized flooding hysteresis phase. A quantitative layer-by-layer analysis shows that accumulation each component layer strongly depends both RH thermal process. Moderate promote efficient vapor-phase transport minimize while avoiding membrane dehydration. These findings highlight as key factor influencing performance provide new insights into management for more robust strategies toward next-generation systems.

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Cooling system for fuel cells in vehicles like aircraft that uses water droplets sprayed into the air cooling the fuel cell to absorb heat. The water droplets evaporate, absorbing more heat than air alone. After the fuel cell, a condenser removes moisture from the air and returns it to the sprayer. This provides more effective cooling with less airflow. It also uses a PCM coolant in the fuel cell channels that evaporates partway to further absorb heat. This allows using smaller cooling components.

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Water extraction system for a fuel cell stack to extract water from the exhaust flow and provide it back to the fuel cell stack to maintain hydration levels. The system uses a condenser to cool the exhaust, an extractor to remove water, a turbine to extract energy from the dehumidified exhaust, and a reheater to transfer heat from the turbine exhaust back to the dehumidified exhaust. This allows extracting water, extracting energy, and transferring heat in a closed loop.

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<title>Abstract</title> In a Proton Exchange Membrane Fuel Cell (PEMFC), the geometry of flow channels plays critical role in mass transport, electrochemical current distribution, and water management. The objective this study is to investigate effect obstacle aspect ratio (AR) cathode channel on cell performance under various operating conditions (temperature 333363 K, pressure 14 atm, anode/cathode relative humidity 0100%). To end, three-dimensional numerical model was developed, governing equations for species energy, electric were solved using computational fluid dynamics (CFD) with finite-volume method. geometric parameters included AR = 0 1 rectangular obstacles both anode channels, boundary corresponding temperature, pressure, simulated independently. results showed that intermediate-sized 0.250.50 significantly enhance oxygen transport reduce concentration losses; example, at mid-range temperatures (343353 K) pressures 12 power density increased by more than 20%. Specifically, 343 K 0.75, rose from 0.3769 0.5289 W/cm. At higher (34 atm), however, be... Read More

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A condensate water drain control system for fuel cells that can accurately drain condensate water from the fuel cell stack even when the water level sensor fails. The system estimates the fuel cell's chemical reaction amount and opens the drain valve based on that. When the valve is open, it closes it again based on the fuel supply state to prevent over-draining. This allows condensate drainage without relying on the sensor.

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&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;This study presents a novel biomimetic flow-field concept that integrates triply periodic minimal surface (TPMS) porous architectures with hierarchical leaf-vein-inspired distribution zone, fabricated through 3D printing. By mimicking natural transport systems, the proposed design enhances oxygen delivery and water removal in proton exchange membrane fuel cells (PEMFCs). The results showed &lt;b&gt;&lt;i&gt;I&lt;/i&gt;&lt;/b&gt;-FF &lt;b&gt;&lt;i&gt;G&lt;/i&gt;&lt;/b&gt;-FF significantly improved mass management compared to conventional CPFF. integrated &lt;b&gt;&lt;i&gt;I&lt;/i&gt;&lt;/b&gt;-FF-LDZ achieves up 32% improvement power density at 1.85 &lt;b&gt;&lt;i&gt;A&lt;/i&gt;&lt;/b&gt;/&lt;b&gt;&lt;i&gt;cm&lt;/i&gt;&lt;/b&gt;&lt;sup&gt;&lt;b&gt;2&lt;/b&gt;&lt;/sup&gt;@0.4 V delays onset of losses. also reveals optimizing volume fraction &lt;b&gt;&lt;i&gt;V&lt;/i&gt;&lt;/b&gt;&lt;sub&gt;&lt;b&gt;&lt;i&gt;f&lt;/i&gt;&lt;/b&gt;&lt;/sub&gt; affects gas penetration, lower (30%) improving performance mass-limited r... Read More

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A fuel cell exhaust system that efficiently separates water from the exhaust gas without additional flow obstructions. The system has a condenser to condense water vapor from the exhaust and a separator with a curved channel surrounded by a chamber. The chamber collects condensed water as it flows through the channel due to centrifugal and gravitational forces. This eliminates the need for further water separation measures in the fuel cell exhaust system.

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This study investigates the effects of anode and cathode inlet flow rates () on power performance bipolar plates in a polymer electrolyte membrane fuel cell (PEMFC). The primary objective is to derive optimal rate conditions by comparatively analyzing concentration loss IV curve crossover phenomena at anode, thereby establishing that prevent reactant depletion water flooding. A single-cell computational model was constructed assembling commercial plate with gas diffusion layer (GDL), catalyst (CL), proton exchange (PEM). simulates current density generated electrochemical oxidation-reduction reactions. Hydrogen oxygen were supplied 1:3 ratio under five proportional conditions: hydrogen (mH2 = 0.763.77 LPM) (mO2 2.3911.94 LPM). ButlerVolmer equation employed voltage drop due overpotential, while numerical simulations incorporated contact resistivity, surface permeability, porous media properties. Simulation results demonstrated 24.40% increase when raising mH2 from 2.26 3.02 LPM mO2 7.17 9.56 LPM. Further increases 3.77 11.94 yielded 10.20% improvement, indicati... Read More

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Closed loop cooling system for fuel cell stacks that enables efficient water management and cooling without the need for external water injection or exchange columns. The system recycles water from the fuel cell exhaust streams to cool the stack and maintain hydration. It uses a controller to automatically manage the water injection and removal based on stack conditions. This allows optimized water management for performance and reduces contamination compared to external water injection. The controller calculates the water balance and adjusts injection based on stack water generation, stack temperature, and cooling needs.

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Real-time monitoring of water flooding in fuel cells using optical imaging and machine learning to predict cathode pressure drops. The system involves capturing high-speed images of the cathode backing layer during operation and using computer vision techniques to detect water droplets as anomalous pixels surrounded by humidity. A mask is applied to ignore background noise and separate water droplets inside each channel. Machine learning models are trained to predict cathode pressure using the extracted water features. This allows real-time monitoring of water flooding without extensive resources and equipment, as well as estimating the effect of water flooding on oxygen pressure.

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Abstract The porosity of the Gas Diffusion Layer (GDL) has an impact on mass transport within Proton Exchange Membrane Fuel Cells (PEMFC), thus affecting output performance cells. In this research, a three-dimensional (3D) geometric model PEMFC with two-channel serpentine flow field at anode and seven-channel sinusoidal cathode was created. also considered water mechanisms in electrolyte phase change between surrounding pores. Simulations were conducted for GDL porosities 50%, 40%, 30%, 20%, 10%, respectively. results show that medium to high current density range, significantly affects cell performance. As increases, uniformity distribution membrane is enhanced. Under given voltage condition, increasing leads higher power output. Compared 50% peak 40% greater.

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Overhumidification is a critical challenge to the performance and durability of polymer electrolyte fuel cells (PEFCs). This review evaluates current methods for detecting quantifying overhumidification, focusing on simulation, imaging, sensor technologies. Each method assessed based five key criteria: precision, sensitivity, realtime capability, interpretation complexity, validation strength. Physically grounded modeling approaches such as computational fluid dynamics lattice Boltzmann offer high accuracy but are computationally demanding. Imaging techniques, including neutron imaging magnetic resonance provide valuable insight face limitations regarding scalability application. Sensor technologies, from commercial sensors artificial intelligenceenhanced nanostructured platforms, enable monitoring require improved robustness under operando conditions. By comparing these techniques individually collectively, this identifies promising hybrid strategies outlines research priorities achieving intelligent, water management in PEFCs.

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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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&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;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&lt;sup&gt;3&lt;/sup&gt; 0.075 mm&lt;sup&gt;3&lt;/sup&gt;) 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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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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&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;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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Unitized fuel cell stack design with internal water drainage to prevent flooding of the cell reaction area. The design involves a 3D-printed frame around the cell components that has integrated drainage channels. The frame is made of multiple sheets bonded together to form a discharge flow field inside the frame. This allows water generated during cell operation to flow out and prevent it from pooling on the cell components. The frame also has through-holes to connect the drainage channels to the cell manifold ports for water removal.

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A fuel cell system anode gas recirculation device with integrated water separation and cooling for the blower motor. The device has a blower with a rotor wheel, motor, and delivery channel to recirculate anode gas. The blower motor cooling channel surrounds the motor and connects to a condensate drain channel below. A valve in the drain channel allows controlled discharge of separated water. This integrates water separation, motor cooling, and condensate management in the blower housing.

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Fuel cell system that suppresses white smoke in the exhaust to reduce visibility issues when the system is installed in public areas. The system mixes exhaust gas with air in a mixing section to dilute it. This diluted exhaust is then discharged. A water receiver collects condensed water formed by the exhaust condensation. A drainage section empties the receiver to prevent flooding.

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Fuel cell device with improved water management to prevent mixing of condensed water and rainwater. The device has separate chambers for collecting condensed water from exhaust and rainwater entering through the exhaust port. An intermediate chamber between the chambers prevents mixing. This allows efficient condensed water recovery without contamination.

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Fuel cell system with multiple water drainage locations to allow reliable water removal from the fuel cell stack regardless of vehicle orientation. The system has two water collection areas, one for normal operation and one for uphill operation. It has valves to close and open the drains based on learned liquid levels and orientation. This allows water to be removed from both areas during operation. It also allows purging gas through the secondary drain when the primary one is blocked.

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Fuel cell device with integrated evaporative cooling to simplify cooling and eliminate external water needs. The fuel cell exhaust air contains water from the reaction. This water is collected and reused to cool the fuel cell by a dedicated evaporative cooler. A water separator removes excess water from the exhaust, which is then fed to the cooler. This closed loop prevents freezing in cold temperatures by recycling the water from the exhaust instead of needing external water. The evaporative cooler avoids the need for a separate external water source for cooling.

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Fuel cell system with improved condensate management to prevent flooding and improve reliability. The system has a drain valve to remove condensate from the fuel cell stack, an inlet port in the humidifier to suck condensate from the drain valve, and a negative pressure application unit in the humidifier to create suction at the inlet port. This allows condensate to be sucked from the drain valve and supplied to the humidifier without needing a separate pump. The negative pressure is generated by surrounding the inlet port with a housing and guide port to direct airflow. The negative pressure area is defined between the outlet port and negative pressure application hole.

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A fuel cell system with an integrated humidification and water replenishment method that addresses the issue of low humidity in fuel cell air supply. The system uses exhaust gas from the fuel cell stack to humidify the intake air. It collects exhaust gas moisture in a tank, feeds it to an atomizer to humidify the intake air, and separates the moisture from the exhaust gas. This allows sufficient humidification without external humidifiers. The system also has a water replenishment method that optimizes liquid levels in the tank based on stack operation. It replenishes water when levels are low and stops when full. This prevents dehydration during stack shutdowns.

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Stack structure for fuel cells that improves stack performance by preventing low cell voltage and flooding issues. The stack has a stack body with true cells connected by channels, and false cells at the ends. The false cells have channels connected to the main channels. A water guide plate collects condensation from the air inlet channels and directs it to the false cell channels. This prevents water flooding the true cells and reduces stack temperature gradients. The false cells also improve stack temperature uniformity by cooling the stack body through channels connected to the coolant inlet/outlet.

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Fuel cell system with improved humidification to extend operating limits without increasing complexity. It recycles water from the anode outlet to humidify the oxidant line. A water detection unit measures the anode water flow to optimize cathode humidification. This prevents dehydration of the membrane and cathode entry area, especially at high temperatures or altitudes.

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Fuel cell system with active humidification to precisely control humidity for optimal fuel cell performance. The system has a dedicated module to collect water discharged from the cathode and a humidification module to use that water to humidify intake air. A control module adjusts the water injection based on target humidity, environment, and stack data. This allows real-time optimization of humidity levels inside the fuel cell stack. An impedance spectrometer measures stack humidity to further refine the control.

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Improving water management in the cathode catalytic layer of proton exchange membrane fuel cells (PEMFCs) to enhance performance and durability. The technique involves creating a three-layer structure with a hydrophilic-hydrophobic gradient in the cathode catalytic layer. The layers are prepared using catalyst slurries with different sulfonated perfluorosulfonic acid resins having varying water contents. A hydrophilic layer close to the membrane is made with a low EW (equivalent weight) resin, a hydrophobic layer near the gas diffusion layer is made with a high EW resin, and an intermediate layer uses a mixture of resins with varying EW. This gradient helps balance water retention and distribution in the cathode catalytic layer for better fuel cell performance and longevity.

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Fuel cell system with improved humidification for high load conditions that reduces cost and size compared to conventional humidifiers. The system has a conventional humidifier with water-permeable membranes to transfer moisture from exhaust to supply air. But it also has an additional moisture return path with a water separator, collector, and injector. Exhaust air is separated to remove water droplets, then stored temporarily. This separated moisture can then be injected into the supply air for humidification. This allows the conventional humidifier to be sized for nominal load rather than peak load, reducing cost and size. The additional moisture return provides supplemental humidification for high load conditions.

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