Hydrogen Flow Optimization in Fuel Cells

This study investigates the structure of a metal hydride (MH) cartridge as hydrogen storage tank for small-scale fuel cells (FCs). is designed to be stacked and used in layers, allowing flexible capacity adjustment according demand. MH enables compact safe cell (FC) applications due its high energy density low-pressure operation. However, because desorption from an endothermic reaction, external heat supply required stable performance. To enhance both transfer efficiency usability, we propose method that utilizes waste air-cooled proton-exchange membrane (PEMFC). The proposed incorporates four cylindrical tanks require uniform transfer. Therefore, arrangements within minimize non-uniformity distribution on surface. flow exhaust air PEMFC into was analyzed using computational fluid dynamics (CFD) simulations. In addition, empirical correlation Nusselt number developed estimate coefficient. As result, it concluded utilization rate flowing 13.2%.

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A system and process for efficiently converting liquid hydrogen to gaseous hydrogen for fuel applications while minimizing hydrogen losses. The system uses thermal compression to compress the hydrogen from liquid to high pressure without mechanical compressors. It involves transferring hydrogen between reservoirs at different pressures and temperatures to optimize compression efficiency. The steps include cooling liquid hydrogen, transferring it to a lower pressure reservoir, then heating it to compress it. This cycle can be repeated in multiple reservoirs to achieve multiple compression stages. By using the cold energy from higher pressure reservoirs to compress lower pressure ones, the process is more efficient than mechanical compressors.

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Enhancing energy efficiency is essential for proton exchange membrane fuel cells (PEMFCs) operating in a dead-ended anode (DEA) mode. This study proposes the integration of buffer tank, positioned between mass flow meter and cell, to reduce hydrogen loss during purge events. The tank stores when valve closed releases it opens, thereby stabilizing pressure, minimizing waste, improving overall system efficiency. effectiveness experimentally evaluated under varying load currents, supply pressures, intervals, durations. objective determine optimal duration that maximizes efficiency, both with without tank. results show consistently improves Under conditions (0.1 bar, 8 A, 0.1 s duration, 20 interval), increases by 3.3%. non-optimal 1 improvement reaches 71.9%, demonstrating tanks performance across wide range conditions.

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Fuel cell system with electrochemical fuel recovery that extracts unused fuel from the exhaust to improve overall fuel utilization efficiency. The system has a fuel cell stack, an electrochemical pump separator containing an anode, cathode, and electrolyte, a fuel exhaust line connecting to the anode, and a product line connecting to the cathode. The exhaust fuel is pumped back to the fuel inlet using the electrochemical pump separator. This recovers unused fuel from the exhaust and sends it back for reuse in the stack, improving overall fuel utilization compared to just venting the exhaust.

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Separator design for electrochemical devices like fuel cells and batteries that improves performance by providing optimized flow paths for fluid flow. The separator has streamlined walls with non-parallel end segments that connect the inlet and outlet. This shape reduces pressure drop, improves flow efficiency, and provides a large contact area between the fluid and the separator walls. The streamlined walls alternate between protrusions in a direction perpendicular to the flow direction.

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A nozzle assembly for combustion chambers of engines, like hydrogen fuel cell engines, with a unique design to optimize fuel injection and mixing. The nozzle has a central fuel pipe that seals against air ingress. Fuel flows into the pipe through a reservoir and multiple openings. This allows even distribution of fuel into the pipe. The pipe has a flow body to improve fuel flow homogeneity. Radially offset air-guiding ducts create an air flow around the fuel at the nozzle exit, drawing it outward and forming a recirculation zone for fuel-air mixing.

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Hydrogen generation system with improved efficiency by bypassing a portion of the air flow to the stack and using it to cool the hydrogen product instead. This allows reducing the air flow through the recuperator and heater, lowering their power requirements. The bypassed air cools the product stream without overheating it, preventing damage to the hydrogen processor. The remaining air still goes through the recuperator and heater to supply oxygen for the stack.

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Cryostorage system for hydrogen fuel cells that allows filling and extraction from the inner tank without external equipment like blowers. The system has a cryocontainer with an inner tank and outer container. A cryopump inside the inner tank extracts liquid/gaseous hydrogen for the fuel cell at higher pressure. Filling is via an interface that bypasses the pump. It uses a valve in the fill line to divert filling into the inner tank or through the pump. This allows filling via the pump's extract line without pumping. A shuttle valve switches between pump and fill line access. A return line from the fuel cell pumps hydrogen back into the inner tank. This maintains inner tank pressure for future fillings.

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Mobility with hydrogen fuel cells that limits power during refueling to prevent pressure drops that could restrict hydrogen flow to the fuel cell. When entering refueling mode, the storage vessel pressure is lowered to prevent hydrogen supply pressure from dropping below the fuel cell's needs. If the hydrogen pressure is below the target during refueling, power is limited. This prevents pressure drops from vaporizing hydrogen and reducing refueling capacity. The user is notified of power limits to understand why.

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Fuel cell stack design with parallel feed gas flow for improved performance and stack compression. The fuel cell stack has fuel cells where the anode or cathode has an extended edge seal chamber that receives and outputs the feed gas in a direction parallel to the other gas flow. This allows the anode and cathode feed gases to flow parallel through the stack instead of perpendular. This provides a one-dimensional current distribution and temperature gradient, avoiding hot corners and stack distortion.

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Controlling a fuel cell system with a mixed gas fuel tank to accurately estimate the hydrogen composition of the mixed gas for optimal fuel cell operation. The method involves estimating the hydrogen composition by solving simultaneous equations with unknowns like fuel flow rate and air flow rates to the combustor. Equations represent relationships between air flow, exhaust gas oxygen and temperature. This allows calculating hydrogen composition without knowing it initially. The estimated hydrogen composition is then used to set the fuel cell fuel flow rate.

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Fuel cell separator design to prevent gasket burrs and improve gas flow for better performance. The separator has a reaction region with manifolds around it, one of which is for reaction gas intake. Holes connect the intake manifold to the reaction region. An inlet flow field plate replaces the traditional gasket support. This prevents blockages while maintaining pressure. The plate forms a smooth gas flow path between the holes and reaction region.

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Hydrogen purification system with improved efficiency by periodically increasing and decreasing the pressure of the anode in the hydrogen purification module. This removes trapped gases and moisture from the anode flow path to improve hydrogen purification. A pressure control unit connects to the anode outlet and a control unit opens/closes it. Increasing anode pressure >0.04 bar helps hydrogen diffusion and decreasing removes trapped gases.

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A hydrogen supply system for fuel cells that allows reusing excess hydrogen gas that wasn't consumed in the fuel cell, preventing wasteful release into the atmosphere. The system has multiple hydrogen tanks connected to the fuel cell via supply paths. Some tanks are reserve tanks connected to the supply paths via recovery paths. When the fuel cell doesn't use all the hydrogen, the excess goes to the reserves instead of venting. This allows reusing unused hydrogen from the reserves later.

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Abstract This study investigates the thermal behavior of polymer electrolyte membrane (PEM) fuel cells using hydrogen and methanol fuels. An extensive 3D model was constructed for simulation temperature, current density, efficiency distribution, with Nafion EW1100 membranes under high-temperature conditions COMSOL Multiphysics. Moreover, this highlights essential connection between temperature profiles performance entire cell. However, at a given voltage 0.4 V 0.8 V, consistently operated lower temperatures Gas Diffusion Layer (GDL), Electrode (GDE), PEM compared to fuel. For instance, 4-5 K than that hydrogen, difference increased 4-6 K. The differential is indicative hydrogen's ability manipulate its heat-generating dissipating processes more efficiently PET. demonstrates hydrogens advantages over other because density correlates temperature. all temperatures, provides higher densities hydrogen-methanol, supporting usefulness in improving cell efficiency. management not only improves but also prolongs PEM, GDL, GDE life by decreasing stress. Hence, from analysis, it shown contri... Read More

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The effect of electrolyte binders (ionomers) in the anode catalyst layer (ACL) on chemical degradation rate polymer membranes (PEMs) fuel cells was examined a single cell with an accelerated stress test (AST) at 90 C, while H 2 O formation rates, j (H ), and activities for hydrogen oxidation reaction (HOR) ionomer-covered Pt/C catalysts were measured half 0.1 M HClO 4 solution 80 C. A sulfonated polyphenylene (SPP-QP) conventional Nafion used as ionomer PEM. It demonstrated that PEM decreased remarkably use SPP-QP together lower Pt-loading carbon support. suppression via specific adsorption Pt its low permeability contributed to longer lifetime AST.

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Minimizing fuel cell stack degradation and efficiently satisfying the required output of the stack by employing an air recirculation valve and a hydrogen recirculation pump. The fuel cell system has separate air and hydrogen supply lines. It recirculates some of the air and hydrogen from the cathode and anode back into the stack. The recirculation flow rates are controlled based on stack output voltage and current. This helps balance cell pressures and prevent voltage/current imbalances that cause stack degradation when output is low.

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A fuel cell flushing system and method to remove nitrogen from the fuel cell stack without restarting the fuel cell. The system uses the fuel supply valve and hydrogen line purge valve to change hydrogen flow velocity. First, adjust hydrogen pressure in the supply line. Then, open supply valve and cut off purge valve to increase flow. This flushes nitrogen from the cell without restarting.

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Hydrogen fuel cell system with improved performance and reliability through pulsed jet recirculation and pulse width modulated (PWM) injectors. The system reduces hydrogen pressure from high to medium using pulsed injectors instead of mechanical pressure reducers. This provides better control, stability, and controllability. The pulsed injectors have discrete open and closed states. PWM control allows adjusting recirculation rate by pulse width. This pulsed recirculation improves efficiency and stability compared to continuous recirculation. The pulsed injectors also have lower stress and longer life than continuous valves.

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Improving hydrogen utilization in fuel cell systems by decoupling the pressure and hydrogen flow control of the anode purge valves. The method involves determining compensation values for adjusting the proportional valve opening and tail exhaust valve closing to compensate for the influence of one variable on the other. By using these compensated values instead of the original openings, stable anode pressure can be achieved while mitigating hydrogen waste during purge cycles. This allows single variable control of both pressure and utilization instead of the coupled multi-variable control.

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