Fuel Cells最新文献

The stabilized Bi₂O₃ electrolyte bilayer solid oxide fuel cells (SOFCs) are known as promising intermediate temperature SOFCs. However, it is necessary to develop a cost-effective method for manufacturing electrolyte bilayer SOFCs. In this study, atmospheric plasma spraying (APS) is employed to develop a facile method to deposit EWSB ((Bi₂O₃)_0.705(Er₂O₃)_0.245(WO₃)_0.05) and ScSZ ((Sc₂O₃)_0.1(Zr₂O₃)_0.9) electrolytes for assembling SOFCs with an EWSB/ScSZ bilayer structure. Results show that the maximum power density (MPD) of the electrolyte bilayer cell with 20 µm EWSB is increased by 52% compared with the monolayer ScSZ electrolyte cell at 750°C. The cell of electrolyte bilayer with a densified ScSZ presents open circuit voltage of ∼1 V and a remarkable performance enhancement with the MPDs of 1110 mW cm⁻² at 750°C and 581 mW cm⁻² at 650°C, being increased by 57% at 650°C compared with electrolyte bilayer cell with the as-sprayed ScSZ electrolyte. The dense ScSZ electrolyte effectively ensures the superior electrochemical performance and stability of EWSB at the interface between electrolytes of EWSB/ScSZ bilayer cell.

Nanofluids exhibit higher thermal performance than conventional fluids and are preferred as cooling fluids in thermal management of polymer electrolyte membrane (PEM) fuel cells. In order for a nanofluid to be used in PEM fuel cell cooling, it should have high stability, high heat removal performance, and low electrical conductivity (EC). In this study, the utilization of Fe₃O₄-water nanofluid in PEM fuel cell cooling was investigated using a novel technique that considered all three of these features into account. The nanofluid was synthesized in varying mass ratios of 0.1%–0.5% and its thermophysical properties, EC, and zeta potential were measured. According to the findings, when EC and stability were taken into account, the pH value of the Fe₃O₄-water nanofluid should exceed 7. The thermal performance of the nanofluids was assessed using the performance evaluation ratio (PER), Mouromtseff number (Mo), and h_r under both laminar and turbulent flow conditions. A maximum heat transfer improvement of 19% for laminar and 18% for turbulent flow conditions was achieved at a mass ratio of 0.4%. In addition, an artificial neural network (R² = 0.9999, MSE = 0.000944) was used to model the EC. For the first time in the literature, a correlation was proposed to predict the EC of a nanofluid on the basis of pH and mass ratios.

The proton exchange membrane fuel cell (PEMFC) employs lightweight metallic bipolar plates (BPP) with a 0.2 mm thickness, offering a sustainable and recyclable energy solution. These plates are essential for distributing gases through flow channels, conducting electricity, and managing heat transfer while balancing cost-efficiency, lightweight properties, and durability for practical applications. Electromagnetic forming (EMF) is a high-speed, noncontact manufacturing technique that ensures uniform pressure distribution without lubricants and uses a single coil and power supply to produce BPP with intricate patterns, enabling the creation of complex, sharp-edged components with precision. This study investigates the impact of key parameters, such as discharging voltages (10 000, 11 000, and 12 000 V) and capacitor bank energy levels, using a 25 000 J EMF machine to fabricate copper-based BPP. Copper's high conductivity supports magnetic fields, Lorentz forces, and eddy currents, which are critical as electric currents flow through the workpiece during EMF. A novel EMF-based approach is also introduced to manufacture metallic BPP with superior quality and dimensional accuracy in flow field channels, offering significant advantages over traditional methods. This innovative technique, leveraging the unique benefits of EMF, will be discussed in detail, highlighting its potential to transform BPP production for enhanced efficiency and performance.

To alleviate water flooding in cathode electrodes of polymer electrolyte fuel cells (PEFCs), it is necessary to understand the water transport inside diffusion media and design the electrode/channel structure for facilitating the water discharge from porous electrodes to gas channels. The authors proposed the novel modified structure combining the electrode perforation with the channel hydrophilization in their previous study and revealed that its structure has the possibility of encouraging the through-plane water removal from the diffusion media and the oxygen diffusivity to the reaction sites. This study investigated the effects of perforation size and cell compression on the water transport in the cathode diffusion media of the structure-modified cell using x-ray radiography. The constant current operation tests were also conducted to characterize the cell performance. It was shown that the 300 µm perforation and low compression have a large effect on encouraging the in-plane water drainage from the diffusion media to the groove or hole, resulting in reducing the voltage loss due to the water flooding. This innovative structural modification can be put to practical use because of its simple manufacturing process and low cost.

It is widely recognized that direct internal reforming (DIR) solid oxide fuel cells (SOFCs) fueled by biomass are one of the eco-friendly and high-power generation methods. In existing cell configurations, however, the performance and durability degradation of SOFCs are induced by a strong endothermic dry reforming of methane (DRM). They are required to understand the fundamental thermal distribution mechanism and construct new cell configurations to relax thermal distribution effects. We performed a three-dimensional thermal distribution analysis coupled with computational fluid dynamics and chemical reactions in DIR-SOFCs with the three-cell stacking reactor model as a more practical model. As a result of the simulation for temperature distribution in each case of homogeneous and functionally graded paper structure catalysts (PSCs), we have found that the largest temperature drop occurs near the inlet in the bottom layer compared with the upper and middle layers in both cases and temperature distribution is milder in the functionally graded PSC. We also have found the importance of two-dimensional reaction rate controls in gas flow and cell staking directions to uniform temperature distribution of each layer. Furthermore, we investigated the effects of exothermic electrochemical reaction in the anode on thermal distribution.

The performance degradation of proton exchange membrane fuel cells (PEMFC) in low-temperature extreme environments is one of the challenges on the way to their commercialization, and it is important to investigate the performance changes of fuel cells in low-temperature environments for their future development. In this paper, the cold-start performance of fuel cells with different initial water content of the membrane and starting modes was compared. Lowering the initial water content of the membrane could enhance the water storage capacity of the cell and improve the cold-starting performance of the cell, but infinitely low initial water content might cause the reverse polarity phenomenon, which would cause serious corrosion and degradation of the membrane electrode assembly (MEA). In constant voltage starting mode, reducing the starting voltage could increase the heat production of the cell, but it would weaken the water storage capacity of the cell. In the constant current starting process, lowering the starting current could improve the water storage capacity of the cell, which was beneficial to the cold start of the cell. It was also found that the MEA with cold start failure had a serious performance degradation, and cold start failure needed to be avoided as much as possible.

This study presents an integrated heat recovery-proton exchange membrane (IHR-PEM) fuel cell system designed for lightweight vehicles powered by a 2 kW PEM fuel cell. The IHR system captures waste heat through multiple heat exchangers and integrates thermoelectric generator (TEG) modules for electrical regeneration and hydrogen preheating, enhancing PEM fuel cell performance. Utilizing the temperature gradient between the fuel cell's exhaust and the ambient environment, the system effectively converts waste heat into electrical energy, improving energy efficiency. Experimental evaluation under various operating parameters, including cruising speeds, PEM fuel cell loads, rejuvenation conditions, and electrical regeneration strategies, demonstrated the system's effectiveness. Results revealed waste heat absorption of up to 8.5 W and hydrogen preheating by 19°C, leading to an 11.5% increase in electrical power production and a maximum PEM fuel cell efficiency improvement of 11%. This study advances waste heat recovery (WHR) technologies in fuel cell-based transportation, significantly improving energy efficiency and reducing carbon emissions. The findings provide valuable insights into the integration of regenerative WHR systems for lightweight vehicles, fostering the development of sustainable and energy-efficient transportation solutions.