Fuel Cells最新文献

As the flow field structure has a crucial influence on the performance of the proton exchange membrane fuel cell, in this research, the radial flow field R-0 is designed and optimized based on the characteristics of the annular serpentine and annular flow channels to form combined flow field structure (R-1 to R-5). Subsequently, a three-dimensional and two-phase model is established and the effects of each flow field on the cell performance are numerically investigated. Results indicate that the R-0 can enhance the gas vertical velocity on the diffusion-catalyst interface compared to the parallel flow field, which increases the effective concentration of reaction gases within the catalyst layer, thereby accelerating the electrochemical reaction rate, and the performance of the combined flow fields is further improved. In addition, the effect of the percentage of annular serpentine within the combined flow field on the concentration distribution, uniformity, and output performance is analyzed. Results indicate that increasing the percentage of annular serpentine structure can increase the pressure between adjacent channels, and thus the higher pressure and concentration gradient generated can enhance the gas transport and reduce the water accumulation under the ribs thus effectively improving the cell performance.

In this study, we developed a new technique, simultaneous foam electrospinning and electrospraying (FE/E), that produces nanofiber/nanoparticle electrodes at higher production rates compared to needle-based electrospinning and electrospraying (E/E). Herein, the nanofiber amount was precisely controlled by applying various voltages on the foam electrospinning process at a fixed platinum (Pt) loading, which enables an exclusive investigation into the impact of ionomer nanofiber on fuel cell performance at ultra-low Pt loadings for proton exchange membrane fuel cells. The results show that fuel cell performance is strongly dependent on ionomer nanofiber content. At 0.04 mg/cm² nanofiber amount, the electrodes exhibited the highest fuel cell power density of 1.09 W/cm² and Pt utilization of 11.5 kW/g_Pt, which are 28% and 39% higher than those of the electrode produced via electrospraying alone, respectively. The improvement results from enhanced proton and gas transport stemming from the nanofiber network as verified by cyclic voltammetry, electrochemical impedance spectroscopy, and oxygen gain voltage analysis. The FE/E technique provides a pathway to produce ultra-low Pt nanofiber/nanoparticle electrodes at high production rates and high fuel cell performance.

The treatment of high concentration and low C/N ratio of nitrate wastewater is a promising and challenging research topic. Combining electrochemical reduction and anammox is a technology with great development potential for nitrogen removal from wastewater. In this work, Cu─Ag─Co cathode materials were prepared by two-step electrodeposition method. The effect of current density and initial pH value on nitrate reduction efficiency was investigated in a single chamber electrolytic cell equipped with Cu─Ag─Co cathode and Ti/RuO₂─IrO₂ anode. The results showed that under the conditions of initial NO₃⁻─N concentration of 500 mg L⁻¹, Na₂SO₄ concentration of 0.125 mol L⁻¹, current density of 10 mA cm⁻², initial pH value of 7, and treatment time of 5 h, NO₃⁻─N removal ratio was 84.5%, the concentration of NO₂⁻─N and NH₄⁺─N was 180.2 mg L⁻¹ and 173.2 mg L⁻¹. Wastewater with a concentration ratio of NO₂⁻─N and NH₄⁺─N of 1.04:1 meets the influent requirements for anaerobic ammonia oxidation. Through the combination process, the final NO₃⁻─N removal ratio was 82.6%, the NO₂⁻─N concentration was 3.2 mg L⁻¹, and the NH₄⁺─N concentration was 26.4 mg L⁻¹. It provided a reference for the treatment of wastewater with low C/N ratio nitrate by combining electrochemical reduction and anammox.

Solid oxide fuel cell (SOFC) systems have become a research focus because of their clean and high-efficiency properties. Control of output voltage and fuel utilization is critical to the energy management for multi-energy systems incorporating SOFC energy supply. However, maintaining precise control of the system's voltage in the presence of perturbations can be challenging. Moreover, the system's voltage control process can lead to fuel utilization fluctuations, which may affect the economy and safety. The design of the controller must meet both of these requirements. The stringent control requirements lead to poor parameter adaptability of existing controllers. This paper designs a nonlinear function and adopts a nonlinear/linear active disturbance rejection controller (ADRC) based on state switching to solve the output voltage tracking control problem of SOFC and maintain the fuel utilization rate in the ideal range. The simulation experimental results show that the proposed method has the advantages of strong and superior parameter adaptability with less control effort, which provides theoretical guidance for the design of the output voltage controller of the actual SOFC system.

Fuel cell technology is a promising alternative to traditional internal combustion engines in various applications, especially in transportation applications. This paper proposes a framework of strategic energy management for fuel cell electric vehicles (FCEVs), which is developed to safeguard the dual vehicle energy sources, that is, fuel cells and power batteries. This is accomplished by applying an energy management strategy (EMS) from a prognostic perspective. A fuzzy energy management approach is used to manage the power flow in the FCEV, enabling safe and predefined operation at multiple degradation points. To guarantee reliable and continuous energy source functioning, prognostics algorithms are incorporated into the EMS to identify energy source degradation. The prediction results are integrated into the controller by refining the controller parameters geometrically. Simulation outcomes show that the proposed EMS offers efficient use the dual energy sources, which improves the durability of the energy sources.

In a polymer electrolyte membrane (PEM) fuel cell, the following degradation mechanisms are associated with the catalyst particles and their support: carbon support corrosion triggered by carbon and platinum oxidation, platinum dissolution with redeposition, and particle detachment with agglomeration. In this work, an electrochemical model for those degradation effects is presented as well as its coupling with a three-dimensional computational fluid dynamics PEM fuel cell performance model. The overall model is used to calculate polarization curves and current density distributions of a PEM fuel cell in a fresh and aged state as well as the degradation process during an accelerated stress test with 30 000 voltage cycles. The obtained simulation results are compared to measurements on a three-serpentine channel PEM fuel cell with an active area of 25 cm² under various temperatures and humidities. The experimental data are obtained with a segmented test cell using respective degradation protocols and test conditions proposed by the United States Department of Energy. In addition to the temperature and humidity changes, the influence of geometry and material parameters on the degree of degradation and the resulting fuel cell performance is explored in detail.