Real time power management strategy for fuel cell hybrid electric bus based on Lyapunov stability theorem

The fuel cell/battery durability and hybrid system stability are major considerations for the power management of fuel cell hybrid electric bus (FCHEB) operating on complicated driving conditions. In this paper, a real time nonlinear adaptive control (NAC) with stability analyze is formulated for power management of FCHEB. Firstly, the mathematical model of hybrid power system is analyzed, which is established for control-oriented design. Furthermore, the NAC-based strategy with quadratic Lyapunov function is set up to guarantee the stability of closed-loop power system, and the power split between fuel cell and battery is controlled with the durability consideration. Finally, two real-time power management strategies, state machine control (SMC) and fuzzy logic control (FLC), are implemented to evaluate the performance of NAC-based strategy, and the simulation results suggest that the guaranteed stability of NAC-based strategy can efficiently prolong fuel cell/battery lifespan and provide better fuel consumption economy for FCHEB.     

Electrooxidation reactions of methanol and ethanol on Pt–MoO3 for dual fuel cell applications

Pt–MoO₃ was synthesized by microwave-assisted chemical reduction. The physicochemical characterization showed that the electrocatalyst contained nanoparticles of Pt and clusters of MoO₃. The average particle size of the catalytic material was 2.5 nm. The electrochemical results showed that the Pt–MoO₃/C was suitable to carry out the electrooxidation reactions of ethanol and methanol indistinctly, avoiding CO poisoning. It was possible to compare the results with commercial Pt/C. The synthesized material showed a better electrochemical performance. Different simulations were performed using the Nernst equation to evaluate the influence of temperature, internal resistance, and the current density losses as a function of the fuel used. The theoretical results indicated that the electrical power of the mono-cell improves by 21.5% when the energy vector is changed from methanol to ethanol at the maximum power point, obtaining an electrical potential change ΔE = 87.02 mV and a variation of the electric power of Δp = 114.14 mW cm^?2. The use of dual fuels could improve the performance of experimental fuel cells.     

Investigation of liquid water heterogeneities in large area proton exchange membrane fuel cells using a Darcy two-phase flow model in a multiphysics code

Proper management of the liquid water and heat produced in proton exchange membrane (PEM) fuel cells remains crucial to increase both its performance and durability. In this study, a two-phase flow and multicomponent model, called two-fluid model, is developed in the commercial COMSOL Multiphysics® software to investigate the liquid water heterogeneities in large area PEM fuel cells, considering the real flow fields in the bipolar plate. A macroscopic pseudo-3D multi-layers approach has been chosen and generalized Darcy's relation is used both in the membrane-electrode assembly (MEA) and in the channel. The model considers two-phase flow and gas convection and diffusion coupled with electrochemistry and water transport through the membrane. The numerical results are compared to one-fluid model results and liquid water measurements obtained by neutron imaging for several operating conditions. Finally, according to the good agreement between the two-fluid and experimentation results, the numerical water distribution is examined in each component of the cell, exhibiting very heterogeneous water thickness over the cell surface.     

具有保护肠上皮细胞HT-29免受大肠杆菌和H2O2损伤潜力的植物乳杆菌的筛选

益生菌可在肠道定植从而发挥抗炎或抗氧化活性，有利于宿主肠道健康。本实验研究了从新疆传统发酵乳制品中分离得到的8?株植物乳杆菌对大肠杆菌侵袭和过氧化氢刺激肠上皮细胞HT-29的保护作用。结果表明：在8?株植物乳杆菌中，植物乳杆菌35具有最高的黏附能力。植物乳杆菌35可通过取代、竞争、排阻的方式抑制大肠杆菌对HT-29细胞的黏附，抑制率分别为42.60%、59.17%、60.19%。植物乳杆菌35及其多糖可抑制大肠杆菌刺激HT-29细胞产生白细胞介素-8；同时保护HT-29细胞免受过氧化氢的损伤，增加超氧化物歧化酶、谷胱甘肽过氧化物酶活力水平并降低丙二醛含量。结论：植物乳杆菌35及其粗胞外多糖具有抑制大肠杆菌O157诱导的炎症性肠病的潜力。     

Dynamic simulation and lifecycle assessment of hydrogen fuel cell electric vehicles considering various hydrogen production methods

In this research study, a real model of a hydrogen fuel cell vehicle is simulated using Simcenter Amesim software. The software used for vehicle simulation enabled dynamic simulation, resulting in more precise simulation. Furthermore, considering that fuel cell degradation is one of the significant challenges confronting fuel cell vehicle manufacturers, we examined the impact of fuel cell degradation on the performance of hydrogen vehicles. According to the findings, a hydrogen vehicle with a degraded fuel cell consumes 14.3% more fuel than a fresh fuel cell hydrogen vehicle. A comprehensive life cycle assessment (LCA) is also performed for the designed hydrogen vehicle. The results of the hydrogen vehicle life cycle assessment are compared with a gasoline vehicle to fully understand the effect of hydrogen vehicles in reducing air emissions. The methods considered for hydrogen production included natural gas reforming, electrolysis, and thermochemical water splitting method. Furthermore, because the source of electricity used for electrolysis has a significant impact on the life cycle emission of a hydrogen vehicle, three different power sources were considered in this assessment. Finally, while a hydrogen vehicle with a degraded fuel cell emits lower carbon dioxide (CO₂) than a gasoline vehicle, the emitted CO₂ from this vehicle using hydrogen from electrolysis is approximately 25% higher than that of a new hydrogen vehicle.     

Combined effect of channel to rib width ratio and gas diffusion layer deformation on high temperature – Polymer electrolyte membrane fuel cell performance

The present study investigates the combined influence of Channel to Rib Width (CRW) ratio and clamping pressure on the structure and performance of High Temperature-Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) using a three-dimensional numerical model developed previously. It also considers the impact of interfacial contact resistance between the Gas Diffusion Layer (GDL) and Bipolar Plate (BPP). The structural analysis of the single straight channel HT-PEMFC geometry shows that the von-Mises stress greatly increases in the GDL under the ribs as the CRW ratio increases resulting in considerably high deformation. The cell performance analysis depicts the significance of ohmic resistance and concentration polarization for different CRW ratios, particularly at higher operating current densities. However, in low to medium current density regions, the CRW ratio has little influence on cell performance. A substantial impact on the species, overpotential, and current distributions is observed. The findings also reveal that the CRW ratio significantly affects the temperature distribution in the cell.     

Manufacturing catalyst-coated membranes by ultrasonic spray deposition for PEMFC: Identification of key parameters and their impact on PEMFC performance

This study deals with the manufacturing of catalyst-coated membranes (CCMs) for newcomers in the field of coating. Although there are many studies on electrode ink composition for improving the performance of proton-exchange membrane fuel cells (PEMFCs), there are few papers dealing with electrode coating itself. Usually, it is a know-how that often remains secret and constitutes the added value of scientific teams or the business of industrialists. In this paper, we identify and clarify the role of key parameters to improve coating quality and also to correlate coating quality with fuel cell performance via polarization curves and electrochemical active surface area measurements. We found that the coating configurations can affect the performance of lab-made CCMs in PEMFCs. After the repeatability of the performance obtained by our coating method has been proved, we show that: (i) edge effects, due to mask shadowing - cannot be neglected when the active surface area is low, (ii) a heterogeneous thickness electrode produces performance lower than a homogeneous thickness electrode, and (iii) the origin and storage of platinum on carbon powders are a very important source of variability in the obtained results.     

β-FeOOH modified carbon monolith anode derived from wax gourd for microbial fuel cells

The preparation of high-performance anode materials is of significance for enhanced power generation in microbial fuel cells (MFCs). Herein, porous carbon monolith was prepared by simple freeze drying of wax gourd and subsequent pyrolysis (WGC). β-FeOOH was coated on WGC to further improve the performance of the anode (β-FeOOH/WGC). The maximum power density of the MFCs with WGC and β-FeOOH/WGC anode was 913.9 and 1355.1 mW/m² respectively, which was much higher than that of the control (558.2 mW/m²). WGC possessed three-dimensional pore structure, nitrogen and oxygen-containing functional groups, which endowed it with satisfactory bacterial loading. Improved MFC performance after β-FeOOH modification could be ascribed to two aspects: β-FeOOH enhanced the electrochemical activity and decrease the transfer resistance; β-FeOOH was conducive to exoelectrogens formation. This study demonstrated that the synthesis of β-FeOOH modified carbon monolith anode offered an efficient route to enhance the power generation of MFCs.     

Numerical simulation of a PEM fuel cell: Effect of tortuosity parameters on the construction of polarization curves

Fuel cells (PEMFCs) are considered a clean alternative for the production of electricity. To improve their efficiency, it is necessary to understand the transport phenomena that determine their performance. This work analyzes the effective diffusion coefficients in the gas diffusion and catalyst layers (GDL and CL, respectively) based on theories such as effective medium approximation and percolation theory of a 3D multiphase nonisothermal model of a single channel PEMFC. We calculate polarization curves with different effective diffusion models and tortuosity factors m, n using OpenFOAM. The best model that approaches to experimental data is the Tomadakis-Sotirchos model with n = 4.0. The exponent m that represents the tortuosity due to the geometry has a high impact on the polarization curve construction compared to the exponent n. High values of diffusibility do not mean high values of current densities showing that there are other phenomena involved, such as water flooding.     

A new signal processing-based islanding detection method using pyramidal algorithm with undecimated wavelet transform for distributed generators of hydrogen energy

Machine learning-based fault detection methods are frequently combined with wavelet transform (WT) to detect an unintentional islanding condition. In contrast to this condition, these methods have long detection and computation time. Thus, selecting a useful signal processing-based approach is required for reliable islanding detection, especially in real-time applications. This paper presents a new modified signal processing-based islanding detection method (IDM) for real-time applications of hydrogen energy-based distributed generators. In the study, a new IDM using a modified pyramidal algorithm approach with an undecimated wavelet transform (UWT) is presented. The proposed method is performed with different grid conditions with the presence of electric noise in real-time. Experimental results show that oscillations in the acquired signal can be reduced by the UWT, and noise sensitivity is lower than other WT-based methods. The non-detection zone is zero and the maximum detection and computational time is also 75 ms at a close power match.