固体氧化物直接碳燃料电池的模型计算

直接碳燃料电池(DCFC)是直接以碳或煤为燃料的燃料电池。本文以一种以固体氧化物为电解质的固定床直接碳燃料电池为对象,基于文献中的实验数据,建立了物理模型和数学方程,求解出电池在三个特定温度下的Ⅴ-Ⅰ曲线以及能量转换效率,并与文献中的实验结果进行对照,验证了对固定床直接碳燃料电池的反应过程的假设,分析了电池性能的影响因素,为直接碳燃料电池的应用打下了理论基础。

基于实测数据的车载燃料电池电堆模型的快速构建

本文通过分析燃料电池电堆运行特性,搭建了包含参数提取功能的电堆模型,对一个完整运行周期的燃料电池发动机实际运行报文进行特性参数的自动提取,快速准确的得到基于实测数据的燃料电池电堆模型。实验导入了一段某款车载60kW氢燃料电池发动机实际运行报文,模型自动提取特性参数,仿真结果符合预期。

基于最小二乘法的PEMFC电堆模型参数辨识

质子交换膜燃料电池(PEMFC)电堆的优化控制需要精确的电堆模型和参数。该文基于半经验机理模型,根据PEMFC电堆输出特性经验公式以及电化学、热力学原理建立电堆输出电压的机理模型,采用线性回归最小二乘法进行模型参数辨识。仿真实验辨识结果的误差分析表明,其电堆模型参数辨识精度满足控制要求,验证了所提方法的有效性和可行性。

微电源建模及其在微电网仿真中的应用

为节能减排的需要,微电网开始进入人们的视野。通过MATLAB/Simulink软件搭建光伏电池模型、简化燃料电池模型以及柴油发电机模型等微电源的Simulink模型,并利用MATLAB自带的风机模型一起,构建简单的微电网模型。对严重故障情况下该微电网系统故障恢复能力和维持电能质量能力进行仿真试验,结果表明所建微电源及微电网模型都能较好模拟实际运行情况,为微电网的进一步研究提供了仿真平台。

微电网的建模仿真研究

研究微电网的建模仿真问题,针对微电网中的微电源种类多样且输出特性各异,由传统的简易微电源模型所构成的微电网平台很难对现今微电网的研究进行仿真。针对以上情况,构建了结构、功能完整的风电机组、燃料电池、带有MPPT(最大功率点跟踪)光伏电池以及柴油发电机等微电源模型,及具有调频作用的二次负载模型,仿真验证了所建模型的合理性及有效性。在此基础上,又构建了一个含多种能源负荷的微型电网模型,对负荷突变及严重故障的条件下微电网维持电能质量和快速恢复的能力予以评估,结果表明所构建的微电源模型和微电网模型能较好地仿真实际情况,为微电网的进一步研究提供了良好的仿真平台。

Simulation of the Internal Transport Phenomena for PEM Fuel Cells with Different Modes of Flow

A numerical model for proton exchange membrane (PEM) fuel cell is developed, which can simulate such basic transport phenomena as gas-liquid two-phase flow in a working fuel cell. Boundary conditions for both the conventional and the interdigitated modes of flow are presented on a three-dimensional basis. Numerical techniques for this model are discussed in detail. Validation shows good agreement between simulating results and experimental data. Furthermore, internal transport phenomena are discussed and compared for PEM fuel cells with conventional and interdigitated flows. It is found that the dead-ended structure of an interdigitated flow does increase the oxygen mass fraction and decrease the liquid water saturation in the gas diffusion layer as compared to the conventional mode of flow. However, the cathode humidification is important for an interdigitated flow to acquire better performance than a conventional flow fuel cell.

车用燃料电池系统建模及参数辨识

高效可靠的控制单元是燃料电池高性能、长寿命工作的关键,而一个可以准确描述燃料电池动态特性的系统模型则是控制策略实施的前提。针对燃料电池系统的空气供给系统,介绍了一种由阴极腔体和各辅助组件组成的集总参数动态模型,基于工况数据利用非线性最小二乘法对模型进行参数辨识;同时,建立燃料电池输出电压模型,采用混合遗传粒子群优化算法辨识电压模型参数,最终实验证明模型稳态输出误差在4%以内,可满足在线反馈控制应用。

Efficient Thickness of Solid Oxide Fuel Cell Composite Electrode

The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.

A model and simulation of cathode flooding and drying on unsteady proton exchange membrane fuel cell

A water balance has a significant impact on the overall system performance in proton exchange membrane fuel cell.An actual fuel cell application has a dynamic electrical load which means also dynamic electrical current.Therefore,since this electrical current is known,the water production from the fuel cell reaction is also able to be predicted.As long as the fuel cell water transportation model is provided,the present liquid water inside the porous medium is also able to be modeled.A model of the liquid water saturation level in a fuel cell in unsteady load condition was proposed.This model is a series of the water transportation model of water saturation level for the final output of proton exchange membrane(PEM) fuel cell to predict the flooding or drying of PEM fuel cell.The simulation of vehicle fuel cell in different dynamic load profiles and different inlet air conditions was done using this model.The simulation result shows that PEM fuel cell with different dynamic load profiles has different liquid water saturation level profiles.This means that a dynamic load fuel cell requires also a dynamic input air humidification.

One-dimensional Dynamic Modeling and Simulation of a Planar Direct Internal Reforming Solid Oxide Fuel Cell

This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell （DIR-SOFC） comprehensively. A one-dimensional dynamic model of a planar D1R-SOFC is first developed based on mass and energy balances, and electrochemical principles. Further, a solution strategy is presented to solve the model, and the International Energy Agency （IEA） benchmark test is used to validate the model. Then, through model-based simulations, the steady-state performance of a co-flow planar DIR-SOFC under specified initial operating conditions and its dynamic response to introduced operating parameter disturbances are studied. The dynamic responses of important SOFC variables, such as cell temperature, current density, and cell voltage are all investigated when the SOFC is subjected to the step-changes in various operating parameters including both the load current and the inlet fuel and air flow rates. The results indicate that the rapid dynamics of the current density and the cell voltage are mainly influenced by the gas composition, particularly the H2 molar fraction in anode gas channels, while their slow dynamics are both dominated by the SOLID （including the PEN and interconnects） temperature. As the load current increases, the SOLID temperature and the maximum SOLID temperature gradient both increase, and thereby, the cell breakdown is apt to occur because of excessive thermal stresses. Changing the inlet fuel flow rate might lead to the change in the anode gas composition and the consequent change in the current density distribution and cell voltage. The inlet air flow rate has a great impact on the cell temperature distribution along the cell, and thus, is a suitable manipulated variable to control the cell temperature.

Modeling and control of a small solar fuel cell hybrid energy system

This paper describes a solar photovoltaic fuel cell (PVEC) hybrid generation system consisting of a photovoltaic (PV) generator, a proton exchange membrane fuel cell (PEMFC), an electrolyser, a supercapacitor, a storage gas tank and power conditioning unit (PCU). The load is supplied from the PV generator with a fuel cell working in parallel. Excess PV energy when available is converted to hydrogen using an electrolyser for later use in the fuel cell. The individual mathematical model for each component is presented. Control strategy for the system is described. MATLAB/Simulink is used for the simulation of this highly nonlinear hybrid energy system. The simulation results are shown in the paper.

New hybrid model of proton exchange membrane fuel cell

Model and simulation are good tools for design optimization of fuel cell systems. This paper proposes a new hybrid model of proton exchange membrane fuel cell (PEMFC). The hybrid model includes physical component and black-box com-ponent. The physical component represents the well-known part of PEMFC, while artificial neural network (ANN) component estimates the poorly known part of PEMFC. The ANN model can compensate the performance of the physical model. This hybrid model is implemented on Matlab/Simulink software. The hybrid model shows better accuracy than that of the physical model and ANN model. Simulation results suggest that the hybrid model can be used as a suitable and accurate model for PEMFC.

Research on the Model Emulator and Experiment Checkout of the Fuel Cell

In this paper a fuel cell emulator model suitable for each fuel cell type and power level is proposed. A power interface to the electronic load and a digital section are provided. The fuel cell steady-state, dynamic and thermal behaviour is modeled by the digital controller. The emulator architecture is deeply analyzed and remarks on hardware implementation algorithms are provided for further applications. The system is tested on a 10 W Proton Exchange Membrane （PEM） fuel cell and the high accuracy of the proposed emulator is shown by the comparison between experimental and simulation results.

Simulation and optimization of SOFC-BCHP system

As the prime motor of dispersed energy system, the high-temperature solid oxide fuel cells (SOFC) are high efficient with large heat recovery. This study presents a simulation of SOFC building-based cooling, heat and power (BCHP) system, which can meet basic requirements in power and heating (cooling) of the designated customers. The peak power load can be met by power grid, while the peak heating (cooling) load requirement can be met by backup equipments. In order to solve the economic dispatch problem of the energy system, a restricted nonlinear optimization model has been developed. The production costs can be minimized via both the equality constraints of customer’s heat and power demands, and other inequality constrains of equipments’ capacities. The sequential quadratic programming method has been used to search the solution. The study indicates that the model can be used to optimize the system’s capacities and run strategy. An office building case has been computed, and it is indicated that the model can be served in design and optimization of SOFC-BCHP system.

Dynamic Modeling of Tubular SOFC for Marine Power System

Solid oxide fuel cell (SOFC) has been identified as an effective and clean alternative choice for marine power system.This paper emphasizes on the dynamic modeling of SOFC power system and its performance based upon marine operating circumstance.A SOFC power system model has been provided considering thermodynamic and electrochemical reaction mechanism.Subcomponents of lithium ion battery, power conditioning unit, stack structure and controller are integrated in the model.The dynamic response of the system is identified according to the inertia of its subcomponent and controller.Validation of the whole system simulation at steady state and transit period are presented, concerning the effects of thermo inertia, control strategy and seagoing environment.The simulation results show reasonable accuracy compare with lab test.The models can be used to predict performance of a SOFC power system and identify the system response when part of the component parameter is adjusted.

Polymer Electrolyte Fuel Cell Stack Modelling in VHDL-AMS Language with Temporal and EIS Experimental Validations

This paper deals with two basic issues of fuel cell research： modelling and experimental validation. In particular, the EIS （electrochemical impedance spectroscopy） technique is applied to a PEMFC （proton exchange membrane fuel cell）. Experiments have been performed using a low-cost test bench and instrumentation developed around a 1,200 W Ballard Nexa fuel cell system. An electrical and dynamic model in VHDL-AMS language for PEM fuel cell stack is described. The privileged approach in this paper is an electrical method. Few papers deal with the modelling of a fuel cell in VHDL-AMS language with an electric approach. The fuel cell is characterised cell wise in VHDL-AMS; AC and DC measurements show the good agreement between the simulation results of the model and those measured in experiments. The model is capable to predict accurate stack profiles. The model is validated using temporal and impedance spectroscopy method; the impedance spectroscopy is performed at low and high frequencies. The experimental and simulated Nyquist plots show that the frequency response of the fuel cell stack can be predicted by the proposed fuel cell stack model. At high frequencies, comparisons between experimental and model impedance results are performed and show some similarities between the two Nyquist. Error between the two approaches is below 1.5%.

Process Flow Model of Combined High Temperature Fuel Cell Operated with Mixture of Methane and Hydrogen

One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.

Vehicles PEMFC Power System Mathematical Model for Integrated Design

In this paper, the mathematical dynamical model of a PEMFC （proton exchange membrane fuel cells） stack, integrated with an automotive synchronous electrical power drive, developed in Matlab environment, is shown. Lots of simulations have been executed in many load conditions. In this paper, the load conditions regarding an electrical vehicle for disabled people is reported. The innovation in this field concerns the integration, in the PEMFC stack mathematical dynamic model, of a synchronous electrical power drive for automotive purposes. Goal of the simulator design has been to create an useful tool which is able to evaluate the behaviour of the whole system so as to optimize the components choose. As regards the simulations with a synchronous electrical power drive, the complete mathematical model allows to evaluate the PEMFC stack performances and electrochemical efficiency.

Numerical Modeling and Investigation of PEM Fuel Cell for Performance Augmentation

Fuel cell is an important promised source of clean renewable energy that is being under extensive scientific investigation and developments. One important type of fuel cells is PEM （proton exchange membrane fuel cell）, which is considered in this study. Specifically, this study aimed at building-up of mathematical computerized model to simulate the stages of PEM fuel cell and to investigate the effects of cell design and operation parameters on its general performance. These include membrane thickness, cell area, hydrogen pressure and ionic current density. One-dimensional model has been introduced and appealed to analyze the effects of PEM fuel cell parameters on its overall performance. The results demonstrate that the cell power （and electrical efficiency） reduces as the thickness of cell membrane gets larger. Moreover, the peak point of cell power gets its maximum value at membrane thickness of 0.005 cm and its minimum value at 0.05 cm. However, the optimum value for ionic current density to get relative high cell power and electrical efficiency is equal 0.81 A/cm^2. These findings enhance research efforts toward new design and materials of PEM fuel cell.

Performance of a Double Catalyst Fuel Cell Cathode with a Tubular Oxygen Breathing and Preliminary Reduction Zone

This paper discusses a mathematical model for a liquid phase reacting flow occurring at the cathode of a patent pending novel fuel cell geometry, where a non homogeneous catalysis carried by gold and Prussian Blue, with the first reducing air O2 and the second the resulting H2O2. The breathing zone is porous walls microtubes, with three different types of pores in its walls. Inside the microtubes there is water solution of sulfuric acid. The microtubes possess an external layer of extremely porous polymer hydrophobic agent. A Prussian Blue thin porous layer is over the selective membrane. Appropriate porous and tubular connecting elements close the fluid loop. The asymmetry induces proper current and electric potential profiles, which leads to a mainly electrocapillary electrokinetic flow, which enhances the oxygen transport and assures the H2O2 flow to its reduction layer.