全钒液流电堆换热器顺/逆流效率研究

全钒液流电池(VRFB)的电堆内部工作温度不仅影响反应速度,而且影响电解液和膜的电导率、充电时间和循环能源效率,对电池的性能影响很大。VRB系统在实际应用中为了更好地控制温度,通过安装强制冷却装置如换热器进行温度调节,因此换热器的很多参数需进行优化设计。本文主要对控制电堆温度的换热器模块进行顺流和逆流下的效率分析,运用热力学理论,依据钒电池的热力学属性,通过Matlab/Simulink搭建VRB电堆热力学模型;在热力学定律的基础上研究电堆温度与时间函数的热模型,建立ε与传热单元数、冷热流体温度、传热功率参数之间的函数关系,分析在给定传热系数的条件下换热器效率优化,实现对电堆温度更好地控制,为电堆的实际运用提供设计参考。     

基于FBG阵列的光伏电池板表面温度场测量与研究

针对光伏电池板表面温度场检测问题,该文使用空分复用与波分复用相结合的技术,提出了一种基于FBG阵列的光伏电池板表面温度场测量系统。该系统可在复杂环境下实现对光伏电池板表面温度的实时多点监测。同时,实验研究了光伏电池板表面温度场变化规律与太阳辐射功率之间的关系。实验结果表明,光伏电池板表面温度、环境温度与太阳能辐射功率变化情况基本相同。正常工作的光伏电池正面温度略高于背面,发生热斑故障的光伏电池背面温度略高于正面温度。该系统提高了光伏组件温度的测量效率,也为其它领域的表面温度场测量提供了借鉴和参考。此外,依据实验所得数据,可进一步优化和改进光伏电池板冷却方式,对于改善发电性能具有重要意义。     

空冷型质子交换膜燃料电池电堆温度控制系统设计

空冷型质子交换膜燃料电池（Air-Cooling PEMFC）电堆的工作条件中,电堆温度对电堆性能的影响最大,电堆温度的控制直接影响电堆的性能指标。首先分析了空冷型PEMFC电堆的温度特性,通过实验手段获得了电堆的最佳工作温度-电流曲线,并拟合出了经验公式。在此基础上设计了该类电堆的温度控制系统,提出了模糊PID融合控制算法。实验结果表明该温度控制系统具有良好的静态和动态特性,有效地解决了空冷型PEMFC电堆的温度控制问题。     

水冷型PEMFC温湿度建模与智能控制

当负载电流一定时,质子交换膜燃料电池(PEMFC)的工作温度和质子膜的相对湿度是影响电池输出性能的主要因素。分析电池电流密度与最优工作温湿度的关系,建立基于温湿度耦合模型的最优温湿度操作条件的电压模型。通过对冷却水流量和阴阳极气体加湿度进行综合控制,保持电堆的工作温湿度在最佳状态,不仅保证了电池最优的输出性能,还可以延长其使用寿命。根据仿真试验结果比较可以看到,所建立的温湿度模型能够有效降低温湿度之间的耦合作用,设计的变论域模糊比例积分微分(PID)温度控制器和反向传播(BP)神经网络湿度控制器能够快速地响应负载电流的变化,明显减少进气气体湿度以及电堆出口冷却水温度的调节时间和超调量,具有更准确的控制精度。     

导弹热电池温度测量系统

本文介绍了能实现与导弹热电池放电同步进行的表面温度自动测量系统。该测量系统具有实现方便、数据可靠的特点,能完成各种型号导弹热电池表面温度的性能测试,并能实时显示温度采样曲线,为实现温度测量自动化提供了一种可行的方案。     

导弹热电池温度测量系统

本文介绍了能实现与导弹热电池放电同步进行的表面温度自动测量系统.该测量系统具有实现方便、数据可靠的特点,能完成各种型号导弹热电池表面温度的性能测试,并能实时显示温度采样曲线,为实现温度测量自动化提供了一种可行的方案.     

基于Fluent的微型直接甲醇燃料电池阳极流场结构分析

微型直接甲醇燃料电池中阳极流场结构对电池的性能有着重要的影响。为了合理设计阳极流场结构,改善甲醇燃料在阳极流场中的分布,采用计算流体动力学(CFD)软件Fluent对微型直接甲醇燃料电池进行建模并仿真分析。分析比较了点型、平行和蛇形3种不同流场图案下得到的压降与流速分布,得出蛇形流场能够更有利于甲醇燃料的均匀分配。在此基础上分别建立不同流道宽度(800,400,200,100μm)的蛇形流场模型,通过仿真计算甲醇燃料的分布情况来分析其对燃料电池性能的影响,并结合实验结果进行对比得出流道宽度为200～400μm之间为优化值。     

质子交换膜燃料电池建模与动态仿真

对质子交换膜燃料电池（PEMFC）电堆进行电输出特性研究,有助于改善燃料电池的设计,提高其性能。运用MATLAB的Simulink仿真工具对PEMFC建立仿真模型,通过所建立的电堆参数模型,就能够研究主要运行参变量对电堆动态输出性能和电堆非线性内阻产生的影响。当电堆输出电流出现阶跃变化时,对电堆电压,输出功率,消耗功率,电堆效率,非线性内阻的动态响应,进行了仿真和结果分析。仿真结果符合文献[7]实验数据,表明此参数模型是可操作和有效的,并可方便地用于PEMFC控制方法研究。     

基于LabVIEW的PEMFC特性研究

空冷型质子交换膜燃料电池(PEMFC)的氢气流量、氢气压力、环境温度等参数对电堆的发电性能影响较大。首先通过实验,研究了电堆最佳工作温度的确定方法和输出电压特性,其次采用了广义多项式拟合以及一维插值的方法,获得了它们的描述公式,最后,基于LabVIEW设计了电堆温度和输出电压的特性研究软件,软件仿真结果与实验数据拟合精度较高,为研究PEMFC系统提供了一种切实有效的方法。     

卫星电池组温度监测系统

卫星电池组温度监测系统。该系统由计算机控制,在不同充电和放电条件下,监测电池组每节电池的温度,进行电池性能评估,优选出温度一致性高的电池,用于卫星供电。该系统已经成功应用于清华大学微小卫星的电池性能评估和优选中。     

Control of the mass and energy dynamics of polybenzimidazole-membrane fuel cells

The dynamic modes related to mass and energy of a high-temperature proton-exchange-membrane fuel cell are investigated. For a particular configuration, three lumped-parameters dynamic equations are considered to represent hydrogen pressure in the anode, oxygen fraction in the cathode, and stack temperature. For each of these, a simple controller algorithm is developed. These algorithms are tested against a standard driving cycle for vehicles, and are found to be able to maintain the necessary conditions for the fuel cell stack to operate. It is possible to control temperature by using only air cooling, without significant additional requirements on air flow manipulation.     

Nano-structured solid oxide fuel cell design with superior power output at high and intermediate operation temperatures

A solid oxide fuel cell (SOFC) with a thin-film yttria-stabilized zirconia (YSZ) electrolyte was developed and tested. This novel SOFC shows a similar multilayer set-up as other current anode-supported SOFCs and is composed of a Ni/8YSZ anode, a gas-tight 8YSZ electrolyte layer, a dense Sr-diffusion barrier layer and a LSCF cathode. To increase the power density and lower the SOFC operating temperature, the thickness of the electrolyte layer was reduced from around 10 μm in current cells to 1 μm, using a nanoparticle deposition method. By using the novel 1 μm electrolyte layer, the current density of our SOFC progressed to 2.7, 2.1 and 1.6 A/cm² at operation temperatures of 800, 700 and 650°C, respectively, and out-performs all similar cells reported to date in the literature. An important consideration is also that cost-effective dip-coating and spin-coating methods are applied for the fabrication of the thin-film electrolyte. Processing of 1 μm layers on the very porous anode substrate material was initially experienced as very difficult and therefore 8YSZ nanoparticle coatings were developed and optimized on porous 8YSZ model substrates and transferred afterwards to regular anode substrates. In this paper, the preparation of the novel SOFC is shown and its morphology is illustrated with high resolution SEM pictures. Further, the performance in a standard SOFC test is demonstrated.     

Active disturbance rejection control for voltage stabilization in open-cathode fuel cells through temperature regulation

Temperature regulation is an important control challenge in open-cathode fuel cell systems. In this paper, a feedback controller, combined with a novel output-injection observer, is designed and implemented for fuel cell stack temperature control. The first functionality of the observer is to smooth the noisy temperature measurements. To this end, the observer gain is calculated based on Kalman filter theory which, in turn, results in a robust temperature estimation despite temperature model uncertainties and measurement noise. Furthermore, the observer is capable of estimating the output voltage model uncertainties. It is shown that temperature control not only ensures the fuel cell temperature reference is properly tracked, but, along with the uncertainty estimator, can also be used to stabilize the output voltage. Voltage regulation is of great importance for open-cathode fuel cells, which typically suffer from gradual voltage decay over time due to their dead-end anode operation. Moreover, voltage control ensures predictable and fixed fuel cell output voltages for given current values, even in the presence of disturbances. The observer stability is proved using Lyapunov theory, and the observer's effectiveness in combination with the controller is validated experimentally. The results show promising controller performances in regulating fuel cell temperature and voltage in the presence of model uncertainties and disturbances.     

Observer Based Fuel Delivery Control for PEM Fuel Cells with a Segmented Anode Model

In the anode of proton exchange membrane (PEM) fuel cells, the measurable outlet pressure is usually different with the actually utilized stack pressure. In this paper, the anode of PEM fuel cells is divided into three segments to reduce the modeling error between these two pressures and the impact of the spatial distribution of pressure, electrochemical reaction, and gas permeation. Specifically, we first model the fuel delivery system with anode recirculation and bleeding in a MIMO nonlinear compact form based on the segmented anode model. Then, a Lyapunov‐based full state feedback controller is proposed based on the developed model to guarantee adequate hydrogen supply and maintain the anode hydrogen at a suitable concentration level. Moreover, a high order sliding mode observer is proposed to estimate the unmeasurable pressure and the partial pressure in the fuel delivery system with known disturbance. Furthermore, an output feedback controller based on the proposed observer is developed with guaranteed stability. Simulation results illustrate the effectiveness of the proposed control and the estimation approaches.     

基于栈的匹配模式发现算法

提出了属性相关度衡量标准——C衡量标准;提出了一组基于栈的匹配模式发现算法,该组算法利用堆栈来保存已发现的相关属性组,从而减少不必要的搜索;采用降次降维法对算法进行了优化,对算法进行了理论分析和实验研究,实验结果表明,该组算法的查全率和查准率均优于其它算法.     

最优全方位结构元约束二维层叠滤波器

在最优层叠滤波器设计中引入全方位结构元,定义了一类全方位结构元约束下的最优二维层叠滤波器。理论分析和图象处理仿真实验表明,该类滤波器既能够充分保留图象信号微细节信息,又可在无须噪声和输入信号先验统计知识的前提下,实现ＭＡＥ和ＭＳＥ准则下最优。     

微通道重整器的动态特性建模与仿真

燃料电池通常需要根据负载的变化而调整工作状态,因此其动态特性是关系到系统性能的关键因素.而重整器作为燃料电池系统的一个重要部件,其动态特性的研究显然就十分必要.选用结构紧凑、性能优良的微通道重整器,通过机理建模得到其集总参数动态数学模型,然后在Matlab平台上构建了其仿真模型.根据燃料电池实际运行过程中负荷变化的特点,分别对重整器的主要调控参数,如流量、温度和压力在发生动态变化的情况下进行了动态响应的仿真.仿真结果与参考文献结论一致,表明该模型能预估重整器动态特性,从而为重整器乃至燃料电池的控制系统设计提供参考.