固体氧化物燃料电池发展及展望

在21世纪的今天,能源和环境对人类的压力越来越大.当人们把能源供应仍然寄托于煤的综合利用为主时,可以直接使用多种碳基燃料的高温固体氧化物燃料电池(SOFC)发电技术将是新型高效洁净能源的有效途径之一.在发展大型电站技术的同时,固体氧化物燃料电池作为分布式电站和备用电源技术及示范工程蓬勃开展.世界范围内,各种相关鼓励SOFC快速发展的政策陆续出台.千瓦量级的SOFC发电系统将在军方首先试用,多国联合的SOFC商业化进程正在加速实施.     

A bond graph model-based evaluation of a control scheme to improve the dynamic performance of a solid oxide fuel cell

A control strategy for a solid oxide fuel cell (SOFC) is developed in this paper to maintain required cell operating conditions while ensuring good fuel efficiency and satisfying the constraints on the transient performance. To verify the controller performance, a zero-dimensional true bond graph model of an SOFC system is developed which makes use of a C-field for two gas species in order to model the cathode and anode channel gases. Moreover, an existing R-field model has been extended for modeling of forced convection of a mixture of two gas species. The coupling between the chemical, thermal, mechanical and the hydraulic domains, which is encountered in a fuel cell system, is represented in a unified manner by using true bond graphs. The fuel utilization (FU) and the air utilization (AU) are interpreted in terms of the partial pressures of the gases. The static characteristics of the fuel cell obtained are in good agreement with the data from the literature. The dynamic response of the fuel cell to step changes in load current is obtained. From the simulations it is shown that all the control objectives are achieved by the proposed control system.     

Utilizing High Entropy Effects for Developing Chromium-Tolerance Cobalt-Free Cathode for Solid Oxide Fuel Cells

Solid oxide fuel cell (SOFC) is regarded as an environmentally friendly energy conversion device, which can directly convert the chemical energy stored in the fuel to the electrical energy. However, the degradation of cathodes caused by Cr-containing steel interconnects is a major problem that limits the broader application of SOFC. Herein, a novel A-site high entropy oxide, based on the cobalt-free PrBaFe₂O_5+δ (PBF) cathode, La_0.2Pr_0.2Nd_0.2Sm_0.2Gd_0.2BaFe₂O_5+δ (LPNSGBF), is proposed as a high catalyst activity and Cr-tolerance cathode for SOFC. The anode-supported cell with the LPNSGBF cathode exhibits an excellent peak power density of 1020.69 mW cm⁻² at 800 °C, which is better than that of the PBF (794.96 mW cm⁻²). Moreover, under the Cr-containing atmosphere, the outstanding stability of the single cell with the LPNSGBF for 100 h with a degradation rate of 0.17% h⁻¹, is much lower than the 0.79% h⁻¹ for that of the PBF cathode. The study provides a new strategy for achieving the enhanced oxygen reduction reaction and high Cr-tolerance of the cobalt-free cathode by high entropy doping.     

固体氧化物燃料电池的建模与仿真

能源短缺和环境问题已成为本世纪全球面临的最重要课题,作为一种新的能源形式,固体氧化物燃料电池(SOFC)技术日益受到重视。由于现有的SOFC模型过于复杂,难以满足工程上对SOFC系统实时控制的需求,提出利用粒子群算法(PSO)优化径向基函数(RBF)神经网络,从而实现对SOFC的建模。PSO对RBF神经网络的中心值和连接权值进行优化,提高了网络的泛化性能,使其非线性逼近能力更强,从而达到精确模型的目的。仿真实验验证了粒子群算法在SOFC建模的有效性。     

Hybrid Solid Oxide Fuel Cell and Thermoelectric Generator for Maximum Power Output in Micro-CHP Systems

One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating purposes.     

Solid-oxide-fuel-cell performance and durability: resolution of the effects of power-conditioning systems and application loads

We describe methodologies for comprehensive and reduced-order modeling of solid-oxide-fuel-cell (SOFC) power-conditioning system (PCS) at the subsystem/component and system levels to resolve the interactions among SOFC, balance-of-plant subsystem, and power-electronics subsystem (PES) and application loads (ALs). Using these models, we analyze the impacts of electrical-feedback effects (e.g., ripple-current dynamics and load transients) on the performance and reliability of the SOFC. Subsequently, we investigate the effects of harmonics in the current, drawn from the SOFC by a PES, on the temperature and fuel utilization of the SOFC. We explore the impacts of inverter space-vector modulation strategies on the transient response, flow parameters, and current density of the SOFC during load transients and demonstrate how these two traditionally known superior modulation/control methodologies may in fact have a negative effect on the performance and durability of the SOFC unless carefully implemented. Further, we resolve the impacts of the current drawn by the PES from the SOFC, on its microcrack density and electrode/electrolyte degradation. The comprehensive analytical models and interaction-analysis methodologies and the results provided in this paper lead to an improved understanding, and may yield realizations of cost-effective, reliable, and optimal PESs, in particular, and SOFC PCSs, in general.     

Surface‐Modified Low‐Temperature Solid Oxide Fuel Cell

This paper reports both experimental and theoretical results of the role of surface modification on the oxygen reduction reaction in low‐temperature solid oxide fuel cells (LT‐SOFC). Epitaxial ultrathin films of yttria‐doped ceria (YDC) cathode interlayers (<10–130 nm) are grown by pulsed laser deposition (PLD) on single‐crystalline YSZ(100). Fuel cell current–voltage measurements and electrochemical impedance spectroscopy are performed in the temperature range of 350 °C ≈ 450 °C. Quantum mechanical simulations of oxygen incorporation energetics support the experimental results and indicate a low activation energy of only 0.07 eV for YDC, while the incorporation reaction on YSZ is activated by a significantly higher energy barrier of 0.38 eV. Due to enhanced oxygen incorporation at the modified Pt/YDC interface, the cathodic interface resistance is reduced by two‐fold, while fuel cell performance shows more than a two‐fold enhancement with the addition of an ultrathin YDC interlayer at the cathode side of an SOFC element. The results of this study open up opportunities for improving cell performance, particularly of LT‐SOFCs by adopting surface modification of YSZ surface with catalytically superior, ultrathin cathodic interlayers.     

Regulation of Cathode Mass and Charge Transfer by Structural 3D Engineering for Protonic Ceramic Fuel Cell at 400 °C

Lowering the operating temperature (ideally below 400 °C) for solid oxide fuel cell (SOFC) technology deployment has been an important transition that introduces the benefit of reduced operational costs and system durability. However, the key technical issue limiting the transition is the sluggish cathodic performance, namely the oxygen reduction reaction (ORR) rate of the conventional sponge-like cathode dramatically drops as the temperature reduces. In this paper, 3D engineering of a cathode is conducted on a protonic ceramic fuel cell to obtain an enhanced ORR between 400 and 600 °C. Compared with a cell using a conventional sponge-like cathode, 3D engineering improves the cathode ORR by 41% at 400 °C with a peak power density of 0.410 W cm⁻². A phase field simulation is applied to assist the engineering by understanding the competition between the cathode mass and charge transfer with different cathode porosities. The results show that structural engineering of existing well-developed cathodes is a simple and effective method to promote cathode ORR for low temperature SOFC by regulating the mass and charge transfer.     

平板式固体氧化物燃料电池的封接

甲板式固体氧化物燃料电池（SOFC）是目前发展的主要趋势，其中的封接技术很关键。本文综述了云母复合压缩封接和玻璃／玻璃陶瓷封接在平板式SOFC中应用的技术进展，比较了各种封接方式的优缺点，并指出了其在不同国家、地区的研究现状和发展趋势。     

低温共烧结制备阴极支撑管式固体氧化物燃料电池

采用挤出成型法制备锰酸锶镧-氧化钇稳定氧化锆（LSM-YSZ）阴极支撑管,利用浸渍-提拉泥浆涂覆法在LSM-YSZ阴极支撑管上制备了LSM-YSZ阴极功能层、YSZ电解质和NiO-YSZ阳极多层薄膜,经低温一次共烧结制备阴极支撑管式单元固体氧化物燃料电池（SOFC）。利用扫描电镜和电化学工作站等对单元电池的微观结构和电化学性能进行了较系统的表征,结果表明：经1220℃低温共烧结8h后,LSM-YSZ支撑体上的阴极功能层、电解质和阳极各层薄膜结合紧密,电解质薄膜致密无缺陷,厚约15μm;以湿氢气为燃料,空气为氧化剂时,单元电池在700～800℃下的开路电压均高于1.0V,说明电解质薄膜具有足够的气密性,但阴极的低电导率和低孔隙率限制了电池的电性能。采用浸渍-提拉薄膜技术,经一次低温共烧结制备阴极支撑管式SOFC,为SOFC低成本制备奠定了基础。     

Low cost high efficiency DC-DC converter for fuel cell powered auxiliary power unit of a heavy vehicle

In this paper, a new dc-dc converter for solid oxide fuel cell (SOFC) powered auxiliary power unit (APU) is proposed. The proposed converter does not consider the leakage inductance of the transformer as a parasite and uses it for energy transfer, thus avoiding problems of low efficiency and difficulty in control, caused by leakage inductance. The need for a separate filter inductor is also eliminated. Soft switching is done for some of the switches of the proposed converter, thereby further increasing the efficiency of the converter. Thus, the achieved low cost and high efficiency of the proposed converter make it suitable for SOFC powered APU applications. Simulation and experimental results are presented to verify the proposed dc-dc converter. The achieved cost and efficiency of the prototype are 50.8$/kW and 90%, respectively.     

Studies on Effective Utilization of SOFC Exhaust Heat Using Thermoelectric Power Generation Technology

Solid oxide fuel cells (SOFCs) are being researched around the world. In Japan, a compact SOFC system with rated alternative current (AC) power of 700 W has become available on the market, since the base load electricity demand for a standard home is said to be less than 700 W AC. To improve the generating efficiency of SOFC systems in the 700-W class, we focused on thermoelectric generation (TEG) technology, since there are a lot of temperature gradients in the system. Analysis based on simulations indicated the possibility of introducing thermoelectric generation at the air preheater, steam generator, and exhaust outlet. Among these options, incorporating a TEG heat exchanger comprising multiple CoSb₃/SiGe-based TEG modules into the air preheater had potential to produce additional output of 37.5 W and an improvement in generating efficiency from 46% to 48.5%. Furthermore, by introducing thermoelectric generation at the other two locations, an increase in maximum output of more than 50 W and generating efficiency of 50% can be anticipated.     

Hybrid self-organizing fuzzy and radial basis-function neural-network controller for gas-assisted injection molding combination systems

This study proposed a self-organizing fuzzy controller (SOFC) to manipulate a gas-assisted injection molding combination system (GAIMCS) and determined the control performance of the system. However, both the learning rate and the weighting distribution of the SOFC are difficult to select and are fixed after selection. To address this problem, this study developed a hybrid self-organizing fuzzy and radial basis-function neural-network controller (HSFRBNC) for GAIMCSs. The HSFRBNC uses a radial basis-function neural-network to regulate the parameters of the SOFC for achieving appropriate values in real time. It not only overcomes the difficulty of finding appropriate parameters of the SOFC but also reduces the time needed to establish suitable fuzzy control rules for manipulating the GAIMCS. Experimental results showed that the HSFRBNC has better control performance than the SOFC in controlling the GAIMCS.     

Future Hybrid of Photovoltaic and Fuel Cell for Langkawi SkyCab

Langkawi SkyCab has the highest energy demand in Langkawi Island and the demand keeps increasing year by year. This study proposed alternatives energy of a hybrid photovoltaic (PV) and fuel cell system for the SkyCab’s operation. The best sizing and configurations were chosen based on Homer simulation software. A comparative study was done between a conventional system and other hybrid combinations. The results revealed that the proposed system had reduced the cost as well as CO₂ emission almost by 39% and 79%, respectively. The hybrid PV and fuel cell system is aligned with the Malaysian government’s goals of reducing carbon emissions 40% by the year 2030.     

Cost–Performance Analysis and Optimization of Fuel-Burning Thermoelectric Power Generators

Energy cost analysis and optimization of thermoelectric (TE) power generators burning fossil fuel show a lower initial cost compared with commercialized micro gas turbines but higher operating cost per energy due to moderate efficiency. The quantitative benefit of the thermoelectric system on a price-per-energy ($/J) basis lies in its scalability, especially at a smaller scale (<10 kW), where mechanical thermodynamic systems are inefficient. This study is based on propane as a chemical energy source for combustion. The produced heat generates electric power. Unlike waste heat recovery systems, the maximum power output from the TE generator is not necessarily equal to the economic optimum (lowest $/kWh). The lowest cost is achieved when the TE module is optimized between the maximum power output and the maximum efficiency, dependent on the fuel price and operation time duration. The initial investment ($/W) for TE systems is much lower than for micro gas turbines when considering a low fractional area for the TE elements, e.g., 5% to 10% inside the module. Although the initial cost of the TE system is much less, the micro gas turbine has a lower energy price for longer-term operation due to its higher efficiency. For very long-term operation, operating cost dominates, thus efficiency and material ZT become the key cost factors.     

Reversible fuel cell enabled underwater buoyancy control

A variable buoyancy system (VBS) operated by a reversible fuel cell (RFC) with feedback depth control is developed. The system varies its buoyancy by inflating or deflating a bladder via gases produced by electrolysis or consumed through fuel cells. The system has advantages in the perspective of energy efficiency since some of the energy used for the electrolysis process is recaptured by the fuel cell. Furthermore, it is noiseless and compact, facilitating smooth integration with other underwater robots requiring buoyancy control. A PDA (Proportional-Derivative-Acceleration) feedback controller is designed to regulate the electrochemical process to position and stabilize the device at a certain depth. The model describing the VBS’s motion dynamics with bounded gas rates is used to evaluate the range of motion before instability. Then, a jerk-constrained time-optimal trajectory planner is employed to generate a suboptimal trajectory to move the VBS between two known depths. Finally, the effectiveness of the controller is confirmed with experiments. The real-time experiment shows that the controller can track both sinusoidal reference and the suboptimal trajectory planned between two depths. The device can achieve fine depth control with a depth resolution of 0.06 m, which makes its application promising in bio-inspired underwater robots.     

陶瓷-金属封接技术应用的新进展

综述了最近几年来陶瓷-金属封接技术的进展,包括在固体氧化物燃料电池,惰性生物陶瓷的接合,高工作温度、高气密性、多引线芯柱以及半透明Al_2O_3瓷用于金属卤化物灯中的封接工艺等。特别强调了随着应用领域的不同,陶瓷-封接组件的多种性能都需要不同的提高。     

可折叠式太阳能电池板智能追光系统的研究

人类现阶段正面临着石油和煤炭等矿物燃料枯竭的严重威胁,太阳能是一种清洁的绿色能源,是最丰富的可再生能源之一,但是太阳能又存在着低密度、间歇性、空间分布不断变化的缺点,这就使目前的一系列太阳能设备对太阳能的利用率不高。太阳光线自动跟踪装置解决了太阳能利用率不高的问题。本文设计了一种折叠式太阳能电池板智能追光系统的研究设计。     

Advanced Integrated Bidirectional AC/DC and DC/DC Converter for Plug-In Hybrid Electric Vehicles

Hybrid electric vehicle (HEV) technology provides an effective solution for achieving higher fuel economy, better performance, and lower emissions, compared with conventional vehicles. Plug-in HEVs (PHEVs) are HEVs with plug-in capabilities and provide a more all-electric range; hence, PHEVs improve fuel economy and reduce emissions even more. PHEVs have a battery pack of high energy density and can run solely on electric power for a given range. The battery pack can be recharged by a neighborhood outlet. In this paper, a novel integrated bidirectional AC/DC charger and DC/DC converter (henceforth, the integrated converter) for PHEVs and hybrid/plug-in-hybrid conversions is proposed. The integrated converter is able to function as an AC/DC battery charger and to transfer electrical energy between the battery pack and the high-voltage bus of the electric traction system. It is shown that the integrated converter has a reduced number of high-current inductors and current transducers and has provided fault-current tolerance in PHEV conversion.     

水煤浆在工业炉窑应用的市场分析

由于能源价格体系的不合理性,我国近年来水煤浆技术的发展和推广工作受到很大阻碍,甚至处于停滞状态。本文避开暂时的价格因素,从能源发展形势、应用市场前景及相关技术条件等方面对水煤浆的市场问题进行了分析。