Review of High-Temperature Fuel Cell Hardware Materials

Author(s):  
Chao-Yi Yuh ◽  
Ling Chen ◽  
Adam Franco ◽  
Mohammad Farooque

The high-temperature carbonate fuel cell is an ultra-clean and high-efficiency power generator. Its intermediate operating temperature, ∼600–650°C, is considered optimum to facilitate fast fuel cell reaction kinetics, utilize waste heat efficiently in a combined heat and power or bottoming power cycle, and at the same time allow use of commercial commodity materials for cell hardware and balance-of-plant (BOP) piping/equipment construction. MW size power plants manufactured by FCE are being operated at customer sites throughout the world. The cell hardware and BOP materials selections are founded on many years of focused research. Microstructure and mechanical property evolution, oxidation, hot corrosion and carburization have been extensively investigated. Long-term subscale stack endurance as well as power plant field operation results to date show that the baseline hardware construction materials meet the endurance goals. Material durability is well understood and solutions are available to further extend life. This paper will review durability experience of hardware materials (cell, stack and BOP).

2019 ◽  
Vol 198 ◽  
pp. 111842
Author(s):  
Xin Zhang ◽  
Jianying Du ◽  
Yee Sin Ang ◽  
Jincan Chen ◽  
Lay Kee Ang

Author(s):  
Nicola Zuliani ◽  
Rodolfo Taccani ◽  
Robert Radu

High temperature PEM (HTPEM) fuel cell based on polybenzimidazole polymer (PBI) and phosphoric acid, can be operated at temperature between 120°C and 180°C. Reactants humidification is not required and CO content up to 1% in fuel can be tolerated, affecting only marginally performance. This is what makes HTPEM fuel cells very attractive, as low quality reformed hydrogen can be used and water management problems are avoided. This paper aims to present the preliminary experimental results obtained on a HTPEM fuel cell fed with LPG using a compact steam reformer. The analysis focus on the reformer start up transient, on the influence of the steam to carbon ratio on reformate CO content and on the single fuel cell performance at different operating conditions. By analyzing the mass and energy balances of the fuel processor, fuel cell system, and balance-of-plant, a previously developed system simulation model has been used to provide critical assessment on the conversion efficiency for a 1 kWel system. The current study attempts to extend the previously published analyses of integrated HTPEM fuel cell systems.


Author(s):  
Dieter Bohn ◽  
Nathalie Po¨ppe ◽  
Joachim Lepers

The present paper reports a detailed technological assessment of two concepts of integrated micro gas turbine and high temperature (SOFC) fuel cell systems. The first concept is the coupling of micro gas turbines and fuel cells with heat exchangers, maximising availability of each component by the option for easy stand-alone operation. The second concept considers a direct coupling of both components and a pressurised operation of the fuel cell, yielding additional efficiency augmentation. Based on state-of-the-art technology of micro gas turbines and solid oxide fuel cells, the paper analyses effects of advanced cycle parameters based on future material improvements on the performance of 300–400 kW combined micro gas turbine and fuel cell power plants. Results show a major potential for future increase of net efficiencies of such power plants utilising advanced materials yet to be developed. For small sized plants under consideration, potential net efficiencies around 70% were determined. This implies possible power-to-heat-ratios around 9.1 being a basis for efficient utilisation of this technology in decentralised CHP applications.


2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen

Abstract A large amount of energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. The thermoelectric generator (TEG) provides a way to reutilize this portion of energy by converting temperature differences into electricity using Seebeck phenomenon. Because the figures of merit zT of the thermoelectric materials are temperature-dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, the authors propose a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The multimaterial TEG is optimized using the solid isotropic material with penalization (SIMP) method. Instead of dummy materials, both the P-type and N-type electric conductors are optimally distributed with two different practical thermoelectric materials. Specifically, Bi2Te3 and Zn4Sb3 are selected for the P-type element while Bi2Te3 and CoSb3 are employed for the N-type element. Two optimization scenarios with relatively regular domains are first considered with one optimizing on both the P-type and N-type elements simultaneously, and the other one only on single P-type element. The maximum conversion efficiency could reach 9.61% and 12.34% respectively in the temperature range from 25 °C to 400 °C. CAD models are reconstructed based on the optimization results for numerical verification. A good agreement between the performance of the CAD model and optimization result is achieved, which demonstrates the effectiveness of the proposed method.


Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen

Abstract Over 50% of the energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. As an attempt to deal with the growing energy crisis, the solid-state thermoelectric generator (TEG), which converts the waste heat into electricity using Seebeck phenomenon, has gained increasing popularity. Since the figures of merit of the thermoelectric materials are temperature dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, this paper proposes a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The objective of the optimization problem is to maximize the output power and conversion efficiency as well. The proposed method is implemented using the Solid Isotropic Material with Penalization (SIMP) method. The proposed method can make the most of the potential of different thermoelectric materials by distributing each material into its optimal working temperature interval. Instead of dummy materials, both the P and N-type electric conductors are optimally distributed with two different practical thermoelectric materials, namely Bi2Te3 & PbTe for P-type, and Bi2Te3 & CoSb3 for N-type respectively, with the yielding conversion efficiency around 12.5% in the temperature range Tc = 25°C and Th = 400°C. In the 2.5D computational simulation, however, the conversion efficiency shows a significant drop. This could be attributed to the mismatch of the external load and internal TEG resistance as well as the grey region from the topology optimization results as discussed in this paper.


2000 ◽  
Vol 124 (1) ◽  
pp. 110-116 ◽  
Author(s):  
A. F. Massardo ◽  
C. F. McDonald ◽  
T. Korakianitis

Microturbines and fuel cells are currently attracting a lot of attention to meet future users needs in the distributed generation market. This paper addresses a preliminary analysis of a representative state-of-the-art 50-kW microturbine coupled with a high-temperature solid-oxide fuel cell (SOFC). The technologies of the two elements of such a hybrid-power plant are in a different state of readiness. The microturbine is in an early stage of pre-production and the SOFC is still in the development phase. It is premature to propose an optimum solution. Based on today’s technology the hybrid plant, using natural gas fuel, would have a power output of about 389 kW, and an efficiency of 60 percent. If the waste heat is used the overall fuel utilization efficiency would be about 80 percent. Major features, parameters, and performance of the microturbine and the SOFC are discussed. The compatibility of the two systems is addressed, and the areas of technical concern, and mismatching issues are identified and discussed. Fully understanding these, and identifying solutions, is the key to the future establishing of an optimum overall system. This approach is viewed as being in concert with evolving technological changes. In the case of the microturbine changes will be fairly minor as they enter production on a large scale within the next year or so, but are likely to be significant for the SOFC in the next few years, as extensive efforts are expended to reduce unit cost. It is reasonable to project that a high performance and cost-effective hybrid plant, with high reliability, will be ready for commercial service in the middle of the first decade of the 21st century. While several microturbines can be packaged to give an increased level of power, this can perhaps be more effectively accomplished by coupling just a single gas turbine module with a SOFC. The resultant larger power output unit opens up new market possibilities in both the industrial nations and developing countries.


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