Development and Experimental Research of kW-scale Molten Carbonate Fuel Cells

A kW-scale molten carbonate fuel cells stack was developed and 800-hours’ operating test and performance experimental research had been done. Utilizing domestic materials completely, we developed NiO cathode and Ni-Al anode with the active area of 336cm 2 and Υ-LiAlO 2 electrolyte tile and bipolar plate with the area of 900cm 2. The stack was composed of thirty cells, with 62%Li 2CO 3+38%K 2CO 3 as its electrolyte. During the 800 hours’ continuous operating, the performance of the stack was stable. With 99.7%(mole fraction) H 2 as fuel and O 2 from air as oxidant, the average operating voltage of a cell was about 0.72 V. The maximal current density attained to 165mA/cm 2, and the maximal output power attained to 1080 Watt. The whole performance of the stack approached to the international level in the early 90’s. This paper gives the main works and experiments results.

MICROSTRUCTURE CHARACTERIZATION OF LiCoO_2 COATINGS FOR MOLTEN CARBONATE FUEL CELLS COMPONENTS

The sol-gel process, sing aqueous solutions, is used for dip coating ontosubstrates of 316L stainless steel. A suitable coating of Li CoO_2 is achieved by varying thethickness and heat treating at 650 deg C for 3 h. Thermal analysis, X-ray diffraction analysis andSEM are carried out to characterize the microstructure of the coatings. The results show that thecoating transforms from an amorphous gel to crystalline phases above 350 deg C, and show a porousstructure. The phase transition mechanism is discussed.

Numerical Simulation of Dynamic Performance of the Molten Carbonate Fuel Cell

A three dimension of dynamic mathematical model of the molten carbonate fuel cell is established,in which the heat generation, mass transfer and electrochemical characteristics are described. The performance of the fuel cell including the distributions of the temperature and the velocity is predicted numerically. Then the experimental data including the output performance of the fuel cell generation system and the temperature distributions are compared. The numerical results are in agreement with the experiment results.

Daily Operation Optimization of a Residential Molten Carbonate Fuel Cell Power System Using Genetic Algorithm

To decrease the cost of electricity generation of a residential molten carbonate fuel cell （MCFC） power system, multi-crossover genetic algorithm （MCGA）, which is based on ＂multi-crossover＂ and ＂usefulness-based selection rule＂, is presented to minimize the daily fuel consumption of an experimental 10kW MCFC power system for residential application. Under the operating conditions obtained by MCGA, the operation constraints are satisfied and fuel consumption is minimized. Simulation and experimental results indicate that MCGA is efficient for the operation optimization of MCFC power systems.

Study and performance test of 10 kW molten carbonate fuel cell power generation system

The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.

Nonlinear modeling of molten carbonate fuel cell stack and FGA-based fuzzy control

To improve the performance of fuel cells, the operating temperature of molten carbonate fuel cell (MCFC) stack should be controlled within a specified range. In this paper, with the RBF neural network’s ability of identifying complex nonlinear systems, a neural network identification model of MCFC stack is developed based on the sampled input-output data. Also, a novel online fuzzy control procedure for the temperature of MCFC stack is developed based on the fuzzy genetic algorithm (FGA). Parameters and rules of the fuzzy controller are optimized. With the neural network identification model, simulation of MCFC stack control is carried out. Validity of the model and the superior performance of the fuzzy controller are demonstrated.

Advance on Molten Carbonate Fuel Cell and Research on Some Key Problems

The paper is a summary of researches on molten carbonate fuel cell. On the same time, several key technology difficulties are discussed. Combining with our recent studies, the accessements to these problems are given out and they will be references for future works.

Performance Evaluation of a Molten Carbonate Fuel Cell-Graphene Thermionic Converter-Thermally Regenerative Electrochemical Cycles Hybrid System

A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed.

Anodic Oxidation of Nickel in Molten(Li_(0.62),K_(0.38))_2CO_3

The anodic oxidation of nickel in molten (Li 0.62 ,K 0.38 ) 2CO 3 was investigated by means of cyclic voltammetry, X ray diffraction and X ray photoelectron spectroscopy. The results indicate that two reactions are involved in the anodic process: one is Ni+O 2- =NiO+2e -, the other reaction is Ni(Ⅱ)=Ni(Ⅲ)+e -.

Hardware Materials in Molten Carbonate Fuel Cell:A Review

The high-temperature molten carbonate fuel cell is an ultra-clean and highly efficient power generator. It is operated at - 550-650 ℃, which is considered optimal in facilitating fast fuel cell reaction kinetics, utilizing waste heat efficiently, and allowing use of commercial construction materials. Commercial MW-size （mega watt） power plants of FuelCell Energy products have already been deployed worldwide. Metallic hardware materials are extensively utilized and may experience high-temperature reducing and oxidizing atmospheres in the presence of molten alkali carbonate electrolyte. Material selections are founded on many decades of focused research and development and field experience. Results to date show that the baseline stack module materials meet 5-year life goal and BOP （balance of plant） construction materials meet 20-year life goal. Material durability is well understood, and solutions are available to further extend the durability. This paper will review hardware materials experience and development approaches that would further reduce cost and extend life.

Multi-objective optimization of molten carbonate fuel cell system for reducing CO2 emission from exhaust gases

The aim of this paper is to investigate the implementation of a molten carbonate fuel cell （MCFC） as a CO2 separator. By applying multi-objective optimization （MOO） using the genetic algorithm, the optimal values of operating load and the corresponding values of objective functions are obtained. Objective functions are minimiza- tion of the cost of electricity （COE） and minimization of CO2 emission rate. CO2 tax that is accounted as the pollution-related cost, transforming the environmental objective to the cost function. The results show that the MCFC stack which is fed by the syngas and gas turbine exhaust, not only reduces CO2 emission rate, but also produces electricity and reduces environmental cost of the system.

Neural-networks-based Modelling and a Fuzzy Neural Networks Controller of MCFC

Molten Carbonate Fuel Cells (MCFC) are produced with a highly efficient and clean power generation technology which will soon be widely utilized. The temperature characters of MCFC stack are briefly analyzed. A radial basis function (RBF) neural networks identification technology is applied to set up the temperature nonlinear model of MCFC stack, and the identification structure, algorithm and modeling training process are given in detail. A fuzzy controller of MCFC stack is designed. In order to improve its online control ability, a neural network trained by the I/O data of a fuzzy controller is designed. The neural networks can memorize and expand the inference rules of the fuzzy controller and substitute for the fuzzy controller to control MCFC stack online. A detailed design of the controller is given. The validity of MCFC stack modelling based on neural networks and the superior performance of the fuzzy neural networks controller are proved by Simulations.

Submicron γ-LiAlO_2 Powder Synthesized from Boehmite

The present study reports a simple,effective and energy-efficient method to prepare γ-LiAlO2 powder as a matrix in a molten carbonate fuel cell(MCFC).In our experiments,aqueous solution based sol-gel technique was used to synthesize γ-LiAlO2.Highly dispersed AlOOH·nH2O and LiOH·H2O aqueous solutions were mixed to form a colloid mixture,which was calcined to synthesize γ-LiAlO2.Thermogravimetric analysis(TGA),X-ray dif-fraction(XRD),and scanning electron microscopy(SEM) were used to study the composition and morphology of the intermediate and final products.The analysis results showed that an intermediate product Li2Al4CO3(OH)12 was produced after the colloid mixture was dried at 80 ℃,and highly purified γ-LiAlO2 powder with fine particle size was resulted from the subsequent calcinations.A single MCFC was assembled with a matrix of the γ-LiAlO2 pow-der.The testing results showed that the matrix performed well in preventing gas leakage.

LS-SVM model based nonlinear predictive control for MCFC system

This paper describes a nonlinear model predictive controller for regulating a molten carbonate fuel cell (MCFC). In order to improve MCFC’s generating performance, prolong its life and guarantee safety, it must be controlled efficiently. First, the output voltage of an MCFC stack is identified by a least squares support vector machine (LS-SVM) method with radial basis function (RBF) kernel so as to implement nonlinear predictive control. And then, the optimal control sequences are obtained by applying genetic algorithm (GA). The model and controller have been realized in the MATLAB environment. Simulation results indicated that the proposed controller exhibits satisfying control effect.

Application of Nonlinear Predictive Control Based on RBF Network Predictive Model in MCFC Plant

This paper described a nonlinear model predictive controller for regulating a molten carbonate fuel cell (MCFC). A detailed mechanism model of output voltage of a MCFC was presented at first. However, this model was too complicated to be used in a control system. Consequently, an off line radial basis function (RBF) network was introduced to build a nonlinear predictive model. And then, the optimal control sequences were obtained by applying golden mean method. The models and controller have been realized in the MATLAB environment. Simulation results indicate the proposed algorithm exhibits satisfying control effect even when the current densities vary largely.

Catalytic action of rare earth oxide(La_(2)O_(3),CeO_(2),Pr_(6)O_(11))on electrochemical oxidation of activated carbon in molten KOH-NaOH

The oxidation of anode carbon fuel directly affects the electrochemical performance of molten hydroxide direct carbon fuel cell(MHDCFC).In general,the anode carbon fuel can be oxidized at high temperature,thus the direct carbon fuel cell(DCFC)can show great electrochemical performance.In this study,rare earth oxides(La_(2)O_(3),CeO_(2),Pr_(6)O_(11))were prepared by the method of precipitation.Activated carbon was prepared by pretreatment of lignite.Rare earth oxides and activated carbon were mixed as anode carbon fuel,and rare earth oxides were used to catalyze the electrochemical oxidation of anode carbon fuel.The results show that CeO_(2)has better electrocatalytic activity compared with La_(2)O_(3)and Pr_(6)O_(11) in the MHDCFC.The electrochemical test results show that the current density(at 0.4 V)increases from 81.02 to 112.90 mA/cm^(2)and the maximum power density increases from 34.78 to 47.05 mW/cm^(2)at 450℃,when the mass fraction of CeO_(2)is increased from 0 to 40%.When the mass fraction of CeO_(2)is 30%,the current density(82.55 mA/cm^(2)at 0.4 V)at 400℃is higher than that(81.02 mA/cm^(2)at 0.4 V)without CeO_(2)at 450℃.The electrochemical oxidation mechanism of CeO_(2)catalyzed anode carbon fuel is discussed.