Jarosław Milewski

Advanced Methods of Solid Oxide Fuel Cell Modeling

Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. Advanced Methods of Solid Oxide Fuel Cell Modeling proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. Advanced Methods of Solid Oxide Fuel Cell Modeling provides a comprehensive description of modern fuel cell theory and a guide to the mathematical modeling of SOFCs, with particular emphasis on the use of ANNs. Up to now, most of the equations involved in SOFC models have required the addition of numerous factors that are difficult to determine. The artificial neural network (ANN) can be applied to simulate an objects behavior without an algorithmic solution, merely by utilizing available experimental data. The ANN methodology discussed in Advanced Methods of Solid Oxide Fuel Cell Modeling can be used by both researchers and professionals to optimize SOFC design. Readers will have access to detailed material on universal fuel cell modeling and design process optimization, and will also be able to discover comprehensive information on fuel cells and artificial intelligence theory.

Influences of The Type and Thickness of Electrolyte on Solid Oxide Fuel Cell Hybrid System Performance

This paper sets out the results of mathematical modeling and numerical simulations with regard to the influences of the type and thickness of electrolyte on Solid Oxide Fuel Cell Hybrid System (SOFC-HS) performance. A change of electrolyte materials can result in total hybrid system efficiency increasing from around 48% HHV (53% LHV) to about 65% HHV (72% LHV) in an environment where turbine inlet temperature and gas turbine subsystem pressure ratio remain unchanged. The governing equations of SOFC-HS modeling are given. An adequate simulator of the SOFC stack was made and described. Based on this simulator, a model of the 260 kWe Siemens Westinghouse unit was built. The performance of this SOFC-HS with different electrolyte materials and thicknesses is shown, and some characteristics are given and described. The advantages and disadvantages of different electrolyte types from a hybrid system performance point of view are indicated.

Reducing CO2 Emissions From a Coal Fired Power Plant by Using a Molten Carbonate Fuel Cell

A Molten Carbonate Fuel Cell (MCFC) is shown to reduce CO2 emissions from a Coal Fired Power Plant (CFPP). The MCFC is placed in the flue gas stream of the coal fired boiler. The main advantages of this solution are: higher total electric power generated by a hybrid system, reduced CO2 emissions and higher system efficiency. The model of the MCFC is given and described. The results obtained show that use of an MCFC could reduce CO2 emissions by 56%, which gives a relative CO2 emission rate of 288 kgCO2 per MWh.Copyright

Investigation of SOFC material properties for plant-level modeling

AbstractThis article describes results of a recent study of SOFC (Solid Oxide Fuel Cell) material properties using a numerical tool. The created model was validated against experimental data collected for two different solid oxide fuel cells. With focus on ionic and electronic conductivities, temperature influence was investigated. Results are presented, compared with available data, and discussed.Model of a micro-CHP (Combined Heat and Power) unit based on a SOFC stack was used for evaluation of system performance with different cells. On-site generated bio-syngas was considered as a fuel fed for the unit.The overall system efficiency was analyzed using an Aspen HYSYS modeling environment. Properties of two generic electrolyte materials were implemented in the models for evaluation of a co-generative unit operation. Electrical and overall efficiencies of systems based on those cells were compared and differences were observed. Micro-scale power units with fuel cells are a promising technology for highly efficient distributed cogeneration. As it was concluded, selection of a proper cell is crucial to assure high system efficiency.

Variant Analysis of the Structure and Parameters of SOFC Hybrid Systems

The paper presents a variant analysis of the structure of SOFC hybrid system. The systems are divided into two gropus: atmospheric and pressurized. The main parameter of such systems are indicated and commented. The comparison of various configurations is shown in a view of efficiency obtained. The ultra high efficiency (65% HHV, 72% LHV) of electricity production seems to be possible by systems like these.

Mathematical Model of SOFC (Solid Oxide Fuel Cell) for Power Plant Simulations

Presentation of concept of SOFC model is given. The SOFC model was built in HYSYS.Plant environment based on its standard libraries. Main elements of SOFC model and chemical reactions are presented. Selected performance characteristics at the design point of stand-alone SOFC are presented. The new equation to define of SOFC voltage, which was obtained based on new assumptions and which can be used instead of the Nernst equation, is given.© 2004 ASME

Heat Accumulator in Large District Heating Systems: Simulation and Optimisation

Heat accumulators in large district heating systems are used to buffer heat production. Their main purpose is to make heat production as independent as possible from district heating system demand. To do this effectively a heat accumulator of appropriate capacity must be selected. In large district heating systems, heat accumulators can be used for equalising production over periods lasting a few hours. Accumulators can be used for optimising electricity and heat production to achieve possible highest income. It may be important in situations where on-line prices change. An optimising algorithm for heat accumulator use is shown and commented. Typical working situations are simulated and results presented.Copyright

Boosting the Efficiency of an 800 MW-Class Power Plant through Utilization of Low Temperature Heat of Flue Gases

This article presents an analysis on possible ways of utilizing low-temperature waste heat. If well-designed, this could contribute to increasing the efficiency of power plants without introducing many complex changes to the whole system. The main analysis focuses on the location of the regenerative heat exchanger in the facility. This could differ with varying temperatures of working media in the system. The base for investigations was a 800 MW-class power unit operating in off-design conditions and supplied with steam from an BB2400 boiler. Modifications to the model were made using commercially available software and by applying the Stodola equation and the SCC method. It allowed to determine the most suitable position for installing the low-temperature heat exchanger. Calculations for off-design conditions show that, after making some modifications to the system, both heat and electricity generation could be increased through the addition of a low-temperature heat exchanger.

Seasonal Thermal Energy Storage - A Size Selection

The paper presents a theoretical investigation of using a Seasonal Thermal Energy Storage facility (STES) to cover the heat demand of a complex of four buildings. The STES is placed in the ground and connected to both the local district heating network and solar panels. A number of scenarios were investigated to find an adequate size of the STES (tank size and solar panel area.) The results obtained show that the use of a STES could reduce heat consumption by 22100% depending on the architecture solution chosen.

The Reduction of CO2 Emission of Gas Turbine Power Plant by Using a Molten Carbonate Fuel Cell

The possibility of using a Molten Carbonate Fuel Cell (MCFC) to reduce the CO2 emission from Gas Turbine Power Plant (GTPP) is shown. The MCFC is placed after a gas turbine. The main advantages of this solution are: higher total electric power generated by hybrid system and reduced CO2 emission with remained system efficiency. A comparison of three systems: standard GTPP, GT-MCFC, and GT-MCFC with additional heat exchangers is shown. The application of MCFC could reduce CO2 emission of 73% (absolutely) and 77% relative to produced power.Copyright