Jakub Kupecki

Comparative Study of Biogas and DME Fed Micro-CHP System with Solid Oxide Fuel Cell

This paper presents results of a comparative study of a micro-combined heat and power (CHP) unit with solid oxide fuel cell (SOFC) fed by two different fuels. For current analysis biogas and dimethyl ether (DME) were selected. Detailed model of the micro-CHP system with net power output of 3 kWel was created, based on an advanced model of the SOFC. In both power units, steam reforming was employed in order to generate hydrogen-rich gas. Reforming temperatures of 900°C and 350°C were selected for biogas and DME, respectively. Both systems were based on the same reference solid oxide fuel cells. Similar plant outlines was employed, with small changes to accommodate different reformer operating temperatures.

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.

Modeling Platform for a Micro-CHP System with SOFC Operating under Load Changes

Paper presents a novel approach to modeling of a micro-combined heat and power (μ-CHP) unit with solid oxide fuel cells (SOFC). The proposed numerical simulator can be applied both to the analysis of a system operation in the design point and in off-design. Main components of the power system have been represented by dedicated sub-models, incorporated in the numerical simulator of a complete μ-CHP unit. The proposed modeling platform offers the possibility of analyzing system with different solid oxide fuel cells, its operation at partial loads and with various fuels. Components of the system can be modified, technical specifications can be adjusted in order to allow simulation of other components. The main equations for electrical and overall efficiency calculations are given and discussed.

Multi-Level Mathematical Modeling of Solid Oxide Fuel Cells

In recent years, numbers of questions concerning energy generation have arisen. Emission levels, delivery security, and diversification of the portfolio of technologies have been exten‐ sively discussed. Well-established generation based on fossil fuels in large-scale power sta‐ tions is criticized for big environmental impacts, and limited sustainability due to high fraction of process losses. Not only emissions, but also extraction of resources, alternation of the landscape, transmission and distribution inefficiencies are often pointed as the main downside. As a solution for rapidly increasing energy consumption, and emerging threat of current resources depletion, distributed generation based on highly efficient microand small-system was proposed. Moreover, combined heat and power (CHP) units with high achievable efficiency are seen as possible substitutes for stand-alone electricity generators. Most of technologies from that group are currently under development, however selected systems are already reaching market availability. In 2004 European Commission indicated selected systems, with guidelines for promotion and development of highly efficient co-gen‐ erative units [1]. List of technologies, which can provide high electrical and overall efficiency with limited environmental impacts, includes the following:

Selected Aspects of Design, Construction, and Operation of SOFC-Based Micro-Combined Heat and Power Systems

This chapter deals with micro-cogenerative power system based on solid oxide fuel cells. Such systems are composed of several devices and machines which operate at temperatures ranging from 20 to 1000 ℃ or more. The challenges related to thermal and electrical integration of such systems are discussed. The alternative configurations of micro-CHP units based on SOFCs are presented in this chapter. The authors present the key issues related to the components of a system with electric power output of 2000 W and thermal power of up to 2000 W. This is followed by a discussion on the technical measures required to achieve proper electrical and thermal integration of the system. A power unit designed, constructed, and operated in the Institute of Power Engineering (Poland) is discussed in detail. Key aspects of the design and its functionality are described, followed by a presentation of a typical heating profile of the micro-cogenerator. Some of the unique features of the system, including the dual start-up module, are described in depth. Differences and challenges related to the use of either the electric heaters or the auxiliary start-up burner are discussed. A conceptual schematic chart, visualization of the unit, and its actual final form are presented, followed by a demonstration of the temperature characteristics of the main components once the system achieves a quasi-steady-state mode of operation. The system presented in this chapter is a first-of-its-kind unit constructed in Poland producing electricity and usable heat in SOFCs.

Modeling of SOFC-Based Power Systems

Chapter 1 introduces the topic of solid oxide fuel cells, setting out the principles of operation and the governing equations used to compute the balances. Depending on the level of detail required, these equations can be reduced to discrete forms, can be simplified under certain assumptions or substituted by alternative mathematical descriptions. Some modeling techniques go as far as omitting the equations altogether. Alternative methods are often proposed to predict cell and stack performance and perform mass, energy, and charge balances instead of using a purely analytical approach and the governing equations. This chapter looks at the different modeling approaches and discusses the method which was found to be best suited to system-level studies in SOFC-based power systems. Development of a SOFC-based power units is usually an iterative procedure in which modeling is coupled with a conceptual phase which includes a definition of the design. This chapter will present different modeling methods applicable to SOFC-based power systems. Selected approaches are discussed and evaluated for the purpose of analysis of a micro-CHP unit with SOFCs. It also highlights the main parameters affecting the performance of SOFC stacks.

Computational fluid dynamics analysis of an innovative start-up method of high temperature fuel cells using dynamic 3d model

Abstract The article presents a numerical analysis of an innovative method for starting systems based on high temperature fuel cells. The possibility of preheating the fuel cell stacks from the cold state to the nominal working conditions encounters several limitations related to heat transfer and stability of materials. The lack of rapid and safe start-up methods limits the proliferation of MCFCs and SOFCs. For that reason, an innovative method was developed and verified using the numerical analysis presented in the paper. A dynamic 3D model was developed that enables thermo-fluidic investigations and determination of measures for shortening the preheating time of the high temperature fuel cell stacks. The model was implemented in ANSYS Fluent computational fluid dynamic (CFD) software and was used for verification of the proposed start-up method. The SOFC was chosen as a reference fuel cell technology for the study. Results obtained from the study are presented and discussed.