Principles and applications of high temperature ion conducting ceramic in power generation - fuel cells and oxygen membranes

High temperature membranes can be used in numerous applications including ceramic filters, selective sieves, removal of impurities, oxygen and hydrogen separation, electrochemical devices such as solid oxide fuel cells and solid oxide electrolysers. The fabrication process is oriented at achieving desired properties of the final product, including proper conductivity, size and density of pores, tortuosity, mechanical stability in high operating temperatures and others. Among the mentioned applications, solid oxide fuel cells and oxygen separation membranes represent materials with mixed ionic and electronic conductivity (MIEC) which will be further discussed in the lecture. Such material are often referred as membranes designed specifically for transport of ions and electrons

Modelling of Physical, Chemical, and Material Properties of Solid Oxide Fuel Cells

This paper provides a review of modelling techniques applicable for system-level studies to account for physical, chemical, and material properties of solid oxide fuel cells. Functionality of 0D to 3D models is discussed and selected examples are given. Author provides information on typical length scales in evaluation of power systems with solid oxide fuel cells. In each section, proper examples of previous studies done in the field of 0D–3D modelling are recalled and discussed

Considerations regarding modeling of MW-scale IG-SOFC Hybrid Power System

RES Master´s Thesis Verkefnið er unnið í tengslum við Háskóla Íslands og Háskólann á AkureyriThe main objective of this thesis is to evaluate various modeling approaches for large systems employing high temperature fuel cell (particularly SOFC) modeling. It also includes a brief discussion of current trends and various designs. This thesis will review recently published papers investigating the hundred MWe scale SOFC hybrid Brayton-Rankine power systems. It goes into details discussing the crucial parameters influencing the cycle’s operation and performance. For better understanding, the basics of the fuel cell operation, involved processes and all phenonena are provided in Chapter 2. In the next chapter the SOFC based systems with integrated gasification reactors are widely described. Current state-of-the-art trends and their background are presented. Finaly the desired system configuration is proposed and investigated. These particular arragements correspond to the U.S. Department of Energy (DoE) baseline for systems employing high temperature fuel cells, hence certain design solutions are involved. The SOFC stack feedstock is provided by the gasification of coal, however different fuel can also be gasified (biomass for example). In the last chapter, the modeling and optimisation in the software are extensively described. Because of the fact that ASPEN Plus and Hysys are comonly used in the majority of cases when cycles involing high temperature fuel cells are analyzed, the attention will be focused on these two programs. Both of them have built-in tools allowing the modeling of heat exchangers, compressors and expanders (i.e. gas and steam turbines) by available units. ASPEN Plus is Fortran based software and the SOFC stack can be modeled as a user unit using this programming code. The modeling approach to the electrochemical and chemical processes within the SOFC stack will be delivered, since it is important for the modeling of the entire power cycle. Analysis of the whole system with the proposed tools allows the determination of the overall system thermal efficiency with high fidelity, thus the biggest effort must be made to correctly determine all input parameters and define the proper assumptions as well as simplifications. The final discussion emphasises the most crucial parameters. The proposed system represents a clean energy source, which substantialy reduces the polutants flow associated with the power generation. Desulphurisation and gases clean-up processes are also involved in the cycle, therefore it meets all environmental requirements

Modeling the dynamic operation of a small fin plate heat exchanger – parametric analysis

Given its high efficiency, low emissions and multiple fuelling options, the solid oxide fuel cells (SOFC) offer a promising alternative for stationary power generators, especially while engaged in micro-combined heat and power (μ-CHP) units. Despite the fact that the fuel cells are a key component in such power systems, other auxiliaries of the system can play a critical role and therefore require a significant attention. Since SOFC uses a ceramic material as an electrolyte, the high operating temperature (typically of the order of 700–900 °C) is required to achieve sufficient performance. For that reason both the fuel and the oxidant have to be preheated before entering the SOFC stack. Hot gases exiting the fuel cell stack transport substantial amount of energy which has to be partly recovered for preheating streams entering the stack and for heating purposes. Effective thermal integration of the μ-CHP can be achieved only when proper technical measures are used. The ability of efficiently preheating the streams of oxidant and fuel relies on heat exchangers which are present in all possible configurations of power system with solid oxide fuel cells. In this work a compact, fin plate heat exchanger operating in the high temperature regime was under consideration. Dynamic model was proposed for investigation of its performance under the transitional states of the fuel cell system. Heat exchanger was simulated using commercial modeling software. The model includes key geometrical and functional parameters. The working conditions of the power unit with SOFC vary due to the several factors, such as load changes, heating and cooling procedures of the stack and others. These issues affect parameters of the incoming streams to the heat exchanger. The mathematical model of the heat exchanger is based on a set of equations which are simultaneously solved in the iterative process. It enables to define conditions in the outlets of both the hot and the cold sides. Additionally, model can be used for simulating the stand-alone heat exchanger or for investigations of a semiadiabatic unit located in the hotbox of the μ-CHP unit

Zastosowanie wysokotemperaturowej elektrolizy opartej na stałotlenkowych ogniwach elektrochemicznych (SOC) w układach P2X

W artykule omówiono potencjalne zastosowanie wysokotemperaturowej elektrolizy opartej na stałotlenkowych ogniwach elektrochemicznych (SOE), jako kluczowej technologii w układach wytwarzania paliw syntetycznych, w tym paliw gazowych (P2G - power-to-gas), paliw ciekłych (P2L - power-to-liquid) oraz amoniaku (P9A - power-to-ammonia)

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

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

Comparative study of biogas and DME fed micro-CHP system with solid oxide fuel cell

abstractEN: 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.score: 0collation: 53-5