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- Andersson, Daniel, et al.
(författare)
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Dynamic Modeling Of A Solid Oxide Fuel Cell System In Modelica
- 2010
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Ingår i: Proceedings of the Asme 8th International Conference on Fuel Cell Science, Engineering, and Technology 2010, Vol 2. - 9780791844052 ; 2, s. 65-72
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Konferensbidrag (refereegranskat)abstract
- In this study a dynamic model of a solid oxide fuel cell (SOFC) system has been developed. The work has been conducted in a cooperation between the Department of Energy Sciences, Lund University, and Mode Ion AB using the Modelica language and the Dymola modeling and simulation tool. Modelica is an equation based, object oriented modeling language, which promotes flexibility and reuse of code. The objective of the study is to investigate the suitability of the Modelica language for dynamic fuel cell system modeling. A cell electrolyte model including ohmic, activation and concentration irreversibilities is implemented and verified against simulations and experimental data presented in the open literature. A ID solid oxide fuel cell model is created by integrating the electrolyte model and a ID fuel flow model, which includes dynamic internal steam reforming of methane and water-gas shift reactions. Several cells are then placed with parallel flow paths and connected thermally and electrically in series. By introducing a manifold pressure drop, a stack model is created. The stack model is applied in a complete system including an autothermal reformer, a catalytic afterburner, a steam generator and heat exchangers. Four reactions are modeled in the autothermal reformer; two types of methane steam reforming, the water-gas shift reaction and total combustion of methane. The simulation results have been compared with those in the literature and it can be concluded that the models are accurate and that Dymola and Modelica are tools well suited for simulations of the transient fuel cell system behaviour.
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| 5. |
- Eborn, Jonas, et al.
(författare)
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Modeling of a Boiler Pipe with Two-Phase Flow Instabilities
- 2000
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Ingår i: Modelica Workshop 2000 Proceedings. ; , s. 79-88
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tubes with boiling are common elements of many processes. They appear in steam generators and refrigerators and many other systems. The behavior of such systems is complicated and many physical phenomena are involved. It has for example been observed that different types of instabilities can occur. In this paper we will discuss modeling of tubes with boiling. As an application we will discuss an instability phenomenon due to pressure oscillations that has been observed experimentally in many different situations. We will first derive a simple analytical model which is able to capture the oscillations qualitatively. The simple model also gives insight into the mechanisms that generate the oscillations. A more complicated model is then built using a recently developed model base library in Modelica. A comparison between the simple and the complicated model is also given
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| 8. |
- Eborn, Jonas
(författare)
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On Model Libraries for Thermo-hydraulic Applications
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mathematical modelling and simulation are important tools when dealing with engineering systems that today are becoming increasingly more complex. Tightly integrated production and process optimization are trends that give rise to heterogeneous systems, which are difficult to handle without expertise in several engineering disciplines. Model libraries provide an excellent way to package engineering knowledge of systems and units to be reused by non experts. Many commercial simulation packages provide good model libraries, but they are usually domain specific and closed. Heterogeneous, multi-domain systems requires open model libraries written in general purpose modelling languages. Modelica(TM) is such an open standard for an object-oriented modelling language for dynamic systems. The thesis describes principles for object-oriented equation-based model libraries. The main topic is modelling of thermo-hydraulic applications. Two different model libraries are presented, the Omola model library K2 for thermal power plants and the Modelica base library ThermoFlow for general thermo-hydraulic applications. The models are based on first principles. Lumped or 1D-discretized control volumes contain the thermodynamic balance equations. The base library is built for flexibility; the control volume can have different medium descriptions, single- or multi-component, and the momentum dynamics can be replaced by static descriptions. Some applications of the libraries are also described: a heat recovery steam generator, a drum-boiler model and a model of evaporating two-phase flow in a pipe. The thesis consists of four articles. Papers I and II describe the two model libraries. Paper III covers the two-phase flow application and gives a simplified physical analysis that shows under what conditions there will be pressure-drop oscillations in an evaporating pipe. Model libraries for industrial use must be validated against measured data. Paper IV describes how parameter estimation methods can be used for model structure validation. The thesis also has a short discussion on other model validation methods.
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