Dynamic Modeling And Analysis Of Domestic SOFC-CHP Systems

Solid Oxide Fuel Cell (SOFC) is a kind of green energy resources with high efficiency, which could convert the chemical energy into electrical energy directly. Household SOFC that used in the Combined Heat and Power (CHP) system as distributed power generating device has many advantages such as high overall efficiency, no pollution, no noise and so on. Therefore, this issue has a great research significance.In this thesis, a SOFC CHP system with reformer producing hydrogen from natural gas was built and its stable state and open loop dynamic characteristics were analyzed. The main contents of this thesis could be divided into the following three parts.Firstly, a model of reformer that produces hydrogen from natural was identified on the basis of the relevant results. The mathematical model was built according to the chemical and thermal dynamic processes, in which the parameters were identified by Improved Genetic Algorithm (IGA) and checked by operating data of the prototype machine. Based on this model, the influences of Steam Carbon Ration (S/C) and the temperature of reforming reaction on hydrogen production efficiency were analyzed.Secondly, SOFC stand alone power generation system with reformer producing hydrogen from natural gas was built. Firstly, SOFC system model was built according to physical conservation laws and validated by steady state experimental data. Then, the reformer subsystem was integrated into the SOFC system. The open loop steady state properties of the integrated system was tested by 5% input disturbance and the thermal and electrical characteristics all responded within certain limits. Finally, a "Two Step Switch" power switching strategy was designed, which could greatly shorten the system power switching times.Thirdly, a design and operation scheme was proposed for the household SOFC CHP system. The scheme was based on the heat and electric consumption of users in spring and summer. The optimal parameters of storage battery capacity and water tank volume were given. Compared with the traditional thermal power generation, the SOFC CHP system is much more energy saving.