The Study And Application Of In Situ Adaptive Tabulation In Multiscale Simulation

The development and utilization of the traditional nonrenewable energy accompany serious pollution and waste. Furthermore it will be exhausted in the near future. In order to achieve coordinated and sustainable development of economic, energy and environment, the efficient, clean and advanced energy forms must be developed. Advanced energy system requires a very high efficiency and near zero emissions, and the highly complex and multi-scale are its essential features. Multiscale study must consider the coupling effect between the various scales of the system, which will produce much more complex problems, and one of the main difficulties is the computational cost of the multi-scale model. In this case, how to solve the problem of high computational cost of multiscale model is particularly critical.In order to solve the problem of excessive computation of multiscale simulation and optimization, this paper adopted the kinetic Monte Carlo (kMC) to simulate the microscopic variables, in the microscopic scale. And in the macroscopic scale, in situ adaptive tabulation (ISAT) was utilized to process the macroscopic variables, avoiding time-consuming kMC simulation steps, so as to save computation time and improve computation efficiency. Furthermore, it also lays the groundwork of multiscale simulation and optimization.With the purpose of testing the performance of saving computing time and improving the efficiency of ISAT, the solid oxide fuel cell (SOFC) is taken for study. The ISAT method is applied to hydrogen-oxygen chemical reaction process and kMC simulation of oxygen vacancy diffusion process in yttria stabilized zirconia (YSZ) electrolyte, respectively. The main work includes:1. Much attention was paid on the principle and method of in situ adaptive tabulation (ISAT). Discussde the error control of ISAT methods with different orders, and made a detailed introduction to the different operating methods of data storage structure, finally summarized the specific steps of ISAT.2. The solid oxide fuel cell (SOFC) hydroxide chemical reaction was taken as a study object, and applied ISAT to the kMC simulation of hydrogen and oxygen reaction at different temperature and hydrogen-oxygen ratio. Get the current density and the mole percentage of each component at different time and analyze the effect of different parameters on the current density especially the efficiency and accuracy of ISAT. 3. ISAT method was applied to one-dimensional kMC model of oxygen vacancy diffusion process in SOFC electrolyte, and the process was simulated at different temperature, spontaneous diffusion migration energy barrier, frequencies of applied potential, number of cells in electrolyte and initial number of oxygen vacancies in each cell. Finally, the effect of different parameters on the potential especially the efficiency and accuracy of ISAT was analyzed.The simulation results show that: ISAT method guarantees the simulation accuracy, at the same time greatly reduce the computation time and improve computing speed, moreover, the method lays the groundwork of multiscale simulation and optimization.