Inaugural US-EU-China Thermophysics Conference-Renewable Energy 2009 (UECTC 2009 Proceedings)
47 Radiative Properties of High Temperature Particles in Their Phase Transitions and Inverse Radiation Problem of Particles
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The radiative properties of high temperature particles in their phase transitions and inverse radiation problem of particles are investigated in present paper. (1) The transient radiative property during the Al2O3 particle's phase transition is simulated firstly. Based on the kinetic equation of Al2O3 particle's crystallization process, the time dependence of volume fraction of each phase is calculated. The multilayered sphere model and “effective medium” sphere model are developed based on two possible solidification modes which are layer by layer solidification and normally solidification. In the “effective medium” sphere model, the values of effective optical constants of Al2O3 particle during the phase transition are calculated by several different mixing rules. The transient radiative property of Al2O3 particle with the diameter of 1.2mm during phase transition is simulated using these two models. (2) Three different particle swarm optimization (PSO) algorithms, including the standard PSO, stochastic particle swarm optimizer (SPSO) and Multi-Phase particle swarm optimization (MPPSO), are applied to the inverse radiation problems. To illustrate the performance of these algorithms, some different cases are investigated, in which the source term, the extinction coefficient, the scattering coefficient, the non-uniform absorption coefficients, and particle size distribution are retrieved. The effects of swarm size, searching space, phase change frequency, and velocity reinitializing frequency on the convergence velocity and computational accuracy of MPPSO are also investigated. In conclusion, the MPPSO algorithm is proved to be fast and robust, which has the potential to be implemented in various fields of inverse radiation problem.