Simultaneous estimation of thermal and optical properties of molten salt based on improved colliding bodies optimization

Abstract

Inverse estimation of thermal and optical properties of molten salt is studied in this study. An improved colliding bodies optimization (ICBO) algorithm is developed to solve inverse problems, in which three improvements is proposed: (1) chaos theory is introduced to optimize initial positions of colliding bodies; (2) a self-memory strategy is proposed to improve local search ability; and (3) a random search strategy is proposed to improve global search ability. And the test functions prove that the ICBO algorithm is more efficient and robust than the original colliding bodies optimization algorithm. A two-step retrieval strategy is proposed to overcome serious crosstalk problem among different parameters, in which optical parameters are inversed based on the transmittance-reflectance model firstly, and then thermal parameters are inversed based on the transient coupled conduction-radiation model and known optical parameters obtained in the first step. All research outcomes indicate that the constant and temperature-dependent thermal and optical parameters of molten salt can be estimated accurately by the ICBO algorithm and two-step retrieval strategy. Even if considering 10% of measurement error, the maximum relative error is only 6.50% (estimation of thermal conductivity). Therefore, this work is beneficial for improving utilization of molten salt for harvesting solar energy.