Modeling and Simulation of a Thermophotovoltaic System with NaF Heat Storage

This paper presents the modeling and simulations of a solar thermophotovoltaic (STPV) system with sodium fluoride (NaF) as thermal storage material. A Cassegrainian optical concentrator is modeled using Ray Tracing to determine its optical efficiency under realistic solar irradiance data. Also, a tungsten photonic crystal (W PhC) selective emitter with a Germanium (Ge) PV cell are simulated using PC1D software where the cell efficiency and power density are evaluated. Thermal analysis is carried out using COMSOL-Multiphysics to study the system thermal behavior and determine the overall system efficiency and power output. The results show that the designed system can reach 85.2% solar to thermal efficiency and a corresponding 11.9% efficiency for the Ge cell. We also concluded from the thermal analysis that NaF does not allow a uniform temperature distribution inside the system due to its low thermal conductivity.