High-efficiency concentrated solar power plants need appropriate materials for high-temperature heat capture, conveying and storage

Particle suspensions can be used in Solar Power Towers to capture the solar heat at a high temperature, and convey it to the storage and the subsequent use in the power block. Thermal Energy Storage (TES) needs to be integrated. Temperatures of 600-900 °C foster the use of high-efficiency power generation cycles. Appropriate Phase Change Materials (PCMs) in that temperature range were examined, i.e. Sb2O3 for the lower melting point range, and BaCO3 and its Na2CO3 compounds as high melting PCMs. Cooling rates of the melt and solid phases follow a linear-time relationship. The time for solidification of the melt is also measured. Rates and times are compared with the theoretical approaches of unsteady state conduction and phase transition. The cooling rate of the melt is significantly higher than the cooling rate of the solid phase. The time of phase transition is a function of the latent heat. Natural convection within the melt enhances the heat transfer, and is predicted by assigning an effective thermal conductivity to the melt. The thermal cycling of the encapsulated PCMs demonstrates that the selected encapsulation material retains its mechanical properties for 1250 charge/discharge cycles. Practical considerations on TES design conclude the research.