Aging characteristic of solar coating and their cost-effectiveness

Abstract

Pyromark 2500 high-temperature coatings are widely used on the surface of solar power tower (SPT) receivers. However, the optical properties of these coatings decrease with increasing working time. Experimental conditions for aging tests, such as aging temperature and temperature change, were obtained using a three-dimensional model. The isothermal temperature was 630 °C for constant high-temperature aging test. The temperature variation rate was 20 °C/min and 330 °C/min for slow- and extreme-temperature-variation aging tests, respectively. The absorptance of the coating on Inconel 625 decreased by 0.18 %, 1.49 %, and 1.09 % after 2800 h at constant-high-temperature, after 2000 cycles under slow-temperature-variation, and after 100 cycles under extreme-temperature-variation, respectively. Moreover, the aged coating was characterized via scanning electron microscopy and energy dispersive spectroscopy. An innovative on-site test method for determining the absorptivity by mining operational data is proposed in this study. The absorptivity is 92.44 % and 90.74 % after 580 days and 1117 days of operation, respectively, obtained from the test data and the simulation results of the Solar Two receiver. The electricity loss due to coating absorptivity attenuation was 24447.6 MWh over three years without reapplication. Furthermore, the optimal reapplication interval ranged from 2 to 3 years, which is determined by the levelized cost of energy (LCOE).