Numerical simulation of atmospheric transmittance between heliostats and heat receiver in Tower-Type solar thermal power station

Based on the Simple Model for Atmospheric Transmission of Sunshine and meteorological observations, a simulation method for atmospheric transmittance between tower solar thermal power heliostats and heat receivers is developed. This method is verified by the vertical radiation observations in Tianjin, China. The results indicate remarkable differences between the simulated global horizontal irradiation (GHI) and the observations under different weather types, and the magnitude of the difference is mainly influenced by near-surface visibility and cloud cover. However, the ratios of the simulated GHI at the altitude of 40 m to that of 200 m are basically consistent with the observations, with deviations of less than 0.02 for more than 97 % of the moments, indicating this method is applicable to simulating the ratio of GHI at different heights. Results show a 20-m increase in altitude leads to an increase of 0.009 % in atmospheric transmittance within 200 m above the ground. Due to the influence of meteorology, the atmospheric transmittance shows obvious diurnal and seasonal variations. Assuming the vertical altitude of a heat receiver is 200 m and its horizontal distance from a heat receiver is 50 m, the average atmospheric transmittance between them is 94.72 %, and the transmittance drops to 76.49 % at the horizontal distance of 1000 m. This method estimates atmospheric transmittance between heliostats and heat receiver, and provides reference for the design of tower type solar thermal power station and the evaluation of the operation status.