ATMOSPHERIC ATTENUATION IN CENTRAL RECEIVER SYSTEMS FROM DNI MEASUREMENTS

摘要

Atmospheric attenuation loss between the heliostat field and receiver has been recognized as a significant source of loss in Central Receiver System. Methods that can improve estimation of attenuation loss using available measurements will be useful in reducing uncertainty in estimation of CSP plant production, particularly in locations and climates that differ in atmospheric composition from typical arid desert locations. In clear sky situations, Direct Normal Irradiance (DNI) is primarily impacted by aerosols in the atmosphere. Aerosols extinct direct radiation with the photons either being absorbed or scattered based on the aerosols optical characteristics. As aerosol loading is high close to the surface, the attenuation loss between heliostat and receivers is significantly influenced by amount of aerosols present on a particular day. The purpose of the study is to understand the impact of aerosols on attenuation loss and model this loss as a function of ratio of measured DNI to a calculated DNI for an "aerosol-free" atmosphere. The assumption here is that the reduction in clear sky DNI due to aerosols when compared to a theoretical "clean environment" value can provide valuable information about aerosol loading at the surface and therefore attenuation loss between heliostat and receiver. Preliminary analysis shows that such an approach is viable.