Towards a Simple Sand and Dust Abrasion and Soiling Prediction on Solar Components: Design of a Sand and Dust Accelerated Abrasion Chamber based on a Vertical Particle Blower

摘要

The extreme conditions of desert locations put a lot of stress on the components of CSP systems. Solar reflectors, in particular, are sensitive to soiling and abrasion from sand and dust and might see their ability to reflect and concentrate light compromised. Whereas soiling is usually reversible with cleaning, the abrasion of the mirrors' surface is non-reversible and lead to a permanent loss in reflectance. However, a specific guidelines to predict the reflectance degradation of solar mirrors in sand and dust abrasion prone environments is yet to be defined. The work presented here is a first step towards defining a low cost, simple testing procedure to realistically predict the surface degradation of solar reflectors, due to sand abrasion, under arid and semi-arid conditions. An accelerated sand abrasion aging chamber was designed and constructed with the aim of improving the reliability and repeatability of experiments of already existing sand abrasion apparatuses. The sand abrasion chamber is based on the open circuit sand blower design, and comply with relevant guidelines of the U.S. Military's sand and dust abrasion standard: MIL-STD-810G. The parameters of the sand abrasion testing apparatus are the wind velocity, the sand concentration, and the time of exposure. Its dimensions are 185×56×44 cm. The preliminary testing campaign yielded good particles' homogeneity in the flow and sand injection control, confirming the success of the design. Further tests with mirrors, revealed an exponential loss in reflectance with increased exposure time. This finding is in agreement with earlier work on sand abrasion of reflective materials.