Observation and modeling of dust deposition on glass tube of evacuated solar thermal collectors in Mongolia

The present study investigated the effects of dust deposition on transmittance of glass tubes of a solar thermal collector in Ulaanbaatar during the cold period and presents the results based on real exposure tests conducted between October 2015 and May 2016. In addition, the dust deposition on glass tubes was empirically modeled using the test results and the environmental data such as wind speed and direction, daily average airborne dust rate, snow, and rain. Based on observation of long- and short-term tests, snow was deduced to be able to clean dust accumulation on the glass tubes even if the ambient temperature is below zero. Also, the snow was found to be more effective in decreasing dust accumulation than rain according to the estimation. (C) 2018 Elsevier Ltd. All rights reserved.