A novel experimental method to find dust deposition effect on the performance of parabolic trough solar collectors

Abstract

One main reason why the performance of a parabolic trough collector measured experimentally differs from the simulation results is inaccurate prediction of absorbed solar energy. The amount of absorbed energy of such systems mainly depends on optical properties of mirrors, absorber tube and transmissivity of glass cover of absorber tube. This study examines the thermal performances of three collectors during different periods regarding the weight and thickness of deposited dust. A transient computer code is prepared to estimate thermal performances of clean collectors and compare the results with dusty collectors. A special optical instrument is designed and constructed to measure the reflectivity of mirrors with respect to the thickness of dust deposited on the surface of the mirrors. Based on the measurements a new correlation is developed to find thermal performance of a parabolic collector for various dust thicknesses in comparison to a clean collector. Different cleaning schedules are proposed for the collectors’ field; and thermal performance and yearly solar energy absorption of collectors according to each cleaning schedule are also determined. The performance of a solar-fossil hybrid power plant is studied and the impact of different cleaning schedules on reducing fossil fuel consumption and CO2 emission is investigated.