| المستخلص: |
Many of the concentrating solar power (CSP) systems are expected be installed in desert locations where lack of water and sand storms might be an issue. The solar reflectors are considered to be among the main effective components. The negative effects of the harsh weather conditions, including sand storms of the desert might have strong influence on the reflector properties, leading to a decrease in the thermal performance of such solar system. This thesis studies the sand storm influence on solar reflector surfaces, where two different types of Libyan sands were considered and taken from sites suitable for the installation of CSP. These sands have different shapes, sizes and chemical compositions. Sand "A" has particle sizes that vary from 0.025 to 0.355 mm, while Sand "B" has particle sizes in the range of 0.124-0.479 mm. An erosion rig was designed and built at Cranfield University, UK. the tests were conducted under different simulated sand storm conditions for both sand samples. The results have shown that Sand "A" has more severe influence than Sand "B" because the smaller particles of Sand "A" help the spread out over a larger surface area of the reflector. The higher sand storm speed has more strong impact influence, while increasing the mass quantity results in less consequences. The reflectivity of the un-cleaned surface drops by 5% in case of using Sand "A" and by 7% in case of Sand "B", both at storm speed of 21 m/s with specific sand mass of 18 g/m 3. Sand storms with the speed exceeding 6 m/s, generate sand impact on the reflector surface causing degradation to the surface, while storms with speeds less than 6 m/s, result in wakes of suspended small particles as a consequence of the transport mechanism in the atmosphere. Sealing simulation and cleaning process, using Ultrasonic Cleaner Model, show that sand "B" makes a loss of about 3% of the surface reflectivity, due to the salt-chemical composition leading to create spots and marks on the reflector surface. However, Sand "A" has recorded no chemical reaction. Sand storm history should be taken seriously, reflector surface materials should be suitable for the sites, and cleaning operations should be considered.
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