Abstract 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 0.355mm, 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 21m/s with specific sand mass of 18g/m3.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.
عصام ميلاد اندايا (2015)

Abstract Using the ground to produce condensate water for drinking and irrigation is A new application. This study simulates numerically the use of humid air flow in a buried pipe in the ground to obtain fresh water. The temperature difference between the humid air and the environment (ground) is exploited in this condensation process. The finite difference method is employed with pressure Correction method on staggered grid to simulate the flow of humid air through Buried pipes. The condensation occurs due to the decrease of the humid air Temperature below the dew point, as a result of the heat exchange between the humid air and the ground. The amount of condensation depends upon the flow Velocity, absolute humidity, Relative humidity and pipe geometry. For a selected pipe geometry of 22m long, and 0.2m diameter, the amount of condensation is about 26 kg/hr (0.006944kg/s). The results of the current study are in agreement to within ±10% of the results given by Jenney Lindblom.
مروان عبد السلام الهمشيري (2010)

Abstract Erosion wear is recognized as an engineering problem for slurry handling equipments. It plays an important role in design and operation of slurry transportation systems. The present work reports experimental and theoretical investigations of erosion wear of carbon steel and stainless steel in sandwater mixture. However, carbon steel (AISI-CS1060) and stainless steel (AISI-SS316L). They have been chosen as target materials, and then studied the effect of various parameters that may leads to good understanding to the erosion behavior of ductile materials such as impact angle, particle velocity as well as erosion time on erosion wear. The impingement jet erosion test rig built at our laboratory in order to carry out the experimental results. Aluminum oxide (Al2O3) is used as erodent particles after it mixed with water for slurry preparation at various impact angles of 15°, 30°, 60° and 90°, the solid concentration range of (10-30) wt%, for sized ranging between of 800µm to1700µm in the velocity range of 5 m/s to 24 m/s, with periodic time of 10 minutes at room temperature. The data points that collected in this work showed that the experimental values are agreement with the ductile erosion behavior for both materials, also showed that the erosion rate increasing linearly with increases in impact velocity and erosion time, also showed scars were characterized by an elliptical shape at 15° and 30° whereas a nearly circular shape was observed at 60° and 90° due to the horizontal component of velocity at shallow angles has value more than the normal component of velocity whereas in contrast at high angles.
فاضل رزق شحات (2014)