Water and energy are the most important topics on the environment and sustainable energy development agenda. The social and economic health of the modern world depends on sustainable supply of both energy and water. Many areas worldwide suffering from fresh water shortage are becoming increasingly dependent on purification as a highly reliable and non-conventional source of fresh water. Therefore, purification market has greatly expanded in recent decades and expected to continue in the coming years. The integration of renewable energy resources in purification and water purification has become increasingly attractive. This is justified by the fact that areas of fresh water shortages have plenty of solar energy and these technologies can be used due to their low operating and maintenance costs. This review paper discusses the systems that can be used to harness renewable energy sources including, solar collectors, solar ponds, photovoltaics, wind energy and geothermal energy and finally a discussion and conclusion about some distinguished features of each process. Merging of these renewable energy sources with conventional sources has led to optimize the performance of purification plant, less maintenance requirement and reduction in overall cost. It was found that, to choose the best renewable energy source for a purification plant in a particular area, important determinative factors should be considered such as water salinity, area remoteness, plant size, technical infrastructure of the plant, capacity factor, energy consumption and capital cost of the equipment.
Nickel-based superalloys are widely used at elevated temperature applications because of their high corrosion and oxidation resistance characteristics as well as high stability. To improve the hot corrosion resistance of Nickel-based superalloys, different coatings are applied. In this study, nickelbase superalloy Inconel 738LC was coated via a novel hot-dip diffusion siliconizing process and the corrosion behavior was investigated by XRD, SEM and EDS analyses. A sever degradation and poor hot corrosion resistance was detected by the uncoated sample, while the siliconized coated sample possessed high corrosion resistance. It was figured out that the high hot corrosion resistance of the coated sample was due to the formation of SiO 2 protective scale in the surface layer which protects the substrate elements in the hot corrosion environment.
One of the most important coating methods on aluminum surfaces is the electrolytic plasma method. The main objective of the present study is to investigate the potential of aluminum oxide coatings created by electrolytic plasma method. Aluminum series 2 and the electrolyte of sodium silicate, sodium tetraphosphate, sodium aluminate, and potassium hydroxide were used. The results showed that the appropriate voltage to achieve uniform coating with ideal thickness and morphology is 500 V. Adding sodium silicate to the electrolyte solution will create porosity and non-adhesion to the substrate. On the other hand, the use of tetra sodium pyrophosphate increases the adhesion of the coating by penetrating phosphorus into the metal/coating interface. The optimum solution for plasma electrolytic oxidation coatings composed of 10, 3, and 3 g/l of tetra sodium pyrophosphate, sodium aluminate, and KOH, respectively. DC pulsed coating was shown to control the coating process and coating uniformity. Also the appropriate frequency to apply coating was DC pulse potential at 1000 Hz frequency under the 30% duty cycle.
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