A simulation environment allowing steady state and transient modeling is used for assessing several gas turbine based cycles proposed for solar hybridization. First, representative open cycle gas turbine configurations, namely, (a) single shaft (SS), (b) recuperated single-shaft, (c) twin shaft (TS), and (d) two-spool three-shaft, intercooled, recuperated, are evaluated. The importance of design point selection in terms of solar share value is highlighted. Solar steam injection gas turbine cycle (STIG) alternatives, namely, solar steam only and solar/fuel gas steam, are then assessed. Finally, the concept of a dual fluid receiver (DFR) for exploiting the rejected solar power by producing steam during sunny hours with high irradiation is demonstrated. The effects of hybridization on performance and operability are established and evaluated. Solarization effect on performance is estimated in terms of annual produced power and fossil fuel savings. The results indicate that the spool arrangement affects the suitability of a gas turbine for hybridization. Recuperated configurations performed better for the design constrains imposed by current technology solar parts. Solar steam injection is a promising solution for retrofitted fuel-only and conventional STIG engines.
The performance of solar hybrid Brayton cycle materialized by a micro-gas turbine based on a turbocharger is studied. The use of a turbocharger is aimed at investment cost reduction and construction simplification. Two configurations are investigated, namely hybrid and solar-only. Design aspects are discussed, in view of the requirement for minimizing the cost of electricity produced. A key parameter is the turbine inlet temperature and its effect on performance is investigated. The effect of heliostat field size is also investigated. Augmentation of the maximum temperature leads to better performance, as a result of higher cycle efficiency. Solar-only configuration features are compared with hybrid ones and the contribution of different cost components to the final electricity cost is discussed.
Laser-based techniques are used more and more frequently for the cleaning of artifacts. Due to the different behavior of each material, when it is irradiated, studies and experiments are performed in order to find the optimum laser parameters for each case. In this work, the laser cleaning of coins is examined. Coins are studied with analytical methods in order to detect the corrosion products and the accretions. This information along with the composition of the coins' alloys is fed into an in-house developed program which estimates the penetration depth of the laser beam as well as the laser fluence for which the alloy starts to melt. Exploiting this information, laser cleaning of coins is performed with various conditions and parameters. Finally, the result is evaluated by using microscopic methods. From this research, it was found that the laser cleaning of copper, silver and aluminum alloys is feasible with Q-switched Nd:YAG at 1064 nm. Also, higher level of corrosion and accretions requires higher laser intensity. For low corrosion level on copper alloys, a thin water film on the irradiated area is beneficial.
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