Recently, with decreasing oil resources and environmental issues associated to use of fossil fuels, solar thermal power plants have attracted much attention among researches mainly due to zero emission and huge fuel savings they bring about. In this study, a small scale parabolic Trough collector and a thermal storage tank along with an auxiliary heater are coupled to a Kalina cycle to study the performance of the system throughout the year, both thermodynamically and economically. To examine the effect of solar collectors in the system, the model is compared to a fuel driven Kalina cycle. Results show that in 5 months of the year, the solar fraction is more than 50%. The exergy analysis reveals that the main source of destructions are solar collectors (more than 50% of total) and vapor generator. The solar collectors and vapor generator have an improvement potential of 69% and 65%, respectively. The Kalina cycle is responsible for a minor portion of total exergy destruction, thus more investment should be put on solar collectors. Economic analysis shows that, under design conditions, solar Kalina cycle has a levelized cost of electricity of 0.4274 $/kW h which is higher compared to that of fuel driven cycle with 0.3113 $/kW h. On the other hand, the solar system has a yearly fuel saving of almost 40,000 kg/year (natural gas) which is half of fuel driven cycle and can save more than 100 tons of carbon dioxide. Also, solar fraction and daily mean sun to electricity exergy efficiency of 67.71% and 5.24% are obtained, respectively, for July. Also, the thermal storage tank has a vital role on maintaining the stable working condition of Kalina cycle. To find the effect of key parameters on the performance and economic of solar system, a parametric study has been done. The results show that ammonia mass fraction variation has the most effect on exergy efficiency, solar fraction and levelized cost of electricity. This paper provides the reader to examine the performance of a small scale solar plant from exergetic view point and to estimate the overall costs associated to the system.
کلید واژگان :Kalina cycle, Parabolic Trough collector, Exergy efficiency, Levelized cost of electricity
ارزش ریالی : 600000 ریال
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