Exergy analysis and optimization of a solar driven Kalina cycle based on evolutionary algorithm

This paper presents detailed energy and exergy analyses of Kalina cycle integrated with parabolic trough solar collectors. Key exergetic parameters are examined: exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential. It is revealed that as the solar irradiation intensity increases, the energetic and exergetic efficiencies increase. Exergetic analysis shows that the main source of exergy destruction is the solar collectors in which more than 68% of solar inlet exergy is destructed. In addition, more than 15% of the inlet exergy is destructed in the evaporator. This study indicates that there is an exergetic improvement potential of 95% in the system considered. Also, a parametric analysis is conducted to examine the effects of some key thermodynamic parameters on the system performance. The system is also optimized with the exergy efficiency as an objective function by means of genetic algorithm under the given conditions. It is found that there exists an optimal turbine inlet pressure and evaporator pinch temperature difference under given conditions to maximize the energy and exergy efficiencies of system. The energy and exergy efficiencies are less sensitive to a change in the turbine outlet pressure. An optimal ammonia basic concentration and ammonia-water mass rate can be identified that yields maximum energy and exergy efficiencies. Finally, it is shown that system exergy efficiency improves from 5.41 to 8.20% under optimal conditions.

Keywords:

energy , exergy , Kalina , parabolic trough solar collectors , optimization