Exergoeconomic assessment and multi-objective optimization of a solar chimney integrated with waste-to-energy

In this study, an integrated renewable energy system is proposed by integrating Tehran's waste-to-energy plant with a solar chimney power plant. The integration is performed by exploiting warm air of the condensers cooling air for injecting under the turbine of solar chimney power plant. The proposed system is analyzed from energy, exergy, exergoeconomic, and environmental viewpoints through the parametric study. Exergy efficiency, net power output, solar chimney power plant power output, total product cost and cost rates of the system are plotted and compared during the night and daytime. Additionally, influence of the effective parameters is examined on the CO2 emissions indicator. Subsequently, the proposed system is optimized by multi-objective optimization method using a developed MATLAB code based on a genetic algorithm. Four effective design parameters are presumed for multi-objective optimization purpose and exergy efficiency along with total cost rate are considered as the objective functions. Accordingly, a group of the optimal solution points is gathered as a Pareto frontier and the most favorable solution points are ascertained from an exergy/exergoeconomic viewpoints. In addition, a point which is well-balanced between the conflicting objectives is selected as the final solution. Eventually, scatter distribution of the effective parameters are presented to have a better outlook of optimal ranges of the parameters. Results indicate that exergy efficiency of the system is higher during the nighttime while total product cost is lower during the daytime. Results further indicate, turbine inlet pressure has the highest impact on the CO2 emissions and the solar chimney power plant has the highest exergy destruction. Results of the multi-objective optimization demonstrate that at the best solution point, exergy efficiency and total cost rate of the system are 7.56% and 406.8 $/h. Furthermore, analyzing scatter distribution of the effective parameters reveals that higher values of the superheater temperature difference may be a better choice for designing the system.