Optimum power performance of a new integrated SOFC-trigeneration system by multi-objective exergoeconomic optimization

•We apply a multi-objective optimization for an integrated SOFC-trigeneration plant.•An example of decision-making for finding a final optimal solution is introduced.•Multi-objective optimization increases the exergy efficiency from 62.85% to 64.5%.•The optimization process decreases the system unit cost of products about 14%.•Comprehensive sensitivity analyses perform on the unit cost of products.

In the present study a comprehensive thermodynamic modeling and multi-objective exergoeconomic optimization of a new integrated SOFC-trigeneration system is carried out to determine the optimum decision parameters, accounting for exergetic, economic and environmental factors. Results of optimal designs are obtained as a set of multiple optimum solutions, called the Pareto optimal solutions. An example of decision-making is presented and a final optimal solution is introduced. Moreover, the optimized results are compared with the working data from a base case design of an actual system. This new approach shows that by selecting final optimum solution, the trigeneration unit cost of products reduced by 13.88% and exergy efficiency increased from 62.85% in the base case to 64.5% in the optimum case. Also, the optimization results demonstrate that fuel cost, exergy destruction cost and environmental impacts (CO2 emissions cost) are reduced by 17.54%, 17.05% and 18.22% respectively; although these are achieved with 8.03% increase in the capital investment cost. Finally, sensitivity analysis is carried out to examine the effect of changes in the Pareto optimal solutions to the system economic parameters.