Multi-objective optimization of two hybrid power generation systems for optimum selection of SOFC reactants heat exchangers mid-temperatures

Abstract

Increasing efficiency and decreasing cost are the main purposes in the design of the power generation systems. In this study two hybrid systems: solid oxide fuel cell (SOFC)-gas turbine (GT) and SOFC-GT-steam turbine (ST); are considered. Increasing the SOFC input temperature causes thermodynamics improvement in the hybrid system operation. For this purpose, using two set of SOFC reactants heat exchangers (primary heat exchangers and secondary heat exchangers) are recommended. Selection of The primary heat exchangers output temperature and therefore the secondary heat exchangers input temperature (heat exchangers mid-temperatures) influences on the thermodynamics and economics operation of the hybrid system. This work shows that the annualized cost (ANC) and the levelized cost of energy (LCOE) act in conflict with each other. The MatLab genetic optimization algorithms are used to obtain the optimum solutions. The maximum achievable efficiency is 0.599 and the minimum LCOE is 0.0163 $/kWh. Also results show that the heat exchangers mid-temperature of air has the main role in the operation of the hybrid system.