In addition, as shown in Fig. 8, the power output slightly increased with the increase in the stoichiometric ratio due to the reduced concentration loss. The thermal energy and compression work almost linearly increased with the stoichiometric ratio because of the elevated flow rate. Consequently, the system efficiency decreased with the stoichiometric ratio because the increased thermal energy and compression work was more substantial than the increased power output. At high current density conditions, the cell performance increment might be more pronounced because the concentration loss becomes more significant.