Fig. 5

Predicted effect of R_f and L_f on NIFTE performance using the NTP model. Two distinct cyclic steady states are detected, denoted by CSS1 and CSS2, which are overlapping for certain (R_f,L_f) combinations. The effect on both the exegetic efficiency η_ex (left plots) and the average power output \(\dot {W}_{\mathrm {l}}\) (right plots) is shown for each cyclic steady-state. \(R_{\mathrm {f}}^{+}\) and \(L_{\mathrm {f}}^{+}\) refer to R_f and L_f normalized by their respective nominal values in Table 2. The remaining parameters are set to their nominal values. The separatrix between stable and unstable limit cycles are shown in white, with arrows pointing in the direction of stable limit cycles