From Figure a number of informative findings appear. As seen from the maximum compression stage temperature (highest of all stages), all cases with 4 or more stages appear feasible with little effect of the applied inter-stage pressure drop. When zero pressure drop is applied, the minimum power is found at the highest stage number. However, with increasing pressure drop between stages, the optimal number of compression stages decrease. The reason for this is that the cumulative pressure drop for a certain level of stage pressure drop is higher for a higher number of stages. Limiting the number of stages also limits the cumulative pressure drop. Thus, a trade-off appears between a higher number of stages being optimal in terms of compression power and on the other hand a lower number of stages limit the cumulative pressure drop (and hence the power penalty to overcome this pressure drop).