The carousel system considered in this study has a number of multi-carrier carousels (rotary racks) served by two traveling robots. One robot is dedicated to storage operations and the other to retrieval operations. We develop an economic design model for the system based on a recursive optimization / simulation procedure. With a non-linear integer optimization model, we seek key design parameters minimizing the total cost while complying with the desired level of performances. Also, through simulation study we consider the dynamic nature of the system and integrate the results within the optimization model. The validity of the model is examined with an example. Significance: When we design the economic carousel system, the dynamic nature should be considered. The MIP model we developed includes the dynamic nature and is solved through a recursive optimization/simulation procedure.