Self-Optimizing Control of a Two-Stage Refrigeration Cycle

The application of self-optimizing control theory to a two-stage refrigeration cycle was investigated. Defining the cost function as the economical trade-off between the power consumption and the evaporator outlet temperatures, it was found that the optimal point of operation leaves two unconstrained degrees of freedom for implementing a self-optimizing control structure. We consider two cases: (1) where the self-optimizing control structure is designed to optimally reject only physical process disturbances, and (2) where the control structure in addition handles changes in the economic parameters of the cost function. The control structure is able to keep the process close to optimal despite disturbances and changes in the product prices, and thus makes a supervisory real-time optimization (RTO) layer unnecessary. (C) 2016, IFAC (International Federation of Antomatic Control) Hosting by Elsevier Ltd. All rights reserved.