Ice-cream storage energy efficiency with model predictive control of a refrigeration system coupled to a PCM tank

Abstract

A model predictive controller (MPC) was developed in order to optimise energy management of an ice-cream warehouse refrigeration system coupled to a phase-change material (PCM) tank. The controller's internal model was based on a steady-state refrigeration cycle model and energy balances on the PCM tank and warehouse. Considering crystal growth in ice-cream, the quality evolution was based on Ostwald ripening equation. The product temperature field was determined by a 1-D finite difference equation. An original PCM model was developed for better performance of Levenberg–Marquardt's optimisation algorithm which was modified in order to take into account control variables' bounds. Simulation of the ice-cream storage for a period of 90 days lead to good results on the optimised control sequence with efficient energy management thanks to the PCM tank. Ice crystals size remained below the defined target: 26 μm. This study showed the great potential of MPC to reduce energy consumption and guarantee food quality.