Control optimization for cold-room (walk-in) refrigeration units.

Abstract

Cold-rooms are widely used in food retail and food service industry. The objective of this work is to present an optimized control strategy to enhance the performance of the cold-rooms, with special emphasis on energy savings through defrost optimization. A novel cold-room control algorithm was developed to predict the frost level accumulated on the evaporator so the controller is able to launch defrosts only when necessary, skipping unnecessary defrosts, which negatively affects energy consumption. The control is also able to manage the evaporator fans according to the frost level, providing free-cooling when the frost level is suitable to cool down the cold-room without using the compressor. The new algorithm was tested in four cold-rooms working under different conditions and satisfactory results were obtained. All cold-rooms drastically decreased their number of defrosts (reaching up to 90% reduction) and obtained important energy savings, from 15.9% to 39.3%.