Our refrigeration system used natural refrigerants due to zero rating for ozone depletion and negligible global warming potential (GWP). A centralised ammonia (GWP=0) refrigeration system with a secondary glycol-water brine circuit delivering the cooling requirements to the medium and high temperature areas within the facility was chosen.
To achieve a full natural refrigerant solution a sub-critical CO2 cascade system was used for the low temperature freezers. Along with satisfying the natural refrigerant criteria the CO2 subcritical configuration offers very high efficiencies in low temperature operations. Fan motors and main pumps were all selected with high efficiencies and variable speed control to minimise energy usage.
A programmable logic control system was developed to achieve close control of all system and room operating parameters. A full supervisory control and data acquisition system was incorporated into the control system to gather, analyse and report on the system’s real time data. The extensive use of LED lighting and insulated rapid roller doors throughout the facility.