The Project

The first transcritical carbon dioxide refrigeration system in New Zealand has been installed in a supermarket at Devonport, Auckland. It is equipped with control and monitoring systems by Resource Data Management (RDM), ensuring the smooth running of the plant and optimising energy use across the store’s advanced integrated cooling and heating system.

The Challenge

The New Zealand government is introducing tough controls on the use of synthetic HFC refrigerants. This takes the form of a levy on sales of refrigerants with a high Global Warming Potential (GWP) under the country’s Emission Trading Scheme. Cooling technologies based on high GWP HFC refrigerants will be subject to sharp rises in costs, with users facing significant additional expense in the event of a major leak. As a result, end users are searching for safe and efficient alternatives in order to reduce potential emissions and future-proof their businesses.New World supermarket, based on Auckland’s North Shore, is owned and operated by John Ashton, a businessman with an enlightened view of environmental issues with a willingness to explore innovative solutions. As part of a planned refurbishment of the 26-year-old supermarket, Mr Ashton was seeking to replace the existing refrigeration system and cabinets throughout the store. The challenge was to design a safe, efficient and reliable system that was not reliant on HFC refrigerants. John Ashton worked closely with EcoChill on a fresh approach to meet these requirements.

The Solution

The solution, designed, built and installed by EcoChill, is based on a transcritical CO2 refrigeration pack with a linked heat recovery system.

This harnesses waste heat from the high temperature condensing side of the refrigeration system to generate hot water for use in store heating and the domestic water supply. At the heart of the system are two newly designed and constructed CO2 packs: a booster system provides cooling to the Low Temperature (LT) and some Medium Temperature (MT) equipment, with the remainder of the MT load being cooled by the second CO2 pack. The heat recovery circuit draws energy from both packs to heat the retail area of the store, as well as providing hot water to meet the store’s entire hot water requirements. The air conditioning system, also upgraded as part of project, has been integrated into the store’s refrigeration and heating system, to create “a single store energy system”.

The installer removed the standard control system supplied with the packaged air conditioning unit, replacing it with an RDM PR0600 TDB unit, in order to provide a “helicopter view” of the entire mechanical and refrigeration system in operation. Matthew Darby, managing director of EcoChill, says: “The key to delivering an energy efficiency solution is, first, to ensure effective control of the transcritical refrigeration system; then, second, to fully integrate this with the heat recovery, heating and air conditioning systems – to manage it as one seamless, integrated system.” RDM plant was chosen to deliver this, controlling and managing all aspects of the system’s operation. It is based on RDM’s Data Manager, with Mercury 2 case controllers for the refrigerated merchandisers, an RDM Intuitive unit for controlling the transcritical CO2 pack, and hubs for remote pressure control. Programming was carried out by technical engineer James Darby of EcoChill.