ALDI US Tests Innovative CO2 and Propane Control Systems by Carel for Enhanced Efficiency

At two newly opened ALDI US locations, the Italian control system manufacturer, Carel, has initiated comprehensive control and monitoring system testing. These systems oversee each store’s transcritical CO2 (R744) compressor racks and propane (R290) plug-in spot merchandisers. Encouraged by the successful trials, 15 additional stores are set to receive similar state-of-the-art equipment by the end of this year.

The ingenious control system, introduced by Giacomo Favari, North American Refrigeration Marketing Manager at Carel, was unveiled at the ATMOsphere America Summit 2023, hosted from June 12 to 13 in Washington, D.C., and organized by ATMOsphere, the publisher of

Favari explained, “By providing the monitoring system, we can build synergies among every single element of the system,” including heat reclaim. However, this distributed controller also allows individual components to operate independently up to a certain level.

The collaboration with ALDI US stemmed from the company’s desire to gather data for the centralized CO2 refrigeration system and some spot merchandisers using propane.

U.S.-based OEM Hillphoenix manufactured the transcritical CO2 racks for the initial two pilot stores, a system that combines low-temperature subcritical scroll compressors with transcritical medium-temperature compressors using reciprocating technology. Austrian manufacturer AHT supplied the propane (R290) plug-in spot merchandisers.

Efficiency was a key focus. The control boards communicate with several components, including the high-pressure valve, the flash gas bypass valve, and an electronic evaporator pressure regulation (EEPR) valve, enhancing overall performance.

Carel incorporated mechanical components from various vendors into their controllers in an impressive display of flexibility. Besides refrigeration equipment, Carel integrated the store’s wastewater vacuum collection system supplied by EVAC into the control system.

Two separate Modbus RTU (remote terminal unit) lines feed into the total-store-control supervisory system. One connects to the vacuum collection system and the spot merchandisers, equipped with Secop compressor controllers. The other relates to the gas leak detectors, remote case and walk-in controllers, and the rack controller, allowing seamless flow of information into Carel’s monitoring system.

Favari emphasized the importance of a comprehensive approach: “For reliability and safety, having a total store approach allows us to apply anti-liquid return and safe restore algorithms.” This ensures that safety measures are in place to minimize loss in case of CO2 leaks.

The store can visualize and interact with each element on a 17-inch touchscreen monitor using a single controller. Furthermore, their open protocol strategy enables data stored in the supervisory system to be shared with third-party digital platforms such as IMS Evolve, ADT, Service Channel, and Carel’s Red Optimize platform.

Bluetooth connectivity facilitates interactions with case controllers, allowing field technicians to use apps for startup, commissioning, and servicing, with the added advantage of remote OEM support.

Favari recognized the importance of servicing in transcritical CO2 systems, stating, “Servicing is one of the most important dimensions for transcritical CO2 systems.”

With ALDI monitoring energy data from the two pilot stores, plans are underway to equip 15 additional new stores with these advanced controls in the second half of 2023. This expansion signifies that Carel’s systems are delivering energy efficiency to ALDI.

Reflecting on the journey, Favari acknowledged that extensive training was provided to multiple stakeholders involved in the projects, including OEM departments, contractors, and field service technicians. Carel is now developing structured training programs, including a contractor certificate program and an online training portal, ensuring safe and efficient service for transcritical CO2 technology.

Looking ahead, the integration of HVAC systems into the controller is on the horizon, fostering collaboration among the various groups responsible for the store’s mechanics. To optimize the entire store’s operation, incorporating artificial intelligence (AI) algorithms for prospective analytics is also underway to enhance energy efficiency during startup and maintain it over time.

Headquartered in Brugine, Carel has installed over 11,000 natural refrigeration control systems since 2016, with a significant focus on CO2-based systems and high-efficiency propane systems. In recognition of their outstanding achievements, ALDI US received the Best in Sector/Retail award at the 2023 ATMOsphere America Summit and the 2022 GreenChill Store Certification Excellence Award from the U.S. Environmental Protection Agency (EPA) for having the most GreenChill-certified stores in the previous year. According to ALDI’s 2022 sustainability report, nearly 500 ALDI US stores were already equipped with CO2-based refrigeration systems, with additional stores planning to apply for GreenChill certification shortly.

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