Automated cold-storage facility in Canada to employ integrated CO₂ system

September 20, 2023

One of North America’s most automated vertical cold-storage facility, located in Varennes, Quebec (Canada), will employ an integrated transcritical CO₂ (R744) system serving refrigeration, air-conditioning and heating.

Logistics operator Groupe Robert will invest $CAD 150 million (€103 million) to build the 150ft (45.7m)-tall facility, equipping it with 60,000 product pallets, five times more than any of the company’s previous undertakings.

Giacomo Pisano, CO₂ compressor Business Development Manager, Dorin, called the facility “one of the most innovative automated large vertical cold storages.”

Pisano explained the project, which incorporates Dorin compressors, during his presentation at the ATMOsphere (ATMO) America Summit 2023 on natural refrigerants. The conference took place June 12–13 in Washington, D.C., and was organized by ATMOsphere, publisher of R744.com.

Canadian OEM Zero-C is supplying the CO₂ system, which delivers 180TR (633kW) at -30°F (-34°C) SST and 450TR (1,483kW) at 18°F (-8°C) SST.

“The introduction of a full CO₂ system not only highlights an eco-friendly approach to refrigeration but also positions the building as completely self-sufficient,” said Pisano.

The system’s design incorporates three adiabatic gas coolers, parallel compression, and pumped CO₂ for both low-temperature (LT) and medium-temperature (MT) duties. The facility’s integrated air conditioning keeps the electrical room temperature below 85°F (29°C). Moreover, a hot-gas defrosting system is employed for the evaporators. In addition, there is also a heat recovery mechanism, ensuring winter comfort heating and frost prevention at the loading docks.

The excess heat produced by the facility’s rack isn’t wasted. Instead, it’s redirected for the benefit of the local community, providing warmth to approximately 100 family homes.

Geographic and system comparison

Pisano provided calculations identifying the energy consumption of various ammonia/NH₃ (R717) and CO₂ systems at progressively warmer locations in North America, from Montreal, Boston and New York to Washington, Atlanta and Orlando.

The systems included CO₂/NH₃ with evaporator condenser (baseline/100%), NH₃ with evaporative condenser, NH₃ tower, CO₂/NH₃ tower, CO₂ FGBV, CO₂ FGBV with evaporative condenser, CO₂ with parallel compression, CO₂ with parallel compression and evaporative condenser, CO₂ with ejector and CO₂ with ejector and evaporative condenser.

Pisano reported that the most efficient system was the CO₂ with ejector and evaporative condenser, which posted an energy consumption of 84% versus baseline in Montreal and was even with baseline in Orlando, which has the warmest climate. The CO₂ system with only an ejector was even with baseline in Montreal.

The CO₂ system with parallel compression and evaporative condenser was also more efficient than baseline in Montreal (97%), but less efficient (111%) in Orlando.

The CO₂ system with only FGBV was 111% in Montreal, and 133% in Orlando.

All of the NH₃ systems and the other NH₃/CO₂ system were close to, though higher than, baseline

“In Montreal, a CO₂ FGBV system would traditionally consume more energy than an NH₃-CO₂ cascade system,” said Pisano. “However, by incorporating CO₂ parallel compression coupled with adiabatic cooling, the CO₂ system’s efficiency and appeal were significantly enhanced.” In regions like Orlando, characterized by higher temperatures, the CO₂ FGBV system inherently demands more energy. Yet, with the integration of ejector technology, an Epta CO₂ system can achieve efficiency levels comparable to the CO₂/NH₃ cascade system, he noted.