An integrated CO2 (R744) refrigeration, heating and cooling system installed last year by Swiss cold storage operator Grünenfelder in Quartino used 30% less energy than the previous system that used R507A and R404A for cooling and heating.
That finding was reported by Luca Rossi, Engineer, an Engineer and Project Manager at Biaggini Frigoriferi, the Swiss manufacturer of CO2 commercial and industrial refrigeration systems that supplied the integrated system, called TotalGreEnergy. Rossi described the project last November at the ATMOsphere Europe Summit, held in Brussels; he was accompanied by Mirko Guidetti, Co-owner of Grünenfelder, a family-run company specializing in the distribution of food and non-food products.
The integrated CO2 unit provides the store’s refrigeration, HVAC and hot water production requirement in a single system throughout the year. Previously, the store had an R507A refrigeration compression rack and a reversible R404A heat pump for refrigeration, HVAC, and hot water.
Energy consumption measurements were taken for 45 days after the installation of the TotalGreEnergy solution. In a comparison to the previous five years during the same annual period, the energy consumption was reduced by 30% compared to that of the old system (without considering solar power energy), said Rossi.
In addition to the decreased energy consumption, the new CO2 unit provided an improved temperature level, he noted. For example, the new system provides low temperatures ranging from -23 to -27℃ (-9.4 to -17°F). The lowest temperature the old system reached was -18℃ (-0.4°F), which was insufficient to preserve food items in the distribution storage area.
Moreover, remote surveillance is able to monitor the functioning of the unit, which reduces issues during maintenance and emergency situations.
Rossi also cited remarks made by Guidetti that the integrated CO2 is providing “100% satisfaction.”
The integrated TotalGreEnergy CO2 system services five medium-temperature cold rooms, a 1,000m2(10,764ft2) low-temperature room and an unloading ramp. The system provides 150 and 300KW (42.7 and 85.3TR ) for low- and medium-temperature applications, respectively.
It has a chiller capacity of 250KW (71.1TR) to provide cooling to offices and stores during summer and 300KW for space heating during winter along with hot sanitary water production. In addition, two electrical rooms are also cooled by R744 evaporators.
The CO2 system contains 12 compressors: three primary and one auxiliary for low-temperature applications and five primary and three auxiliary for medium temperature applications. It uses Dorin compressors, LU-VE evaporators and gas cooler and Eliwell controllers.
The heat recovery takes place in two stages to produce chilled water at 10℃ (50°F) and hot water at 45℃ (113°F). Chilled water is used to provide cooling in offices and stores whereas hot water is used to provide heating services in winter.
The installation of the new system was done during the old system’s operation, assuring normal business hours at the Grünenfelder facility. The company installed 3,160m2 (34,014ft2) of photovoltaic panels that had a power production capacity of 662,560kW at peak.