- Energy consumption: expected 8% energy savings on the project, countries with more experience claim around 25% energy savings;
- Climate: in the Southern United States this type of system is currently more suitable than a CO2 only system;
- Environmental concerns: on average a standard refrigeration system in a grocery store has a 25% leak rate, leaking 1000 lbs of refrigerant;
- State and National Codes and Regulations: compliance with energy code requirements, State, National Codes, EPA rulings, and avoiding future penalties for HFC leaks, possible taxes on HFCs or HFC refrigerant charge limits;
- Preventing the need for future refrigerant conversions.
The NH3/CO2 system consists of a low temperature direct expansion CO2 system and a medium temperature pumped CO2 secondary system, and NH3 chiller modules. The individual ammonia module systems have less than 10 lbs of ammonia and are separated from each other, to make them safe for highly populated areas.
- Ammonia primary system with 250 lbs of ammonia located in an outdoor enclosure that will condense CO2;
- A water cooled system that allows for a reduction in refrigerant charge;
- “Combined” CO2 refrigeration system with one vessel that contains liquid pumped to the low and medium temperature display cases and walk-in cabinets;
- R290 spot display case.
According to Jim Armer, P.E. CTA Architects Engineers, Refrigeration Group Manager, the natural refrigerant solution will allow SUPERVALU “to prepare for the future, for any refrigerant modifications that could be required in the US.”
- 29% TEWI reduction for the NH3/CO2 system compared to the R407A/CO2 system;
- 15% compressor saving for the NH3/CO2 system compared to the R407A/CO2 system;
- 18% first cost increase for the NH3/CO2 system compared to the R407A/CO2 system;
- 35% life cycle cost increase for the NH3/CO2 system compared to the R407A/CO2 system.
Overall the TEWI reduction compared to an R407A DX will be 77% for the R407A/CO2 systems and 84% for the NH3/CO2 cascade system.