The Carbon Dioxide Interest Group (c-dig) met this week in Stockholm to explore and discuss latest advancements in R744 (CO2) systems for supermarkets, food processing, fishing vessels and ice rinks, amongst others.
Frigo Consulting: The Swiss consultancy specialized on planning and optimizing CO2 systems and ice slurries, presented its cascade system leading to 10-20% reduced energy consumption. The system includes a transcritical unit for medium and a subcritical unit for low temperature applications, as well as a heat recovery function to provide for additional space heating. The company confirmed that R744 is thus more energy efficient than R134a with cost efficiency of new CO2 installations largely depending on local climatic conditions and cooling capacities. Frigo Consulting’s systems have already been installed in supermarkets of the leading retail group Coop, among others.KTH: Yang Chen from the host organization Royal Institute of Technology (KTH) presented the EffSYS 2 project which includes testing of a commercial heat pump sold in Sweden, and the creation of a permanent testing center at the KTH for CO2 heat pump system research. He then focused on other R744 novel systems, such as a power system in low-grade heat source utilization and a CO2 double loop system. A reverse CO2 refrigeration cycle can thus be used to generate power, while a solar panel will provide the compressor with energy to keep the system operating. KTH estimates that once the energy gained from the cycle will be transferred to the compressor, the new Coefficient of Performance (COP) could be at 4.45, which translates to a 40% COP improvement for a CO2 cooling and power combined system. (see presentation attached)