Integrated CO2 solutions for supermarkets
Journal article, Peer reviewed
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Original versionScience et technique du froid. 2018, 2018-June 1411-1421. 10.18462/iir.gl.2018.1410
Supermarkets represent a refrigeration application area which is spearheading towards the total phase in of natural working fluids. Exposed to demanding customers where reputation is an important part of the business, focus is given to cost of ownership, and therefore the energy efficiency of the technical equipment, and the environmental profile. Due to the EU F-gas regulation, vendors supplying conventional, non-natural working fluid refrigeration equipment are facing challenges related to the legislative requirements and supply shortages. It forces them to implement less conventional refrigerants with lower Global Warming Potential (GWP) in their new products. The newly introduced next generation of hydrofluorocarbons (HFCs) with ultra-low GWPs do have a very short (atmospheric) lifetime, however, the decomposing products are highly toxic in combination with water, and distributed everywhere it becomes a question whether they represent a safe and sustainable alternative. As Gustav Lorentzen said: “We should not try to solve a problem by introducing another problem”. Natural working fluids like CO2 have demonstrated to be an energy efficient and environmentally benign alternative, especially for supermarket applications. Since its fluid- and thermosphysical properties are quite different from most other working fluids, the refrigeration system designs have to be carefully adapted to the properties of CO2, thereby maximising the energy efficiency and minimising the total cost of ownership. Integrated CO2 systems can simultaneously provide refrigeration capacities at various temperature levels, air conditioning (AC) & dehumidification, heating and even sanitary hot water at adequate temperature levels. A further integration of advanced thermal storage devices can enable centralised supermarket refrigeration systems to become a valuable element within smart (thermal) grids. Well designed and integrated systems can demonstrate reduced power consumption typically by more than 30 %. The article gives examples of the latest system developments applicable in commercial refrigeration / supermarkets.