Sammendrag
Supermarkets are commercial buildings with major energy consumption and contribute also to rela¬tively large direct emissions of greenhouse (GHG) through emissions of refrigerants from the refriger¬ation plants and the air conditioning system installed.
The huge majority of these systems, which are installed in European supermarkets, are applying HFC-404A as working fluid. Average annual leakage rates in Europe are in the range of 15-20 % of the total charge. Worldwide the figure is about 30 % and HCFC-22 being the main refrigerant in use. Re¬strictions on the use of synthetic refrigerants are coming into force in several countries. There is a need for a natural refrigerant which allows for a safe investment in efficient refrigeration systems which will not be forced to be retrofitted by legislation in the future. Systems applying R-744 as the only re¬frigerant have been developed and more than 500 supermarkets exist in Europe, mainly in northern and mid-European countries. However, the systems still have large potential in development with re¬spect to energy efficiency, heat recovery and cost efficiency.
The paper describes the calculation method to identify the possible annual energy savings for different supermarket systems layout. The adoption of non-controlled ejectors and additional function such as heat recovery are evaluated. Results show relevant improvements in system efficiency when heat recovery has been adopted. Ejector usage is not widely spread at the moment. Thus, a theoretical analysis applying the programming language Modelica has been carried out.
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