The debate about what constitutes the 'right choice' of refrigerant for supermarkets has intensified in recent years. Considerable reductions in emissions are possible, but at what cost?
Supermarket refrigeration technology is developing rapidly and there is considerable interest in alternative refrigeration systems and refrigerants. The intention is to highlight differences in the key factors between today's good practice systems and possible future system alternatives with today's known technology.
Comparisons made using this model are applicable to a supermarket of the type commonly found throughout Europe. Typically such an installation could have 1000-1200 m2 sales area and a medium temperature cooling load of 75kW with a corresponding low temperature load of about one quarter of this value. The size of the installation can be varied to suit individual requirements. The system types are appropriate to this type of application and therefore comparisons will lose their validity if very small or very large sizes are considered. The same applies to applications other than commercial supermarket refrigeration.
Alternatives to the direct expansion (DX) system with central plant room have been successfully employed. And natural refrigerants such as R744 offer the advantage of close to zero direct emissions, although they may have penalties in terms of energy consumption, indirect emissions and investment cost.
Whilst it is recognised that many users are considering integrating air conditioning, heating and heat recovery, these "total building" solutions are not covered in this model. For ease of use we focused on the cabinet cooling systems that play the major role in supermarket refrigeration.