AIR (R729)

The air refrigerating cycle has very low energy efficiency comparing with the vapor cycles at standard applications. In the composition of the air cooling machines, centrifugal compressor and expansion turbine are used, and in order to improve the cooling cycle, recuperator is placed.

Today air systems are applied in some specific applications as air conditioning of the planes, however they have a very good energy efficiency compared to vapour compression cycles at large temperature differences making them suitable for heat pumps and low temperature refrigeration applications, but not at the standard applications such as chilled and frozen stores and air conditioning.