High efficient integrated CO2 refrigeration systems with ejectors and pivoting compressor arrangements.

Equipment manufacturers of refrigeration units are facing challenges related to the legislative requirements forcing them to implement less conventional refrigerants with lower Global Warming Potential (GWP). 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, short life HFCs and their blends do not represent a safe and sustainable alternative.
CO2, a natural working fluid applied since the early days of refrigeration, has demonstrated to be an energy efficient and environmentally benign alternative. Design effort has to be made to develop affordable high efficient integrated refrigeration systems applicable in high ambient temperature areas. One way to reduce size and costs is to adapt the number of compressors at the various suction groups. Another enhancement possibility is the utilisation of the normally unused expansion work by applying ejectors.
The article will describe how enhancement measures like ejectors and pivoting compressors will influences the energy efficiency and can help to downsize systems. Cold energy storage is also an interesting feature, supporting the refrigeration systems with accumulated cooling capacity, applicable during peak capacity periods, without additional compressors.