US Patent 7845190 Transcritical refrigeration cycle

A transcritical vapour compression refrigeration apparatus including: a compressor, a gas cooler, an economiser, an evaporator and a refrigerant; the refrigerant being compressed in the compressor, heat being rejected from the compressed refrigerant at supercritical pressure in the gas cooler, the cooled compressed refrigerant being then expanded in a first stage to first temperature and pressure conditions in the economiser and then expanded in a second stage to second temperature and pressure conditions; a stream of refrigerant from the economiser at said first temperature and pressure conditions then being compressed in a first stream in the compressor, refrigerant at said second temperature and pressure conditions absorbing heat in the evaporator and then being compressed in a separate second stream in the compressor; said first and second compressed streams then being combined before passing to the gas cooler or passing through separate gas coolers before being combined.