Abstract: 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.

Abstract: A transcritical vapour compression refrigeration apparatus which comprises a compressor (1), a gas cooler (3), an economiser (7), an evaporator (9) 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 the first and second compressed streams passing through separate gas co

Abstract: A refrigerant composition which is suitable as a substitute for conventional refrigerant R12 in a vapour compression system employing a centrifugal compressor, comprises a mixture of tetraflouroethane and at least one additional refrigerant. The refrigerant mixture has a vapour density which renders it suitable for use as an R12 replacement in a centrifugal compression refrigeration system. The molecular weight of the mixture approximates 121. Preferred mixtures include 67 wt. % tetraflouroethane and 33 wt. % octafluoropropane; 69 wt. % tetrafluoroethane and 31 wt. % octafluorocyclobutane; and 66 wt. % tetrafluoroethane and 34 wt. % heptafluoropropane. Refrigeration effect and coefficient of performance are similar to R12.

Abstract: A refrigerant composition for use in a vapour-compression refrigeration apparatus as a replacement for currently used refrigerants R22 and R12 comprises a mixture of pentafluoroethane (R125), tetrafluoroethane (R134a), a hydrocarbon selected from isobutane (R600a) and propane (R290), and optionally octafluoroethane (R218). The composition contains no chlorine atoms and is non-depleting to atmospheric ozone; but specific compositions have pressure-temperature relations substantially the same as R22 and R12 thereby allowing their use as direct replacements therefor in existing refrigeration apparatus.