A refrigeration system using CO2 as a refrigerant includes a receiver having a liquid outlet connected to expansion valves, which are connected to evaporators, which are connected to the suction side of the compressor. The receiver includes a second gas outlet connected to a second pressure reduction device, to reduce the energy consumption in CO2 cooling systems and to protect the compressors against liquid CO2 by heating the suction gas. The second pressure reduction device is connected by tubing to a first heat exchanging device, which is integrated in the receiver, so that gas that is evaporated in the top of a receiver can be used for cooling the liquid part of the same receiver.