A refrigeration system includes a chiller unit and a freezer unit. The freezer unit is provided with a freezing compressor for compressing a refrigerant in a total of two stages together with a compressor in an outdoor unit. The freezing compressor is formed by an inverter compressor. An oil separator is disposed on the discharge pipe of the freezing compressor. On the inlet pipe of the freezing compressor, a heat exchanger is provided for cooling an inverter with an refrigeration oil separated by the oil separator and a suction refrigerant. Space saving and cost reduction by reducing the cascade condensers are accomplished. |