A refrigeration system, comprising: a first refrigerant passage (204, 204e, 204h); a π-type silencer (20c, 20d, 20e, 20h) having a first silencing space communicating with the first refrigerant passage, a second silencing space disposed side-by-side with the first silencing space, and a communication path extending from the lower end of the first silencing space to the lower end of the second silencing space through the outside of the first silencing space and communicating with the second silencing space; a second refrigerant passage (205, 205e, 205h) communicating with the second silencing space; and a compressor, characterised in that the refrigeration system further comprises an outdoor unit, a four-way switch valve, an outdoor heat exchanger and an indoor heat exchanger, wherein the π-type silencer (20c, 20d, 20e, 20h) is disposed between a discharge side of the compressor and the four-way switch valve; wherein a discharge path of the compressor is connected to the first silencing space via the first refrigerant passage, and a heat transfer path of the outdoor heat exchanger or the indoor heat exchanger is connected to the second silencing space via the second refrigerant passage. a first refrigerant passage (204, 204e, 204h); a π-type silencer (20c, 20d, 20e, 20h) having a first silencing space communicating with the first refrigerant passage, a second silencing space disposed side-by-side with the first silencing space, and a communication path extending from the lower end of the first silencing space to the lower end of the second silencing space through the outside of the first silencing space and communicating with the second silencing space; a second refrigerant passage (205, 205e, 205h) communicating with the second silencing space; and a compressor, characterised in that the refrigeration system further comprises an outdoor unit, a four-way switch valve, an outdoor heat exchanger and an indoor heat exchanger, wherein the π-type silencer (20c, 20d, 20e, 20h) is disposed between a discharge side of the compressor and the four-way switch valve; wherein a discharge path of the compressor is connected to the first silencing space via the first refrigerant passage, and a heat transfer path of the outdoor heat exchanger or the indoor heat exchanger is connected to the second silencing space via the second refrigerant passage. a first silencing space communicating with the first refrigerant passage, a second silencing space disposed side-by-side with the first silencing space, and a communication path extending from the lower end of the first silencing space to the lower end of the second silencing space through the outside of the first silencing space and communicating with the second silencing space; a second refrigerant passage (205, 205e, 205h) communicating with the second silencing space; and a compressor, characterised in that the refrigeration system further comprises an outdoor unit, a four-way switch valve, an outdoor heat exchanger and an indoor heat exchanger, wherein the π-type silencer (20c, 20d, 20e, 20h) is disposed between a discharge side of the compressor and the four-way switch valve; wherein a discharge path of the compressor is connected to the first silencing space via the first refrigerant passage, and a heat transfer path of the outdoor heat exchanger or the indoor heat exchanger is connected to the second silencing space via the second refrigerant passage.