Pipe fitting and refrigerating system

The invention relates to the technical field of refrigeration, in particular to a pipe fitting and a refrigeration system.The pipe fitting comprises a pipe body and a sound insulation part, the pipe body comprises a noise reduction part, the noise reduction part comprises a first pipe part and at least two second pipe parts, the pipe diameter of the second pipe parts is larger than that of the first pipe part, and the first pipe part is arranged between the two adjacent second pipe parts; a first vent hole is formed in at least one first pipe part; the sound insulation part is arranged on the outer side of the pipe body in a sleeving mode, a closed cavity is formed between the sound insulation part and the pipe body, and the first vent hole communicates with the closed cavity. In the process that the pipe diameter is continuously increased and decreased, the refrigerant is subjected to multi-stage pressure relief under the gradual expansion-contraction pressure change, the phase change intensity of the refrigerant in the transition pipe can be effectively reduced, and therefore the refrigerant noise is obviously reduced. The first vent holes communicated with the interior of the first pipe part are formed in the pipe wall of the first pipe part with the small pipe diameter, the large turbulent flow form in the refrigerant can be destroyed, then the refrigerant is recombined into the small vortex form, and noise energy carried by the refrigerant is also weakened through reduction of the vortex size.