Investigation on dynamic stress of the discharge valve in the transcritical CO₂ compressor

During the development of the 3000 r·min⁻¹ transcritical CO₂ compressor, the discharge valve plate is fractured frequently. To study the dynamic stress of discharge valve in CO₂ compressor, a simplified FSI model is established. Both the stress variation of the discharge valve plate during the operation of the compressor and the influence of different parameters on dynamic stress of the valve plate have been studied. The results show that the pressure difference between suction and discharge is the primary factor affecting dynamic stress of the valve plate. The failure of the valve plate is partly because of the alternating stress caused by the valve plate hitting the limiter, but principally because of the sag stress to discharge orifice caused by the pressure difference on the valve plate. When the discharge pressure rises from 8 MPa to 12 MPa, the impact stress and sag stress of the valve plate increase by 76.7 % and 87.5 % respectively. When the diameter of discharge orifice decreases from 12 mm to 6 mm, the maximum stress decreases from 287.7 MPa to 136.8 MPa, with a reduction of 52.4 %. The results show that reducing diameter of discharge orifice is an effective way to reduce the dynamic stress.