Design and Experimental Research of Noise Reduction Method for Semi-hermetic Variable Frequency Twin-screw Refrigeration Compressor

Variable frequency twin-screw refrigeration compressors have become a development trend of twin-screw refrigeration compressors due to its part-load energy-saving characteristics. Broad frequency pulsation noise is becoming the key limitation of its market application and competitiveness. Based on the structural characteristics and noise principle of the variable frequency twin-screw refrigeration compressor, two noise reduction methods are proposed. One is the discharge end pulsation damping device and the other is the discharge pipe muffler. An experimental study is carried out to verify the effectiveness of each method. The results show that the discharge end attenuation device can attenuate the noise at different positions of the compressor. The discharge pipe muffler can only significantly reduce the discharge side noise. After adopting two noise reduction methods at the same time, the average noise reduction effect of the compressor at different rotating speeds can reach 5.0～10.0 dBA, and the running noise of the compressor is no higher than 85.5 dBA. In conclusion, the two noise reduction methods of the discharge end pulsation damping device and discharge pipe muffler can reduce the base frequency and double frequency noise of the discharge side, which will promote the technical development and application of variable frequency twin-screw refrigeration compressors.