Energy saving with minimum of noise and vibration levels has been very important tasks, specially, in the refrigeration and air conditioning field. Variable speed reciprocating compressor is used in small residential unit to control the load capacity instead of on/off control. Based on this, it is important to study the noise and vibration generated at different compressor loads speed and fluid flow parameters.
One of the causes of excitation of the housing of the hermetic compressors in commercial refrigeration is the periodic gas pressure variation, which interact with many compressor elements. These variations are mainly due to the opening and closing movement of the suction and exhaust valves. Unbalanced pressure effects cause shaking of the Compressor which, in turn, cause compressor suspension forces to excite the compressor shell. The compressor shell then radiates acoustic noise.
The noise and vibration generated from fluid flow are found function of compressor Speed. The excitation frequencies seen in sound pressure response that are most influenced by the fluid dynamics are 12, 16, 20, 30, 32, 41, 75 times of the running speed. Also, the vibration frequencies that dominate the acceleration level and that are affected by the aerothermodynamic parameters on the compressor levels are 12, 22. 26, 41, 75 times of running speed This speed control gives a wide range of capacity load control operation with decreasing sound and vibration level, which is much lower than on/off control.