Acoustical Cavity Resonance in Hermetic Compressor: A Literature Review Rohit T. Waghmare* *Research Scholar (Final Year), M. Tech. Mechanical - Design Engineering, Rajarambapu Institute of Technology (R.I.T.), Islampur, Sangli, (Maharashtra). rohitwaghmare1990@gmail.com Abstract The noise level of refrigerating units is one of the very important factors to determine the quality of product. This paper reviews literature based on cavity resonance phenomenon in compressor, experimental setup designed to find out cavity resonance as well as effect of various parameters on cavity resonance has given. Keywords: cavity resonance, acoustic resonance, resonance etc. Introduction Cavity resonance in fractional horse power refrigeration compressors has been suggested as a potential source of compressor noise. The hermetic shell of the compressor generally serves as a noise container. The cavity between the compressor and the shell filled with gas has its own natural frequency (Fig.1) when the gas cavity natural frequencies are excited by the various sources of compressor that generates acoustic resonance which elevates perceived noise [2] by experience it is accepted that cavity resonance occurs normally at lower frequencies ranges from 300Hz to 500Hz. Fig.1: Typical cross-section of fractional horsepower refrigeration compressor. Jang Moo Lee et al [1] approaches cavity resonance problem by FEM and experiment. Noise sources interconnected paths through which the sound energy can reach to the shell and its possible countermeasures has identified. Influence of cavity resonance on low frequency up to 500Hz and natural frequency of cavity is function of volume, shape, pressure and temperature has suggested. In FEM all the boundaries are assumed to be solid boundaries, but in the actual state, the lower boundary is oil surface that is more flexible than other boundaries, i.e., the compressor case which is made of steel. It also suggests that the cavity resonance frequency is proportional to the speed of sound which is proportional to the square root of the temperature. Half inch microphones were mounted on one inside and other outside of compressor. The frequency of sound had swept using function generator and FFT divides the sound pressure of microphone B by that of microphone A (Fig. 2). By repeating this execution at many other points of compressor, the natural frequency and mode shapes were obtained. The experiment was performed in