noise reduction experience
Jn Kakalejck
Engineering Department, Embraco Slovakia spol r.o.
Odornska cesta 2, 05201 Spišsk Nov Ves, Slovak Republic
Marek Zgliczynski
Engineering Department, Embraco Europe S.r.l.
Via Buttigliera 6, 10020 Riva presso Chieri (To) Italy
1.Abstract
The market every increasing demands leads to a continuos new development in the
compressor design. Starting from the domestic refrigeration area a new era has begun: the
focus is to combine the cost, efficiency, noise and vibration. An increment in the compressor
efficiency is generally linked to a negative influence in the compressors noise hence the
necessity of a deep problem understanding in terms of noise path, natural frequency analysis,
suction & discharge pulsation evaluation. On the basis of the above mentioned considerations
the impact of a new shell design has been analysed. Based on the results, some general
considerations are presented and some possible future development are taken into
considerations.
2. Introduction
Compressor performance improvement in the commercial refrigeration is becoming more and
more urgent. Efficiency and cooling capacity improvements linked to a noise reduction are
becoming standard market requirements. The reciprocating compressors represent one of the
main noise sources in refrigeration applications therefore in a total quality vision the noise
reduction items should be addressed. The noise path understanding, to identify which
compressor parts are responsible for the noise propagation, is probably the most difficult step.
3. Theory
The compressor noise is generated by different sources: the mechanical vibration of the
compression process, the magnetic vibration of the electrical motor and gas pulsation inside
the compressor and compressor shell during run. Noise and vibrations are transmitted to the
shell by transmission paths (Figure 1). In general we know 3 transmission paths:
a) The mechanical path.
b) The refrigerant gas path.
c) The lubricating oil path.