An experimental investigation on pulsation & noise reduction by shunt pulsation trap with a nozzle for compressors operating in under-compression

Abstract

This paper is a continuing work from the same authors on the same topic on gas pulsation and noise control using a shunt pulsation trap (SPT) method by Huang [1, 2, 3]. Traditionally, a serial pulsation dampener/muffler, often a reactive type, is connected AFTER the discharge of a positive displacement compressor. It has been demonstrated in the previous experimental investigations that gas pulsations from under-compression (UC) can be as effectively controlled by an alternative scheme - shunt pulsation trap (SPT), which is more compact and tackles the gas pulsations BEFORE the compressor discharge. Two dampening SPT schemes were investigated and compared: using a perforated plate (p-plate) vs. a perforated tube (p-tube). However, the pulsation induced noise is still a challenge with SPT employment alone. The focus of the present paper investigates experimentally the effect of a new dampening scheme - combining a SPT with a nozzle and an integrated absorptive silencer (IAS) to undertake both pulsation and noise problems at source. It is found that an ASME nozzle SPT with IAS scheme has superior noise reduction capability than both the p-tube + IAS scheme and the traditional scheme using premium silencers. Furthermore, the addition of an integrated absorption silencer (IAS) is not suffering as much back pressure drop associated with traditional reaction type silencers and therefore will not affect system efficiency. The integration of absorptive silencer into a nozzle or p-tube based SPT would provide an optimal design choice for size/weight and pulsation/noise reduction and potentials for energy saving for PD compressors operating in UC mode.