Numerical and experimental study on the reduction of refrigerant pressure pulsation within compressor pipes

Abstract

The pulsation of compressor pipe refrigerant pressure that occurs during the suction and discharge processes of a compressor is a major cause of vibration and noise. This makes it important to be able to predict the pressure pulsation within the pipe using numerical analysis, leading to a design that can reduce it. In this study, a method is presented to obtain the complex propagation speed and impedance boundary conditions of the refrigerant, which are necessary for the numerical analysis, by using the least square estimation and experimental data. Experimental verification was carried out by installing a total of 14 pressure sensors at 100 mm intervals on the compressor suction pipe connected to the refrigerant supply equipment. To verify the numerical analysis model the pressure pulsation was measured by varying the compressor operating frequency. Also, a pressure-structure interaction analysis was used to investigate whether an elastic structure installed within the pipe would affect any reduction in the pressure pulsation. The results showed that installation of the elastic structure within the pipe resulted in a significant pulsation reduction effect for the first operating frequency, while a slight reduction effect was observed for the second operating frequency. It was found that the pressure pulsation reduction was most significant when the longitudinal natural frequency of the installed elastic structure matches the operating frequency of the compressor.