compressor, muffler, pressure drop, noise, transmission loss
During its operation, a refrigerator compressor produces pulsating noise, primarily driven by the suction and discharge processes. Sound attenuating mufflers need to be designed without any additional pressure drop on both suction and discharge side. An additional pressure drop at the suction and discharge side will lead to lower charging and discharging of the compressor and hence reduces cooling capacity. Since a one dimensional formulation with plane wave assumption to calculate transmission loss is not applicable for small mufflers (ratio of length to diameter is less than 1), a numerical methodology was established and validated using an impedance tube. Detailed three dimensional Computational Fluid Dynamics (CFD) simulations were used to further study the pressure drop across the mufflers for a given flow and compressor operating frequency. In the proposed new methodology, the pressure distribution is observed as a function of frequency and an optimal position of inlet and outlet pipes is decided to improve transmission loss. Mufflers designed with this approach showed better acoustic performance on the suction and discharge side of refrigerator compressor. The effect of various refrigerants on acoustic frequencies is also studied, which would additionally help in tuning the muffler to improve its effectiveness.