An Experimental Study for Reduction of Refrigerant Flow Induced Noise in a Passenger Vehicle

Air conditioning these days has become an indispensable part of human comfort due to rising global temperatures. Air conditioners are installed to achieve thermal comfort in enclosed spaces such as rooms, vehicle passenger cabins, laboratories etc. As the air conditioning units employ dynamic processes to maintain thermal comfort it creates many unwanted noises which lower the acoustic comfort. One of these unwanted noises is the refrigerant flow induced noise inside passenger cabin of an automobile when the air conditioning is switched on in a thermally soaked vehicle. This paper elaborates about the study done on a calorimetric bench inside a semi-anechoic environment for identification of the noise signature and its acoustic interpretation. It also compares the noise readings obtained on the bench and at vehicle level in a semi-anechoic setting. The paper discusses about the possible mechanism for the occurrence of the refrigerant flow induced noise. It also discusses about various countermeasures evaluated to eliminate / suppress the refrigerant flow induced noise using a standard NVH analysis setup. Further, this paper also attempts to classify and compare the noise quality deterioration caused by a continuous refrigerant induced flow noise inside vehicle passenger cabin.