Investigation of HVAC Kinematics Mechanism & Door Noise through Acoustical Duct Method 2023-28-0032

As HVAC noise is becoming one of the key factors to end users in terms of enhanced comfort, it is important to understand and evaluate various noise sources of HVAC in details. With detailed understanding of various sources, it becomes easier to take appropriate countermeasures in design and subsequently eliminate. There are many methods available in industry to investigate the noise sources in details however those options are expensive and time consuming and require deep understanding of the acoustic. Acoustical duct methods are one such method which proves to be very much helpful in identifying the noise sources from different aggregates like kinematics mechanism, door/damper, servomotors, heat exchangers etc. These sources are typically defined minor noise sources.

The present paper describes the detailed investigation of those minor noise sources through the use of acoustical duct method. An existing HVAC from passenger car was considered for this study. In order to take the noise measurement, acoustical duct was prepared as per standard. The HVAC was kept in a semi-anechoic test chamber and desired DC supply was provided to the HVAC. Noise sources from kinematics mechanism, servomotor, door/dampers were marked and measurement was done for those areas. Comparative matrix was prepared out of all the sources and evaluation was done to assess the noise level. This technique is already applied to major noise source identification and comparison like fresh air/recirculation air opening, face, defrost and blower motor. The study showed a remarkable difference between the minor noise sources leading to prominent sources. The method is quite helpful in order to prioritize the noise sources and take appropriate countermeasure to reduce the noise.