In both internal combustion engine (ICE) and electric vehicles, Heating, Ventilation, and Air Conditioning (HVAC) systems have become significant contributors to in-cabin noise. Although significant efforts have been made across the industry to reduce noise from airflow handling systems, especially blower noise. Nowadays, original equipment manufacture’s (OEMs) are increasingly focusing on mitigating noise generated by refrigeration handling systems. Since the integration of refrigeration components is vital for the overall Noise Vibrations and Harshness (NVH) refinement of a vehicle, analysing the impact of each HVAC component during vehicle-level integration is essential.This study focused on optimizing the NVH performance of key refrigeration components, including the AC compressor, thermal expansion valve (TXV), suction pipe, and discharge line. The research began with a theoretical investigation of the primary noise and vibration sources, particularly the compressor and TXV, followed by an analysis of vibration transmission paths through the refrigerant lines. To ensure an optimal acoustic and thermal balance among these four components, both design parameters and dynamic operating characteristics were studied for their impact on thermoacoustic performance inside the vehicle. The compressor was identified as a major source of low and mid frequency noise and vibration, while pressure pulsations in the refrigerant lines contributed to structure-borne and airborne noise. These issues were addressed by developing new design guidelines aimed at improving isolation and damping characteristics. Specific efforts included designing stair-gated modal decoupling strategies to avoid resonance between the compressor bracket and engine or aggregate excitation frequencies. In addition, the standing wave behaviour in the suction and discharge lines was analysed to identify and control resonant modes that amplified NVH issues. The TXV was also studied in detail, with a particular focus on mid-frequency noise caused by its internal dynamics. Parameters such as spring stiffness, natural frequency, and superheat setting behaviour were optimized to improve cabin acoustic comfort.The outcome of this paper is a comprehensive component-level NVH validation combined with practical design guidelines for minimizing integration-related noise and vibration issues in HVAC systems. These findings provide a robust framework for engineers to enhance both thermal performance and in-cabin acoustic refinement, ensuring superior comfort in modern vehicles.
Titave et al. (Thu,) studied this question.