Experimental Analysis of HVAC System Level Noise in Mobile Air-Conditioning (MAC) System 2020-28-0035

With the advent of new technologies and rigorous research and development work going on vehicle engines, cars are becoming quieter and more refined than ever before. This has led to the observance of subjective noises being audible to passenger compartment which were earlier masked behind engine noise. The vehicle HVAC system has several moving parts and transient flow of refrigerant which can cause certain types of irritant noise. Thus having a refinement in of air-conditioning (AC) system would aid us in cutting down on this parasitic noise source. Thus noise refinement should be one of the important parameters during the design and development of the Heating, Ventilation and Air-Conditioning (HVAC) system for a vehicle program. However, due to packaging constraints, improper integration or selection of different AC parts, there is a possibility that the noise generated from the AC system will get amplified with the refrigerant flowing through the thermal expansion valve (TXV) or through pipes. There is a pressure pulsation in the refrigerant flow generated by compressor which travels along the pipes and can amplify the noise if it is not properly damped out. Also, TXVs can also be a source for noise if the quality of refrigerant dryness fraction is not optimized at the entry and exit of it.

The objective of the current work is to identify sources of noise, its propagation through pipes and recommendations to minimize it. Current work also presents the detailed analysis of different parameters affecting refrigerant flow noise, like mass flow rate, suction and discharge pressures and dryness fraction of refrigerant at system bench level. With above analysis new methods can be generated to identify and to subsequently minimize AC compressor noise.