An Experimental Setup for Vibroacoustic and Fluid-Borne Noise Characterization of Electric Refrigerant Compressors using R1234yf or R744

The increasing electrification of vehicles leads to a broader range of tasks for heating, ventila-tion and air conditioning systems and a shift in its priority assessment. Air conditioning systems in electric cars are no longer primarily responsible for cooling the passenger compartment, but also have to temperature-control the battery, especially during rapid charging, which repre-sents a high-load operating point. Additionally, the elimination of the combustion engine as a major noise source brings the NVH behaviour of the refrigerant compressor a higher priority in product selection. In order to investigate the vibration and acoustic behaviour, as well as fluid dynamic forces resulting from the cyclic compression principle of an electric refrigerant compressor, a test rig was previously developed, allowing compressors to be operated and measured isolated in an anechoic chamber under various defined operating points. This test rig has been expanded in two ways within the scope of this work. Firstly, there is the option of either rigidly attaching the compressor to a dead mass using a VDA mount – a mass-determined system – or measuring it freely suspended as a stiffness-determined system. Secondly a completely new R744-compatible refrigeration cycle has been added to the test rig, enabling also to test compressors that operate with the more environmentally friendly refrigerant CO2, which has a Global Warming Potential of 1. The measurement results obtained with this test rig provide good insight into the vibration be-havior and the sound spectra of fluid, structure and airborne noise of the refrigerant compres-sor working in different operation points.