In electrified vehicles, auxiliary units can be a dominant source of noise, one of which is the re-frigerant scroll compressor. Compared to vehicles with combustion engines, e-vehicles require larger refrigerant compressors, as in addition to the interior, also the battery and the electric motors have to be cooled. Currently, scroll compressors are widely used in the automotive industry, which generate one pressure pulse per revolution due to their discontinuous compression principle. This results in speed-dependent pressure fluctuations as well as higher-harmonic pulsations that arise from reflections. These fluctuations spread through the refrigeration circuit and cause the vibration excitation of refrigerant lines and heat exchangers. The sound transmission path in the air con-ditioning heat exchanger integrated in the dashboard is particularly critical. Various silencer con-figurations can be used to dampen these pulsations. This paper compares the acoustic damping performance and pressure loss of two mufflers and a resonator for different operating points. Measurements of the pressure pulsations before and after the flow silencer are carried out using a refrigeration circuit acoustic test rig. The experimentally determined values are compared with analytically calculated sound attenuation curves of the silencers. In addition, the pressure loss generated by the flow silencer is measured, as pressure losses in the refrigeration circuit have a negative effect on thermal efficiency. The damping range of the resonator starts at a lower frequency compared to the mufflers. This allows the reduction of high-amplitude 1st order pressure pulsations. Furthermore the resonator generates a lower pressure loss than the mufflers. The findings on the operation principle and damping performance of different refrigerant circuit silencers enable the reduction of flow-induced noise in thermomanagement system components in vehicles.
Session:
Poster
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