Reduction of Flow-Induced Noise in Refrigeration Cycles

L. Saur, Patrick Heidegger, Christoph Naeger, Stefan Becker
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Abstract

In electrified vehicles, auxiliary units can be a dominant source of noise, one of which is the refrigerant 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 cycle and cause the vibration excitation of refrigerant lines and heat exchangers. The sound transmission path in the air conditioning heat exchanger integrated in the dashboard is particularly critical. Various silencer configurations can be used to dampen these pulsations. This paper compares the acoustic and thermodynamic performance of two mufflers and a resonator for different operating points. It is shown that the installation of the various flow silencers has no influence on the thermodynamic efficiency of the refrigeration cycle. Measurements of the pressure pulsations before and after the flow silencer are carried out using a refrigeration cycle acoustic test rig. The experimentally determined transmission loss values are compared with impedance tube measurement results and analytically calculated sound attenuation curves of the mufflers. The three different flow silencers dampen the pressure pulsations in the refrigeration cycle across a wide frequency range. The single-chamber muffler has the highest transmission loss in the low-frequency range up to 200 Hz and attenuates the high-amplitude 1st order pressure pulsations by up to 20 dB. The multi-chamber muffler achieves a transmission loss of up to 30 dB in the higher frequency range from 400 Hz. For both mufflers, there is good agreement between the measured values in the refrigeration cycle, in the impedance tube and the analytically calculated values. For the resonator, the measured transmission loss in the refrigeration cycle is significantly lower than in the impedance tube. The transmission loss of the resonator in the refrigeration cycle is constant at approx. 5 dB up to 600 Hz. The findings on the operation principle and damping performance of different refrigerant cycle silencers enable the reduction of flow-induced noise in thermomanagement system components in vehicles.
降低制冷循环中的流动噪音
在电动汽车中,辅助装置可能是噪音的主要来源,制冷剂涡旋压缩机就是其中之一。与内燃机汽车相比,电动汽车需要更大的制冷剂压缩机,因为除了内饰,电池和电动马达也需要冷却。目前,涡旋式压缩机广泛应用于汽车行业,由于其不连续压缩原理,每转产生一个压力脉冲。这就导致了与速度相关的压力波动以及反射产生的高次谐波脉冲。这些波动在制冷循环中传播,并引起制冷剂管路和热交换器的振动激励。集成在仪表板中的空调热交换器的声音传播路径尤为重要。各种消音器配置可用于抑制这些脉动。本文比较了两个消声器和一个谐振器在不同工作点的声学和热力学性能。结果表明,安装各种流量消音器对制冷循环的热力学效率没有影响。使用制冷循环声学试验台对消音器前后的压力脉动进行了测量。将实验确定的传输损耗值与阻抗管测量结果和分析计算的消声器声衰减曲线进行了比较。三种不同的流量消声器都能在很宽的频率范围内抑制制冷循环中的压力脉动。单腔消声器在高达 200 Hz 的低频范围内具有最高的传输损耗,并能将高振幅一阶压力脉动衰减高达 20 dB。多腔消声器在 400 Hz 以上的高频范围内的传输损耗最高可达 30 dB。对于这两种消声器,制冷循环和阻抗管中的测量值与分析计算值之间的一致性很好。对于谐振器,制冷循环中的测量传输损耗明显低于阻抗管中的测量值。谐振器在制冷循环中的传输损耗在 600 Hz 以下保持不变,约为 5 dB。有关不同制冷剂循环消音器的工作原理和阻尼性能的研究结果有助于降低车辆热管理系统部件中的流动诱发噪声。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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