Research On The Noise Of Flowing And Its Suppression In The Refrigerating System Of The Refrigerator

Complicated flow in the refrigerating system of the refrigerator induced thenoise of flowing. With the reducing of the noise of the compressor, the noise offlowing seems outstanding day by day. However, there is seldom systematic deepgoing investigation in this area. This paper has carried on the experiment andtheoretical research to the actually flowing situation in the refrigerator and thefunction on the noise of flowing, has got the following conclusions:Results of the pulsating experiment of the fluid pressure within the refrigeratingtube and the noise experiment of the complete machine prove: (1) The periodicitybreathes in and exhausts of the compressor has very strong energy on the amplitudeof the pulsating pressure, and wave ranges in the operating frequency of thecompressor and its harmony of 10 times on frequency; (2) The pulsating pressureabove 500Hz is mainly raised from the high speed sprays of the refrigerant at thecapillary exports, and was mainly distributed in 500Hz-1500Hz, 2300Hz-3700Hzand 4500Hz～5000Hz three frequency bands; (3) Above-mentioned three frequencysections occupy the important composition in the spectrum of the whole machine.A capillary emulation model which includes six parts of flowing obstruction hasbeen developed in this paper. Combine with relevant experiment research, followingmain conclusions were obtained: (1) "Drop-Down Pressure", velocity and vacuolecoefficient are the three main parameters of causing the noise of flowing at the exportof the capillary; (2) Experiment proves: In the course of operation of the refrigerator,with the reducing of the evaporate temperature, "Drop-Down Pressure" keeps in ahigh level; (3) Refrigerant velocity, vacuole coefficient and pressure increase as thereducing of the evaporate temperature at the export of the capillary. While flow waschoked up, the three values keep in a comparatively steady value; (4) The decliningof the environment temperature reduced .the refrigerant temperature entering thecapillary, improved the flow rate of the capillary, also can reduce the vacuole coefficient and velocity at export of the capillary to a great extent, but this change hasa little effect on the "Drop-Down Pressure".A calculation model of the perforated tube silencer was developed in this paper,and emulation research was carried on to investigate the influence of thecharacteristic parameter, such as sound velocity, sound-absorbing material and thepeforate condition, to the noise elimination effect. Result shows: (1) The air-flowexerts an important influence to the performance of the noise elimination. Though theexistence of the air-flow has reduced the transmission loss, it has expanded thefrequency band of the noise elimination; (2) The function of the sound-absorbingmaterial is obviously weakened with the increase of the velocity of air-flow; (3)Increase the peforation porosity shifts the frequency band of the noise elimination tohigher frequence; (4) The experimental result indicates that the noise suppressesdevice researched in this paper can make the noise of the complete machine dropabove 2dB.