The Study Of The Ratio Control Of Noise Reduction And Isolation From Central Air-conditioning System In Urban Complex

Urban complex is the symbol of modern urbanization. Central air conditioning system is widely used for the thermal environment of urban complex, which is one of the important elements that ensure the normal operation of complex operations. At the same time, central air conditioning system is close to people’s life, so the noise of air conditioning system is serious. This paper firstly introduced the central air conditioning’s working principle, classification and the noise and vibration sources. This paper focused on the noise from underground heating water pumping station and cooling tower in central air conditioning system. Especially, the paper put forward a ratio control for the noise from underground heating water pumping station, to make sure noise indoors reach to the request of Table.2.and Table.3. in<Emission standard for community noise>(GB22337-2008).The vibration and noise from underground heating water pumping station which is mainly in low-frequency have great affect on the acoustic environment upstairs in the buildings. And it is difficult to control. This text did research on the underground heating water pumping station which is located in acoustic ribbon Ⅱ area. The prediction models were used to analyzes the attenuation distribution regularity noise and vibration. It concluded that the noise came from the structure-borne vibration of the pump system indoors is at least 80% of the total exceeded the value of the noise on the first floor, the rest came from direct spread of the noise. On the second floor and above, the noise indoors all came from the structure-borne vibration of the pump system. This paper researched on the ratio of noise and vibration impact. According to the ratio and on the purpose of low-frequency noise 31.5-500Hz can reach to the standard, isolate and noise reduction experiments were did step by step. This paper chosen a composite vibration isolation technology of three level, combined concrete base, damping spring shock absorbers with double rubber damping pads, and then two-stage pipeline isolation, isolation efficiency was 98%, and noise in living room 101 at night dropped from 62.6dB(A) to 36.4dB(A). And sound absorption in low-frequency noise and insulation in pump station had been done. The noise in living room 101 at night dropped from 42.6dB(A) to 36.4dB(A). It means not only the noise equivalent sound level in upstairs tenants indoors on the first floor but also the noise octave band sound level in upstairs tenants indoors on every floors have reached to the standard limits.Cooling tower is one of most important noise sources. This text did research on the cooling tower which is located in acoustic ribbon Ⅱ area. Noise characteristics of noise sources are analyzed. The prediction model was used to analyzes the attenuation distribution regularity noise. Noise insulation and elimination experiments had been done. It included inlet, outlet silencers and overall sound insulation covers. The noise in sensitive value at night dropped from 63.9 dB (A) to 45.9 dB (A) and treatment effect reached to the request of Table.1. in<Emission standard for community noise>(GB22337-2008).