The main noise sources of air conditioning units are condenser fan noise and compressor noise.
Fan noise is an aerodynamic noise that includes turbulent noise and rotational noise. When the airflow flows through the surface of the blade, it will be detached from its back, and a series of eddy currents will be formed at the tail due to the viscous airflow, resulting in turbulent noise, which has continuous spectral characteristics. Rotational noise is generated by the formation of pressure pulsations when the blades rotate. Its spectrum is characterized by a narrow band of low IF and a distinct peak. The fan noise radiates outward through the inlet and exhaust vents.
The compressor is a multi-sound source, and its noise is mainly composed of the following components: intake noise, drive mechanism and body radiation noise, exhaust, pipeline and tank noise, abandonment of venting and valve noise.
There are three aspects to the noise radiation:
(1) aerodynamic noise radiated from the air inlet and the air outlet;
(2) mechanical noise radiated from the casing, the pipe wall and the motor bearing;
(3) "solid sound" of basic vibration radiation;
Equipment noise management method:
1. Install the unit sound insulation cover, equipped with the same amount of air inlet and exhaust muffler;
2. Install a sound insulation barrier between the sound receiver and the sound source to effectively control the sound source transmission path;
3. Install an exhaust muffler or a muffler to reduce fan noise.