Main Noise Sources:

There are three main noise sources in the outdoor unit of an air conditioner: first, the axial flow exhaust fan at the top of the unit; second, the compressor at the bottom of the unit; and third, the circulation pump that delivers cold and hot water.

The noise spectrum exhibits broadband characteristics, with an equivalent continuous A-weighted sound level generally ranging between 75 and 90 dB(A), peaking at 250–500 Hz. The noise level of the exhaust fan is typically 3–5 dB(A) higher than that of the compressor, while the noise level of the circulation pump is 10–15 dB(A) lower than that of the fan. Here, the noise from the circulation pump can be considered negligible.

Noise Reduction Measures:

1. Muffler

Noise control at the intake and exhaust vents of the outdoor unit's exhaust fan can be achieved using intake and exhaust mufflers. The pressure loss of the muffler should be controlled within 50 Pa; otherwise, it may affect the heat dissipation efficiency of the outdoor unit and the cooling temperature of the circulating water.

Noise reduction capacity of the muffler: 15–30 dB(A).

2. Sound Barrier

Combining the intake muffler louver with soundproof panels to form a suitable sound insulation structure is an effective method to reduce the overall noise of the outdoor unit. This sound insulation structure can mitigate aerodynamic noise from the intake and exhaust vents, as well as mechanical and electromagnetic noise from the compressor, motor, and circulation pump.

Sound barriers are suitable for noise reduction requirements not exceeding 15 dB(A) and can be used in combination with exhaust mufflers.

3. Soundproof Enclosure

Enclosing the outdoor unit with a soundproof enclosure is like building a house for the equipment. However, it must include intake and exhaust devices, with air intake on both sides and exhaust at the top, equipped with intake and exhaust mufflers.

Soundproof enclosures are suitable for situations requiring significant noise reduction, approximately 20–30 dB(A). They are generally used for large outdoor units or when the outdoor unit is very close to noise-sensitive areas, causing severe noise pollution.

Project Features:

? Targeted noise reduction measures are selected based on specific noise control requirements.

? The noise reduction measures feature a rational structure and excellent noise reduction performance, meeting national acceptance standards.

? After implementation, the measures have minimal impact on the normal operation, maintenance, and inspection of the original equipment.

? The newly added measures are aesthetically pleasing, robust, and have a service life of up to 15 years.