Large air conditioning unit is a large and medium-sized integrated air conditioning equipment with cooling source and air cooling. Its refrigeration, heating, humidification, air supply, air purification, electrical control, etc. are assembled in horizontal box. Because it is mostly installed on the roof, it is called roof type air conditioning unit, In actual use, because of the difference between the product characteristics of each type of air conditioning unit manufacturer and the feeling degree of the residents, the noise of the air conditioning unit in operation has different feelings. But the noise of air conditioning unit is always a problem which needs to be effectively controlled. Putsman precision aviation has many years of experience in air conditioning unit vibration control, and has carried out vibration control for many customers' air conditioning units.
Noise control technology of air conditioning unit and key points of noise reduction of air conditioning unit, the noise of air conditioning unit mainly includes the following three aspects:
(1) Airborne noise of air conditioning unit: the rotating noise, mechanical noise, electromagnetic noise and vortex noise of fan in the form of unit equipment, motor and fan are caused by multiple reflections of air flow in the wall of the machine room, which results in reverberation noise of reflected sound wave and incident light superimposing sound wave again to increase sound energy. At present, most of the partition walls are light walls, with poor sound insulation. Air borne noise will pollute the nearby area through the wall.
(2) Noise at the air inlet and outlet of the air conditioning unit: since the air conditioning unit must introduce new air for circulation, because the air propagates aerodynamic noise, the air inlet and outlet of the air conditioning unit or the machine room will produce sound, affecting the surrounding environment.
(3) Vibration of air conditioning unit: generally, the air conditioning unit has not been subject to vibration reduction treatment during the initial installation, nor has it been subject to professional vibration isolation design and selection according to the unit equipment and weight. Therefore, when the equipment works, the equipment will vibrate. The structural sound is formed along all steel members connected with the pipes and fittings as well as the main structural frame of the equipment. This noise has the characteristics of low frequency and far less propagation. In addition, through the structure of the building, the noise causes pollution to the upper, lower and adjacent areas.
In terms of the vibration reduction of air conditioning units, the current one that can be better applied is the high-density damping system, which can weaken the vibration transmitted by fans to the foundation, in fact, eliminate the rigid connection between them, that is, install the vibration reduction device between the vibration source and its foundation. If the fan is installed on the vibration damping pedestal, the vibration damper or damping pad shall be installed between the pedestal and the floor or the foundation, so as to cause the vibration damping effect.
The commonly used damping pads and dampers for ventilation and air conditioning equipment are butyl damping rubber damping pad, butyl damping rubber damper, spring damper, etc.
1. Putsmier high density butyl damping adhesive damping patch
High density butyl damping rubber has good elasticity, high damping ratio and convenient manufacture. It is a kind of ideal vibration isolation material in common use. It can be used in one or more blocks. High density damping rubber is not easy to be eroded by temperature, oil, sunlight, chemical solvent and aging. It can effectively reduce the vibration frequency of air-conditioning noise. This kind of damping device is mainly made of oil-resistant NBR after vulcanization. High density damping is to cut the damping rubber material into the required area and thickness, and directly stick it on the metal sheet metal surface of the equipment. It does not need to be fixed and is easy to install, but it is not easy to age and deform, and the vibration reduction effect is stable.
2. Damping rubber damper
It is a cone-shaped elastomer made of NBR and pasted on the inner and outer metal rings under the action of shear force. It has low natural frequency and sufficient damping, good damping effect and convenient installation and replacement.
3. Spring damper
It is composed of single or several springs and cast iron shields of the same size, which are used for the installation and hoisting of the unit base. It has the advantages of low natural frequency, large static compression, large bearing capacity, good damping effect, stable performance and wide application, but its price is relatively expensive. In addition, a 10 mm thick rubber plate is padded under the bottom plate of the spring damper, which can also play a sound insulation role.