How to solve the noise caused by parallel operation of two fan coils

Phenomenon: The air conditioning system of a building is a low-speed single duct system.  The forced draft fan is two air inlet fans.  When the two fans run at the same time, noise will be generated.

Cause: The two fan-coil units run in parallel and interfere with each other, resulting in unstable operation and noise.

Countermeasures: A long splitter plate is set between the two fans, so that the airflow at the fan outlet does not interfere with each other, that is, the noise problem is solved.

Phenomenon: Failure of exhaust mixing chamber.  A centralized exhaust mixing room is adopted in the design of a project.  Many fans work in parallel, and they are discharged from one exhaust tower.  Results The air volume is much less than the design air volume.

Cause: The air flow in the mixing room interferes with each other, and the air discharged by the running fan flows back through the non-running fan.

Countermeasures: Reasonable selection of air duct section.  Install a flexible and tight one-way valve at the outlet of each fan.  Try to reduce local resistance of pipeline.  A partition wall is set in the exhaust mixing room, so that the high-speed airflow at the fan outlet can reach the exhaust tower without mutual interference. When the air outlet of each exhaust fan enters the mixing room, a 45-degree elbow is added, and the airflow direction is directly aligned with the passage of the exhaust tower.