In addition to providing fresh air for passengers, the ventilation system of the train has another function to ensure proper air pressure in the carriage, that is, when the air pressure outside the carriage changes significantly, the ventilation system will maintain the air pressure in the carriage at a comfortable level for people.

The ventilation system is an important part of the air conditioning device. Its function is to transmit and distribute the treated air to the passenger compartment and obtain a reasonable air distribution. At the same time, it also discharges the dirty air in the passenger compartment out of the room, so that the indoor air parameters meet the design requirements.

Ventilation system is the only system that operates for a long time regardless of seasons. Therefore, its quality directly affects the comfort of passengers and the economy of air conditioning devices

When the system works, under the action of the ventilator, the outdoor fresh air is sucked into the car through the fresh air outlet, filtered by the dust filter and mixed with the return air, and then sent to the air treatment room, cooled by the evaporator or preheated by the electric preheater, sent to the main air duct, and then evenly sent into the room through each air supply outlet. A part of the indoor air is sucked by the ventilator through the return air outlet and return duct and reused as recycled air; The other part is discharged out of the vehicle through the exhaust outlet and exhaust fan.

The ventilation system is generally composed of fans, air inlet and exhaust devices, air ducts and air purification equipment. The ventilation system of high-speed trains usually also includes air pressure fluctuation control devices.

The ventilator unit is the power unit of the ventilation system, which is composed of centrifugal ventilator and motor. It is generally installed in the upper space of the flat roof plate at the end of the vehicle, and can also be installed in the lower part of the vehicle. Its installation location mainly depends on the location of the air treatment equipment.