The invention discloses an
external variable-cross-section balanced ventilation
system for rapid trains. The
external variable-cross-section balanced ventilation
system comprises an air-conditioning unit, a variable-cross-section main air supply channel, at least one secondary air supply channel and an air
return channel, wherein the variable-cross-section main air supply channel is arranged on a longitudinal
central line of a
train body, and one end of the air supply channel is connected with an exhaust end of the air-conditioning unit; the secondary air supply channels are arranged on two longitudinal sides of the main air supply channel and are provided with at least one air supply opening; the end part of the air
return channel is connected with an air inlet end of the air-conditioning unit, and the air
return channel is provided with at least one air return opening; the secondary air supply channel is connected with the main air supply channel through a spiral air
pipe; and the secondary air supply channel and the air return channel are communicated with areas to be supplied with air in carriages respectively through the air supply opening and the air return opening. The
external variable-cross-section balanced ventilation
system has the beneficial effect that in a long and narrow
carriage, because the length of the main air supply channel and the length of the secondary air supply channel are equal to the length of the areas to be supplied with the air and a single-pore-plate regulating device is arranged on a connecting part between the spiral air
pipe and the main air supply channel, equivalent air is ensured to be supplied to various areas, so that the uniformity in air supply is enhanced and the traveling comfortableness is guaranteed.