US Patent 8257155 Selectively routing air within an electronic equipment enclosure

A method of cooling electronic equipment mounted in an enclosure includes routing air from beneath the enclosure to an upper portion of the enclosure, selectively routing air to electronic equipment mounted in the upper portion of the enclosure, and exhausting heated air from the electronic equipment to an enclosure outlet. In addition, preventing recirculation includes installing and arranging an internal air duct within an enclosure in such a manner that recirculation is prevented, and balancing air temperature around an enclosure includes using an internal air duct.