Side-exhaust cooling system for rack mounted equipment

A cooling system for rack mount electrical or electronic equipment comprises a hollow, box-shaped exhaust shelf having a vent on at least one end face thereof. The exhaust shelf may be configured for rack mounting. A side duct, open on its inner side, is mounted between the exhaust shelf and a top rail adapted to be mounted between a front post and an opposing rear post in a four-post rack mount enclosure. A plenum in the side duct is in fluid communication with the interior chamber of the exhaust shelf. A chassis having a side-facing exhaust for cooling air may be mounted on or over the exhaust shelf such that warm air exiting the chassis is collected in the plenum of the side duct and channeled into the exhaust shelf and out through the vent. In this way, the desired front-to-back cooling air flow within a rack mount enclosure may be maintained even if one or more individual chassis mounted in the enclosure have side cooling air exhausts. In other embodiments of the invention, the airflow may be in the reverse direction-i.e., cooling air may be drawn into the shelf, pass through the side duct and enter the chassis.