In a data center with a raised floor, air-conditioned cold air is often delivered to each rack through channels under the floor. However as the cold air is delivered to a remote rack, airflow is reduced. Raised floors are often laid with cables and pipes that hinder the delivery of cold air and result in major hot spot issues. Air distribution units(ADU) are designed to address these problems.

An ADU is a cooling device for raised floor applications that mounts at the bottom 2U of any EIA-310 19 inch rack that has an open base. The ADU connects into the raised floor and pulls supply air directly into the enclosure. This prevents the conditioned air from mixing with warmer room air before reaching the equipment. The ADU minimizes temperature differences between the top and bottom of the enclosure. It also prevents hot exhaust air from re-circulating to the inlet of the enclosure.

Above picture illustrates an Air Distribution Unit (ADU) installed in a rack system. The blue lines represent cold airflow.

An ADU is only recommended as a problem-solver for heat densities of up to 3.5 kW per rack. An ADU is good for overcoming low ventilation pressure under raised floors. 

Side Air Distribution Unit 

Side Air Distribution Unit is a different model of air distribution unit whereas it’s located in the rack itself along with other devices. The side ADU pulls air in from the cold aisle, redirects, and distributes it to the equipment inlet, located on the right side.

Below picture shows a side ADU installed on a rack with side-to-side airflow. The blue lines represent cooling airflow. The red lines represent warm airflow.

Air Removal Unit (ARU) 

The Air removal unit(ARU) is a scalable cooling solution, because it can be added to an existing rack enclosure, and requires no internal rack space or raised floor connections to install. It replaces the rear door of an enclosure.

Below picture shows a unit with a redundant fan for improved availability. It shows the airflow for an Air Removal Unit (ARU). 

Cool air enters the rack, exhausts out the rear of the rack equipment, is pulled through the rack Air Removal Unit, and is released through the top. The high powered fans in the Rack Air Removal Unit overcome the air resistance of cables in the rear of the rack and prevent exhaust air re-circulation. An optional, ducted exhaust system delivers hot air to space above a drop-down ceiling or some other type of enclosed overhead space and eliminates the possibility of hot air mixing with room air. 

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