Cooling Rack-Mounted Electronics

Frame and cabinet-mounted electronics in commercial and telephone installations have an increasingly difficult task removing the heat generated by high performance electronic circuitry. To remove the heat, vertical flow fans draw air from below and drive it upward through the electronic equipment. This approach has shortcomings solved by a baffled fan tray design.

Typical vertical flow fans used to cool rack-mounted electronics draw 90W and each electronic unit requires a fan. While a 7-ft frame has 44 vertical mounting spaces for electronics and fans, each 1.75-inches high called a "U," power for the entire frame is limited to 1,000W by Network Equipment Building System (NEBS) standards. For five electronic unit/fan (EUF) combinations with 450W consumed by the fans, only 550W remain for the electronics. Since most electronic units draw more than 110W, less than five EUFs can be installed wasting precious floor space. Furthermore, the power consumption of the fans preheats the airstream and those units at the top of the rack have significantly reduced cooling.

New Age Fans' baffled fan tray design addresses these problems. The design starts with a much smaller fan motor that only consumes 6W or 30W for a fully populated frame. Using an angled integral baffle, the fan draws cooling air from the space in front of the frame and directs it up through its associated electronic unit. Heated air exits at the rear of the frame, remote from the cooling air intakes of neighboring equipment. This provides fresh, unheated air to each electronic unit. Based on the lower power consumption, the electronic units can draw 194W each, a 75 percent increase, and still comply with NEBS requirements. Adjusting the working depth of the baffled fan tray allows it to accommodate electronic units depths from 7 to 12 inches. The baffled fan tray design does not move as much air as the vertical flow fan tray. However, based on the air flow path, the technique provides cooling as good as, or better than, the vertical flow fan tray. Another benefit of the approach is quiet operation of 43 dBA.

Contact: Bill Winter, New Age Fans

E-mail: [email protected]