Development and Testing of Forced-Air Cooled Enclosures for High Density Electronic Equipment

A family of standardized avionics enclosures has designed, fabricated and tested. These enclosures accommodate Standard Avionics Module circuit cards which utilize aluminum base plates and are cooled by conduction to their mounting guiderails in the enclosure. The guiderails incorporate high performance module clamps and state-of-the-art brazed-fin heat exchangers for air cooling. The enclosures are designed to be cooled by air delivered from an aircraft environmental control system. Cooling effectiveness and enclosure thermal performance have been determined by laboratory tests. Typically, the enclosures provide 85°C (185°F) module edge temperatures while operating with 27°C (80°F) cooling air in a 71°C (160°F) ambient environment. With an operating pressure loss of 374 Pa (1.5 inches of water), their outlet cooling air temperature approaches 71°C (160°F). This results in cooling effectiveness of about 22.7 g/s (3 lb/min) of cooling air per kW.

This paper describes engineering analyses, enclosure thermal and airflow design features, and performance testing results.