Evaluation of breathable enclosures for thermal management of outdoor electronics

Thermal design of electronic enclosures for outdoor use is complicated by the need to isolate the system from moisture, dust, and other environmental contaminants. Traditionally this isolation is achieved by using sealed enclosures; however, breathable, water-resistant materials present an opportunity to achieve the thermal benefits of a vented enclosure while also maintaining the isolation offered by sealed enclosures. While breathable vents are routinely incorporated into enclosures for the purpose of pressure equalization, the concept of using breathability as a thermal management tool has not been fully realized. In this paper we describe the use of a computational fluid dynamics (CFD) model to explore the application of breathable polymers, or textiles, as a part of the enclosure and assess the thermal benefit of this approach compared to a fully sealed enclosure. The results of the study reveal that there are several water-resistant textiles, traditionally used in sportswear, that have sufficient air permeability to achieve a significant cooling benefit when used in combination with internal fans. This study also reveals that the polytetrafluoroethylene (PTFE) membrane materials that are typically used for enclosure pressure equalization are too air-impermeable to achieve a significant cooling benefit.