An approximate thermal model for outdoor electronics cabinets

Electronic systems are installed in outdoor loop plant in metal cabinets which are essentially unventilated. The current trend toward greater circuit miniaturization and higher power density increases the difficulty in the thermal design and points up the need for comprehensive thermal design guidelines. As a step toward that end, an approximate lumped thermal-conductance model is presented for calculating steady-state temperatures at three points of the cabinet the hot sunny wall, the coot shaded wall, and the top row of circuit hoards) as functions of input parameters of cabinet geometry, wind speed, solar radiation, and internal heat dissipation (assumed to be uniformly distributed). Calculated results are found to be in agreement with tests within about 10 percent.