Sensitivity of simulated circuit pack thermal performance to geometric arrangement variation

A prototype electronic enclosure consisting of two boards with multiple power dissipating components in a vented enclosure is studied for its thermal performance under forced and natural air cooling conditions. Internal geometry and physical orientation are also varied. Results in terms of effective board thermal resistances and local heat transfer coefficients are reported. Forced convective resistances were a factor of five smaller than natural convection values. Physical orientation was seen to be the second most important sensitivity after convection mode due to the potential for local buoyancy effects. Overall thermal performance can be affected by as much as 25% due to non-convection-mode-related variations. Design implications as well as the applicability of the data to various analysis methods are discussed.<>