Background
Compact electronic enclosures arise in a number of applications including circuit breakers, small
power supplies and portable communications equipment. Such equipment is usually passively
cooled. Usually very limited open space exists in such systems and heat transfer is by a
combination of conduction, weak natural convection and radiation. While convection in larger
enclosures has been studied, very little information exists on the thermal characteristics of
compact enclosures. Effects of venting have been quantified even less. Such information is
essential for the thermal design of a range of current and future electronic equipment.
Work Accomplished
A representative compact enclosure with two different heating configurations was selected. Both
vented and unvented cases were studied. A list of parameters likely to have a significant effect
on the enclosure interior
temperatures was compiled. By using a fractional factorial approach, the number of cases to be
studied was narrowed to a manageable number. System level numerical
simulations using CFD technique were then made to obtain temperature and fluid flow
information for the various cases.
For each selected case, numerical simulations were made using a CFD/CHT code to
determine the temperatures and air flow velocities at all selected grid points within the enclosure.
The parametric studies examined effect of power dissipation, heat source size and
distribution, case material thermal conductivity and blockage of free space.
Information from various cases was tabulated and empirically correlated to provide the
maximum temperatures for the range of conditions studied.
