THERMODYNAMIC OPTIMIZATION OF COOLING TECHNIQUES FOR ELECTRONIC PACKAGES

This paper describes several fundamental trade offs that govern the op timization of cooling techniques for heal generating electric devices. Five basic cooling configurations are optimized. It is shown that in forced air cooling above room temperature the fan power requirement is minimum when the heat transfer contact area is optimized to a value t hat is of the order of 10(2) A(f), where A(f) is the flow cross-sectio nal area. This optimal contact area is independent of whether the cool ant is mixed or unmixed inside the heat generating enclosure. In air c ooling with natural updraft, the heat generation rate (or amount of el ectronics, or overall thermal conductance) is maximum when the heat tr ansfer contact area is of order 10(2) A(f). In forced convection cooli ng at cryogenic temperatures, the refrigerator power requirement has m inima with respect to the cold-end (refrigeration load) temperature an d the heat transfer contact area. The optimal heat transfer area is ag ain of the order of 10(2) A(f).