a) Electronics thermal control
The constant reduction in electronic device sizes, allied to the increase of Joule effect cause
such components to be under constant and crescent levels of heat flux. The devices must be cooled
in order to assure that temperatures remain within acceptable levels of operation. The conventional
cooling methods use a heat sink under forced convection. However, such devices are reaching their
performance limit.
A new cooling technique for reduced surfaces has been under development in LABTUCAL: the use of
vapor chamber thermosyphons. In a conventional heat sink, copper or aluminum block conducts heat.
However, heat conduction is always associated with a temperature gradient. A vapor chamber thermosyphon
is geometrically similar to a conventional heat spreader, only hollow. The hollow volume is filled with
working fluid. The fluid remains in the bottom, in direct contact with the hot electronic device.
The heat evaporates the liquid and the vapor naturally spreads through the entire vapor chamber internal
surface. The vapor condenses in the internal walls of the vapor chamber, including in hollow fins.
Therefore the vapor spreads heat from the electronic device to the entire heat sink. When condensed,
the fluid returns by gravity to direct contact with the hot electronic device at the bottom of the
chamber. Figure 1 shows the geometry of a vapor chamber heat sink.
Publications
OLIVEIRA, A. S.; MANTELLI, M. B. H.; MILANEZ, F. H. Use of Vapor Chamber on~ Electronic Devices to Eliminate Hot Spots Under Fin Heat Sinks. In: 14th International Heat Pipe Conference (14th IHPC), 2007, Florianópolis.
MICHELS, V.; MILANEZ, F. H.; MANTELLI, M. B. H. Analytical Model to Predict Thermal Resistances of Hollow Fin Heat Sinks. In: 19th International Congress of Mechanical Engineering - COBEM 2007, 2007, Brasília. 19th International Congress of Mechanical Engineering, 2007.
ÂNGELO, W. B.; MANTELLI, M. B. H.; MILANEZ, F. H. Design of a Heater for Natural Gas Stations Assisted by Two-Phase Loop Thermosyphon. In: 14th International Heat Pipe Conference, 2007, Florianópolis. Proceedings 14th International Heat Pipe Conference, 2007. v. único. p. 386-391.
