Calculates the dissipated power by a commercial or not commercial heatsink
with variable dimensions and shape, valid for heatsinks without forced ventilation.
Data input
Maximum ambient temperature expected.
°C
Maximum work temperature of the heatsink.
°C
Physical characteristics.
Vertical surface exposed
cm2
Horizontal surface exposed
cm2
Material and surface finish
Compact heatsink (irradiation compensation).
R
Results
Thermal resistance of the heat sink
°C/W
Maximum power dissipable
W
Notes.
In exposed surfaces, if air can circulate, must be entered both sides of the wall,
(in practice development of one side x 2).
Depending of the thermal resistance of the contact, the heat sink temperature
will be lower than the heating element itself.
Ignoring the thickness of the walls, that has influence on the uniformity of the
temperature and than on the global efficiency of heatsink, is necessary to
severely declass the results.
Ignoring the air density in function of the altitude which has influence
degrading the global efficiency, is necessary to declass the results.
Pay attention on typing ambient temperature because in sun exposition it can exceed 70 °C.
The bad dimensioning of heatsinks is one of the main causes
of breakdown or reduced duration for electronical devices for civil and industrial use.
It is very common to find televisions, monitors, hi-fi amplifiers, switching power supplies,
printers, computers or any other device with components (transistors, MOSFETs, ICs or resistors)
that in summer are working with 100 °C or higher with the sure result of failure
after many fewer hours compared to other well-dimensioned equipments.
