Osram PrevaLED Core Z2 Manual de usuario descargar pdf (Pagina 16)

THERMAL CONSIDERATIONS

4.2. Heat sink

Basically, the heat sink has to fulﬁ ll two tasks:

a) Heat spreading through heat conduction

The task here is to spread the heat as uniformly as possi-

ble from the contact surface of the LED module through

the heat sink material and into the cooling ﬁ ns. In this

respect, the thermal conductivity and the material cross

sections of the heat sink play a decisive role (cf. the thermal

conductivities table below).

b) Heat dissipation to the surrounding medium

(usually ambient air)

For this task, the heat sink design in terms of ﬁ n and sur-

face conﬁ guration is decisive. By adequate geometrical

forming, heat conduction through convection and IR radia-

tion can be signiﬁ cantly inﬂ uenced and improved (cf. the

table with the IR emission coefﬁ cients on the next page).

Thermal conduction

resistance (R

) formula:



Thermal conductivities of selected materials

Material Speciﬁ c heat

conductance value

 [W/(m · K)]

Copper 380–401

Aluminium 200–220

Brass 120

Steel 42–58

Stainless steel 15

Glass 1

Wood 0.13–0.18

Air (dry at 1013 mbar,

no dissipation)

0.0256 at 20 °C

Very good heat

conduction

Bad/no

cooling

L: Length through the material in

ﬂ ow direction [m]

A: Material cross section/surface

of the heat sink [m

]

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 26 27

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Osram PrevaLED Core Z2 Manual de usuario Pagina 16

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