Specifications
Philips Fortimo HBMt Gen 3 System Design In Guide 21
Heat sink material
The type of material used has a signicant inuence on the nal result. For example,
a comparison of the thermal conductivity (k) of copper with that of corrosion-
resistant steel (see Table 19) shows that a substantially smaller heat sink can be
made with copper. The best material for heat sink is (soft) aluminum. The thickness
(H) of the heat sink is also of major importance. If identical heat sinks made from
different materials were used, a similar effect would be achieved with 1 mm copper,
2 mm aluminum, 4 mm brass, 8 mm steel and 26 mm corrosion-resistant steel.
Table 19. Thermal conductivity
In summary a thermally more conductive material helps heat spreading over the
body and activates more effective cooling area.
Thermal radiation and emissivity coefcient
Thermal radiation accounts for a substantial part of the total heat transfer. The
amount of thermal radiation is highly dependent on the emissivity coefcient of
the surface. For example, a polished aluminum surface has a very low emissivity
coefcient, while a painted surface has a very high one. A higher emissivity
coefcient means more effective heat transfer.
Table 20. Thermal emissivity coefcients of common materials
Material W/mK
Copper 400
Aluminum 200
Brass 100
Steel 50
Corrosion-resistant steel 15
Material Finish Emissivity coefcient
Aluminum New/polished 0.04-0.06
Blank 0.20-0.30
Anodized 0.80-0.95
Steel New/polished 0.1
Painted/
coated
0.80-095
Maximum rated
luminaire ambient
temperature
(Tmax. amb)
4000ml
/840
4000lm
/740
4000lm
/757
6000lm
/840
6000lm
/740
25˚ C 106-127 103-123 97-117 164-197 155-185
35˚ C 127-159 123-154 117-146 197-246 185-232
45˚ C 159-212 154-205 146-195 246-329 232-309