The low energy efficiency of conventional light sources is mainly caused
by generation of waste heat. We used infrared (IR) imaging in order to
monitor the heating of both LED tube luminaires and ordinary T8 fluorescent
tubes. The IR images showed clearly how the surface temperatures of the
fluorescent tube ends quickly rose up to about +50...+70°C, whereas the
highest surface temperatures seen on the LED tubes were only about
+30...+40°C. The IR images demonstrated how the heat produced by the
individual LED chips can be efficiently guided to the supporting structure in
order to keep the LED emitters cool and hence maintain efficient operation.
The consumed electrical power and produced illuminance were also recorded
during 24 hour measurements. In order to assess the total luminous efficacy of
the luminaires, separate luminous flux measurements were made in a large
integrating sphere. The currently available LED tubes showed efficacies of up
to 88 lm/W, whereas a standard "cool white" T8 fluorescent tube produced ca.
75 lm/W. Both lamp types gave ca. 110 - 130 lx right below the ceiling-mounted
luminaire, but the LED tubes consume only 40 - 55% of the electric power
compared to fluorescent tubes.
|Series||Proceedings of SPIE|
|Conference||SPIE Defense, Security, and Sensing. Thermal Infrared Applications XXXIII. SPIE Defense, Security, and Sensing,|
|Period||26/04/11 → 28/04/11|