A loop-heat-pipe heat sink with parallel condensers for high-power integrated LED chips

In this paper, a systematic experimental study was carried out on a copper–water loop heat pipe (LHP) with dual parallel condensers, especially for high power LED illumination applications. The main highlights of this work include: (1) a general multi-purpose configuration of LED illumination device is proposed with replaceable optical lens; (2) a unique loop heat pipe with parallel condensers is proposed and tested for the first time. From the experimental measurements, at low heat loads, it is observed that the uneven-distribution of working fluid into different condensers exists; with increase of the heating loads, this uneven-distribution will disappear. Meanwhile, the obtained results from the experiments and the theoretical analysis show that different operation modes will result in different heat transfer performance of the loop heat pipe. For the present design, the loop heat pipe heat sink has a total thermal resistance ranging from 1.0 to 0.4 °C/W (heating loads ranging from 30 W to 300 W) from the heating source to the ambient under natural convection situation. If implementing this LHP heat sink into the proposed LED illumination package, the measured thermal performance is superior to any conventional passive thermal management solutions in term of heat sink weight at the same temperature control level.