Thermal performance of passively cooled pico projector equipped with a fin array

Three 120-mm × 53-mm × 19-mm pico projectors featuring different thermal designs were fabricated and horizontally tested to examine the thermal resistance from the heater that was attached to the fin array base in the test pico projector to the ambient. Either a 7-plate fin array or a 37-pin fin array was installed in each test pico projector. The heat transfer coefficient of the fin array in the test pico projector under various conditions was also estimated based on the analysis of a thermal resistance network. The measured results showed that Case-A had the highest thermal resistance while Case-C yielded the lowest thermal resistance. At an input power of 7 W, the thermal resistances of Case-A, Case-B and Case-C having a pin-fin array were 16.3, 15.5 and 15 °C/W, respectively, while the thermal resistances of Case-A, Case-B and Case-C having a plate-fin array were 16.6, 16 and 14.8 °C/W, respectively. The heat transfer coefficient of the plate-fin array in Case-B was higher than that in Case-A due to the extra top openings, whereas the heat transfer coefficient of the pin-fin array in Case-B was similar to that in Case-A because the spacing between pins was so tiny.