By focusing on the cooling requirement of high power LED, the study aims to explore the spray cooling method and analyze its cooling performance. The ultrasonic micro-nozzle plate made of piezoelectric ceramic material was used in this experiment in order to establish a spray cooling system. The nozzle plate array (3 ¡Ñ 2) was used to carry out a cooling test for 24 LEDs with high power (6 ¡Ñ 4). Three different watts (1 W, 3 W, 5 W) of LED were tested, the total input power was 24W, 72W and 120 W, respectively, and the working medium was DI water. The goal is to understand the variance in performance caused by nozzle plates of different nozzle diameters (dj = 7, 35 £gm) in varied nozzle distances (z = 10, 20, 30, 40, 50 mm). The experiment used thermocouples to measure the slug temperature of LED. By applying thermal resistnace to the LED to calculate its chip temperature, and using micrometer resolution particle image velocimetry (£gPIV) to observe the spray flowfield inside the LED chamber, this study analyzes the influence of flowfield change on cooling performance.

This study aims to explore the use of an ultrasonic micro-nozzle plate, made of piezoelectric ceramic material, as a core material to establish a set of spray cooling system for high power LED. The system uses a single nozzle plate to implement a cooling test for 4 high power LEDs (2 ¡Ñ 2). The total input power was 4 W, 12 W and 20 W, and working medium was DI water. In order to understand the performance variance introduced by utilizing nozzle plates with differing nozzle diameters (dj = 7, 35 £gm) across various nozzle exit to test distance (z = 10, 20, 30, 40, 50 mm). By using micrometer resolution particle image velocimetry (£gPIV) to observe the spray flowfield inside the chamber, and using thermocouples to measure the temperature of LED slug and thermal resistance was used to calculate the LED junction temperature , Tj, for analyzing the influence of flowfield change spread in chamber on its cooling performance. The possibility of an LED spray cooling system is also explored.