A microjet array cooling system for thermal management of high-brightness LEDs

In this paper, a microjet-based cooling system is proposed for the thermal management of high-power light-emitting diodes (LEDs). Preliminary experimental investigation and numerical simulation on such an active cooling system are conducted. In the experiment investigation, thermocouples are packaged with LED chips to measure the temperature and evaluate the cooling performance of the proposed system. The experimental results demonstrate that the microjet-based cooling system works well. For a 2 x 2 LED chip array, when the input power is 5.6 W and the environment temperature is 28 degrees C, without any active cooling techniques, the temperature of 2 x 2 LED chip array substrate reaches 72 degrees C within 2 min and will continue to increase sharply. However, by using the proposed cooling system, when the flow rate of micropump is 9.7 mL/s, the maximum LED substrate temperature measured by the thermocouples will remain stable at about 36.7 degrees C. As for the numerical optimization, the comparison between the simulation and experimental results is presented to confirm the feasibility of the simulation model. By using the simulation. model, the effects of microjet diameter, top cavity height, micropump flow rate, and jet device material on system performance are numerically studied. According to the preliminary test and numerical optimization, an optimized microjet cooling system is fabricated and applied in thermal management of a 220-W LED lamp. The temperature test demonstrates that the cooling system has good performance.