Two-phase cooling of light emitting diode for higher light output and increased efficiency

High Power Light Emitting Diode (HP LED) is one of the promising candidates for future lighting systems with efficient energy consumption. However, around 70% of the input power will be still transferred to heat. Recently, to obtain more light output, the increased electrical currents consequently cause more significant heat. To solve the thermal problem, this paper presents a cooling solution with phase change phenomenon based on microelectromechanical (MEMS) technology. Tests were performed on a miniaturized evaporator with a fluid channel and an embedded bulk silicon temperature sensor. A commercial HP LED package was mounted on the evaporator with power ranging from 0 W to 2.8 W, aiming to achieve maximum light output and possibly very small flow rate of coolant. Results show the package can obtain higher efficiency and correspondingly increased light output by the two-phase cooling. It is confirmed that the proposed device is quite promising for an integrated water-based thermal management and HP LED would benefit from the two-phase cooling approach. Additionally, numerical simulation was applied to understand the phase change phenomenon and temperature distribution inside the evaporator. Moreover, optimized water flow rates for specific input powers of the package were calculated.