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ABSTRACT
In this study, a novel heat sink which has many fluid pockets in its base was designed and fabricated. An experimental setup was built to study the heat transfer characteristics of the novel heat sink while cooling a high-power light emitting diode (LED). In this investigation, an attempt has been made to increase the heat transfer rate by adopting passive cooling. This study reports the effect of parameters such as fill ratio, orientation, type of cooling liquid, and the geometry of fluid pockets on the junction temperature of the LED. The fluid pockets were filled with various heat transfer fluids on % Vol basis. Parameters were optimised for the optimal thermal performance of the heat sink. To compare, the novel heat sink was found to record temperatures at least 19% lesser than a conventional heat sink of the same configurations. The experimental results indicated that the novel heat sink acts as an economical supplement for effective heat transfer and that liquid cooling is a powerful technique for heat dissipation of high power LEDs. Introducing the fluid pockets in heat sinks is feasible and useful for outdoor street light applications.
Keywords: Heat transfer; fluid pocket; passive cooling; tilt angle; liquid cooling.
INTRODUCTION
The energy saving, long life, environmental protection, and high luminance output characteristics of LEDs have long attracted the lighting community to develop LED lighting solutions for various applications from household to commercial purposes. The thermal management of LED module is a key design parameter as higher operating temperatures can directly affect the LED's maximum light output, quality, reliability and lifespan. In previous literature, it was observed that increased electrical inputs used to drive LEDs have led to thermal issues [1]. In an LED street light device, the temperature of a high-power LED is an important parameter that affects the performance of the system. The maximum light output, quality, reliability, and the life span of LEDs are all closely related to the junction temperature. Thus, thermal management has become a key reliability issue for LED modules for which various solutions have earlier been proposed. Different means of cooling systems can be used to reduce the operating temperature of LEDs: a simple one is the use of an extruded fin heat sink. Heat sinks...