16th International Heat Pipe Conference (16th IHPC) Lyon, France, May 20-24, 2012 THERMOSYPHONS FOR HIGH POWER LED LIGHTING PRODUCTS Valery M. Kiseev...
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16th International Heat Pipe Conference (16th IHPC) Lyon, France, May 20-24, 2012

THERMOSYPHONS FOR HIGH POWER LED LIGHTING PRODUCTS Valery M. Kiseev, Victor G. Cherkashin Ural Federal University, Institute of Natural Science, Lenin av. 51, 620083, Ekaterinburg, Russia, Phone: (+7) 343-261-6775, Fax: (+7) 343-261-6778 e-mail: [email protected]

ABSTRACT Extensive development of the light-emitting diode (LED) devices on the basis of LED matrix offers capabilities to occupy LED at the top place for the street and industrial lighting as one of the most reliable and energy-efficient devices. However, there are not enough experimental data on the optimization of the cooling systems for LED devices. Traditionally, the cooling systems for LED devices are designed with even pitch of LED locations on the radiator’s surface. With the increase of LED power the radiator’s surface and the distance between the LED locations grows correspondingly. It results in the increase of mass and size of the LED device. This paper presents some designs of two-phase thermal control systems for LED cooling on the basis of conventional thermosyphon (TS) and loop thermosyphon (LTS) and studies the experimental data, which were investigated for the two-phase systems considering the gravity influence. Additionally, the paper presents a comparative study between different working fluid, LED power and the radiators. KEY WORDS: Two-phase thermal control system, conventional thermosyphon, loop thermosyphon, heat pipe, LED lamp, radiator, working fluid, heat transfer

1. INTRODUCTION The main attractive quality of LED devices is its high level of luminous efficiency in comparison to alternative light sources. Therefore, employing LED technology may result in different economic and social effects. The most important effect among others is a considerable reduction in electrical energy consumption, used for illumination purposes, which, according to different estimations, is about 18-20% of overall produced electricity ( port_web1.pdf). The comparison of available light sources is presented in Table 1. Although LED lamps are more than 50 times as expensive as bright white lamps and about 7 times as expensive as compact luminous lamps, the price has been decreasing recently. Assuming that the characteristics improve and the price reduces, it is predicted that within a few years LED sources will be used in the majority of lighting systems. However, some of the factors that prevent LED from wide application should be taken into

account. Thus, diode’s parameters are very sensitive to working temperature, applied voltage, current etc. ( For example, when the temperature of a diode is more than 80°C the luminous efficiency reduces, while at 120 C° it tends to zero (Staroverov K., 2008). Table 1. Characteristics of light sources Light source type (LS) Glow lamp halogen lamp Compact luminous tube lamp metal-halide lamp luminous tube lamp Semiconductor LED (Cree XR-E) Sodium highpressure lamp

8–13 16–37

Efficiency of lamps with respective LS, lm/W 6–10 12–20




50 000 15 000–


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