Study On Heat Dissipation Of New Type Integrated High Power LED Street Light

High power LED lighting industry has developed rapidly at an unprecedented rate in recently years as a result of the invention of high-brightness blue in the1990s, dramatic increase of the energy price as well as people’s energy-saving awareness. However, the electro-optical energy conversion efficiency is still less than25%. The small size of COB packaging LED causes the high power intensity, therefore, resulting in low luminous efficiency, high failure rate, high light failure and low reliability. Heat dissipation problem has become a bottle-neck of the development of LED road lighting industry.This paper brings forward an innovative structure design of LED street lamp. A gravity heat pipe is used in the lamp structure. The traditional method of enhancing heat transfer coefficient by increasing the surface area of heat sink is abandoned. The design is lightweight and open. The findings of this paper will play an important role in the popularization of high power LED street lamp.This paper is based on the research of heat dissipation problem of high power LED street lamp. The main contents and contributions are as follows:(1) This study summarizes the previous research findings of heat sink using in LED luminaries and analyzes the irreconcilable conflict between the weight and surface area. Furthermore, a new heat sink design of LED street lamp using the gravity heat pipe is brought forward. Besides, the definition, fundamental, compatibility, material and sort of heat pipe are presented.(2) The effect on heat transfer performance brought about by filling rate and inclination angle is deeply investigated. The optimum design parameters are obtained by experiments. Thus, a conclusion has been reached that when the filling rate is between25to30percent and inclination angle is between60°to80°espectively, the heat pipe has the minimum temperature difference and highest temperature rise rate.(3) A summary of the heat dispatch methods using in LED luminaries is made in this paper. The different test methods of junction temperature are introduced. A new junction temperature testing method using the infrared thermal imaging instrument is put forward. An experiment of testing the junction temperature of blue led chip is designed to prove the good performance of heat pipe radiator. The optimum design parameter of heat pipe radiator is between75～95cm2/W. (4)In this paper, the calculating formulas of thermal resistance, heat transfer coefficients and heat transfer ability of heat pipe radiator are derived. The luminous efficiency measured by the distribution photometer proves the good performance of heat pipe radiator of the innovative structure design of LED street lamp. The light failure of the new design of LED street lamp is tested and the use life of the street lamp using heat pipe radiator is analyzed is this paper. Additionally, the feasibility of using heat pipe radiator in LED street lamp is proved by lighting the lamp designed based on the research of this paper.