Applied to the heat and humidity affect the centralized heat source for the electro-hydraulic power

• Main Authors: Chia-Hui Lin, 林佳輝
• Other Authors: Yi-Yang Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/56869791073045982758

碩士 === 國立雲林科技大學 === 機械工程系 === 102 === ABSTRACT Light-emitting diodes (LED) is a kind of semiconductor that has many advantages, such as energy-saving, environmental protection, small size, fast response and so on. However, only 20~30% of the input power is converted into light, while the rest of energy becomes waste heat which leads to an increase of junction temperature and a reduction of its life and luminous intensity. In this experiment, the main heat transfer mechanisms are heat conduction occurred from LED die to the substrate and heat convection transferred from the substrate to environment. The ionic wind is employed to enhance the cooling effect of 1WLED. First is to attach a prepared EHD (Electric Hydraulic Dynamometer) structure to the substrate of 1WLED, and then applying a voltage from 1 to 12 kV in a needle electrode to generate the ionic wind. This kind of EHD effect can be also applied to some micro-electronic products. In order to investigate the cooling effect at different ambient temperature and relative humidity, this study keeps the same of the needle type, the height of the LED substrate-electrode (10mm), the distance between the grounding and electrode (10mm), and the inclined angle of the mesh (25 degrees). Results show that different ambient temperature do not affect the decrement of temperature and thermal resistance, but the thermal resistance of 1WLED can still be reduced up to 50% under different relative humidity and operating voltage (0~12kV). In addition, the main influence of relative humidity is on the current of grounding. It is found that the current becomes larger when the humidity becomes higher before the operating voltage reaches 11 kV. However, if the operating voltage is more than 11 kV, the opposite phenomenon occurs due to the mass increase of ions.