| Summary: | 碩士 === 國立成功大學 === 機械工程學系專班 === 98 === LED, the illuminating light source in energy saving, can save more power and have longer life cycle comparing to traditional light source. In fact, LED is a lighting component with high heat. That high heat of LED can’t be transferred effectively will seriously result in lower illuminating efficiency. Thus, heat transfer function of LED has played an important role in its working efficiency. A fin is a basic heat transfer system of the LED lamp, which is not only easy to produce, but also stable and economical.
The present study applies the finite-difference method in conjunction with the least-squares scheme and measured temperatures to estimate the average convection heat transfer coefficient, total heat transfer rate, and fin efficiency on a vertical rectangular fin. The heat transfer coefficient on this rectangular fin is non-uniform. Thus the whole plate fin is divided into several sub-fin regions in order to predict the average heat transfer coefficient. The heat transfer coefficient on those sub-fin regions is assumed to be constant. The results show that the average heat transfer coefficient increases with increasing the fin spacing and decreases with increasing the fin height in free convection. The average heat transfer coefficient decreases with increasing the fin spacing for a fixed air speed in forced convection.. However, this value approaches its corresponding asymptotical value obtained from a single fin as S → ∞ . In order to evidence the accuracy of the present inverse scheme and the reliability of some experimental formulas, a comparison of the average heat transfer coefficient between the present predicated results and those obtained from correlation recommended by current textbook is made.
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