| Summary: | 博士 === 國立臺灣大學 === 機械工程學研究所 === 99 === Two analytical models were used in this study to predict the performance of a plate-fin array heat sink in forced convection and natural convection cases respectively. The optimization of geometry variables for designing a plate-fin heat sink in both cases was also analyzed in this study.
While the pressure drop of heat sink was fixed at 10 mmAq, and the height was fixed at 24 mm in forced convection situations, optimal values for fin spacing, base thickness, base width and base length were found. In natural convection situation, it was found that there are lower limits for the variation of fin height, base length, base width and base thickness of heat sink. Increase of these parameters has limited benefit of performance. Considering the limits of these parameters and the cost factors, the optimal values of these design parameters were suggested in this study.
As the airflow rate through the heat sink becomes small in force convection, the effect of nature convection has to be considered. For the case of a fixed size of heat sink with a slow airflow velocity considered in this study, it’s found the overall performance of forced convection (with thermal resistance of 4.62 ℃/W) is worse than that of nature convection (with thermal resistance of 4.38 ℃/W) when airflow rate was under 0.68 cfm.
In the case of forced convection using fan as driving force, the effect of fan performance curve has to be considered in the design optimization process of heat sink’s geometry variables. The optimal operating points of airflow rate, pressure drop and sizes of heat sink, can be found with this model for a single heat sink with a fixed fan. Example of the optimal operating point was illustrated in this study.
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