改善毛細泵吸迴路熱傳性能應用在電子冷卻之實驗研究

Abstract

摘要 本實驗主要是研究並建立一套應用於電子冷卻的改良式毛細泵吸迴路系統，數種改良蒸發器設計以增進熱傳性能的方法在本實驗中被研究。這些方法包括在蒸氣溝槽的側面及底面製造粗糙面，使多孔材料中的液體能潤濕溝槽表面以增加蒸發面積。其次，在蒸發器內部加入一均熱片的影響也被探討。由針狀及平板鰭片構成的蒸氣通道對毛細泵吸迴路性能的影響也進一步在本研究中探討。 本研究中使用一加熱面積為30×30mm2的加熱銅塊來模擬發熱中的晶片，均熱片的加熱面積為57×57mm2並直接連接在加熱銅塊的上方。均熱片上方刻有10個溝槽供蒸氣流進蒸氣管路，每個溝槽的深度為3mm，寬度為2.4mm，溝槽的尺寸和文獻[34]中未使用均熱片的系統相同以便於比較。 實驗的結果指出工作流體的填充量會影響到整個系統的熱傳能力，且在最高的散熱功率以及最低的熱阻值會發生在一最佳的充填量，在大於最佳填充量時，增加填充量反而會使系統的最高散熱功率下降、最低熱阻值升高，增加蒸發器及冷凝器間的相對高度也會提高整個系統的熱傳能力。另外，使用針狀鰭片來構成溝槽的設計並無法增進整個系統的熱傳能力，使用均熱片則能有效的提升熱傳能力，在溝槽的側面及底面使用粗糙面的設計亦能有效的增進整個系統的熱傳能力。

ABSTRACT In the present study, an experimental capillary pumped loop for electronics cooling based on an improved system design is established. Several methods to improve the thermal performance of the loop by improving the evaporator design are investigated. These include roughing the vertical and bottom surfaces of the grooved channels to allow the liquid in the wick to wet the surfaces, which in turn greatly increases the surface area for the liquid vaporization. Besides, the possible heat transfer augmentation in the evaporator section through the use of a heat spreader on the heat dissipating chip is explored. Furthermore, the CPL performance difference between the vapor channels formed by plane fins and pin fins is also examined. The heat dissipating chip with a surface area of 30×30mm2 is modeled by a heated copper plate of the same surface area in this study. The heat spreader, also a copper plate, is chosen to have a much larger surface area of 57×57 mm2, which is mounted directly on the heated copper plate. Ten grooved channels are machined on the surface of the heat spreader. Each grooved channel is 3mm in height and 2.4mm in width. The height and width of the channel are the same as that in the previous study [34] without using heat spreader. The measured data indicate that an optimal liquid inventory exists at which Qe,max is the highest and Rth is the lowest for a given relative condenser-evaporator height for the CPL with a given evaporator design. Besides, increasing or decreasing the liquid inventory from this optimal value causes a reduction in Qe,max and a raise in Rth. Moreover, an increase in the relative height between the condenser and evaporator results in a significant improvement in the CPL performance with a much higher Qe,max and a much lower Rth. Furthermore, there is no noticeable enhancement in the heat transfer performance of CPL by using a pin fin block to form the grooved channels. However, the use of a large heat spreader in the evaporator can enhance the heat transfer performance greatly. Finally, roughing the vertical and bottom surfaces of the grooved channels can also significantly enhance the heat transfer performance of the CPL.