側向穿孔空心圓柱交錯排列散熱結構之熱傳實驗

Heat Transfer Measurements of Perforated Hollow Cylindrical Fins in Staggered Alignment

徐熊群(Hsiung-Chun Hsu)

指導教授 ： 周榮源

國立虎尾科技大學/工程學院/機械與機電工程研究所/碩士(2011年)

https://doi.org/10.6827/NFU.2011.00063

摘要

本文研究目的在探討一具側向穿孔交錯式柱狀散熱結構之熱傳實驗，藉由實驗量測觀察此散熱結構在自然對流與衝擊流兩種條件下之散熱特性。本研究之側向穿孔交錯式柱狀散熱結構的陣排列數量分為8柱、14柱、23柱、33柱等四種設計，其對應之間距比SX範圍為1.7至0.9。在自然對流實驗中，瓦數範圍從10W變化至30W，雷諾數在1 x 106至5 x 106範圍；而在衝擊流實驗中，則控制瓦數在32.5W至181.45W範圍，雷諾數Re在16699至150291範圍。自然對流實驗所使用之加熱平台為電木材料之正方形測試段，而衝擊流實驗之測試段為倒T型之壓克力測試段，配合各散熱方式之控制參數進行實驗，再進行實驗數據分析。
由本研究之實驗結果顯示，在自然對流條件下，與文獻[32]之實心柱及空心柱結果比較得知，本文所研究之側向穿孔空心圓柱散熱結構之鈕賽數大於其他兩種型式之散熱結構，相較於實心結構，紐賽數約提高30%至35%，相較於空心結構，Nu值約提高2%至5%。在衝擊流條件下，當間距比SX從0.9增至1.7時，壓降值大小減少約40%左右。由此得知隨著間距比SX增加，會提升散熱效果。間距比的降低會造成壓降值的增加，進而降低對流效果，但隨著瓦數的提升，熱阻最高可降低至50%以上。最後從鰭片效率結果得知，隨著雷諾值增加，鰭片效率隨著SX間距比的降低而減少，表示在高雷諾數與低間距比之條件下，將產生不良之散熱效率。由本文研究結果得知，側向穿孔空心圓柱交錯排列散熱結構未來在LED燈具或是電子元件之散熱應用上，均有其可行性與實用性。

關鍵字

針柱式鰭片 ； 熱傳量測 ； 衝擊流 ； 自然對流

並列摘要

In this study, heat transfers of perforated hollow cylindrical fins in staggered alignment are experimentally measured. Both of the natural convections and impingement flows of four cases of fin structure are investigated. The fin structures are designed with 8 pins, 14 pins, 23 pins, and 33 pins, respectively; and the corresponding spacing ratio Sx is ranging from 1.7 to 0.9, respectively. As to the natural convection experiments, input powers are varied from 10W to 30W and its corresponding Rayleigh numbers are varied from 1 x 106to 5 x 106. Considering the impingement flow experiments, the input powers are varied from 32.5W to 181.45W, and Reynolds numbers are changed from 16699 to 150291. The test rig of natural convection experiments is constructed by Bakelite materials and is carefully insulated. A T-tube channel made by Acrylic is used to conduct the impingement flow experiments. Both experiments are conducted according to the corresponding experimental conditions, and experimental data are collected by a logger for post analysis.

According to the experimental results shown, for natural convection flows, the Nusselt numbers evaluated from experiments, as comparing to the reference [31], is higher than the one of solid and hollow fins under the same conditions. Comparing to the case of solid fins, its Nussult number increases from 30% to 35%; comparing to the case of hollow fins, its Nussult number increases from 2% to 5%. For impingement flow experiments, if spacing ratio Sx is increasing from 0.9 to 1.7, pressure drops will decrease 40%. Therefore, it can be noted that increasing Sx will increase the heat transfer of the fin structures. Increasing input powers can decrease the thermal resistances up to 50%. By the results of fin efficiency, for higher Reynolds numbers, fin efficiency is decreased as spacing ratio. It shows that for higher Reynolds numbers and smaller spacing ratio, the fin efficiency is smaller. This study shows that the fin structures with perforated hollow cylindrical fins in staggered alignment is feasible to and applicable as heat dissipation mechanisms of LED lightings or electronic devices.

並列關鍵字

Pin Fin ； Heat Transfer Measurement ； Impingement Cooling ； Natural Convection

參考文獻

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