本研究探討具潛熱冷卻頂板平行毫米流道熱沉內氧化鋁-水奈米流體於穩態等溫加熱條件下之熱散逸性能。單一流道截面積尺寸為寬1mm、高3mm。本研究相關參數範圍：純水與氧化鋁-水奈米流體重量百分濃度分別為5%、10%；體積流量 為 、 、 ，以純水物性為基礎，換算成基底流體雷諾數為161至968之間；等溫加熱條件是依流道底部壁溫來設定，溫度分別50 與55 ；流體入口溫度設定為40 與45 ；相變化微膠囊層使用二十二烷相變化微膠囊，熔點為43 ，相變化微膠囊層須配合等溫冷却頂板將熱能帶走，等溫冷却頂板在本研究設定為25 、30 以及35 。由本實驗結果顯示加熱片所提供之熱能，80%由平行毫米流道熱沉帶走，而潛熱冷却頂板只帶走5%。說明潛熱冷却頂板效果不佳。添加氧化鋁奈米流體之工作流體，有提升平均熱傳增益，但也因壓降增加，造成此研究之效能指標皆小於一。高溫流體入口溫度能使相變化微膠囊層吸收較多之潛熱，但須配合低溫之等溫冷却底板，避免膠囊層溫度超過熔點。

SUMMARY

The study was to research an experimental study that is heat dissipation characteristics of Al2O3-water nanofluid flow in a mini-channel heat sink under isothermal condition and with microencapsulated phase change material(MEPCM) layer. The multi-channel heat sinks of a length of 50 mm and a width of 25.1 mm were fabricated of oxygen-free copper with eight parallel mini-channels, each with an inlet cross-section of 1 mm in width and 3 mm in height. The MEPCM uses n-docosane as a core material and urea-formaldehyde as a shell material. The melting temperature of MEPCM is 43℃, so we need Cooling ceiling to take away heat and prevent MEPCM melting. The pertinent experimental conditions considered are in the following ranges: the volumetric flow rate of working fluid through the heat sink, Q ̇= 100, 300, 600 cm3/min; the mass fraction of Al2O3-water nanofluid, ωnp = 5%, 10%; the isothermal condition of channel wall average temperature, (T_w ) ̅ =50℃, 55℃; the inlet temperature of working fluid, Tin =40℃, 45℃; and the isothermal condition of cooling ceiling average temperature, T ̅_cw =25℃, 30℃, 35℃.
The study was to research an experimental study that is heat dissipation characteristics of Al2O3-water nanofluid flow in a mini-channel heat sink under isothermal condition and with microencapsulated phase change material(MEPCM) layer. The multi-channel heat sinks of a length of 50 mm and a width of 25.1 mm were fabricated of oxygen-free copper with eight parallel mini-channels, each with an inlet cross-section of 1 mm in width and 3 mm in height. The MEPCM uses n-docosane as a core material and urea-formaldehyde as a shell material. The melting temperature of MEPCM is 43℃, so we need Cooling ceiling to take away heat and prevent MEPCM melting. The pertinent experimental conditions considered are in the following ranges: the volumetric flow rate of working fluid through the heat sink, Q ̇= 100, 300, 600 cm3/min; the mass fraction of Al2O3-water nanofluid, ωnp = 5%, 10%; the isothermal condition of average temperature of channel wall, (T_w ) ̅ =50℃, 55℃; the inlet temperature of working fluid, Tin =40℃, 45℃; and the isothermal condition of average temperature of cooling ceiling, T ̅_cw =25℃, 30℃, 35℃.
The experimental results obtained reveal that using Al2O3-water nanofluid can get better heat transfer coefficient than pure water. The pressure drop of nanofluid is larger than pure water. As concentration increases, pressure drop increases. The heat sinks take away 80% heat energy from heater, on the other hand, the MEPCM layer take away 5% heat. That shows MEPCM layer effective is very lower, but raise working fluid inlet temperature can improve MEPCM layer effective.

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