Abstract
本文針對多孔矩形槽中非達西強制熱對流的熱傳效應進行實驗研究，並探討在電子裝備冷卻方面的應用。實驗是以水及5×5×1公分加熱的燒結銅粒槽來進行，其中燒結銅粒的平均顆粒直徑共有0.72及1.59 ㎜兩種尺寸。所量測的參數包括沿水流流動方向的局部壁溫、進出口處的壓力差和溫度、及所對應的局部熱傳係數。實驗的邊界狀況是上板加熱且另外三邊絕熱，所加的等熱通量為2–9 W/c㎡，水流速度介於0和11.7cm/s之間，量測結果包含熱進口區及全展區。實驗的主要目的在於瞭解不同的顆粒直徑、雷諾數、等熱通量、及軸向位置下對於熱傳效果的影響。實驗結果顯示：當在較大的雷諾數與較小的顆粒直徑時，熱進口區的局部熱傳係數有較高的值，並隨著軸向位置的增加而遞減，至某一距離以後便趨向一常數值而達到全展的狀況。由於高熱傳係數多孔介質的存在，使得局部熱傳率提高並大大地降低局部壁溫。本實驗中對流熱傳係數可從 0.25提高至4 W/c㎡℃，若以空氣為工作流體，則對流熱傳係數的範圍約為0.01–0.5 W/c㎡℃。A study of non-Darcian forced convection in an asymmetricheating sintered porous channel was carry out to investigatethe feasibility of using this channel as a heat sink for highperformance forced water cooling in microelectronics. Thispaper presents the results of heat transfer measurement for two5×5×1 cm porous channels with sintered bronze beads of d=0.72and 1.59 mm. The local wall temperature distribution, inlet andoutlet pressures and temperatures, and heat transfercoefficients were measured for heat fluxes between 2 and 9 W/c㎡, and with water velocity ranging from 0 to 11.7 cm/s. Themeasurement covers the data in both the thermal entrance andthermal fully developed regions. The main objective of thepresent study is to examine the effects of the particleReynolds number, the Peclet number, and the ratio of channelheight to particle diameter on the local Nusselt number. In thethermal developing region, the results show that the local heattransfer coefficients increase with the decrease in theparticle size and the increase in the fluid velocity, butdecrease with the increase in the axial distance beforereaching its fully developed value. The high conductivityporous channel enchances the heat transfer and the maximum walltemperature could be reduced drastically. For example, theforced water cooling can be extended upto 0.25–4 W/c㎡℃ by aporous heat sink and maintaining a maximum wall temperatureless than 45℃. But for forced air cooling, the heat transfercoefficents are about from 0.01 to 0.5 W/c㎡℃。