2008-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/709991摘要：本研究計畫為已結案之『多孔性沸騰熱傳之研究(I)』以及現正執行之『多孔性沸騰熱傳之研究(II)』的第三年期延續計畫。在第一期中，藉由陽極處理產生多孔性表面，製成池沸騰實驗之加熱器；透過相關實驗設備，得以觀察純水中添加鹽類、介面劑於多孔性表面的沸騰熱傳現象。在第二期中，我們著手以多孔性表面針對奈米流體進行池沸騰實驗，除實際驗證文獻中所述臨界熱通量的提升外，亦希望藉由高速影像的輔助，探討奈米流體對氣泡脫離半徑、頻率的影響。因研讀奈米流體相關文獻後，發現近期論文指出極低濃度之奈米流體，加熱沸騰後於加熱表面出現奈米顆粒沉積、產生類多孔性的表面結構，顯著提升熱傳效能。故期望延續第二期的研究基礎，針對此現象進行深入探討，進而繼陽極處理後，尋得第二種有效提升沸騰熱傳之表面處理技術。 此外，文獻中有關奈米流體應用於均熱板的記載並不多見，或多未有明確結果。本研究將以實驗方式持續探討奈米流體應用於均熱板的可行性，與最佳化參數的尋得。最後，由於氣泡於加熱表面的堆積與聚集，致使沸騰現象進入過渡沸騰與膜沸騰區域，使臨界熱通量受限。本研究將探討以電場、超音波與加熱器內部通入氣體之方式輔助氣泡脫離，藉以提高臨界熱通量。 <br> Abstract: This proposal is for the consecutive 3rd stage of the completed “Research of Boiling Heat Transfer in Porous Media (I)” and the currently running “Research of Boiling Heat Transfer in Porous Media (II)”. In stage I, anodized heater was used in pool boiling experiments, and the effects of dissolved salts and addition of surfactant were studied. In stage II, nanofluids are tested in the pool boiling experiments with porous heater, and the enhancement of boiling heat transfer by nanofluids is explored. Besides, the effects of nanofluids on the bubble departure diameter and frequency are studied by analyzing high-speed images. Also, studies in literatures point out that the deposition of nanoparticles on the heater surface is the major reason of CHF enhancement. Experiments will be conducted to verified their discovery, and it is hopeful that another surface process can be found to enhance pool boiling heat transfer. Moreover, the applications of nanofluids in vapor chambers are seldom found in literatures. In this study, tests will be performed to find out the feasibility of nanofluid utilization and the optimized parameters. Finally, we are going to examine several methods, such as electrical field, ultrasonic vibration, and assisted-gas, to facilitate the departure of bubbles, further rising the CHF.池沸騰奈米流體多孔性pool boilingnanofluidporous