探討單向方波電流電解對於水平銅管池沸騰熱傳影響

Abstract

沸騰傳熱具有高效的傳熱效率，可以在較小的溫度差的情況下進行大量的的熱量傳遞，從而提升能量傳遞的效率和系統性能，廣泛應用於熱交換器，電子冷卻和工業過程中。本研究探討了單向方波電流電解對水平放置銅管池沸騰傳熱性能的影響。本研究的實驗在一大氣壓的飽和狀態下進行，使用碳酸鈉溶液作為工作流體。通過電解水產生氫氣以增加沸騰時的核化點數量，進而提升相變位點數量，從而增強熱傳性能。本研究分析並比較了無電解、直流電流電解和單向方波電流電解條件下的傳熱過程中的傳熱係數（Heat Transfer Coefficient）和氣泡動態特性。實驗的結果顯示，當電流為12mA時，單向脈衝電流頻率在25mHz電解的情況下，熱傳係數(HTC）的提升最為顯著，相較於無電解情況下，熱傳係數提升了1.31倍。實驗中透過高速攝影機進行捕捉沸騰時氣泡的圖片，進而觀察在不同電解條件下氣泡動態特性。我們還比較了在不同熱通量度條件下，在水平銅管上下表面的溫度分佈情況。這些研究結果對在提升能量傳遞效率和系統性能方面具有潛在應用價值。

Boiling heat transfer is crucial due to its high heat transfer efficiency, allowing significant heat transfer with slight temperature differences, thereby enhancing energy efficiency and system performance. This is especially important in power generation, electronics cooling, and industrial processes. This research examined how unidirectional square wave current electrolysis influences the heat transfer performance of a copper tube positioned horizontally. The experiment was conducted at atmospheric pressure and saturation conditions, using sodium carbonate solution for the working fluid. We used a high-speed camera to capture images of the process for analyzing bubble dynamics. This study compared the heat transfer coefficient （HTC）and bubble dynamics in the heat transfer processes with and without electrolysis, including direct current (DC) electrolysis and unidirectional square wave current electrolysis. The experimental results show that when the current is 12mA, under unidirectional pulse current electrolysis at a frequency of 25mHz, the heat transfer coefficient (HTC) is enhanced the most, with an increase of 1.31 times compared to the condition without electrolysis. We then analyzed the bubble dynamics to investigate bubble aggregation on the upper and lower surfaces of the horizontal copper tubes under different heat flux conditions. The bubble formation and detachment processes on both surfaces of the tube were examined using high-speed camera comparisons to determine the nature of the bubbles. The dynamics properties of the bubbles were analyzed under different electrolysis conditions. These findings are significant as they contribute to the understanding of boiling heat transfer and can potentially be applied in various industries to enhance energy efficiency and system performance.