碩士生: 高孝瑄
畢業年分: 2022年7月
論文名稱: 碳氫預混火焰在不銹鋼-鉑分段式反應器之燃燒特性與性能優化研究(中文) / Study on combustion characteristics and performance optimization of hydrocarbon premixed flames in stainless steel-platinum segmentation reactor(英文)
中文摘要:
本研究主要探討具有穿孔之不鏽鋼/白金觸媒微管燃燒器的燃燒性能與優化研究。由於燃燒過程會伴隨著化學反應、熱傳導與質量擴散等不可逆性的過程發生，而這些不可逆性的過程稱之為熵。熵之生成會造成能量損失，然而這些能量損失無法藉由實驗測得求得，因此需要藉著模擬之幫助以探討微反應器內部能量損失之來源。藉著分析熵生成率之後，可以進一步求得微燃燒器的熱力學第二定律效率，以判別燃燒器性能。然而，本研究提出3種燃燒器的孔洞設計以及針對會影響燃燒效率的四種參數進行探討，其中討論的參數包含甲烷/空氣的流速、氫氣/空氣的流速、甲烷/空氣的當量比，以及氫氣/空氣的當量比。隨著操作區間的搭配，將會有許多參數組合，若要探討所有排列組合條件的性能，勢必會浪費許多時間與金錢。因此本研究利用克里金代理優化模型協助以較少的組數得到然燃燒效率的趨勢，並且能以一定量的實驗組數去建立優化模型。其中，所建立的克里金代理優化模型可以成功預測3種燃燒器的燃燒效率，以及其燃燒模態的區間界定。例如，在六個孔洞設計中，氫氣/空氣速度、甲烷/空氣速度、甲烷/空氣的當量比與氫氣/空氣的當量比的敏感性係數值分別為 -1.7、-0.22、0.4 和 0.15。代表氫氣/空氣的當量比在六個孔洞設計中將影響燃燒效率甚大。
英文摘要:
This study primarily investigates the combustion performance and optimization of a stainless steel/platinum catalytic microchannel combustor with perforations. During the combustion process, irreversible phenomena such as chemical reactions, heat transfer, and mass diffusion occur, contributing to entropy generation and resulting in energy loss. However, these losses cannot be measured directly; thus, simulations are necessary to explore the sources of energy losses within microreactors. By analyzing entropy generation rates, we can further determine the thermodynamic second law efficiency of the microcombustor, assessing its performance.
This study introduces three perforation designs and explores four parameters affecting combustion efficiency: methane/air flow rate, hydrogen/air flow rate, methane/air equivalence ratio, and hydrogen/air equivalence ratio. Due to the multitude of parameter combinations across the operational range, exhaustive experimentation across all permutations would be time-consuming and costly. Therefore, this study employs the Kriging surrogate model to predict combustion efficiency trends with fewer experimental runs, thereby aiding in establishing an optimization model.
The Kriging model successfully predicts combustion efficiency and determines the boundaries of combustion regimes for all three combustors. For instance, in six perforation designs, sensitivity coefficients for hydrogen/air flow rate, methane/air flow rate, methane/air equivalence ratio, and hydrogen/air equivalence ratio were -1.7, -0.22, 0.4, and 0.15, respectively. This implies that the hydrogen/air equivalence ratio significantly influences combustion efficiency among the six designs.
