| 摘要: | 本研究分析光電化學反應器內的熱傳與流場特性，並探討反應器設計對熱流特性與產氫效率的影響。使用ANSYS FLUENT套裝軟體作為數值分析的工具。主要研究的參數有反應器的幾何外型與熱傳機制設計、光電極材料能隙、照光密度與量子效率。模型中並考慮AM 1.5的太陽光照射進入反應器後，與玻璃、水及各壁面的輻射特性交互作用。研究結果顯示，使用方形反應器於照光密度4000 W/m2、量子效率 30 %的條件下，若僅使用短波能量產氫，對應1.5 eV、2.0 eV、2.5 eV和3.0 eV的光電極之理論產氫量分別為251 L/m2-hr、150 L/m2-hr、73 L/m2-hr及25 L/m2-hr；若加入分光機制，有效地利用長波和短波中因量子效率無法用於產氫的能量，將之利用加熱反應器降低分解電位；在case 3的絕熱材加玻璃反應器設計將可提升產氫量至271 L/m2-hr、161 L/m2-hr、79 L/m2-hr及27 L/m2-hr。而理論產氫效率可由22 %、13 %、6.5 %及2.23 %，於case 3中可提升至24 %、14 %、7 %及2.4 %。The design of a photo-electrochemical (PEC) reactor is very important; it affects the energy transportation and the hydrogen production rate. In this study, the thermal and fluid flow characteristics of a PEC reactor are investigated. Using ANSYS FLUENT as a tool, the effects of the reactor design, material properties, energy bandgap of the photo-electrode, incident solar intensity, and the quantum efficiency on the thermal-fluid characteristics and the hydrogen production efficiency of are studied and discussed.Results show that, for a rectangular glass reactor with 4000 W/m2 incident solar intensity, 30 % quantum efficiency, only the short wavelength energy, the hydrogen production rate is 251 L/m2-hr, 150 L/m2-hr, 73 L/m2-hr and 25 L/m2-hr respectively for 1.5 eV, 2.0 eV, 2.5 eV and 3.0 eV bandgap photoanodes. On the other hand, using the long wavelength energy to heating the reactor and lowering the water dissociation energy, and with the case 3 reactor design, the hydrogen production rate can be increased to 271 L/m2-hr, 161 L/m2-hr, 79 L/m2-hr and 27 L/m2-hr, respectively. The corresponding solar-to-hydrogen efficiencies are increased from 22 %, 13 %, 6.5 %, and 2.23 % to 24 %, 14 %, 7 % and 2.4 %. |
