本論文使用計算流體力學(Computational Fluid Dynamics，CFD) 軟體FLUENT配合一系列之使用者自定函數(User Defined Function, UDF)完成了自甲烷的自熱重組反應(ATR, Autothermal Reforming)生成氫氣之填充床式觸媒反應器(Packed Bed Catalytic Reactor，PBR)之三維模式模擬，模式納入了填充床球型觸媒顆粒反應器中(1)巨相之流力、熱傳與質傳；(2)觸媒顆粒內之流力、熱傳、質傳與化學反應；(3)巨相與觸媒顆粒間之流力、熱傳與質傳。 透過模擬探討了反應器內部之特性分佈，包括壓力、速度、溫度與組成，並探討了參數之影響，包括觸媒球表面處理、雷諾數、孔徑、觸媒球粒徑、不同進氣條件等。針對填充床之摩擦因子以及觸媒顆粒與巨氣相間之熱傳係數與質傳係數，本研究並比較模擬結果與文獻關聯式，結果顯示摩擦因子與Durst等人修正之Ergun方程式較吻合，熱傳係數與質傳係數則分佈零散，並未呈現特別與某一關聯式較吻合之情形。 This thesis uses Computational Fluid Dynamics, combining with a set of User Defined Functions (UDF) to accomplish the simulation studies for the Packed Bed Catalytic Reactor (PBR) for hydrogen generation from steam reforming of methanol.
The model encompasses all important mechanisms for PBR, including (1) the hydraulic, heat and mass transfers of bulk gas; (2) the hydraulic, heat and mass transfers and chemical reaction of catalyst; (3) the hydraulic, heat and mass transfers between bulk gas and catalyst. The simulation is for turbulent flow regime.
The simulation facilitates the discussions on the profiles inside the reactor, including pressure, velocity, temperature and composition. The effects of catalyst particle pore size, catalyst particle diameter, fluid inlet velocity and the location in the reactor are studied. The ways of treating catalyst particle surface friction are investigated too. The friction factor of the bed and the heat and mass transfer coefficients between catalyst particle and bulk gas are compared with the correlations reported in the literature. The friction factor vs. Reynolds number relation is close to the Durst et al. modified Ergun equation, while Nusselt number vs. Reynolds number and Sherwood number vs. Reynolds number relations are scattered distributed and cannot be described well by reported correlations.
