| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 107 === This study presents a newly developed preheat system for methanol steam reforming by reducing energy consumption. An exergy analysis is performed at power generation system for hybrid fuel cell vehicle while producing hydrogen to be fed into the fuel cell. Dynamic modelling is performed for multi-tube annular membrane methanol reformer (MTAMMR) with energy efficient raw material preheating system for hydrogen production. The MTAMMR is composed of several annular membrane methanol reformers (AMMRs). All the AMMRs in the MTAMMR are in the same specification and operated under the same operating conditions for hydrogen production. The MTAMMR is modelled by using a professional chemical engineering software named gPROMS®. The governing equations of the mathematical model in this research are calculated by the model builder in gPROMS® and thermodynamic properties are calculated by Aspen Plus. Characteristic finite difference method (CFDM) is selected to solve partial differential equations. Further kinetic expressions validation is performed for this newly developed AMMR design.
Newly developed preheat system is proposed with reducing the energy requirements by utilizing waste heat of streams from the heat exchangers with the addition of a heater and a cooler to achieve target temperatures. Plate Fin Heat exchangers are used which were designed in software named Aspen Exchanger Design ＆ Rating, which enabled to find feasible design with respect to heat duty and weight of heat exchangers. Aspen Plus is used to design heating and cooling system for required streams. Study shows by the implementation of newly proposed preheat system, energy requirements can be reduced to 40%.
Exergy analysis, which is used to find maximum available work, is performed on 114 kW power generation system for hybrid fuel cell vehicle to analyze the irreversibilities and losses. Exergetic efficiencies are discussed on individual units and on the overall power generation system. The heat integration analysis is performed to improve the exergetic performance. Due to the exergy analysis, it is found that the newly developed integrated process can improve the exergy efficiency by 7.08%. By performing the analysis on newly proposed preheat design, exergetic losses and destruction reduced by 31.3 % and 26.90 % respectively.
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