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Tham khảo tài liệu 'heat and mass transfer modeling and simulation part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Process Intensification of Steam Reforming for Hydrogen Production 71 preheating evaporation and superheating of water and this also affects the reaction temperature. So W M should not be too high. In this study W M of 1.3 is optimal at which the mole content of CO is only 0.4 . Fig. 2. Effects of W M on methanol conversion hydrogen yield H2 and CO in the products. Methanol conversion increased with the rise of reaction temperature and it approached to almost 100 at Tr 250 T and WHSV 0.2 h 1 as can be seen in Fig.3. Hydrogen yield mole contents of H2 and CO also increased with increasing of temperature. Hydrogen yield reached 0.2 mol h gcat under condition of Tr 260 T WM 1.3 and WGHV 0.2 h-1 which can provide hydrogen for 10.2W PEMFC with a hydrogen utilization of 80 and an fuel cell efficiency of 60 . Owing to the strongly endothermic nature of MSR reaction increasing of reaction temperature can promote SR reaction and then raise methanol conversion and mole content of H2. However DE was also a strongly endothermic reaction so temperature increase can also promote this reaction leading to increase of CO content although it was less than 1 in this study. In practical application the reaction temperature of MSR for hydrogen production has an optimal value which depends on WHSV and is about 250T in this experiment. Fig. 3. Effects of temperature on methanol conversion hydrogen yield H2 and CO in the products. 72 Heat and Mass Transfer - Modeling and Simulation It can be seen in Fig.4 that with the increasing of WHSV methanol conversion reduced from 95.7 to 49.1 mole content of H2 was also decreased from 70.3 to 38.3 whereas CO rose firstly and then decreased. Hydrogen yield mounted from 0.2mol h gcat. to about 0.5 mol h gcat then dropped quickly. With the increase of WHSV residence time of the reactants in the reactor was reduced which resulted in reducing of methanol conversion and H2 mole content. Consequently in order to increase methanol conversion at higher WHSV
