碩士 / 國立清華大學 / 化學工程學系 / 89 /

碩士 / 國立清華大學 / 化學工程學系 / 89 / This research applies Cartesian Grid Method along with Collocated Cell-Centered Finite Volume Method to simulate polymer extrusion process. A automated Cartesian Grid generation program is developed. Users only have to input STL format geometry and mesh parameters to generate Cartesian Grid. The outline of the grid gets closer to actual geometry as the level of Cartesian Grid grows. The saw-toothed geometric boundary of Cartesian Grid has bad influences to the simulation convergence. However, under the circumstances that grid is smooth (i.e. without the saw-tooth boundary), the simulation converges better as the grid level increases. This study uses Cartesian Grid to simulate polymer flow in a fishtail flat extrusion die, reasonable velocity, pressure, temperature and viscosity profile is obtained. This research proves that Cartesian Grid method, a fast and fully automated mesh generation method, has practical application in the CAE analysis of polymer processes.

碩士 / 國立清華大學 / 化學工程學系 / 89 / The present research was mainly concerned with the immobilization of lipase（EC 3.1.1.3）from Pseudomonas fluorescens IFO 12055 on chitosan bead, for preparing S-AMPA（S-Acethylthio-2-Methylpropionic Acid） by enantioselective hydrolysis of racemic MAMP（Methyl-3-Acetylthio- 2-Methylpropionate）. We found that MAMP and AMPA could hydrolyze not only the ester-bonding but also the thioester-bounding. The Molecular Weight of the lipase estimated by Gel Filtration and SDS-PAGE was 68kDa. This enzyme was constituted of two subunits （about 36kDa）.The optimum temperature for free lipase and immobilized lipase on chitosan bead was 50℃, and optimum pH was 8.0. The Km（Michaelis constant）value of the immobilized enzyme was close to that of free enzyme. The Vmax value of the immobilized enzyme was lower than that of the free enzyme. Immobilized enzyme retains more than 80% of its activity for 30 batchs. It was confirmed that S-AMPA with 88%（e.e.）of optical purity was produced when reaction was done at 30℃ pH=7.6 by immobilized enzyme.

碩士 / 國立清華大學 / 化學工程學系 / 89 /

碩士 / 國立清華大學 / 化學工程學系 / 89 / Biofiltration was successful applied to treat volatile organic compounds (VOCs) from contaminated air streams. The experimental approach involved operating a bench-scale biofilter with using granular activated carbon as supports. There was no inoculation and only microorganisms indigenous to the bed medium were used throughout the whole process. Trichloroethylene (TCE) was degraded cometabolically with toluene as primary carbon source. In our work, we investigated that TCE is a potent competitive inhibitor of toluene oxidation because it competed with toluene for oxidation by the enzyme of toluene dioxygenase (TDO). Above a toluene concentration of 0.3 g/m3, the TCE removal efficiency decreased. In turn, TCE existing always decreased the toluene elimination capacity. Under steady-state, at 3 mines-gas-retention time and at 25℃, we get an optimum operation : removal efficiency of toluene and TCE are 70% and 90%.

碩士 / 國立清華大學 / 化學工程學系 / 89 /

碩士 / 國立清華大學 / 化學工程學系 / 89 /

碩士 / 國立清華大學 / 化學工程學系 / 89 / Liquid mixing characteristics were studied for the airlift reactor operating with net draft tube. The experimental reactor had a working volume of 26 L, column diameter of 0.13 m, and total height of 2 m. Experiments were carried out using air, water (or CMC solution), and polystyrene particles. Mixing in the liquid phase was assessed by the tracer-response technique and fast conductivity measurements. It was found that the flow pattern in an airlift reactor with net draft tube was similar to that in bubble columns instead of traditional airlift reactor. The mixing time decreased and the axial dispersion coefficient increased with increasing net mesh number. Moreover, the axial dispersion coefficient increased while rising superficial gas velocity except the transition from bubbly to churn-turbulent flow regime. The better diameter ratio of draft tube to column was 0.6, and the reactor with higher draft tube had better mixing performance. However, the top section had slight influence on liquid mixing, and the dispersion coefficient didn’t change with the reactor. Furthermore, adding solids and increasing liquid viscosity would enhance the mixing efficiency. In addition, the correlation between dispersion coefficient and these variables was established and the observed values were in agreement with the calculated values with a deviation of 30 %.

碩士 / 國立清華大學 / 化學工程學系 / 89 /

碩士 / 國立清華大學 / 化學工程學系 / 89 /