Dissertations / Theses on the topic 'Micro Channel Plate'

For ammonia-water absorption refrigeration technology it is suggested to use bubble type absorbers because the higher contact surface area provides a higher mass transfer rate. Furthermore, dispersion of bubbles in the bulk of liquid phase also exhibits better heat transfer characteristics that facilitate the recovery of dissipated heat of the exothermic absorption.In this context, plate heat exchangers are believed to be an option to be employed as absorber in some applications. Commercial plate heat exchangers have only one inlet and outlet for a working fluid and as a result, gas and liquid should be mixed before supplied to a gap between the two adjacent plates. The consequence is the high risk of bubble mergence to form a bigger bubble and to follow the shortest flow paths in vertical direction so that not all the heat transfer surface can be effectively used. Furthermore this feature makes plate heat exchangers sensitive to the angle of plate relative to the vertical which would be worst when it is laid to its side on a horizontal plane.Austrian Institute of Technology (AIT) develops an efficient Bubble Plate Absorber for applications in high-pressure absorption systems and this work tries to investigate design possibility of this Bubble Plate Absorber based on a plate heat exchanger equipped with microchannels between plates.Two sets of seven parallel microchannels same in shape and dimension were tested. The first set had a continuous wall which means fluids could flow independently along the microchannels; whereas, the other set was benefiting from some linkages between channels that fluids could cross from one microchannel to another one. Ammonia vapour was injected via one and two-holed distributors.It was found that microchannels with continuous wall deliver higher concentration and less unabsorbed bubbles at the microchannels outlet. In visual analysis by high-speed camera, changing the vapour distributors from single-hole to double-hole had no significant effect on the bubble distribution quality in lower flowrates; however, double-hole vapour distributor showed better performance in higher vapours flowrates.

Questa tesi descrive una prima serie di misure effettuate per caratterizzare le prestazioni di un rivelatore di fotoni MCP-PMT a multi anodo, con particolare enfasi sulla risoluzione temporale e spaziale. I risultati sono stati confrontati con quelli relativi a tre ulteriori rivelatori (un MCP-PMT a singolo anodo e due fotomoltiplicatori a silicio). Le misure sono state effettuate presso i Laboratori dell’Istituto Nazionale di Fisica Nucleare (INFN - Sezione di Bologna) per conto del Dipartimento di Fisica dell’Università di Bologna. La rivelazione della luce ha sempre occupato un posto fondamentale nella Fisica Nucleare e Subnucleare. Il principio base della rivelazione consiste nel trasformare la luce incidente in un segnale elettrico misurabile e i primi strumenti storicamente utilizzati furono i fotomoltiplicatori. Successivamente furono introdotti dei nuovi rivelatori di fotoni chiamati Micro Channel Plates, composti da un array di canali di dimensioni microscopiche, ciascuno in grado di moltiplicare gli elettroni prodotti per effetto fotoelettrico dai fotoni incidenti. Questo nuovo modello presenta ottime prestazioni in particolare per quanto riguarda la risoluzione temporale, e questa insieme ad altre caratteristiche (come la segmentazione degli anodi, che permette una risoluzione spaziale migliore), ha spinto a studiarne il funzionamento.

Analytical, computational and experimental studies were carried out to investigate heat transfer and fluid flow in micro-channel absorber plates for compact (thin and light-weight) solar thermal collectors. The main objective of the work was to study different design and/or operating scenarios as well as study the significance of various micro-scaling effects. Analytical investigation showed that, under similar conditions, the proposed design yields a much higher fin efficiency, F and collector efficiency factor, F’ compared with the conventional solar collector design. An analytical model combining convective heat transfer in the collector fluid with axial conduction in the metal plate was developed. The predicted plate temperature profiles from the analytical model were in close agreement with the measured profiles. The model further showed that axial thermal conduction can significantly alter the plate temperature profile. Experiments were designed to represent real life operation of the proposed system. A CFD study, using the same design and operating parameters, produced results comparable with experiments. This numerical simulation also gave further insight into the heat transfer and fluid flow patterns in the micro-channel plate. The effect of channel cross section geometry was studied. The Nusselt number was observed to increase as the aspect ratio approached unity. Measured friction factors were similar in trend to the predictions for rectangular channels, although the overall rise in fluid temperature resulted in slightly lower friction factors. Thermal performance reduced slightly with increase in hydraulic diameter. The significance of various scaling effects was also investigated experimentally and numerically. Most of the typical scaling effects such as viscous dissipation and entrance effects were found to be insignificant however, conjugate heat transfer, surface boundary condition, surface finish and measurement uncertainties could be significant. The results showed a Reynolds number dependent Nusselt number which has been attributed to axial thermal conduction. It was also observed that only three walls were transferring heat; the walls of heat transfer had a uniform peripheral temperature while the heat flux varied peripherally. The closest simplified thermal boundary condition to represent heat transfer in these channels is the H1 with three (3) walls transferring heat. Increased surface roughness (obtained by using an etching technique to create the channels) was found to have a detrimental effect on heat transfer. The results showed that thermal improvement can be achieved by increasing the fluid velocity; however, pumping the thermal fluid above a pump power per plate area of 0.3 W/m2 resulted in marginal improvement. In practice, optimum microchannel geometry in plates should be sized based on fluid properties and operating conditions. The micro-channels should also have thin walls to minimise the effects of conjugate heat transfer. A Photovoltaic pump should be installed alongside the collector in order to provide pumping power required and minimise the overall fluid temperature rise. The results are beneficial for the design of micro-channel absorber plates for low heat flux operation up to 1000W/m2.

Polymer electrolyte membrane fuel cells (PEMFCs) have emerged as a strong and promising candidate to replace internal combustion engines (ICE) due their high efficiency, high power density and near-zero hazardous emissions. However, their commercialization waits for solutions to bring about significant cost-reductions and significant durability for given power densities. Bipolar plate (BPP) with its multi-faceted functions is one of the essential components of the PEMFC stacks. Stainless steel alloys are considered promising materials of choice for bipolar plate (BPP) applications in polymer electrolyte membrane fuel cells (PEMFC) due to their relatively low cost and commercial availability in thin sheets. Stainless steel materials build a protective passive metal oxide layer on their surface against corrosion attack. This passive layer does not demonstrate good electrical conductivity and increases interfacial electric contact resistance (ICR) between BPP and gas diffusion layer GDL in PEMFC. Lower ICR values are desired to reduce parasitic power losses and increase current density in order to improve efficiency and power density of PEMFC. This study aimed to bring about a broader understanding of manufacturing effects on the BPP contact resistance. In first stage, BPP samples manufactured with stamping and hydroforming under different process conditions were tested for their electrical contact resistance characteristics to reveal the effect of manufacturing type and conditions. As a general conclusion, stamped BPPs showed higher contact conductivity than the hydroformed BPPs. Moreover, pressure in hydroforming and geometry had significant effects on the contact resistance behavior of BPPs. Short term corrosion exposure was found to decrease the contact resistance of bipolar plates. Results also indicated that contact resistance values of uncoated stainless steel BPPs are significantly higher than the respective target set by U.S. Department of Energy. Proper coating or surface treatments were found to be necessary to satisfy the requirements. In the second stage, physical vapor deposition technique was used to coat bipolar plates with CrN, TiN and ZrN coatings at 0.1, 0.5 and 1 μm coating thicknesses. Effects of different coatings and coating thickness parameters were studied as manufactured BPPs. Interfacial contact resistance tests indicated that CrN coating increased the contact resistance of the samples. 1 µm TiN coated samples showed the best performance in terms of low ICR; however, ICR increased dramatically after short term exposure to corrosion under PEMFC working conditions. ZrN coating also improved conductivity of the SS316L BPP samples. It was found that the effect of coating material and coating thickness was significant whereas the manufacturing method and BPP channel size slightly affected the ICR of the metallic BPP samples. Finally, effect of process sequence on coated BPPs was investigated. In terms of ICR, BPP samples which were coated prior to forming exhibited similar or even better performance than coated after forming samples. Thus, continuous coating of unformed stripes, then, applying forming process seemed to be favorable and worth further investigation in the quest of making cost effective BPPs for mass production of PEMFC.

A novel surface structure comprising dendritically ordered nano-particles of copper was developed during the duration of this thesis research project. A high current density electrodeposition process, where hydrogen bubbles functioned as a dynamic mask for the materials deposition, was used as a basic fabrication method. A post processing annealing treatment was further developed to stabilize and enhance the mechanical stability of the structure. The structure was studied quite extensively in various pool boiling experiments in refrigerants; R134a and FC-72. Different parameters were investigated, such as; thickness of the porous layer, presence of vapor escape channels, annealed or non-annealed structure. Some of the tests were filmed with a high speed camera, from which visual observation were made as well as quantitative bubble data extracted. The overall heat transfer coefficient in R134a was enhanced by about an order of magnitude compared to a plain reference surface and bubble image data suggests that both single- and two-phase heat transfer mechanisms were important to the enhancement. A quantitative and semi-empirical boiling model was presented where the main two-phase heat transfer mechanism inside the porous structure was assumed to be; micro-layer evaporation formed by an oscillating vapor-liquid meniscus front with low resistance vapor transport through escape channels. Laminar liquid motion induced by the oscillating vapor front was suggested as the primary single-phase heat transfer mechanism. The structure was applied to a standard plate heat exchanger evaporator with varying hydraulic diameter in the refrigerant channel. Again, a 10 times improved heat transfer coefficient in the refrigerant channel was recorded, resulting in an improvement of the overall heat transfer coefficient with over 100%. A superposition model was used to evaluate the results and it was found that for the enhanced boiling structure, variations of the hydraulic diameter caused a change in the nucleate boiling mechanism, which accounted for the largest effect on the heat transfer performance. For the standard heat exchanger, it was mostly the convective boiling mechanism that was affected by the change in hydraulic diameter. The structure was also applied to the evaporator surface in a two-phase thermosyphon with R134a as working fluid. The nucleate boiling mechanism was found to be enhanced with about 4 times and high speed videos of the enhanced evaporator reveal an isolated bubble flow regime, similar to that of smooth channels with larger hydraulic diameters. The number and frequency of the produced bubbles were significantly higher for the enhanced surface compared to that of the plain evaporator. This enhanced turbulence and continuous boiling on the porous structure resulted in decreased oscillations in the thermosyphon for the entire range of heat fluxes.
QC 20111111

A wide range of research fields have studied how emotions and behavior are affected by the physical environment. This gestalt theorist approach of experimental research as well seeks to measure emotion (using the valence-arousal scale) and micro-scale community development interactions when weighted physical environment factors are adjusted. Community development (CD) interactions at the micro-scale have received but slight attention from scholars in the CD research field and this study aims partially to investigate developing objective measures from social observations. CD interactions from recordings along with self-reported emotion through surveys in four quasi-experimental groups (where the environments were constructed based on peer-reviewed literature to cause emotional reactions) and one control group made up the data collected for this experiment. While the results of this experiment displayed apparent convincing quantitative differences in both CD interactions and emotion when the physical environment was manipulated, the results of a one-way ANOVA indicated no statistical significance to either dependent variable. The conclusions suggest limiting the physical factors of the environment to produce more precise changes as a result of the manipulated quasi environments.

The vast distribution and long duration of the Late Mesozoic magmatism in the eastern part of South China presents a unique case in the world. This offers a natural laboratory to study the process of magma genesis, the magma emplacement mode, the relationship between magmatism and tectonics, the geodynamic role on the magma emplacement and lithospheric evolution. Since 50's, particularly 90's of the last century, geoscientists have made important efforts in geological cartography and carried out numerous studies with remarkable scientific achievements, building a solid background to understand the tectonic evolution of the South China Block (SCB). However, certain fundamental questions mentioned above remain unsolved and/or are in hot debate. In order to make progress in these scientific issues, we have carried out in a multi-disciplinary study in the Late Mesozoic Qingyang-Jiuhua massif, Hengshan massif and Fujian coastal zone according to their distance with respect to the paleo subduction zone of the Paleo-Pacific plate, the ages of granitic massifs and related tectonics, including field observation on the structure geology, micro-observation on thin section, U-Pb dating on monazite, AMS, paleomagnetism, gravity modeling and P condition concern the granite emplacement. In the view of deformation in these granitic massifs and their country rocks, mode and influence of regional tectonics on the emplacement, though each studied zone reveals its distinguished characteristics, they show some intrinsic and common relationships between them. With our new results and integrating previous data, in this thesis, we discuss the tectonic context of emplacement of these Late Mesozoic magmatic massifs and the geodynamic evolution of the SCB., We propose a 3-step geodynamic model: (1) during 145-130 Ma period, the Paleo-Pacific plate subducted northwestwardly, the West Philippines micro-continent, approaching to SCB, important subduction-related arc volcanism was produced in the coastal areas of Southeast China coast (Zhejiang-Fujian-Guangdong), forming a back-arc extension tectonic system in SCB; (2) during 130-110 Ma period, due to the collision between the West Philippines microcontinent and SCB, the compressional tectonic structures were developed in the Changle-Na'ao coastal zone, producing ductile deformation zones. However, the inland of the eastern part of SCB was under a NW-SE extensional tectonic regime; (3) during 105-90 Ma period, a new subduction zone was developed in the SE flank of the West Philippines micro-continent, the subducting slab reached the Changle-Nan'ao tectonic belt, with the possible break-off of slab, the asthenospheric ascent was responsible for the important emplacement of plutonic massifs and dykes. The tectonics of the eastern part of SCB was characterized by a general extensional system in this period. This tectonic pattern has been significantly disturbed by the Oligocene-Eocene opening of the South China sea,and the Miocene shortening of the SCB margin in Taiwan. Of course, this model should be improved by more geological, geophysical and geochemical investigations.

碩士
國立勤益科技大學
機械工程系
101
The purpose of this study was to analysis stainless steel spiral micro flow channel bipolar plate stamping process for effect of blank formability and microscopic size effect. Bipolar plate is a key component for proton exchange membrane fuel cell. But it is very expensive and need micro thickness if using conventional graphite bipolar plate. A metal bipolar plate is another choice. This study use finite element analysis method (FEA) to analysis program and simulation stainless steel spiral micro flow channel bipolar plate stamping process. Blank length and width are 25mm, 0.05mm thick stainless sheet (SUS304).Use the rigid punch to machining material to achieve micro stamping process. Punch out of the six spiral flow channel on bipolar plate. Channel width and depth are 0.75mm respectively, discussion the micro-stamping process optimization formability and microscopic size effect. This finite element analysis method (FEA) use the Prandtl-Reuss of plastic flow theorem, combination with the finite element deformation theory and updated Lagrangian formulation (ULF) concept, and then simulate metallic bipolar plates the micro fluidic channel forming processes. This study also uses selective reduction of the integration method SRI (selective reduced integration) and four-node quadrilateral degenerated shell element shape function derivation from the stiffness matrix.This study is focus on during the micro-stamping process to verification simulation and analysis all deformation history data, punch load and stroke relationships, stress and strain distribution, thickness distribution, section depth and section thickness, SUS304 blank sheets were used in the experimental micro-stamping process, and comparison with the simulation results to verify the reliability of the analysis program. In addition, adding different parameters such as: changes coefficient of friction, changes mold chamfers radius, Changes the thickness of the blank, etc., for micro-stamping process analysis. Variation different spiral flow channel number blank formability, after analysis simulation, we get that eight spiral flow channel number can also be formed smoothly, but also increase punch load, In stroke part, except stroke achieve 0.45mm can success forming, In simulation, if stroke is more than 0.45mm, the spiral flow channel center have crack, is same with the experimental results. If close the blank center forming flow channel is deep, outside flow channel during blank warping effect, because the flow channel forming deep shallow. This study construct the finite element analysis mode, compare with conventional macroscopic material model and correct of scale factor after modify material mode, the result indicate the after modify material mode can satisfied actually situation. The correct of scale factor method can be applied to any thickness SUS304 stainless steel. Omission complicated tensile test. This study proposed the effectively method to simulation stainless steel spiral micro flow channel bipolar plate stamping process. It can widely applied on any flow channel shape micro-stamping process, construct and improve the analysis of data for micro stamping process produces all kinds of problems, it can reduce try and error loss and increases production rate, let proton exchange membrane fuel cell toward more precision and minimize.

碩士
國立勤益科技大學
機械工程系
100
The bipolar plate is one of key components of proton exchange membrane fuel cell.But the cost of using the graphite bipolar plate is more expensive and the thickness needs to be increased a few millimeters. These reasons bring metal bipolar plate come into being. This paper is discussed the influence between the stamping process formability and micro-size effect by using the finite element analysis system ,simulating stainless steel bipolar plate pin-type microfluidic stamping process. The length and width of materials are both 15mm, stainless steel sheet (SUS304) 0.05mm in thickness.By micro-stamping process with the rigid punch which is punched pin-type channel as 6*6 circular convex, the width and depth of fluid channel is 0.75mm and 0.5mm. The finite element method in this paper is combined the plastic fluidic rule of Prandtl-Reuss with finite element deformed theory and updated Lagrangian formulation (ULF concept) which builds up the Coulomb law of friction by using the increasing volume-type and large elasto-plastic deformed finite element analysis system to simulate the process of forming metal bipolar board micro-fluid channel. It’s also used the selective reduced integration method of SRI (selective reduced integration) and four-node quadrilateral degenerated shell element derived shape function into the stiffness matrix. In dealing with the contact problem between the status of elastic plastic, mold and the sheet metal by adopting the board rmin way which not only could be effectively solved the calculating problem of elasto-plastic state but extended to contact problem between processing mold and the sheet metal. The main point of the research in this paper would be emphasized that proceeding the micro-punching experiment by selecting SUS304 stainless steel, simulating and analyzing the entire deformed data of micro-punching forming process, the relation between punch load and stroke, the distribution of stress and strain, the distribution of thickness, cross-section depth and section thickness which test and verify the validity of this formula. So far, proceeding the micro-forming process with the different parameter from the variation of friction coeifficent, chamfering mold radius, sheet thickness, the angle of mold and the shape of prism(ladder prism, Rectangular prism, cylinder and Pyramid...etc.) Through analyzing the formability of the different shape of prism finally be concluded the better formability in ladder prism, Pyramid is in second. While forming process, we also proceeded and simulated the experiment using other depth, not only with 0.5mm, but we found that there would have cracks if the depth is deeper than 0.5mm. The depth of fluid channel which is closer to the central of the plate would be deeper and deeper, on the other hand, the fluid channel of the outer plate would be swallow due to warped plate. In this paper, it is to establish finite element analysis model and to compare the model between the traditional material and scale-factor material. The results indicate that the modified material model is closer to real forming condition. This ratio correction could be also adopted SUS304 stainless steel in any micro-thickness to skip the complicated tensile experiment. The methods which are proposed to in this paper could be effectively simulated stainless steel bipolar plate of the micro-stamping process fluid. Therefore, it could be adopted widely in all kinds of channel shape for stamping process, established the completed analysis data, improved all kinds of problems by forecasting the process of micro-punching in order to lower down the missing of test and increase the production efficiency. Furthermore, fuel cell could be moved forward on more accurate miniaturized development.

碩士
華梵大學
機電工程學系博碩專班
98
In this thesis, the computational fluid dynamics software CFDRC is used to establish a three-dimensional numerical model of the methanol steam micro-reformer channels. The effects of the different flow field designs (including E-type flow field, U-type flow field and Z-type flow field) and heat/mass transfer conditions (including wall temperature, inlet temperature, fuel velocity and fuel ratio) on the methanol conversion and heat/mass transfer phenomena of a plate methanol steam micro-reformer are investigated. The results indicate that an appropriate Z-type flow field exists for the three steam micro-reformer channel designs to obtain optimal methanol conversion of the steam micro-reformer. The results also show a more uniform fuel distribution in the flow field lead to a better methanol conversion. This is because of a more uniform fuel distribution in the flow field could improve the chemical reaction, which in turn the enhance methanol conversion. Whereas, a non-uniform fuel distribution in the flow field could reduce the chemical reaction and methanol conversion. In addition, it is found that a better steam micro-reformer performance is noted for a higher wall temperature. The predictions also show that a lower inlet fuel velocity provides an increased reactant gas resident time which raises the chemical reaction time and significantly increases the methanol conversion. Increases of the inlet fuel molar ratio of H2O/CH3OH could decrease the CO concentration.

碩士
國立中正大學
機械工程所
95
Flow boiling in micro-channel is being considered in number of advanced heat transfer application. However, there are many fundamental issues from the heat transfer perspective that still remain unresolved. In this study, the characteristics of two-phase flow boiling heat transfer and pressure drop on dielectric fluid HFE-7100 flowing in micro-channel cold plate is investigated by experimental method. The effects of the heat flux, mass flux and vapor quality on dielectric fluid HFE-7100 are examined in the present study. For single-phase flow, the dielectric fluid mass flux ranges from 100 to 400 kg/m2sec, the heat flux are respectively 14.5, 29.0, 43.5 kW/m2 and the system pressure is 101kpa (Tsat=61oC). The experimental data clearly indicate that the heat transfer coefficient increases with mass flux in single-phase flow. This trend is consistent with that in macro-channel in single-phase flow. For two-phase boiling flow, the mass flux ranges from 90 to 190 kg/m2sec, the heat flux are respectively 25, 50, 100 kW/m2 and the saturation pressure is 135kpa (Tsat=70.5oC). The results show that the heat transfer coefficient in two-phase decreases with increasing vapor quality at low mass flux in micro-channel. Finally, the fluid surface parameter for dielectric fluid HFE-7100 estimated from Kandlikar empirical equation is 1.60.

博士
國立交通大學
機械工程學系
98
This dissertation aims to examine numerically heat and mass transport phenomena in the plate methanol steam micro-reformer (including methanol steam micro-reformer and methanol catalytic combustor). The first focus is to investigate the effects of geometric and thermo-fluid parameters on the methanol conversion and gas concentration distributions of the methanol steam micro-reformer in order to obtain better channel designs and operating conditions. Furthermore, a methanol steam micro-reformer with a methanol catalytic combustor is considered in the present work. The results can provide comprehensive information for designing the plate methanol steam micro-reformer. This study can be divided into two parts. In the first part, the research only considered the plate methanol steam micro-reformer, namely the methanol catalytic combustor is not included in it. Firstly, a 2-dimensional channel model of the methanol steam micro-reformer is established to investigate effects of geometric and thermo-fluid parameters on performance and heat and mass transfer phenomena in micro-reformer channels. The results of the modeling suggest that the methanol conversion could be improved by 49 %-points by increasing the wall temperature from 200 ℃ to 260 ℃. The results also show that the CO concentration would be reduced from 1.72% to 0.95% with the H2O/CH3OH molar ratio values ranging from 1.0 to 1.6. The values of parameters that enhance the performance of micro-reformer were identified, such as longer channel length, smaller channel height, thicker catalyst layer, larger catalyst porosity, lower Reynolds number and higher wall temperature. Secondly, a 3-dimensional channel model of the methanol steam micro-reformer is developed to investigate the effects of various height and width ratios and channel geometric size on the reactant gas transport characteristics and micro-reformer performance. The predictions show that conduction through the wall plays a significant effect on the temperature distribution and must be considered in the modeling. The predicted results also demonstrated that better performance is noted for a micro-reformer with lower aspect-ratio channel. This is due to the larger the chemical reaction surface area for a lower aspect-ratio channel. The results indicate that the smaller channel size experiences a better methanol conversion. This is due to the fact that a smaller channel has a much more uniform temperature distribution, which in turn, fuel utilization efficiency is improved for a smaller channel reformer. Finally, the established 3-dimensional channel model of a plate methanol steam micro-reformer extends to be a plate methanol steam micro-reformer with serpentine flow field. A numerical investigation of the transport phenomena and performance of a plate methanol steam micro-reformer with serpentine flow field as a function of wall temperature, fuel ratio and Reynolds number are presented. The methanol conversion is improved by decreasing the Reynolds number or increasing the S/C molar ratio. When the serpentine flow field of the channel is heated either through top plate (Y=1) or the bottom plate (Y=0), we observe a higher degree of methanol conversion for the case with top plate heating. This is due to the stronger chemical reaction for the case with top plate heating. In the second part, a numerical study is performed to examine the characteristics of heat and mass transfer and the performance of a plate methanol steam micro-reformer with a methanol catalytic combustor. Firstly, a three-dimensional channel numerical model of a micro-reformer with combustor is developed to examine the effects of various flow configurations and geometric parameters on micro-reformer performance. Comparing the co- and counter-current flows via numerical simulation, the results show that the methanol conversion for counter-current flow could be improved by 10%. This is due to the fact that counter-current flow leads to a better thermal management, which in turn improves fuel conversion efficiency. The results also reveal that the appropriate geometric parameters exist for a micro-reformer with a combustor to obtain better thermal management and methanol conversion. With a higher Reynolds number on the combustor side, the wall temperature is increased and the methanol conversion can thus be enhanced. In addition, the three-dimensional models of a plate methanol steam micro-reformer and a methanol catalytic combustor with the parallel flow field and the serpentine flow field have been established to investigate the performance and transport phenomena in the micro-reformer. The methanol conversion of the micro-reformer with the serpentine flow field and the combustor with the serpentine flow field is the best due to a better thermal management in the micro-reformer. The numerical model provides an efficient way to characterize the transport phenomena within the micro-reformer, and the results will benefit the future design for the plate methanol steam micro-reformer.

碩士
國立高雄應用科技大學
模具工程系碩士班
102
Biotechnology constant breakthroughs in recent years , and decoding of the human and a variety of biological success, making the rapid development of biotechnology, bio-chips were on the most representative.among them, the microfluidic chip integrated specimen can quickly analyze complete traditional laboratory analysis process carried out using the micro-channel to transmit the specimen, mixing, reaction, separation purposes, the advantage of miniaturization of the product can be achieved shortening the detection time consuming, and the detection accuracy, and how fast and mass production of microfluidic chips, reduce production costs, will become a very important issue, which microfluidic system mainly consists of two parts mini-mixer, respectively passive and active micro mixer. This study is mainly passive mixer, conduct research and mass production of the part for the rapid in some manufacturing microfluidic chip, using UV roller embossing machine, and turn PDMS mold, pressing and injection molding to replace production, re-use of existing equipment for device fabrication and testing, to take rapid development of different processes and flow tested at last to explore the effect of which produced, in order to facilitate the future to develop a new process.

碩士
國立高雄應用科技大學
模具工程系
103
It includes three parts in improving UV-curing plate-to-plate roller embossing machine. The first part is to better the pressure controlling system by using pneumatic cylinder instead of micrometer caliper to control the pressure. By doing so, it can make the pressure get a more accurate control and make the machine work more stably. The second part is to improve lightproof components. The improvement can precisely control the size of UV light exposure with different UV glues. Thus, UV glue can be solidified accurately after rolling. The third part is to use aluminum-made roller. Therefore, after saving weight, we can enlarge the size of roller. It can let the UV-curing plate-to-plate roller embossing system to be applied to wider areas, to achieve the best value for economic benefit and to make it competitive in the future. Our experiment "UV-Curing Plate-to-Plate Roller Embossing" achieved parameter optimization by using Taguchi’s Method to find out the optimal parameter. We find out the optimal parameter to make the duplication and uniformity of the structure better. It utilizes two micro-channel structures with different shape and different depth to width ratio to make the micro-channel. First, we use UV-curing plate-to-plate roller embossing machine to make the micro-channel. Then we employ PDMS to roll over the micro-channel. After that, we compare the manufacturing process and the depth with the convexity structured micro-channel. Finally, we investigate into the advantages and disadvantages of the two different procedures. The method can replace the current hot compacting prototyping and injection prototyping to make production and develop a different and rapid procedure. At last but not the least, we develop the mixture flow testing of the micro-channel with different-colored food coloring.

碩士
國立勤益科技大學
機械工程系
99
The aim of this study is to resolve the stainless steel bipolar plates with micro channel forming form stamping process and micro-size effect of the impact. Regarding the use of rigid punch on 50μm-thick stainless steel sheet (SUS 304) for micro-channel stamping process in this study, the channel design is 0.8*0.75mm. Besides, the finite element method and the experimental results are used to analyze the micro-stamping process key parameters. The use of finite element method and experimental comparison, to find the best process parameters. The methodology of elasto-plastic three-dimensional incremental finite element model is based on Updated Lagrangian Formulation (ULF). It associated Prandtl-Reuss flow rule and Hill's yield criterion respectively. The shape function derived from a four-node quadrilateral degenerated shell element associated and used selective reduced integration into the stiffness matrix to constitute the finite element model. An extended algorithm is proposed to formulate the altered elasto-plastic state of material, the increment of element and the nodal penetration or separation of mold and blank. The micro material parameters places that the traditional tensile test data requirements for different thickness (0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0 mm) of proportional changes in the amendment to come to a micro scale effects of the material type, so the number of finite element analysis can be more accurate. This study focused on exploring the traditional macro material parameters and scale factor corrected material parameters of the differences, in order to observe the effect of size effect. The Simulation results include the whole deformation history, the relationship between punch load and punch stroke, stress and strain, the distribution of thickness XZ plane and YZ-plane cross-section depth and thickness, during the stamping process were obtained. Changes such as adding different parameters: friction, normal anisotropy value, die chamfer, sheet metal thickness and flow channel shape (trapezoidal, rectangular, triangular, hemispherical) and other micro-stamping process, the results indicate that the most prone to rupture region are in the main channel and sub-flow channel of the corner. Different flow channel shape formability, obtained by the analysis of semi-circular with better formability, followed by the ladder. The results shown by the use of micro-stamping sheet metal bipolar plate production not only reduces costs but also speed up the production process, In this paper, using ULF (Updated Lagrangian Formulation) concept to establish an elastic-plastic deformation finite element analysis model and using scale-factor to modify the calculation could effectively simulate the micro-stamping process for metal bipolar plates. The results indicate that the revised material style more in keeping with the actual shape of the scaling method can be applied to any thickness of SUS304 stainless steel micro was amended to omit the complex tensile test. In addition to applications outside of the establishment of the analysis program, and select the SUS 304 micro-stamping of the experiment, will serve as a micro-stamping test future reference. Method proposed in this paper can effectively simulate stainless steel bipolar plate of the micro-stamping process flow. Therefore, can be widely used in various flow on the shape of the stamping process, establish and improve the analysis of data and forecasts generated in the process of micro-stamping all kinds of problems, loss of benefit to reduce trial and error and increase the production rate, thereby making the fuel cell can move towards more accurate miniaturization of the development.

碩士
國立中山大學
機械與機電工程學系研究所
96
The design and method of cell assembly plays an important role in the performance of PEM fuel cell. The cell assembly will affect the contact behavior between the bipolar plates, flow-channel plates, gas diffusion layers (GDLs) and membrane electrode assembly (MEA). From the past studies, it was noted that the flow-channel plates in the cell will be deformed while the cell was assembled by locking with bolts. This phenomenon may lead to leakage of fuels, high contact resistance and malfunctioning of the cells. The main aim of this research is to study the variation of the deformation mode of the flow-channel plat in a micro-PEM fuel cell assembly subjected to different bolts locking sequences. The commercial FEM package, ANSYS, was adopted to model the three-dimensional single micro-PEMFC FEM model and the numerical simulation analyses were performed. The effect of the bolts locking sequence on the deformations of flow-channel plate in the micro-PEMFC was presented. A most properly bolts locking sequence was proposed also.

碩士
國立臺灣科技大學
機械工程系
101
Bipolar plate is an important component of the fuel cell. Because there is no suitable fabrication process for mass-production of bipolar plate, the cost of portable fuel cell is still too high now a days. In this study, the rubber pad forming process was used to fabricate the micro-channels on metallic bipolar plate and the effect on process parameters of the rubber pad forming were analyzed. Polyurethane rubbers were used for the rubber pads, and SUS316L stainless steel sheets with a thickness of 0.1mm were tested in the experiment. Firstly, finite element analysis (FE, Ansys CFX software) was used to analyze the efficiency of fuel cell by geometric factor of channels numerically, in order to figure out the influence of velocity and pressure on channel depth, channel width, rib width. Secondly, finite element analysis (FE, Abaqus / Standard software) was also used to analyze the rubber pad forming process numerically. Finally, the experimental and numerical results showed a good agreement in this study. Furthermore, an optimization design of micro-channels for fuel cell was developed under rubber pad forming process.

碩士
國立中山大學
機械與機電工程學系研究所
98
In general, a PEMFC was assembled by using a number of locked bolts. But this assembly will cause concentrated loads existed on the upper and lower portions of the end plates, so that the pressure distributed non-uniformly at the internal structures in the PEMFC and thus causing uneven distributed deformations of flow-channel plates. This phenomenon may lead to the leak of reaction gas, and causing not only the decrease of the efficiency of PEMFC, but also the increase of the dangerous. If the fuel cell size getting smaller, the influence may be more severely. The main aim of this study is to simulate the response of a micro-PEMFC numerically by utilizing a 3-D FEM model while the micro-PEMFC was assembled by three pairs of bolts along the upper and lower portions, respectively, of the end plates. The effects of different bolts locking sequences on the deformation and pressure distributions at flow-channel plates and on the porosity of gas diffusion layers in the micro-PEMFC were investigated. The simulated results showed that if one locked the middle bolt either on the upper or lower portion first, then the obtained uniformities of warpage, deformation, von Mises stress and porosity were superior than the corresponding obtained results if one locked either one of the four corner bolts first. Also, among the three pairs of bolts used for assembling the cell, the first locking bolt of the first pair of locking bolts and the first locking bolt of the rest of two pairs of locking bolts were suggested on the reverse portions of the end plates.

The Magnetospheric Multiscale mission led by NASA has been designed to study the micro-physics of Magnetic Reconnection in Earth's magnetosphere by using four identical spacecrafts with instruments with high temporal and spatial resolutions. Among these instruments are the Dual Ion Spectrometers (DIS) engineered to measure the 3D distribution of ion flux in space. The detector assembly of the DIS consists of Micro-Channel Plates (MCP) mounted in Chevron configuration. Centre d'Etude Spatiale des Rayonnements (CESR), Toulouse is responsible for the provision and testing of all fifty MCP pairs for this mission. The goal of the work was to participate in the testing and characterization of the first prototype of the MCPs. It was achieved by understanding the working and characteristics of the MCPs in general and getting familiar with the detector assembly of the DIS i.e. the MCP pair and the detector circuit board in particular. To perform the testing, it was necessary to understand the testing system as well. These topics are described in this report along with the testing procedure and the data analysis. The testing procedure was developed eventually after facing several problems during the testing. MCP pair characteristics like pulse height distributions, gain, resistance and the MCP operating voltages for the mission were determined on analyzing the data. Crosstalk was found in the circuit board of the detector assembly and has also been discussed.
Validerat; 20101217 (root)