Syngas production and hydrogen separation technologies are very mature, and also extremely important for energy and chemical industries. Furthermore, these processes are the most expensive elements for many applications such as hydrogen production from renewable sources. Enhancing or intensifying these very mature technologies is very challenging, but would have tremendous impact on the performance and economics of many processes. Traditional Integrated Gasification Combined Cycle (IGCC) for syngas production need to include a carbon capture process in order to regulate their carbon dioxide emission as more and more countries and regions have implemented carbon tax policy. Integration of this process with Pd membrane has long been considered a key component to make it more feasible. With these two technologies combined together, we can produce high purity hydrogen while capturing carbon dioxide and toxic gases from the syngas product. Besides, although manufacturing the membrane reactor is expensive, after considering the carbon tax factor, it actually is more economically preferable compare with the traditional Pressure Swing Adsorption (PSA) process. Most research on Pd membrane technology has been conducted at lab scale; nonetheless, the contribution of a palladium membrane technology to economic and societal development requires its commercialization, diffusion and utilization. To generate enough incentives for commercialization, it is necessary to demonstrate the scalability and robustness of the membranes in industrial settings. Consequently, a multitube membrane module suitable for IGCC system was designed and manufactured and sent to National Carbon Capture Center (NCCC) for testing. This work developed a Computational Fluid Dynamics (CFD) model for the module and validated the model utilizing the pilot-scale experimental data generated under industrial conditions. The model was then up-scaled and used to determine the intrinsic phenomena of palladium membrane scale up. This study reveals the technical/engineering requirements for the effective design of large-scale multitube membrane modules. Mass transfer limitations and concentration polarization effects were studied quantitatively with the developed model. Methods for diminishing the concentration polarization effect were proposed and tested through the simulations such as i) increasing convective forces and ii) designing baffles to create gas recirculation. For scaled-up membrane modules, mass transfer limitation is an important parameter to consider as large modules showed severe concentration polarization effects. IGCC systems produce H2 from coal combustion; other ways of H2 production include steam-reforming processes, using natural gas or bio-ethanol as the reactant. The product contains a mixture of H2, CH4, CO, CO2 and steam. Thus, steam-reforming processes are often followed by a Pressure Swing Adsorption (PSA) unit in order to obtain pure hydrogen. Palladium membrane, on the other hand, can be integrated with steam-reforming processes and achieve the simultaneous production and purification of H2 in a single unit by reaching process intensification. Higher H2 production rate can be reached by process intensification as one of the products H2 is constantly being removed. Temperature control is a very important topic in steam reforming processes, as the reaction is overall highly endothermic; although implementing an in-unit membrane improves H2 production rate, it also makes the temperature control more difficult as the reaction equilibrium is altered by the removal of one of the products H2. Hereby, an experimental study of catalytic membrane reactor (CMR) was carried out along with both isothermal and non-isothermal CFD simulations that are validated by the experimental data in order to visualize the temperature distribution inside the reactor and understand the influence of the operating conditions including temperature, pressure and the sweep gas flow patter on the permeate side.

In this thesis work the feasibility of using open source OpenFOAM software as a solver part for Computation Fluid Dynamics in Volvo Technology is studied. Since the structure of the case in OpenFOAM is rather complex, one of the main purposes of this thesis work was also to make the process of using OpenFOAM as user-friendly as possible. The general conclusion that can be drawn from this work is that a very streamlined workflow can be, and has been, designed and created.

Computational Fluid Dynamics (CFD) are used to investigate two speech phenomena. The first phenomenon is the English bilabial plosive /pa/. Simulations are compared with microphone recordings and high speed video recordings to study the penetration rate and strength of the jet associated with the plosive /pa/. It is found that the dynamics in the first 10ms of the plosive are critical to penetration rate, and the static simulation was not able to capture this effect. However, the simulation is able to replicate the penetration rate after the initial 10ms. The second speech phenomenon is the English fricative /sh/. Here, the goal is to simulate the sound created during /sh/ to understand the flow mechanisms involved with the creation of this sound and to investigate the simulation design required to predict the sound adequately. A variety of simulation methods are tested, and the results are compared with previously published experimental results. It is found that all Reynolds-Averaged Navier-Stokes (RANS) simulations give bad results, and 2D Large Eddy Simulations (LES) also have poor results. The 3D LES simulations show the most promise, but still do not produce a closely matching spectra. It is found that the acoustic analogy matches the direct measurements fairly well in 3D simulations. The studies of /pa/ and /sh/ are compared and contrasted with each other. From the findings of the studies, and using theoretical considerations, arguments are made concerning which CFD methods are appropriate for speech research. The two studies are also considered for their direct applications to the field and future research directions which might be followed.

This thesis presents detailed investigations of the effect of end wall profiling on the secondary flow in a large scale, linear cascade with nozzle guide vanes. The purpose of this project is to look into the secondary flow structure in the linear cascade and the influence of the shaped end wall on the secondary flow. By applying the non-axisymmetric end wall, the secondary flow is reduced compared to the flat end wall data. The yaw angle variation at the exit of the blade passage is reduced. The cascade was designed according to the nozzle guide vane from ALSTOM Energy Ltd. It was manufactured and connected to the low speed wind tunnel in the Thermo- Fluids Lab in Durham. The data acquisition system was designed and commissioned. Five hole probes were designed and calibrated according to the cascade test condition. The flow field with the flat end wall in the cascade was investigated using five hole probes through different traverse slots. Flow visualisations were conducted as well. The secondary flow structure and the loss development in the cascade are understood. Transitional trips were put on the blade surfaces and their effects on the secondary flow were observed. The CFD code was modified to fit the cascade case. It was validated against the Durham standard case and the flat end wall results. Different numerical schemes and turbulence models were evaluated. Different shaped end walls were systematically tested by the CFD code. The best end wall profile was selected and manufactured. It was then tested in the cascade. Detailed investigations by five hole probes, flow visualisation and wall static pressure measurements were conducted. The results were compared to the flat end wall results and the CFD prediction. The secondary flow and the total pressure loss were reduced. The test data in the cascade will supply the evidence and data for the real turbine design. The chosen end wall profile will hopefully be tested in a test turbine.

No description available.

No description available.

Computational Fluid Dynamics (CFD) are used to investigate two speech phenomena. The first phenomenon is the English bilabial plosive /pa/. Simulations are compared with microphone recordings and high speed video recordings to study the penetration rate and strength of the jet associated with the plosive /pa/. It is found that the dynamics in the first 10ms of the plosive are critical to penetration rate, and the static simulation was not able to capture this effect. However, the simulation is able to replicate the penetration rate after the initial 10ms. The second speech phenomenon is the English fricative /sh/. Here, the goal is to simulate the sound created during /sh/ to understand the flow mechanisms involved with the creation of this sound and to investigate the simulation design required to predict the sound adequately. A variety of simulation methods are tested, and the results are compared with previously published experimental results. It is found that all Reynolds-Averaged Navier-Stokes (RANS) simulations give bad results, and 2D Large Eddy Simulations (LES) also have poor results. The 3D LES simulations show the most promise, but still do not produce a closely matching spectra. It is found that the acoustic analogy matches the direct measurements fairly well in 3D simulations. The studies of /pa/ and /sh/ are compared and contrasted with each other. From the findings of the studies, and using theoretical considerations, arguments are made concerning which CFD methods are appropriate for speech research. The two studies are also considered for their direct applications to the field and future research directions which might be followed.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 163-169) Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 163-169) Also available online.

No description available.