The main focus of this thesis is to characterise and model a novel multiphase mesh microreactor (continuous-phase microsystem) in relation to hydrodynamics, mass transfer/chemical reaction and scale-out operation. The physical understanding gained by the study of interface stability within the mesh pores and the analysis of single-phase flow distribution is then applied to dispersed-phase microsystems, in particular to the bubble formation in a Taylor flow type microreactor and its influence in the design of two-phase scale-out manifolds. In the mesh microcontactor, two phases flow in different channels separated by a thin mesh with openings (pores) through which the two phases can come in direct contact allowing mass transfer by diffusion to take place. A resistance network model was developed to optimise the shape of the reaction plate for even flow distribution and minimum sample dispersion. The meniscus shape, position and stability within the mesh pores was modelled and supported by experimental results in single pores and meshes. Different factors that affect meniscus stability in real meshes were identified and modelled. Parametric maps that define the boundaries of the kinetic control regime were developed (i.e. negligible mass transfer resistance) which allow the reaction kinetics to be directly retrieved from the experimental data of conversion vs. time. Flow distribution between parallel channels, required in the scale up operation of manifolds for high throughput, was analysed by means of a resistance network model validated via CFD simulations and experimentation. The model was applied to understand the effect of manufacturing tolerances, channel blockages and additional pressure losses on flow distribution. The knowledge gained in meniscus stability in single pores and single-phase flow distribution in manifolds was applied to analyse the effect of bubble formation on flow distribution in manifolds during Taylor/bubble flow. Pressure drop during Taylor flow (a function of bubble/liquid slug lengths) and pressure fluctuations during bubble formation were investigated and implemented in the resistance network model. A two-channel manifold structure for water/air and octane/air systems was successfully demonstrated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:439095 |
| Date | January 2007 |
| Creators | ZamarrenĖo, Carlos Amador |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1446295/ |
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