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Itis expected that, in the future, gas turbines will beoperated on gaseous fuels currently unutilized. The ability to predictthe range of feasible fuels, and the extent to whichexisting turbines must be modified to accommodate these fuels, restson the nature of these fuels in the combustion environment.Understanding the combustion behavior is aided by investigation of syngasesof similar composition. As part of an ongoing project atthe Lund University Departments of Thermal Power Engineering and CombustionPhysics, to investigate syngases in gas turbine combustion, the laminarflame speed of...
The objective of this work is to establish the design principles of a proton exchange membrane (PEM) fuel cell (FC) stack for portable applications. A combination of experiments and numerical simulations were carried out and the results analyzed to enhance understanding of the behavior of this portable PEMFC stack. A three-dimensional (3D) computational fluid dynamics (CFD)-based methodology was used to predict such as the current and temperature distributions of this portable PEMFC stack. The results show how the baseline operation and original design of this stack impact the local...
The paper presents a combined experimental and numerical program directed at improving the accuracy of conjugate heat transfer CFD simulations of engine water cooling jackets. As a first step in the process, a comparison between experimental measurements from a test facility at Villanova University and CFD numerical predictions by at the University of Modena is reported. The experimental test section consists of a horizontal aluminium channel heated electrically and supplied with a constant volumetric flow rate. The operating fluid is a binary 50/50 mixture by volume of ethylene-glycol and...
The conventional advection-dispersion equation cannot adequately describe all processes driving solute transport in heterogeneous systems. This dissertation focuses on the individual influences of both chemical (Chapter 2) and physical processes (Chapters 3 and 4) which affect solute transport. In Chapter 2 we analyzed uranium transport in natural sediment using the chemical multirate mass transfer model available within the STAMMT-L software. This model was used due to many uncertainties of the overall mass transfer influences, which were generalized into a distribution of first-order rate...
Most of the CFD (Computational Fluid Dynamics) and nuclear thermal hydraulic analysis codes adopt Eulerian multiphase flow approach based on the two-fluid model for the prediction of two phase flows. In these codes, instantaneous time averaged equations for the conservation of mass, momentum and energy are solved for each phase. However, constitutive models for interfacial transfer terms are required to make a link between the two governing equations for two phases. The interfacial transfer terms are directly proportional to the interfacial area concentration (IAC) and thus it is a prime...
A series of Reynolds-averaged Navier-Stokes (RANS) computations has been performed using block-structured meshes to compare the accuracy of two commercial CFD flow solvers and a bespoke tool in use at QinetiQ. These calculations have been compared with experimental measurements of surface pressure and overall forces and moments. In addition, further calculations have been performed for the cases selected by TTCP for a study of the flow development and its effect on the vehicle stability. These calculations include an initial study of the effects of mesh fineness and also of the importance of...
The very high temperature reactor (VHTR) has been chosen as the concept for the next generation nuclear plant (NGNP), supported by the U. S. Department of Energy. There are two basic designs for the VHTR: a prismatic design and a pebble-bed design. In the prismatic design, the coolant (helium) exits the core into a lower plenum as jets. The helium then turns 90° and flows toward the exit duct around cylindrical support posts. Safety analysis by computational fluid dynamics (CFD) is desired to determine the level of mixing of the jets and check for hot spots. Experimental data were taken in a...
A computational study of the process of sedimentation of spherical particles in suspensions with high particle concentrations has been performed with the two-fluid Eulerian approach. The solid stress induction in the dispersed phase was modelled through modification of the suspension viscosity. Convectional flow patterns were found and studied during the simulations. The presence of these patterns, which are also observed experimentally, makes the sedimentation process dependant on the rheological behaviour of the suspension. The results of the simulation were validated with experimental...
Traditionally, the analysis of two-phase boiling flows has relied on experimentally-derived correlations as the bases of the analysis. While this approach provides accurate predictions of channel-averaged temperatures and void fractions and even peak assembly temperatures within an assembly, it lacks the resolution needed to predict the detailed intra-channel distributions of temperature, void fraction and steaming rates that are needed to address the fuel reliability concerns which result from longer refueling cycles and higher burnup fuels, particularly for the prediction of potential fuel...

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