Fuel channels are used to keep the components of a nuclear fuel bundle in place. The fuel channel of a new nuclear fuel which is being developed at Westinghouse has a complex geometry which creates challenges in the manufacturing process. FE simulations were developed of a two-stage forming process of the fuel channel. Three different simulations were developed, a simulation of the pre-bending, a simplified simulation of bending, and a combined simulation of the two-stage process of pre-bending and bending. The simulations were done in Ansys Workbench. The simulations of the pre-bending could be validated against experimental results. The simulations of the bending showed significant differences in results compared to experiments. A few different sources of error were investigated due to the difference in results. / Höljerör omsluter kärnbränslet i en kärnreaktor och håller komponenterna i bränslepaketet på plats. Höljeröret av ett nytt kärnbränsle som utvecklas på Westinghouse har en komplex geometri som skapar utmaningar i tillverkningsprocessen. FE simuleringar av en tvåstegsprocess av bockningen av höljeröret utvecklades. Tre typer av simuleringar utvecklades, en simulering av förbockningen, en förenklad simulering av bockningen, och en simulering av den kombinerade förbockningen och bockning. Simuleringarna gjordes i Ansys Workbench. Förbockningssimuleringarna kunde valideras mot experiment. Bockningssimuleringen visade dock signifikanta skillnader i resultat gentemot experiment. Några olika felkällor undersöktes på grund av skillnaderna i resultat.

<p> Benzene and water films were passed over an inclined, hot copper plate. The boiling heat transfer to the turbulent liquid films has been measured with local heat-flux meters. These meters have been adopted from a design suggested by Gardon (G10), and could be used to measure boiling heat fluxes with an accuracy of about -20,000 BTU/hr.sq.ft. The results indicate that the heat transfer to the liquid films compares well with that of forced convection subcooled boiling. </p> <p> During boiling the liquid film is destroyed by the growing vapour bubbles and by the separation of the liquid from the hot plate. The break-up of the liquid films has been investigated with high-speed photography but an analysis of the hydrodynamics of this break-up has not been made. </p> / Thesis / Master of Engineering (ME)

<p> Water drops at their boiling point were projected through a steam atmosphere to strike a surface which was varied in temperature from 300 to 900 degrees Fahrenheit. A high-speed motion picture study of the collision process showed that, except at low surface temperatures, the drop flattened out on impact and rebounded in a state of oscillation. Measurements of the change in drop diameter on collision indicated that the amount of evaporation due to heat transfer from the surface was extremely small except when the drop extensively wetted the surface. Solution of a mathematical model of the initial impact dynamics and models of heat transfer through a vapour film beneath the drop and by direct liquid-surface contact confirmed experimental observations. </p> / Thesis / Doctor of Philosophy (PhD)

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<p>In this study, universal databases and semi-empirical correlations are developed for cryogenic two-phase heat transfer and pressure drop in heated tubes undergoing flow boiling.</p>

<p> </p> <p>Over the last few years, there has been a concerted effort to develop and validate models<br> aiding the development of cryogenic refueling technologies. This effort is focused on the goal<br> of one day being able to refuel and store cryogenic propellants in the low gravity environ-<br> ment of space. The purpose of this research is to leverage the capabilities of some of these<br> recently developed models to create new ones and model more phenomena related to the<br> space applications of cryogenics.<br> The modelling work presented here is focused in the areas of cryogenic tank chilldown<br> and tank pressure control during storage/transfer. These tools are meant to help inform<br> future experiments being performed at the Glenn Research Center and elsewhere.<br> The model focusing on cryogenic tank chilldown provides a transient approach using<br> the charge-hold-vent (CHV) methodology to calculate the mass and time required to chill<br> a tank down to a desired temperature. Building on the 1-g Universal No-Vent Fill model<br> developed by NASA, the model captures the flashing of pooling liquid during the rapid<br> de-pressurization caused during the vent stage of the chilldown process. The model is com-<br> pared against two different datasets and successfully predicts pressure response throughout<br> the process to within 22%.<br> The thermodynamic vent system (TVS) model has been designed to be seamlessly inte-<br> grated into the 1-g Universal No-Vent Fill model to predict condensation and heat transfer<br> provided by the TVS during a no-vent fill. The TVS coil is spatially discretized and the<br> axial temperature distribution solved for. The model is capable of adapting to a rapidly<br> lowering or rising fill level that can lower the overall heat removal provided by the TVS.<br> While the heat removal is of primary importance, by capturing secondary phenomena such<br> as two-phase pressure drop, the TVS model is also capable of informing design decisions for<br> future systems. The model is compared against three test cases and predicts heat removal<br> to within 2%.<br> <br> </p> <p> </p>

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