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<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>

L'objectif de cette thèse est d'étudier les différents régimes d'ébullition transitoires rencontrés lors de la mise en froid d'un tube chauffé par un écoulement interne de fluide. Le dispositif expérimental LORETA a été conçu pour réaliser des expériences au sol en écoulement vertical ascendant et en microgravité lors de vols paraboliques. L'effet du débit, de la température du liquide et du niveau de gravité dans les différents régimes d'ébullition a pu être clairement mis en évidence. Une dégradation des transferts thermiques en microgravité est observée, en particulier lors de l'ébullition en film. Une modélisation basée sur la résolution des équations du modèle à deux fluides permet la prédiction pour les deux niveaux de gravité. L'ensemble de la courbe d'ébullition a put être modélisée par des lois adaptées de la littérature. L'utilisation de ces lois pour des fluides cryogéniques semble raisonnable, au vu de la comparaison avec quelques données de la bibliographie. / The objective of this thesis is to study the boiling regimes encountered during the transient cooling of a heated tube by an internal fluid flow. The experimental apparatus LORETA was designed for experiments on ground in vertical upward flow and on microgravity during parabolic flights. The effect of flow rate, liquid temperature and level of gravity in different boiling regimes has been clearly shown. A decrease of heat transfer in microgravity is observed, especially during film boiling. Models based on solving equations of two-fluid model allow the prediction for the two levels of gravity. The entire boiling curve could be modeled by modified laws of literature. The use of these laws for cryogenic fluids seems reasonable, given the comparison with some data from the bibliography.