GRETh

Summary : Two-phase flow-induced vibrations is a phenomenon that occurs when two-phase gas-liquid flows encounter mechanical systems such as pipes, tubes, or heat exchangers. This dynamic interaction between the fluid flow and the structural components can lead to various types of vibrations, which can have detrimental effects on the integrity and performance of the system.

Summary : The study of rapid transient boiling is an important issue in the nuclear safety. Such a phenomenon may occur in the case of a RIA (Reactivity Initiated Accident) in the core of a nuclear reactor powerplant, where a power excursion can trigger the formation of a vapour film around the fuel rod, leading to an important rise of the rod temperature and a risk of failure. Some studies in reactor conditions provided transient boiling curves but the modeling lacks of reliability.

Summary : In Pressurized Water Reactors (PWR), the heat released by the nuclear fuel is transferred to the water flowing in the primary circuit, which is pressurized at 150 bar to avoid boiling. However, water can sometimes reach the Onset of Nucleate Boiling (ONB) under accident conditions that can further lead to the Boiling Crisis.

Résumé : La prédiction des transferts de chaleur en ébullition nucléée est un problème ouvert. La CFD permet des simulations a échelle industrielle, mais nécessite des modélisations de ces transferts. Aujourd’hui, les modèles les plus élaborés sont basés sur une…

Résumé : L’utilisation des échangeurs à plaques et ailettes a été élargie aux procédés cryogéniques tels que la liquéfaction du gaz naturel et aux systèmes de réfrigération. Les ailettes les plus utilisées dans ces évaporateurs sont les ailettes décalées. Bien…