Journal des soutenances de thèses - 2014
Dr. Audrey JOURNOUD
(Soutenance de thèse le 15 octobre 2014)
Thèse de doctorat en Physique et énergétique intitulée : "Etude de la faisabilité technique des installations de production d’énergie thermique des mers ", sous la direction de Monsieur Franck LUCAS.
Développement d'outils d'aide à la conception et au dimentionnement pour l'amélioration des performances, du fonctionnement et des coût d'une centrale d'Enegie Thermique des Mers.
In a sensitive energy context – mounting electricity needs, increasing greenhouse gas emissions, and rising price of fossil fuels – renewable energies propose some "clean" and sustainable solutions. One of them is Ocean Thermal Energy Conversion. Thanks to the temperature difference between hot sea water of the surface, and cold deep sea water, this process is able to produce base load electricity, in opposition to intermittent sources of energy as solar or wind power.
The main objective of this Thesis is to optimize the energy production, the plant operating, and the resale price electricity.
We develop three tools to answer this problematic:
•A steady state model, based on empirical exchange correlations, predicting the electricity production, from the heat exchangers dimensioning data and environmental data.
•A dynamic model of an onshore small scale power plant, based on the irreversible process theory, estimating the intensive conditions of the system at each time step.
•An onshore experimental facility to test the main cycle components and to give validation elements for the models listed.
Then, different evaporator technologies are tested thanks to the experimental installation. The best-performing one, for a hot sea water temperature range over 27,5°C, is a flooded shell and smooth titanium tubes technology. Then, the most influencing dimensioning parameters of the heat exchangers, on the electrical production are determined by a sensitivity analysis of the steady-state model. The net electrical production is improved, in optimizing those parameters, and increase by 11% on average over the year.
Furthermore, the experimental installation and the dynamic model lead to optimize the plant operating and the resale price electricity through three practical examples:
•The stability of the production of power
•The materials’ choice
•The circuit design of the installation