PhD (M/F). Interactions Between Turbulence and Temperature in Concentrating Solar Power Systems

Descrizione

PhD (M/F). Interactions Between Turbulence and Temperature in Concentrating Solar Power Systems Sintesi in italiano (traduzione automatica): Il laboratorio PROMES si occupa di ricerca sull'energia solare, in particolare sulle applicazioni ad alta temperatura. La posizione di dottorato riguarda le interazioni tra turbolenza e temperatura nei sistemi di energia solare concentrata. Il candidato lavorerà su modelli teorici, numerici ed esperimenti per migliorare la comprensione dei flussi turbolenti in condizioni di forti gradienti termici. È richiesta una laurea in ingegneria energetica o un campo correlato. Il progetto è parte del programma SHIP4D, mirato alla decarbonizzazione dei processi industriali. La sede di lavoro è presso il laboratorio PROMES, specializzato in tecnologie solari avanzate. The PROMES laboratory focuses its research on solar energy and, in particular, its high-temperature applications. Concentrated solar power systems offer a range of solar furnaces with power outputs ranging from 1 kW to 1 MW, capable of producing very high temperatures (3,000°C) thanks to very high concentration ratios (15,000 times the sun's intensity). The principle behind concentrated solar power technologies is to use mirrors to concentrate the sun's rays onto a receiver to generate heat. The key component of this process is the solar receiver, which operates at high temperatures and under high heat flux. Within this solar receiver, the interactions between turbulence and thermal phenomena make the physics particularly complex and fascinating. Mastering highly anisothermal turbulent flows is therefore a key scientific challenge for the development of next-generation solar power plants for heat and electricity generation. In addition to the purely thermal conversion of solar energy, compact hybrid (PVT) systems make it possible to simultaneously generate medium-temperature heat (150–250 °C) and electricity using a single device. This device consists of a solar absorber on which a photovoltaic cell is mounted, operating under non-standard conditions. Several solutions are possible, but all require a better understanding of the interactions between flow and heat transfer, as these govern the system's overall efficiency. The answers to these preliminary questions will inform the more applied research conducted as part of the SHIP4D project (“Solar Heat in Industrial Processes for Decarbonization”) under the PEPR SPLEEN program. This dissertation is part of that project. Title. Interactions Between Turbulence and Temperature in Concentrating Solar Power Systems This thesis research aims to improve the understanding and modeling of turbulent flows subjected to strong thermal gradients within solar thermal (T) and photovoltaic-thermal (PVT) collectors used for the conversion of concentrated solar energy. The project will be carried out using theoretical, numerical, and experimental approaches. Unique physical processes occur in these systems. These processes are related to how the heat transfer fluid is heated—either through contact with a high-temperature wall that absorbs concentrated solar radiation or within a volume directly exposed to the radiation. These configurations give rise to interactions between turbulence and thermal gradients, which must be elucidated theoretically and validated experimentally. Several levels of modeling will be developed. Turbulent flows exhibit a highly complex structure, particularly in the presence of temperature gradients. The various characteristic quantities of the flow exhibit a random nature. The technique generally employed involves adopting a statistical representation of turbulence that provides direct access to characteristic global quantities without relying on the complete realizations of turbulent fields, obtained—for example—through direct numerical simulations. This approach, however, introduces a closure problem, meaning that the number of unknowns exceeds the number of equations. Numerous closure attempts have been proposed, ranging from single-point models to more sophisticated theories based on approaches that describe turbulent fields using statistical correlations at multiple points, such as spectral models of the EDQNM type. The theoretical and computational objectives of this thesis are to develop an EDQNM model of turbulent flow in the presence of strong temperature gradients caused by asymmetric heating (only one wall is heated). The inclusion of radiation in the EDQNM model for a flow consisting of an absorbing gas (such as CO₂) will also be considered. Through numerical simulations of the developed model, the primary goal will be to calculate the energy spectra for an isothermal case. The strong temperature gradients will alter the slope of the energy spectrum and thus Annuncio in inglese. Fonte: Euraxess (Commissione europea).