Modelo transiente para recetores externos tubulares de sais fundidos para centrais solares de torre

Jéssica Maria Moreira Lima

Key information

Authors:

Jéssica Maria Moreira Lima (Jéssica Maria Moreira Lima)

Supervisors:

João Pereira Cardoso; Luís Filipe Moreira Mendes (Luís Filipe Moreira Mendes)

Published in

July 11, 2024

Abstract

Currently, solar towers with molten salt mixtures and long-term storage systems are used commercially and have emerged as an alternative to produce dispatchable electricity, with high-capacity factors. This dissertation aims to develop a computational model for the transient thermal analysis of external tubular receivers using molten salt mixtures in concentrating solar tower systems. The model employs one-dimensional computational fluid dynamics and includes a secondary module for integration with the Tonatiuh software, enabling the acquisition of irradiance matrices, adapted from a pre-existing code. The purpose of this model is to facilitate the transient thermal analysis of a receiver with reduced computational costs, allowing its use in the design of cylindrical or flat receivers and in the analysis of operational strategies. The model was verified in a steady-state regime by comparing its results with those obtained from a three-dimensional model implemented in the ANSYS Fluent software, available in the literature. The maximum relative differences obtained were +5.68% and +0.95% for thermal efficiency and fluid temperature, respectively. The transient model was used to design a receiver consisting of a flat panel working with a carbonate mixture, to be studied at the LNEG testing platform. The receiver was simulated during a startup period, taking approximately 46.5 minutes to reach the desired fluid temperature at the outlet (~600 ºC); during a period of cloud passage, to assess its influence on the receiver’s operation; and during a clear sky period at nominal point, where it maintained an outlet fluid temperature of ~600 ºC.