A high-temperature solar receiver, as the vital part of the fifth generation of point-focusing concentrating solar power plants, called VPA-2, was modified and redesigned. Heat transfer analyses are essential for system design and optimization. As an important CFD simulation tool, Ansys Fluent was used for this purpose. A numerical model, based on the energy balance on the receiver and implementing the available heat transfer coefficient in the pieces of literature for the spiral tubes, was developed as a supplement to Ansys Fluent. As the application of this project is thermal storage, a very high temperature of working fluid(air) around 1000 𝐶° at the outlet of the receiver is required. The aim was to modify and redesign the receiver to reduce the maximum wall temperature and the pressure drop. As the first assumption, the constant heat flux distribution over the top surface of the receiver was considered. The preliminary version of the receiver showed a very high maximum temperature, around 2000℃ on its wall, and a pressure drop equal to 1069.1. The last-modified version represented a maximum wall temperature equal to 1068℃ and 716.5 Pa of pressure drop. Considering the actual heat flux distribution for a receiver located at a distance from the focal point of the concentrator, which is in the form of a normal distribution, showed a maximum wall temperature and pressure drop of 1006℃ and 810.7 pa, respectively. The project's goal was fulfilled by achieving the maximum wall temperature close to the outlet temperature and a small pressure drop. The receiver's final configuration was presented to have almost the same wall temperature in different sections, leading to lower thermal stress. Overall, Ansys's Fluent results and developed numerical results were reasonably similar. Results were validated using the experimental data in two pieces of literature.
Un ricevitore solare ad alta temperatura, come parte vitale della quinta generazione di centrali solari a concentrazione puntiformi, chiamato VPA-2, è stato modificato e riprogettato. Le analisi del trasferimento di calore sono essenziali per la progettazione e l'ottimizzazione del sistema. In quanto importante strumento di simulazione CFD, Ansys Fluent è stato utilizzato per questo scopo. Come supplemento ad Ansys Fluent è stato sviluppato un modello numerico, basato sul bilancio energetico sul ricevitore e che implementa il coefficiente di scambio termico disponibile nelle pubblicazioni per i tubi a spirale. Poiché l'applicazione di questo progetto è l'accumulo termico, è richiesta una temperatura molto alta del fluido di lavoro (aria) intorno a 1000 𝐶° all'uscita del ricevitore. L'obiettivo era modificare e riprogettare il ricevitore per ridurre la temperatura massima di parete e la caduta di pressione. Come prima ipotesi, è stata considerata la distribuzione costante del flusso di calore sulla superficie superiore del ricevitore. La versione preliminare del ricevitore mostrava una temperatura massima molto elevata, circa 2000℃ sulla sua parete, e una caduta di pressione pari a 1069,1. L'ultima versione modificata rappresentava una temperatura massima di parete pari a 1068℃ e 716,5 Pa di caduta di pressione. Considerando l'effettiva distribuzione del flusso di calore per un ricevitore situato a una distanza dal punto focale del concentratore, che ha la forma di una distribuzione normale, ha mostrato una temperatura massima di parete e una caduta di pressione rispettivamente di 1006 ℃ e 810,7 pa. L'obiettivo del progetto è stato raggiunto raggiungendo la massima temperatura di parete prossima alla temperatura di uscita e una piccola caduta di pressione. La configurazione finale del ricevitore è stata presentata per avere quasi la stessa temperatura della parete in diverse sezioni, con conseguente minore stress termico. Nel complesso, i risultati di Ansys Fluent e i risultati numerici sviluppati erano ragionevolmente simili. I risultati sono stati convalidati utilizzando i dati sperimentali in due pezzi di letteratura.
Thermal behavior simulation of a high-temperature CSP receiver
DASHTI, REZA
2021/2022
Abstract
A high-temperature solar receiver, as the vital part of the fifth generation of point-focusing concentrating solar power plants, called VPA-2, was modified and redesigned. Heat transfer analyses are essential for system design and optimization. As an important CFD simulation tool, Ansys Fluent was used for this purpose. A numerical model, based on the energy balance on the receiver and implementing the available heat transfer coefficient in the pieces of literature for the spiral tubes, was developed as a supplement to Ansys Fluent. As the application of this project is thermal storage, a very high temperature of working fluid(air) around 1000 𝐶° at the outlet of the receiver is required. The aim was to modify and redesign the receiver to reduce the maximum wall temperature and the pressure drop. As the first assumption, the constant heat flux distribution over the top surface of the receiver was considered. The preliminary version of the receiver showed a very high maximum temperature, around 2000℃ on its wall, and a pressure drop equal to 1069.1. The last-modified version represented a maximum wall temperature equal to 1068℃ and 716.5 Pa of pressure drop. Considering the actual heat flux distribution for a receiver located at a distance from the focal point of the concentrator, which is in the form of a normal distribution, showed a maximum wall temperature and pressure drop of 1006℃ and 810.7 pa, respectively. The project's goal was fulfilled by achieving the maximum wall temperature close to the outlet temperature and a small pressure drop. The receiver's final configuration was presented to have almost the same wall temperature in different sections, leading to lower thermal stress. Overall, Ansys's Fluent results and developed numerical results were reasonably similar. Results were validated using the experimental data in two pieces of literature.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/189979