elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

Konvektive Verluste an offenen volumetrischen Solarstrahlungsempfängern

Maldonado Quinto, Daniel (2016) Konvektive Verluste an offenen volumetrischen Solarstrahlungsempfängern. Dissertation, RWTH Aachen.

Full text not available from this repository.

Abstract

The open volumetric air receiver is a promising technology for solar power towers. Researchers have investigated the behavior of the porous Absorber structures and the operational performance under fluctuating incident solar radiation. All of the research work carried out is based on assumptions on the flow conditions at the receiver front, which so far were not investigated. The flow conditions at the front determine to what extent the receiver cycle is driven as a closed loop, which is quantified by the air return ratio. The energy losses due to the partial exchange of hot cycled air by ambient air are referred to as convective losses. In the present thesis, the influence of the air return ratio on the overall System efficiency was analyzed. More specifically, the interaction between receiver cycle and power cycle was investigated to determine optimized design Parameters for future solar power towers. The simulations demonstrated the significant impact of the air return ratio on the overall system efficiency. This result provided motivation for a thorough examination of the flow conditions at the receiver front. The approach was to develop a measurement setup which provides velocity fields in front of a modular section of the receiver, under real operating conditions. The experimental setup was assembled in the high flux solar simulator in Cologne, and using the installed Particle Image Velocimetry measurement system, a quantitative examination of the flow conditions was feasible for the first time. The measurement results showed the turbulent nature of the gas flow and highlighted the phenomena which affect the convective losses. A numerical model of the system was also developed using the open source software OpenFOAM. Velocity fields and integral temperature values were compared with the experimental data in order to validate the simulations. Good agreement between experiment and simulation allowed for an in depth analysis based on the numerical model. Hence, characteristic operating points for the open volumetric air receiver were determined. A weak dependency of the air return ratio on the overall mass flow was found. Furthermore, an intentional partially open loop for the receiver cycle was identified as an operating mode which can increase the performance of solar power towers in the future. Findings in this work lead to a better understanding of the convective losses and the flow conditions at the receiver front. Further investigations are required in order to transfer this knowledge from the laboratory scale to the power plant scale.

Item URL in elib:https://elib.dlr.de/109026/
Document Type:Thesis (Dissertation)
Title:Konvektive Verluste an offenen volumetrischen Solarstrahlungsempfängern
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Maldonado Quinto, DanielDaniel.MaldonadoQuinto (at) dlr.deUNSPECIFIED
Date:2016
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Open volumetric air receiver, convective losses, PIV, air return ratio, solar tower power plant
Institution:RWTH Aachen
Department:Fakultät für Maschinenwesen
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Concentrating Solar Thermal Technology
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Advanced Heat Transfer Media (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Solar Research > Punktfokussierende Systeme
Deposited By: Uhlig, Tamara
Deposited On:12 Dec 2016 15:16
Last Modified:12 Dec 2016 15:16

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.