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Examination of the heat transfer potential of an active latent heat storage concept

Tombrink, Jonas and Jockenhöfer, Henning and Bauer, Dan (2019) Examination of the heat transfer potential of an active latent heat storage concept. Eurotherm Seminar nº112 - Advances in Thermal Energy Storage, 15.-17. Mai 2019, Lleida, Spanien. ISBN 978-84-9144-155-7

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Abstract

Efficient storage of thermal energy is a key element for the transition of the energy system to renewable energy sources. To reach a high exergetic efficiency, latent heat thermal energy storages offer the opportunity to charge and discharge thermal energy at a constant temperature level. As most Phase Change Materials (PCM) have a low thermal conductivity, the layer of solidified PCM material growing on the heat exchanger surface during discharging typically limits the specific heat transfer to very low values. The state of the art in overcoming this effect is the increase of the heat transfer area by heat transfer structures. Another possibility to increase the heat flux is by means of active latent heat storage concepts. With active concepts, the thickness of the solidified PCM layer can be minimized and controlled by an active motion of the PCM or the heat transfer surfaces. In the presented rotating drum concept, a partially submerged drum is rotating in liquid PCM. A cooled Heat Transfer Fluid (HTF) passes through the drum resulting in a heat flux from the PCM to the HTF. The resulting solidified PCM layer at the outside of the rotating drum is constantly removed by a scraper. The thickness of the PCM layer and therefor the thermal resistance is a function of the rotation speed. Subsequently it is possible to control the heat flux by varying the rotation speed of the drum. An analytical model of the heat transfer has been developed. A detailed examination of the different heat transfer mechanisms shows that the heat transfer is no longer limited by the heat conductivity of the PCM. Instead the heat transfer from the drum wall to the HTF becomes the limiting factor. In the presentation, an improved test rig, aiming for a maximized heat flux density by minimizing the PCM layer thickness and maximizing the heat transfer to the HTF is introduced and experimental results are presented.

Item URL in elib:https://elib.dlr.de/127811/
Document Type:Conference or Workshop Item (Poster)
Title:Examination of the heat transfer potential of an active latent heat storage concept
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Tombrink, JonasJonas.Tombrink (at) dlr.deUNSPECIFIED
Jockenhöfer, HenningHenning.Jockenhoefer (at) dlr.deUNSPECIFIED
Bauer, DanDan.Bauer (at) dlr.deUNSPECIFIED
Date:May 2019
Refereed publication:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
ISBN:978-84-9144-155-7
Status:Published
Keywords:Active Latent Heat Thermal Energy Storage, Phase Change Material, Rotating Drum, Heat Transfer, Solidification
Event Title:Eurotherm Seminar nº112 - Advances in Thermal Energy Storage
Event Location:Lleida, Spanien
Event Type:international Conference
Event Dates:15.-17. Mai 2019
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Thermal Energy Storage
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Thermochemical Processes (Storage)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Thermal Process Technology
Deposited By: Tombrink, Jonas
Deposited On:12 Jul 2019 13:05
Last Modified:12 Jul 2019 13:05

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