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

Validation of a numerical model with a benchmark Experiment for melting governed by natural convection in latent thermal energy storage

Vogel, Julian and Thess, André (2019) Validation of a numerical model with a benchmark Experiment for melting governed by natural convection in latent thermal energy storage. Applied Thermal Engineering, 148, pp. 147-159. Elsevier. DOI: 10.1016/j.applthermaleng.2018.11.032 ISSN 1359-4311

[img] PDF - Registered users only until July 2020
1MB

Abstract

We report a combined experimental and numerical investigation of a melting process representative of latent thermal energy storage systems. The purpose of the work is to assess the accuracy of numerical models of melting governed by natural convection with a benchmark experiment. The experiment consists of a rectangular box filled with a model liquid (n-octadecane) and heated symmetrically from both sides such as to allow access for shadowgraph imaging and particle image velocimetry to measure the phase state and velocities, respectively. Our numerical method for computing fluid flow, temperature, and phase state involves two different approaches: the first is a detailed model using variable thermophysical properties and the volume of fluid method to allow volume expansion in an additional air phase that we solve in two dimensions. The second is a simplified model using constant thermophysical properties and the Boussinesq approximation that we solve either in two or in three dimensions. In the first part of the work, we systematically compare the simplified (Boussinesq) with the detailed (volume of fluid) model. We find that for the given set of parameters (Ra = 2*10^8, A = 4, Ste = 0.092, Pr = 52), the difference between the detailed and the simplified model in predicting global quantities such as the liquid phase fraction and the total heat flow rate is smaller than 4%, whereas velocities differ up to 20%. In the second part of the work, we compare the simulations of the simplified Boussinesq model in three dimensions with the benchmark experiment. We find that the simulation predicts the liquid phase fraction and temperatures with deviations below 4%, but significantly overestimates the velocity magnitudes. Our experimental and numerical tools provide a rational framework in which the accuracy of latent thermal energy storage simulations can be systematically and comprehensively assessed.

Item URL in elib:https://elib.dlr.de/123839/
Document Type:Article
Title:Validation of a numerical model with a benchmark Experiment for melting governed by natural convection in latent thermal energy storage
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Vogel, Julianjulian.vogel (at) dlr.dehttps://orcid.org/0000-0001-9792-2332
Thess, AndréAndre.Thess (at) dlr.deUNSPECIFIED
Date:February 2019
Journal or Publication Title:Applied Thermal Engineering
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:148
DOI :10.1016/j.applthermaleng.2018.11.032
Page Range:pp. 147-159
Publisher:Elsevier
ISSN:1359-4311
Status:Published
Keywords:Phase change material (PCM) Solid-liquid phase change Computational Fluid Dynamics (CFD) Boussinesq approximation Volume of fluid method (VOF)
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: Vogel, Julian
Deposited On:10 Dec 2018 15:06
Last Modified:06 Sep 2019 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.