Change search
ReferencesLink to record
Permanent link

Direct link
An Experimental and Numerical Study of Heat Transfer in Aluminium Melting and Remelting Furnaces
Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, Department of Materials Science and Engineering.
2013 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

This work has been a combined experimental and numerical modeling effort aimed to help in the understanding of heat transfer processes when melting aluminium. In addition a newly developed type of oxy-fuel burner was investigated. Objectives set for this project include improving energy efficiency in a typical industry furnace used today and looking at possible new technology to realize higher efficiencies than normally obtained. As a starting point a literature review was done to get an overview of furnaces and technology used in aluminium remelting and recycling. The most commonly used furnace today for aluminium melting and remelting is the reverberatory furnace which was the focus of this work as well. Understanding the interaction of parameters influencing heat transfer and quantifying how heat is transferred in the furnace are key elements to be able to optimize energy efficiency. Reverberatory furnaces are usually heated by gas burners, more specifically with cold air as oxidizer. Recent developments in burner technology using pure oxygen as oxidizer has showed some promising results and was investigated in experiments and numerical models.

Melting experiments were carried out in a controlled environment in a 500 kg laboratory scale furnace as a basis for understanding the heat transfer mechanisms and quantifying radiation and convection contributions when melting aluminium. The experiments also served as a reference for a numerical 1-dimensional heat transfer model along with more advanced 3-dimensional computational fluid dynamics (CFD) models using a commercial software package. Phenomena as turbulent flow, combustion, convection, conduction and radiation were included in the models along with latent heat release when melting metal. The influence and impact of physical parameters on the heat transfer could be determined in the numerical models and provided a more detailed analysis of the processes in the furnace.

A newly developed Low Temperature Oxy-fuel (LTOF) burner was investigated and compared to a conventional cold air-fuel burner in a pilot scale furnace. Measurements of flame and furnace temperatures, gas composition and heat fluxes were done for both burners at two different input levels. Heating experiments of aluminium samples were performed to look at the difference between the burners for aluminium heating and melting applications. 3-dimensional CFD models were developed to determine unknown quantities such as metal emissivity and quantification of radiation and convection heat transfer. The experiments also confirmed the validity of the numerical models.

Finally a full scale reverberatory industry furnace was modeled using a 3-dimensional CFD model. The air-fuel burners currently installed in the furnace was replaced by LTOF burners in the numerical model. The performance was compared to a previously published numerical model of the same furnace using air-fuel burners for two different metal configurations in the furnace. The influence of parameters such as burner input, metal emissivity, furnace wall emissivity and a dross layer was studied.

The key factor when making improvements in furnaces is understanding the fundamental heat transfer processes in existing technology. The experimental and numerical modeling work presented in this thesis has studied these phenomena and created a basis from which further investigations into furnace efficiency in aluminium remelting and recycling can be done. The performance of a new type of burner was also analyzed and explained through experiments and modeling.

Place, publisher, year, edition, pages
NTNU, 2013.
Doctoral theses at NTNU, ISSN 1503-8181 ; 2013:30
National Category
Materials science and engineering
URN: urn:nbn:no:ntnu:diva-20249ISBN: 978-82-471-4152-6 (printed ver.)ISBN: 978-82-471-4153-3 (electronic ver.)OAI: diva2:606982
Public defence
2013-02-05, 00:00
Available from: 2013-02-21 Created: 2013-02-21Bibliographically approved

Open Access in DiVA

fulltekst(190860 kB)758 downloads
File information
File name FULLTEXT01.pdfFile size 190860 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Department of Materials Science and Engineering
Materials science and engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 758 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 205 hits
ReferencesLink to record
Permanent link

Direct link