mdh.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The dielectric properties of solid biofuels
Mälardalen University, School of Sustainable Development of Society and Technology. (MERO)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of bioenergy has been increasing due to efforts in fossil fuels replacement. Modern bioenergy technologies aim for high efficiency and low pollution levels, which increases the need for methods for the on-line characterization of biofuels.

Dielectric methods have been identified as useful for the sensing of solid biofuels because they allow for rapid, nonhazardous, nondestructive, and bulk determination of material properties. The dielectric properties describe the interaction between the material and the electromagnetic waves. Dielectric properties are intrinsic of the materials and can therefore be used for the development of prediction models that can be applied regardless of the measurement technique. The study of the dielectric properties is also important as it improves the understanding of the dielectric behavior of the materials.

This thesis focuses on the dielectric properties of solid biofuels and their use in the characterization of these materials. The work presented includes the development of new methods permitting the determination of the dielectric properties of solid biofuels with large particle size (waveguide method), broadband measurement of the dielectric properties (coaxial-line probe), and the use of a previously developed method for the accurate determination of the dielectric properties (free-space method). The results includes the dielectric properties of solid biofuels and their dependence on parameters such as frequency, moisture, density, and temperature.

This thesis also presents semi-theoretical models for the determination of moisture content, which obtained a RMSEP of 4% for moisture contents between 34 and 67%, and an empirical model that resulted in a RMSEC of 0.3% for moisture contents between 4 and 13%.

Finally, this thesis includes measurements of the influence of salt content on the dielectric properties and a discussion of its use for estimation of the ash content of solid biofuels.



Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2010. , 64 p.
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 90
Keyword [en]
dielectric properties, solid biofuels, moisture content determination
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-10500ISBN: 978-91-86135-94-2 (print)OAI: oai:DiVA.org:mdh-10500DiVA: diva2:358459
Public defence
2010-11-26, Lambda, Mälardalens högskola, Västerås, 10:00 (English)
Opponent
Supervisors
Available from: 2010-11-11 Created: 2010-10-22 Last updated: 2010-11-11Bibliographically approved
List of papers
1. Dielectric Properties of Woody Biomass at Radio Frequencies
Open this publication in new window or tab >>Dielectric Properties of Woody Biomass at Radio Frequencies
2009 (English)In: Proceedings of the 8th International Conference on. Electromagnenetic Wave Interaction with Water and Moist Substances, Helsinki, 2009Conference paper, Published paper (Refereed)
Abstract [en]

Electromagnetic sensing has been found an interesting technique for the characterization of woody biomass. The knowledge of the dielectric properties is useful for this characterization and to improve the understanding of the dielectric behavior of the material. This study presents the dielectric properties of woody biomass at a center frequency of 555 MHz. A measurement system, previously developed, to determine the water content of biomass was used. This system uses a reflection method and measures a biomass volume of about 0.11 m3. The dielectric properties were extracted from attenuation and velocity of the electromagnetic waves in three types of woody biomass with varying water content.

Place, publisher, year, edition, pages
Helsinki: , 2009
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-7535 (URN)
Conference
ISMEA 09
Available from: 2009-11-20 Created: 2009-11-19 Last updated: 2013-12-04Bibliographically approved
2. Dielectric mixing models for water content determination in woody biomass
Open this publication in new window or tab >>Dielectric mixing models for water content determination in woody biomass
2011 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 45, no 2, 249-259 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study is to determine the dielectric constant of woody biomass at different water contents and describe its behavior with a dielectric mixing model. The use of the model for determination of water content is also verified. Dielectric constants were calculated from the travel times of electromagnetic waves with a center frequency of 555 MHz through collected biomass samples. The power law, Maxwell-Garnett, and Polder van Santen mixing models were applied to the experimental data. In the models, biomass was considered as a mixture of three phases: a solid solution composed of wood cellular material and bound water, free water, and air. The experimental data was found to be better described by the Maxwell-Garnett model. The use of this model along with an independent validation set for the determination of volumetric water content resulted in a root mean square error of prediction of 0.03 within the investigated volumetric water content range of 0.07-0.29.

Place, publisher, year, edition, pages
Berlin: Springer, 2011
Keyword
dielectric constant, mixing model, water content
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-961 (URN)10.1007/s00226-010-0316-8 (DOI)000289477300005 ()2-s2.0-79955804815 (Scopus ID)
Available from: 2008-09-04 Created: 2008-09-05 Last updated: 2013-12-04Bibliographically approved
3. Dielectric properties of peanut-hull pellets at microwave frequencies
Open this publication in new window or tab >>Dielectric properties of peanut-hull pellets at microwave frequencies
2010 (English)In: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010: Proceedings, 2010, 62-66 p.Conference paper, Published paper (Refereed)
Abstract [en]

Peanut-hull pellets are obtained from a waste product, peanut hulls, which after pelleting can have several uses, namely as a renewable fuel. Rapid and nondestructive characterization of peanut-hull pellets is important for industrial utilization of this resource. Properties such as moisture content and bulk density are important for quality control and pricing and control of the energy conversion process. The dielectric properties of peanuthulls pellets can be used for the development of rapid and nondestructive sensors. In this study, the dielectric properties of peanut-hull pellets were measured at frequencies between 5 and 15 GHz, for moisture contents between 4% and 13%, temperatures between -15 °C and 38 °C, and bulk densities between 0.54 and 0.69 g·cm-3.

Identifiers
urn:nbn:se:mdh:diva-10413 (URN)10.1109/IMTC.2010.5488106 (DOI)000287997200012 ()2-s2.0-77957834183 (Scopus ID)978-142442833-5 (ISBN)
Conference
2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010; Austin, TX; 3 May 2010 through 6 May 2010
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2011-11-29Bibliographically approved
4. Measurement of the Dielectric Properties of Sawdust Between 0.5 and 15 GHz
Open this publication in new window or tab >>Measurement of the Dielectric Properties of Sawdust Between 0.5 and 15 GHz
2011 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, Vol. 60, no 10, 3384-3390 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this paper was to measure the broadband dielectric properties of sawdust. Knowledge of dielectric properties is important in improving understanding of a material and can lead to the development of methods for determining physical properties such as moisture and salt content. The broadband dielectric properties of sawdust were measured with an open-ended coaxial-line dielectric probe. Measurements on granular materials with the dielectric probe are dependent on the density of the measured region, which may differ from the average density of the sample. In this paper, a method was developed for determining the actual density for measurements with the dielectric probe. It consists of measurement of the dielectric constant with a different method (in this instance, a free-space transmission method) at a frequency common to both methods and identifying a relationship between the measured dielectric constant and density. The dielectric properties of sawdust samples with moisture content levels between 13% and 45% are presented for frequencies between 0.5 and 15 GHz.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-10415 (URN)10.1109/TIM.2011.2128510 (DOI)000294864700017 ()2-s2.0-80052855747 (Scopus ID)
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2013-12-04Bibliographically approved
5. Influence of sodium chloride on sawdust dielectric properties
Open this publication in new window or tab >>Influence of sodium chloride on sawdust dielectric properties
(English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-10416 (URN)
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2014-05-16Bibliographically approved
6. Dielectric-based method for determining moisture content and bulk density of peanut-hull pellets
Open this publication in new window or tab >>Dielectric-based method for determining moisture content and bulk density of peanut-hull pellets
2010 (English)In: 44th Annual Microwave Symposium Proceedings, 2010, 190-196 p.Conference paper, Published paper (Refereed)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:mdh:diva-10414 (URN)
Conference
IMPI2010, International Microwave Power Symposium Conference, Denver, July 14-16, 2010
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2017-04-05Bibliographically approved

Open Access in DiVA

fulltext(1645 kB)2492 downloads
File information
File name FULLTEXT02.pdfFile size 1645 kBChecksum SHA-512
8be92b8203622ab9b8c5e07d6caf9635179d257708f053efb86dc6a7fac66fd97ba7d93ff361d08636d30a8ee61e778b061465604021b1d362c5b49a86a8c358
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Paz, Ana Marta
By organisation
School of Sustainable Development of Society and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 2492 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: 433 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf