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The dielectric properties of solid biofuels
Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. (MERO)
2010 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
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.



sted, utgiver, år, opplag, sider
Västerås: Mälardalen University , 2010. , s. 64
Serie
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 90
Emneord [en]
dielectric properties, solid biofuels, moisture content determination
Forskningsprogram
energi- och miljöteknik
Identifikatorer
URN: urn:nbn:se:mdh:diva-10500ISBN: 978-91-86135-94-2 (tryckt)OAI: oai:DiVA.org:mdh-10500DiVA, id: diva2:358459
Disputas
2010-11-26, Lambda, Mälardalens högskola, Västerås, 10:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2010-11-11 Laget: 2010-10-22 Sist oppdatert: 2010-11-11bibliografisk kontrollert
Delarbeid
1. Dielectric Properties of Woody Biomass at Radio Frequencies
Åpne denne publikasjonen i ny fane eller vindu >>Dielectric Properties of Woody Biomass at Radio Frequencies
2009 (engelsk)Inngår i: Proceedings of the 8th International Conference on. Electromagnenetic Wave Interaction with Water and Moist Substances, Helsinki, 2009Konferansepaper, Publicerat paper (Fagfellevurdert)
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.

sted, utgiver, år, opplag, sider
Helsinki: , 2009
Forskningsprogram
energi- och miljöteknik
Identifikatorer
urn:nbn:se:mdh:diva-7535 (URN)
Konferanse
ISMEA 09
Tilgjengelig fra: 2009-11-20 Laget: 2009-11-19 Sist oppdatert: 2013-12-04bibliografisk kontrollert
2. Dielectric mixing models for water content determination in woody biomass
Åpne denne publikasjonen i ny fane eller vindu >>Dielectric mixing models for water content determination in woody biomass
2011 (engelsk)Inngår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 45, nr 2, s. 249-259Artikkel i tidsskrift (Fagfellevurdert) 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.

sted, utgiver, år, opplag, sider
Berlin: Springer, 2011
Emneord
dielectric constant, mixing model, water content
HSV kategori
Forskningsprogram
energi- och miljöteknik
Identifikatorer
urn:nbn:se:mdh:diva-961 (URN)10.1007/s00226-010-0316-8 (DOI)000289477300005 ()2-s2.0-79955804815 (Scopus ID)
Tilgjengelig fra: 2008-09-04 Laget: 2008-09-05 Sist oppdatert: 2017-12-14bibliografisk kontrollert
3. Dielectric properties of peanut-hull pellets at microwave frequencies
Åpne denne publikasjonen i ny fane eller vindu >>Dielectric properties of peanut-hull pellets at microwave frequencies
2010 (engelsk)Inngår i: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010: Proceedings, 2010, s. 62-66Konferansepaper, Publicerat paper (Fagfellevurdert)
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.

Identifikatorer
urn:nbn:se:mdh:diva-10413 (URN)10.1109/IMTC.2010.5488106 (DOI)000287997200012 ()2-s2.0-77957834183 (Scopus ID)978-142442833-5 (ISBN)
Konferanse
2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010; Austin, TX; 3 May 2010 through 6 May 2010
Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2011-11-29bibliografisk kontrollert
4. Measurement of the Dielectric Properties of Sawdust Between 0.5 and 15 GHz
Åpne denne publikasjonen i ny fane eller vindu >>Measurement of the Dielectric Properties of Sawdust Between 0.5 and 15 GHz
2011 (engelsk)Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 60, nr 10, s. 3384-3390Artikkel i tidsskrift (Fagfellevurdert) 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.

HSV kategori
Identifikatorer
urn:nbn:se:mdh:diva-10415 (URN)10.1109/TIM.2011.2128510 (DOI)000294864700017 ()2-s2.0-80052855747 (Scopus ID)
Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12bibliografisk kontrollert
5. Influence of sodium chloride on sawdust dielectric properties
Åpne denne publikasjonen i ny fane eller vindu >>Influence of sodium chloride on sawdust dielectric properties
(engelsk)Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662Artikkel i tidsskrift (Fagfellevurdert) Submitted
HSV kategori
Identifikatorer
urn:nbn:se:mdh:diva-10416 (URN)
Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12bibliografisk kontrollert
6. Dielectric-based method for determining moisture content and bulk density of peanut-hull pellets
Åpne denne publikasjonen i ny fane eller vindu >>Dielectric-based method for determining moisture content and bulk density of peanut-hull pellets
2010 (engelsk)Inngår i: 44th Annual Microwave Symposium Proceedings, 2010, s. 190-196Konferansepaper, Publicerat paper (Fagfellevurdert)
HSV kategori
Identifikatorer
urn:nbn:se:mdh:diva-10414 (URN)
Konferanse
IMPI2010, International Microwave Power Symposium Conference, Denver, July 14-16, 2010
Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-04-05bibliografisk kontrollert

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