Effects of temperature and material on sensing moisture content of pelleted biomass through dielectric properties

McKeown, Murat Sean; Trabelsi, Samir; Tollner, E. W.

doi:10.1016/j.biosystemseng.2016.06.002

Cited by 17 publications

(12 citation statements)

References 23 publications

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“…The size of the sample is small (∼0.1 cm 3 ), and is sensitive enough for low loss material such as biomass . The dielectric property measurement procedure and full details of the cavity perturbation set‐up was described in many previous articles . Briefly, the sample was placed in 4 mm ID quartz tube with a 100 mL/min flow of N 2 , and the holder with the sample was preheated to each specific temperature and then rapidly inserted into a high electric field region of a thick‐walled, well‐cooled cavity.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, it is essential to determine the relation between the dielectric properties and those parameters, which is crucial for designing large scale MW systems . Several studies have attempted to characterize the dielectric properties of some types of biomass such as oil palm shell, corn stover, hay and peanut hull, but there is still a lack of fundamental information on the dielectric properties of the different components during pyrolysis. Besides, most published studies are focused solely on the dependence of dielectric properties on the frequency of radiation at room temperature and ignored the need for a comprehensive study of the whole microwave pyrolysis process .…”

Section: Introductionmentioning

confidence: 99%

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Revealing low temperature microwave‐assisted pyrolysis kinetic behaviors and dielectric properties of biomass components

et al. 2018

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The kinetic characteristics of microwave-assisted pyrolysis (MAP) of biomass components were investigated in a selfdesigned microwave thermogravimetric analysis using the KAS model and the master plot method. Compared with conventional pyrolysis, the initial decomposition temperatures of biomass components were reduced by 50-1008C and the fastest weight loss regions were shifted to lower temperatures. The average apparent activation energies of cellulose, hemicellulose, and lignin were 47.82, 44.81, and 51.54 kJ/mol, respectively. Analysis with master plot method suggested the MAP of cellulose followed the 2-D diffusion reaction model, while hemicellulose and lignin could be interpreted by third orderbased and 3-D diffusion model. The change of dielectric properties was consistent with the weight loss behaviors of biomass components during the pyrolysis process. The increase of dielectric properties with temperature can lead to a thermal gradient and "hot spots" within biomass, which accelerated the pyrolysis process at low temperatures and reduced the apparent activation energy.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revealing low temperature microwave‐assisted pyrolysis kinetic behaviors and dielectric properties of biomass components

et al. 2018

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“…The density-independent calibration function for predicting moisture content in porous materials is very well known for the 2-port transmission measurement technique (Trabelsi, Krazsewski & Nelson, 1998a;Trabelsi & Nelson 1998b;Trabelsi & Nelson 1998c;Trabelsi, Paz & Nelson, 2013;McKeown, Trabelsi & Tollner, 2016;McKeown, Trabelsi, Nelson & Tollner, 2017). It is defined in terms of the dielectric properties as (Trabelsi, Krazsewski & Nelson, 1998a):…”

Section: Density-independent Algorithmmentioning

confidence: 99%

“…In section 2, a low-cost open-ended halfmode substrate-integrated waveguide (HMSIW) sensor with grounded flange is described, and details of its use for measuring the dielectric properties of sawdust are given. The density-independent calibration function was developed, based on complex-plane representations of the dielectric properties, each divided by either moist or dry bulk density (Trabelsi, Krazsewski & Nelson, 1998a;Trabelsi & Nelson 1998b;Trabelsi & Nelson 1998c;Trabelsi, Paz & Nelson, 2013;McKeown, Trabelsi & Tollner, 2016;McKeown, Trabelsi, Nelson & Tollner, 2017). Results of moisture prediction by using both approaches (moist and dry bulk density) are presented and the performance of each algorithm is given in section 3.…”

Section: Introductionmentioning

confidence: 99%

Density-independent algorithm for sensing moisture content of sawdust based on reflection measurements

Julrat

Trabelsi

2017

Biosystems Engineering

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A density-independent algorithm for moisture content determination in sawdust, based on a one-port reflection measurement technique is proposed for the first time. Performance of this algorithm is demonstrated through measurement of the dielectric properties of sawdust with an open-ended half-mode substrate-integrated waveguide (HMSIW) sensor. For accurate measurement of the dielectric properties of sawdust, the HMSIW sensor was calibrated by using a three-material calibration technique, with air, water and 25% ethanol aqueous solution. For moisture determination, a density-independent calibration function expressed in terms of the dielectric properties was used. Both moist and dry bulk densities were considered for the complex-plane representation of the dielectric properties. Results of moisture prediction, relative to each complex-plane representation were found to be similar at 5 GHz and 23 °C with the standard errors of performance of 0.955% and 0.957%, respectively.

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“…Dielectric properties of a variety of lignocellulosic biomasses including woody biomass [11][12][13][14][15], grassy biomass [16][17][18], oil palm [19], corn stover [20], and pulp mill sludge [21] have been presented in the literature. Due to the low dielectric loss of most lignocellulosic biomasses, these materials alone, especially if dry, require a lot of energy to reach high temperatures by dielectric heating if not aided by a microwave absorbing material [22,23].…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Biomass/Biochar Mixtures at Microwave Frequencies

et al. 2017

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Material dielectric properties are important for understanding their response to microwaves. Carbonaceous materials are considered good microwave absorbers and can be mixed with dry biomasses, which are otherwise low-loss materials, to improve the heating efficiency of biomass feedstocks. In this study, dielectric properties of pulverized biomass and biochar mixtures are presented from 0.5 GHz to 20 GHz at room temperature. An open-ended coaxial-line dielectric probe and vector network analyzer were used to measure dielectric constant and dielectric loss factor. Results show a quadratic increase of dielectric constant and dielectric loss with increasing biochar content. In measurements on biochar, a strong dielectric relaxation is observed at 8 GHz as indicated by a peak in dielectric loss factor at that frequency. Biochar is found to be a good microwave absorber and mixtures of biomass and biochar can be utilized to increase microwave heating rates for high temperature microwave processing of biomass feedstocks. These data can be utilized for design, scale-up and simulation of microwave heating processes of biomass, biochar, and their mixtures.

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Effects of temperature and material on sensing moisture content of pelleted biomass through dielectric properties

Cited by 17 publications

References 23 publications

Revealing low temperature microwave‐assisted pyrolysis kinetic behaviors and dielectric properties of biomass components

Revealing low temperature microwave‐assisted pyrolysis kinetic behaviors and dielectric properties of biomass components

Density-independent algorithm for sensing moisture content of sawdust based on reflection measurements

Dielectric Properties of Biomass/Biochar Mixtures at Microwave Frequencies

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