scholarly journals Moisture Content and Bulk Density Prediction Using Dielectric Properties for Switchgrass and Corn Stover

2015 ◽  
Keyword(s):  
Dielectric Properties ◽  
Moisture Content ◽  
Bulk Density ◽  
Corn Stover ◽  
Density Prediction

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

scholarly journals Dielectric properties of hops – an effect of bulk density

2017 ◽  
Vol 63 (Special Issue) ◽  
pp. S18-S23
Author(s):  
Lev Jakub ◽  
Kumhála František
Keyword(s):  
Dielectric Properties ◽  
Moisture Content ◽  
Bulk Density ◽  
Relative Permittivity ◽  
Loss Factor ◽  
Drying Process ◽  
Material Loss ◽  
Measuring Device ◽  
Temperature Changes ◽  
Strong Linear Correlation

  Continuous detection of basic physical properties of freshly picked and cleaned wet hop cones would be very helpful for better control and automation of harvesting processes. That is why the main aim of this article was to determine the effects of bulk density changes on dielectric properties of freshly picked hop cones. Relative permittivity and loss factor were measured using a newly developed capacitance measuring device. A strong linear correlation between fresh hops relative permittivity and bulk density was found. This finding could be used e.g. for consequent hop drying process control. Significant differences between tested hop varieties were observed for both relative permittivity and loss factor measurements. These differences cannot be explained only by a slightly different moisture content of the measured varieties and ambient temperature changes. Measured material loss factor was only slightly affected by bulk density changes. However, relative permittivity was affected by bulk density changes significantly. These facts could be used for other properties of wet hop cones estimation.  

scholarly journals Dielectric Properties of Switchgrass and Corn Stover in the Radio Frequency Range

2021 ◽  
Vol 64 (1) ◽  
pp. 243-252
Author(s):  
Augusto M. Souza ◽  
Stuart J. Birrell ◽  
Brian L. Steward
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Moisture Content ◽  
Radio Frequency ◽  
Corn Stover ◽  
Loss Factor ◽  
Prediction Models ◽  
Dielectric Constants ◽  
Frequency Range ◽  
Loss Factors

HighlightsDielectric permittivities of switchgrass and corn stover in the radio frequency range were calculated.Prediction models achieved R2 > 0.9, except for the switchgrass loss factor for the material in motion.The loss factors were different when static and in motion, but the dielectric constants were similar.Abstract. The dielectric properties of biological materials are relevant when developing moisture content sensors. However, little is known about the permittivities of switchgrass and corn stover in a wider frequency range. The goal of this research was to determine their dielectric constants and loss factors at different moisture contents across a frequency range of 5 Hz to 13 MHz and with the material static and in motion inside a sample container. The permittivity of these materials was calculated by measuring their admittance in a test fixture using an impedance analyzer at three different moisture levels (9.0% to 30.5%). Overall, the materials’ dielectric properties increased with moisture but decreased with frequency. Prediction models were developed using the data in a frequency range of 10 kHz to 5 MHz. Model coefficients of determination were higher than 0.90 in general, except for the model measuring the loss factor of switchgrass in motion. Additionally, the dielectric constant was not different with the materials static or in motion, but the loss factor values were distinct. This work can be used for the development of electrical moisture content sensors for switchgrass and corn stover. Keywords: Corn stover, Dielectric constant, Loss factor, Moisture content, Permittivity, Switchgrass.

scholarly journals Comparative Study of the Properties of Wood Flour and Wood Pellets Manufactured from Secondary Processing Mill Residues

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2487
Author(s):  
Geeta Pokhrel ◽  
Yousoo Han ◽  
Douglas J. Gardner
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Raw Materials ◽  
Wood Flour ◽  
The United States ◽  
Red Maple ◽  
Wood Pellets ◽  
Secondary Processing ◽  
Material Costs ◽  
Mill Residues

The generation of secondary processing mill residues from wood processing facilities is extensive in the United States. Wood flour can be manufactured utilizing these residues and an important application of wood flour is as a filler in the wood–plastic composites (WPCs). Scientific research on wood flour production from mill residues is limited. One of the greatest costs involved in the supply chain of WPCs manufacturing is the transportation cost. Wood flour, constrained by low bulk densities, is commonly transported by truck trailers without attaining allowable weight limits. Because of this, shipping costs often exceed the material costs, consequently increasing raw material costs for WPC manufacturers and the price of finished products. A bulk density study of wood flour (190–220 kg/m3) and wood pellets (700–750 kg/m3) shows that a tractor-trailer can carry more than three times the weight of pellets compared to flour. Thus, this study focuses on exploring the utilization of mill residues from four wood species in Maine to produce raw materials for manufacturing WPCs. Two types of raw materials for the manufacture of WPCs, i.e., wood flour and wood pellets, were produced and a study of their properties was performed. At the species level, red maple 40-mesh wood flour had the highest bulk density and lowest moisture content. Spruce-fir wood flour particles were the finest (dgw of 0.18 mm). For all species, the 18–40 wood flour mesh size possessed the highest aspect ratio. Similarly, on average, wood pellets manufactured from 40-mesh particles had a lower moisture content, higher bulk density, and better durability than the pellets from unsieved wood flour. Red maple pellets had the lowest moisture content (0.12%) and the highest bulk density (738 kg/m3). The results concluded that the processing of residues into wood flour and then into pellets reduced the moisture content by 76.8% and increased the bulk density by 747%. These material property parameters are an important attempt to provide information that can facilitate the more cost-efficient transport of wood residue feedstocks over longer distances.

scholarly journals Parameters of Trucks and Loads in the Transport of Scots Pine Wood Biomass Depending on the Season and Moisture Content of the Load

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
Grzegorz Trzciński ◽  
Łukasz Tymendorf ◽  
Paweł Kozakiewicz
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Load Capacity ◽  
Wood Chips ◽  
Total Weight ◽  
Wood Biomass ◽  
Four Seasons ◽  
Gross Vehicle Weight ◽  
Bulk Volume ◽  
Average Quantity

Transport of wood biomass is one of the key operations in forestry and in the wood industry. An important part is the transport of shredded wood, where the most common forms are chips and sawdust. The aim of the research was to present the variability of the total weight of trucks (gross vehicle weight, GVW), the weight of the empty trucks (tare), and loads of chips and sawdust in different periods of the year. Changes in specific parameters were analyzed: GVW; tare weight; trailer capacity; use of the trailer load capacity; bulk volume and bulk density of wood biomass loads; solid cubic meter (m3) and weight of 1m3 of the load; and load weight depending on the season, with simultaneous measurements of wood chips and sawdust moisture. More than 250 transports from four seasons of the year were analyzed in the research. It was found that the total weight of trucks (GVW) was at a comparable level, on average from 39.42 to 39.64 Mg with slight differences (with SD 0.29 and 0.39). The weight of empty trucks was 16.15 Mg for chip-bearing trucks and 15.93 Mg for sawdust-bearing trucks (with SD 0.604 and 0.526). The type of wood material has an influence on the transported volume. The average quantity of load in the bulk cubic meter was 64.783 m3 for wood chips (SD 3.127) and 70.465 m3 (SD 2.516) for sawdust. Over 30% differences in the volume of transported wood chips and approximately 18% for sawdust were observed. The use of the loading capacity of the trailer was on average 72.58% (SD 5.567) for the transport of wood chips and 77.42% (SD 3.019) for the transport of sawdust. The sawdust bulk density was from 0.3050 to 0.4265 Mg⋅m−3 for wood chips and 0.3200 to 0.3556 Mg⋅m−3 for sawdust. This parameter is significantly dependent on moisture content, and the determined correlation functions can be used for estimating and predicting bulk density. The abovementioned absolute moisture content of chips and sawdust also depends on the season, which also affects the selected parameters of wood biomass loads.

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