Identifier

etd-04132012-174640

Degree

Master of Science in Biological and Agricultural Engineering (MSBAE)

Department

Biological and Agricultural Engineering

Document Type

Thesis

Abstract

Due to limited supply of traditional fossil based fuels, and increased interest in air and water quality along with other environmental concerns, there has been a rise in the utilization of biomass based energy sources. Many agricultural materials can be used for the production of biofuels, including materials that are typically underutilized such as sweet sorghum bagasse and otherwise nuisance species such as Chinese tallow tree seeds. The goal of this project was to examine the relationship between the dielectric properties of sweet sorghum bagasse and Chinese tallow tree (CTT) seeds, respectively, and frequency and moisture content; to determine pertinent thermal properties of these materials, and to optimize process parameters of a continuous belt microwave drying system for improved biofuel production. Prior to microwave drying, the elemental composition, fatty acid composition, oil content, and various thermal properties for each of the component layers of CTT seeds were investigated. These tests revealed dramatic differences between each of the component layers of CTT seeds. For both sorghum bagasse and CTT, the dielectric properties across a range of moisture contents and frequencies were measured. The values obtained here were applied to the calculation of the penetration depth of microwaves through the materials in order to illustrate how these materials would behave when exposed to microwave energy. The dielectric properties for each material were found to be dependent on both frequency and moisture content. For microwave drying tests, the parameters investigated include microwave power levels (300W, 750W, and 1.2kW) and ambient air temperatures (room temperature and 55°C) with total residence time of 5 minutes. Data collected included humidity, temperature, sample surface temperature, moisture content, and absorbed microwave power. The moisture removed when microwaves are used is greatly in excess of the internal air moisture holding capacity, due to forced removal of water from the samples via pressure gradients generated by direct interaction with the water molecules in the matrix. Results indicate that microwave drying achieves results better than the control with respect to moisture removed per unit energy input.

Date

2012

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Boldor, Dorin

Included in

Engineering Commons

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