| The goal of our research is to separate crude oil from oil sands by heating them with microwave energy applicator working at 2450 MHz with a power up to 10,000 W which is much higher than Bosisio's first experimental study done in 1977 using 100 W. At this initial step, we seek to determine the complex permittivity of oil sands because the microwave engineering of oil sands would require precise knowledge of its electromagnetic properties. These properties are defined in terms of dielectric constant (epsilon') and loss factor (epsilon"). Permittivity is actually a complex number. Relative complex permittivity is also complex when the permittivity is complex and it is the ratio of epsilon complex to epsilon zero (epsilonr' and epsilonr'').The only study on the complex permittivity measurements of oil sands at 2450 MHz was reported by Erdogan et al [9 -- 11].;There are many techniques for permittivity measurements at microwave frequencies. The cavity perturbation technique has several advantages compared to other permittivity measurement techniques. In general, it is the most accurate technique for measuring very low-loss dielectrics such as oil sands. The sample is placed in the position of maximum electric field. Usually there are p positions in the cavity with a maximum electric field for the TE 1,0,p modes.;Complex permittivity is calculated from the changes of resonant frequency fr and quality factor Q. The basic assumption for the cavity perturbation technique is that the change of electromagnetic field upon the introduction of the sample must be small.;In this study, a rectangular cavity was designed and constructed at Ecole Polytechnique de Montreal laboratories (Poly-Grames). A standard waveguide made of copper was chosen with a width of 72.2 mm and a height of 34.1 mm. The length of the entire waveguide, which was equal to 11lambda g/2, is 1186.55 mm.;The rectangular cavity resonator was excited at both ends through two small loop antennas with Vector Network Analyzer (VNA). First, the empty cavity was excited to find the resonant frequency and Q factor of the empty chamber through signal amplitude measurements at the peak and 3 dB points below. Then, the oil sand was loaded into the cavity and it was excited again to find the resonant frequency and Q factor of the loaded chamber.;The bitumen of our oil sand samples obtained from Alberta oil sand resources were classified into high, low and very low grade samples. The electromagnetic measurements of the oil sand sample obtained by an in-house designed and constructed rectangular cavity resonator are shown in the first three lines of the Table 3.1. Some well-known liquids such as ethanol, methanol and 2-butanol, and a well-known solid such as a Teflon rod were also measured by our in-house system for verification and their values are also presented in the last four lines of the Table 3.1.;After verification, we can conclude that our measurements of the complex permittivity of oil sands match the measurements obtained through the commercial system. Therefore, the results obtained through our in-house cavity resonator are accurate and reliable measurements of the complex permittivity for oil sands from Alberta.;Since there is no study in the literature on the complex permittivity of oil sands at ISM 2.45 GHz, our study serves as an important guide for those who plan to design and manufacture microwave energy applicators in order to extract the bitumen from oil sands. (Abstract shortened by UMI.)... |
