Microwave Heating of Water and Cyclohexane: A Molecular Dynamics Study

• Author / Creator

  Malamace da Silva, Victor Hugo

• The oil sands of Western Canada are among the most abundant and economically important unconventional petroleum resources. Hydrocarbon extraction from oil sands is conducted using warm water or in situ technologies that face considerable environmental challenges. Oil sands can also be valorized using the alternative method of non-aqueous extraction (NAE). However, NAE faces the challenge of solvent removal from post-extraction gangue. Microwave heating (MWH) has been explored as an energy-efficient approach for recovering the residual solvent from the gangue. In this work, the MWH of solvent-water systems present in the pores of NAE gangue was studied using molecular dynamics simulations. In particular, the temperatures changes of water and the NAE solvent cyclohexane were investigated under an external electric field, representative of MWH. The two liquids were simulated in monophasic and biphasic unit cells, applying an electric field with strengths of 0.01 V/nm and 3 V/nm and frequencies of 915 MHz, 2.45 GHz, and 100 GHz under constant pressure or constant volume condition. It was found that the applied electric field heated up the water molecules, due to their high dipole moment, but did not heat the nonpolar cyclohexane molecules that were transparent to the electric field. The simulations of biphasic systems showed that the temperatures of both water and cyclohexane increased, indicating that water was heated by the electric field and its thermal energy was transferred to the cyclohexane. Among the electric field strengths and frequencies tested, only the strength of 3 V/nm provided sufficient heating for each frequency applied, while the strength of 0.01 V/nm was too weak and the frequency of 100 GHz caused rapid heating. The heating mechanism was further explored using the rotational autocorrelation function and diffusion coefficient. It was found that the MWH increased both rotational motion and diffusion. The temperature increase and molecular motion were correlated to explain the microwave heating and thermal transfer. The study provides a possible explanation of the solvent recovery from the gangue generated from NAE using MWH.

• Subjects / Keywords

  • Bitumen
  • Microwave
  • Simulation
  • Heating

• Graduation date

  Spring 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-qdkn-cf18

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.