Thermal Properties and Characterization of Methane Hydrates

• Main Author: Rosenbaum, Eilis Jill
• Format: Thesis
• Language: English
• Published: 2005
• Subjects: Methane hydrate
• Online Access: http://d-scholarship.pitt.edu/10310/; http://d-scholarship.pitt.edu/10310/1/rosenbaum_eilis_June2003.pdf

Renewed interest in methane hydrates as a potential, unconventional energy source has prompted investigation into their thermal properties, which are necessary to determine heat flow through the hydrate for resource production. In this investigation thermal property measurements have been made on unconsolidated pure methane hydrate samples formed in a high-pressure variable-volume viewcell (HVVC). Using a transient plane source (TPS) technique, a single measurement was used to simultaneously determine the thermal conductivity and thermal diffusivity of the methane hydrate inside the viewcell. A vessel was designed to contain the sample around the TPS for thermal property measurements while inside the HVVC. The vessel was successful in containing the sample during the hydrate formation experiments and its design made it possible to recover a methane hydrate sample, which was analyzed with Raman spectroscopy. The striking quality of methane hydrate is that its thermal conductivity is much lower than ice, despite its structural similarities to ice. The thermal conductivity of pure methane hydrate for a temperature range of 264 K to 277 K and pressure range of 11.6 MPa to 13.0 MPa, respectively, can be described by k = (-0.0034 T + 1.2324) W/mK, where T is in Kelvin. The average of the thermal conductivity values within this range of temperatures and pressures is k = 0.30 +/- 0.02 W/mK. The sample was recovered and analyzed with Raman spectroscopy, confirming that the sample was pure hydrate.The thermal diffusivity of methane hydrate has only been reported by one other investigator in preliminary experiments. The thermal diffusivity of methane hydrates determined in the work reported herein for a temperature range of 264 K to 277 K and pressure range of 11.6 MPa to 13.0 MPa, respectively, is diff. = (2.59 +/- 0.16) x 10^-7 m2/s. The thermal diffusivity can also be described by diff. x 10^7ƒn = (0.0005 T + 2.4424) m2/s where T is in Kelvin.