Measurement Apparatus

Thermal property measurement vessel schematic (not to scale).  Cylindrical hydrate samples are formed around a thermal probe (enlarged to show detail). Thermal properties are calculated from the sample temperature change in response to heat from the heater wire.

The HyFI test system is designed to run at pressures in excess of 3000 psi (~20 MPa).  To handle high test pressures, HyFI utilizes custom-designed pressure vessels and sensors in combination with commercially available pumps, valves, tubing and sensors, as shown in the HyFI schematic.

Measurements are made in a physical properties measurement vessel shown in the lower left-center of the HyFI schematic.  To date, we have been measuring thermal properties using an epoxy-filled needle probe with a 1.6 mm outer diameter stainless-steel sheath containing a 4 kW thermistor and a heater wire loop with resistance R = 350 W/m. The 160 mm long probe is inserted through an o-ring seal into a pressure vessel so measurements can be made up to the vessel's pressure limit of 105 MPa.

Needle Probe (Click for larger image)

An HP34970A data acquisition unit logs the thermistor output while an HP6177C DC current source supplies a constant current to the heater wire. The pressure vessel is immersed in a denatured alcohol bath connected to a Polyscience bath circulator, which maintains isothermal conditions at selected temperatures during the experiment. The cylindrical sample is initially 41 mm in diameter, 135 mm in length, with the thermistor located 50 mm below the top of the sample. The sample is jacketed in a 0.1 mm thick Teflon liner, and can be radially compacted around the axial probe by pressurizing the space surrounding the liner with silicone oil using an automated Quizix pump to 34.5 MPa, and by a manual pump for compaction pressures up to 105 MPa.