US 11,719,656 B2
Variable gap thermal conductivity apparatus and method
Ryan C. Gallagher, Oak Ridge, TN (US); Nora D. Ezell, Oak Ridge, TN (US); Austin S. Chapel, Oak Ridge, TN (US); and Nicholas G. Russell, Oak Ridge, TN (US)
Assigned to UT-BATTELLE, LLC, Oak Ridge, TN (US)
Filed by UT-Battelle, LLC, Oak Ridge, TN (US)
Filed on Sep. 24, 2021, as Appl. No. 17/484,566.
Claims priority of provisional application 63/086,932, filed on Oct. 2, 2020.
Prior Publication US 2022/0107281 A1, Apr. 7, 2022
Int. Cl. G01N 25/18 (2006.01); G01K 17/08 (2006.01); G01N 25/20 (2006.01)
CPC G01N 25/18 (2013.01) [G01K 17/08 (2013.01); G01N 25/20 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An apparatus for measuring thermal conductivity of a fluid specimen, the apparatus comprising:
a test chamber to be at least partially enclosed in a furnace that is maintained at a predetermined temperature, the test chamber having a solid base and a solid wall arranged to hold the fluid specimen on a flat surface of the base, wherein the base comprises:
cooling channels disposed inside the base at a predetermined distance from the flat surface of the base, the cooling channels configured to cool a first side of the fluid specimen adjacent to the flat surface of the base, and
a first set of temperature sensors disposed inside the base and distributed between the flat surface of the base and the cooling channels, the first set of temperature sensors configured to sense a temperature of the cooled first side of the fluid specimen and configured to sense a temperature through the base;
a moveable head having a flat surface, the head disposed inside the test chamber such that the flat surface of the moveable head is parallel to and spaced apart by a controllable gap from the flat surface of the base such that the fluid specimen fills the gap, the head comprising:
a heater module disposed inside and adjacent to the flat surface of the head, the heater module configured to heat a second side of the fluid specimen, opposite of the first side of the fluid specimen, adjacent to the flat surface of the head, and
a second set of temperature sensors disposed inside the head and distributed along the flat surface of the head, the second set of temperature sensors being configured to sense a temperature of the heated second side of the fluid specimen;
an actuator module mechanically coupled with the movable head to cause, during operation of the apparatus, the head to move relative to the flat surface of the base to modify the gap between the flat surface of the head and the flat surface of the base;
a distance sensor configured to measure a size of the gap between the flat surface of the head and the flat surface of the base; and
a controller module communicatively coupled with the actuator module, the distance sensor, the heater module, and the first and second set of temperature sensors, the controller module configured to:
a) determine a heater power (Q) based on a configuration of the heater module,
b) instruct the actuator module to translate the movable head to set the gap between the flat surface of the head and the flat surface of the base to a sequence of different gap sizes,
c) for each gap size from among the different gap sizes, obtain the gap size from the distance sensor and determine a temperature difference (dT) between the heated-side temperature obtained from the second set of temperature sensors, and the cooled-side temperature obtained from the first set of temperature sensors, and
d) determine the thermal conductivity of the fluid specimen based on the determined temperature differences for the corresponding gap sizes and based on the determined heater power.