Apparatus and method for regulating temperature in a cryogenic test chamber

• US 4,848,093 A
• Filed: 09/15/1988
• Issued: 07/18/1989
• Est. Priority Date: 08/24/1987
• Status: Expired due to Term

• Current Assignee: Quantum Design, Inc.
• Original Assignee: Quantum Design, Inc.
• Inventors: Sager, Ronald E., Simmonds, Michael B.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US07/244,947
• Time in Patent Office: 306 Days
• Field of Search: 62/49, 62/55, 62/514 R
• US Class Current: 62/49.1
• CPC Class Codes: F17C 13/026 having the temperature as the parameter
• CPC Class Codes: F17C 2203/0621 with three layers
• CPC Class Codes: F17C 2205/037 Quick connecting means, e.g. couplings
• CPC Class Codes: F17C 2221/017 Helium
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/035 High pressure (>10 bar)
• CPC Class Codes: F17C 2250/0439 Temperature
• CPC Class Codes: F17C 2250/0631 Temperature
• CPC Class Codes: F17C 2250/0636 Flow or movement of content
• CPC Class Codes: F17C 2260/02 Improving properties related to fluid or fluid transfer
• CPC Class Codes: F17C 6/00 Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases

Abstract

An apparatus and method for regulating the temperature in a cryogenic test chamber. Liquid helium is drawn into a test chamber located in a cryogenic vessel through a capillary tube which is spaced apart from the test chamber. The capillary tube is thermally insulated from the liquid helium. In a high temperature mode, a heater element heats the capillary tube to a temperature just high enough to boil the liquid helium as the helium is drawn through the capillary tube into the test chamber, thereby insuring that only gaseous helium enters the test chamber and preventing any tendency of the temperature in the test chamber to oscillate when the test chamber is warmed to temperature only slightly higher than the temperature of the liquid helium. In a low temperature mode the heater element heats the capillary tube sufficiently to substantially prevent any helium from flowing into the test chamber, thereby facilitating cooling of the test chamber to temperature below the temperature of the liquid helium by evacuating the test chamber until the liquid therein boils at the desired temperature.

Claims

1. Temperature regulation apparatus comprising:

a cryogenic vessel adapted to contain a fluid in a liquid phase at a cryogenic temperature;

a capillary tube located in the cryogenic vessel;

capillary heater means in thermal communication with the capillary tube;

means defining a test chamber in the cryogenic vessel in spaced-apart relation to the capillary tube;

fluid flow means defining a fluid flow path between the capillary tube and the test chamber;

test chamber heater means in thermal communication with the test chamber; and

evacuation means operative to partially evacuate the test chamber to draw fluid from the cryogenic vessel through the capillary tube and the fluid flow means into the test chamber,

the apparatus being operative to regulate the temperature in the test chamber by maintaining the fluid therein at a desired temperature and

operable in a high temperature mode wherein the capillary heater means is operative to warm the capillary tube sufficiently to boil any liquid flowing therein and thereby to change the phase of the fluid from liquid to gas as the fluid is drawn through the capillary tube into the test chamber and wherein the test chamber heater means is operative to warm any gas in the test chamber to a desired temperature and thereafter to maintain the gas at said temperature,

operable in a medium temperature mode wherein the fluid remains in its liquid phase without undergoing any net change in temperature as it is drawn through the capillary tube into the test chamber and is thereby maintained at the cryogenic temperature in the test chamber, and

operable in a low temperature mode wherein the fluid remains in its liquid phase as it is drawn through the capillary tube into the test chamber until a reservoir of liquid has accumulated in the test chamber, the capillary heater means thereupon being operative to warm the capillary tube sufficiently to substantially prevent the flow of any more fluid through the capillary tube, and the evacuation means thereupon being operative to reduce the pressure in the test chamber sufficiently to lower the boiling temperature of the liquid in the chamber to a desired temperature and thereafter to evacuate any gas produced as the liquid boils and thereby to maintain the liquid at said temperature.

2. Apparatus according to claim 1 wherein the cryogenic temperature is about 4.2 degrees Kelvin.

3. Apparatus according to claim 2 wherein the desired temperature when operating in the low temperature mode includes any temperature between about 1.5 degrees Kelvin and about 4.2 degrees Kelvin.

4. Apparatus according to claim 2 wherein the desired temperature when operating in the high temperature mode includes any temperature between about 4.2 degrees Kelvin and about 20 degrees Kelvin.

5. Apparatus according to claim 1 wherein the capillary heater means comprises a heater element, a temperature sensor, and control means responsive to the sensor to control the quantity of heat provided by the heater element and thereby to raise the temperature of the capillary tube to a desired value.

6. Apparatus according to claim 5 wherein the control means is operative in the high temperature mode to raise the temperature of the capillary tube to about 10 degrees Kelvin.

7. Apparatus according to claim 6 wherein the temperature sensor comprises a material which conducts a electric current in a superconducting mode at any temperature less than about 10 degrees Kelvin and wherein the control means determines the temperature of the capillary tube by determining whether the sensor is in the superconducting mode.

8. Apparatus according to claim 5 wherein the control means is operative in the low temperature mode to raise the temperature of the capillary tube to about 300 degrees Kelvin.

9. Apparatus according to claim 1 and further comprising a test vessel adapted to receive and enclose a test specimen and locatable in the test chamber to maintain the temperature of the specimen approximately equal to the temperature in the test chamber.

10. Apparatus according to claim 1 and further comprising test chamber isolation means to thermally isolate the test chamber.

11. Apparatus according to claim 1 wherein the capillary tube has an inner diameter of about 0.1 millimeters and a length of about ten millimeters.

12. Apparatus according to claim 1 and further comprising capillary isolation means to thermally isolate the capillary tube.

13. Apparatus according to claim 12 wherein the capillary isolation means comprises an impedance capsule defining an elongated impedance chamber having an inner diameter of about 1 millimeter and a length of about 100 millimeters.

14. Apparatus according to claim 13 wherein the fluid flow means comprises a coupling tube having an outer diameter of about 0.6 millimeters.

15. In cryogenic apparatus of the kind including a cryogenic vessel adapted to contain a fluid in a liquid phase at a cryogenic temperature, means defining a test chamber in the cryogenic vessel, test chamber heater means in thermal communication with the test chamber, an opening to admit fluid from the cryogenic vessel to the test chamber, evacuation means operative to partially evacuate the test chamber to draw fluid from the cryogenic vessel through the opening into the test chamber, and a test vessel adapted to receive and enclose a test specimen and located in the test chamber to maintain the temperature of the specimen approximately equal to the temperature in the test chamber, an improvement for regulating the temperature in the test chamber by maintaining the fluid therein at a desired temperature, the improvement comprising:

an impedance capsule located in the cryogenic vessel in spaced apart relation to the test chamber and defining an elongated impedance chamber;

a capillary tube located in the impedance chamber;

capillary heater means in thermal communication with the capillary tube; and

a coupling tube having a diameter larger than that of the capillary tube and in fluid communication with the capillary tube and extending out of the impedance chamber and in fluid communication with the opening to the test chamber,

operable in a high temperature mode wherein the capillary heater means is operative to warm the capillary tube sufficiently to boil any liquid flowing therein and thereby to change the phase of the fluid from liquid to gas as the fluid is drawn through the capillary tube into the test chamber and wherein the test chamber heater means is operative to warm any gas in the test chamber to a desired temperature and thereafter to maintain the gas at said temperature,

operable in a medium temperature mode wherein the fluid remains in its liquid phase without undergoing any net change in temperature as it is drawn through the capillary tube into the test chamber and is thereby maintained at the cryogenic temperature in the test chamber, and

operable in a low temperature mode wherein the fluid remains in its liquid phase as it is drawn through the capillary tube into the test chamber until a reservoir of liquid has accumulated in the test chamber, the capillary heater means thereupon being operative to warm the capillary tube sufficiently to substantially prevent the flow of any more fluid through the capillary tube, and the evacuation means thereupon being operative to reduce the pressure in the test chamber sufficiently to lower the boiling temperature of the liquid in the chamber to a desired temperature and thereafter to evacuate any gas produced as the liquid boils and thereby to maintain the liquid at said temperature.

16. An improvement according to claim 15 wherein the desired temperature when operating in the low temperature mode includes any temperature between about 1.5 degrees Kelvin and about 4.2 degrees Kelvin.

17. An improvement according to claim 15 wherein the desired temperature when operating in the high temperature mode includes any temperature between about 4.2 degrees Kelvin and about 20 degrees Kelvin.

18. An improvement according to claim 15 wherein the capillary heater means comprises a heater element, a temperature sensor, and control means responsive to the sensor to control the quantity of heat provided by the heater element and thereby to raise the temperature of the capillary tube to a desired value.

19. An improvement according to claim 18 wherein the control means is operative in the high temperature mode to raise the temperature of the capillary tube to about 10 degrees Kelvin.

20. An improvement according to claim 19 wherein the temperature sensor comprises a material which conducts an electric current in a superconducting mode at any temperature less than about 10 degrees Kelvin and wherein the control means determines the temperature of the capillary tube by determining whether the sensor is in the superconducting mode.

21. An improvement according to claim 18 wherein the control means is operative in the low temperature mode to raise the temperature of the capillary tube to about 300 degrees Kelvin.

22. An improvement according to claim 15 wherein the capillary tube has an inner diameter of about 0.1 millimeters and a length of about ten millimeters.

23. An improvement according to claim 15 wherein the coupling tube has an outer diameter of about 0.6 millimeters and wherein the impedance chamber has an inner diameter of about one millimeter.

24. In cryogenic apparatus of the kind including a cryogenic vessel adapted to contain a fluid in a liquid phase at a cryogenic temperature, means defining a test chamber in the cryogenic vessel, and a test vessel adapted to receive and enclose a test specimen and located in the test chamber to maintain the temperature of the specimen approximately equal to the temperature in the test chamber, a method of regulating the temperature in the test chamber by drawing fluid into the test chamber and maintaining the fluid at a desired temperature, the method comprising:

selecting a mode of operation;

drawing fluid from the cryogenic vessel into the test chamber through a fluid flow path having a capillary tube by partially evacuating the test chamber;

if a high temperature mode has been selected, applying sufficient heat to the capillary tube to boil any liquid flowing therein and thereby to change the phase of the fluid from liquid to gas as the fluid is drawn through the capillary tube into the test chamber, and applying sufficient heat to the gas in the test chamber to warm the gas to the desired temperature and thereafter to maintain the gas at said temperature;

if a medium temperature mode has been selected, maintaining the fluid in its liquid phase without any net change of temperature as the fluid is drawn through the capillary tube into the test chamber and thereby maintaining the fluid in the test chamber at the cryogenic temperature; and

if a low temperature mode has been selected, maintaining the fluid in its liquid phase as the fluid is drawn through the capillary tube into the test chamber until a reservoir of liquid has accumulated in the test chamber, applying sufficient heat to the capillary tube to substantially prevent the flow of any more fluid through the capillary tube, reducing the pressure in the test chamber sufficiently to lower the boiling temperature of the liquid in the test chamber to a desired temperature, and evacuating any gas produced as the liquid boils to maintain the liquid at said temperature.

25. A method according to claim 24 wherein the desired temperature when operating in the low temperature mode includes any temperature between about 1.5 degrees Kelvin and about 4.2 degrees Kelvin.

26. A method according to claim 24 wherein the desired temperature when operating in the high temperature mode includes any temperature between about 4.2 degrees Kelvin and about 20 degrees Kelvin.

27. A method according to claim 24 wherein in the high temperature mode the capillary tube is heated to about 10 degrees Kelvin.

28. A method according to claim 24 wherein in the low temperature mode the capillary tube is heated to about 300 degrees Kelvin.