Quenched temperature insensitive cryogenic test chamber allowing relative motion

Abstract

The cryogenic test apparatus includes a housing with a cryogenic chamber disposed therein. An upper channel is disposed around the cryogenic chamber and configured to receive a cryogen. A lower channel is disposed below the upper channel and configured to receive a cryogen from the upper channel. As the cryogen flows through the cryogenic test apparatus, it contacts an exterior of the cryogenic chamber. The cryogenic chamber is unsealed and configured to receive a gas to create a positive pressure within the cryogenic chamber.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 63 / 335,141, filed April 26, 2022, the disclosure of which is incorporated by reference in its entirety.

[0002] STATEMENT REGARDING FEDERALLY FUNDED RESEARCH This invention was made with Government support under Award Nos. 80NSSC21C0134 and 80NSSC21C0137 awarded by NASA. The United States Government has certain rights in this invention.

[0003] FIELD OF THE DISCLOSURE This disclosure relates generally to cryogenic systems and more particularly, but not exclusively, to methods and systems for quenching a test chamber. [Background technology]

[0004] This section provides background information to facilitate a better understanding of the various aspects of the present disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

[0005] There is a great need for cryogenic testing equipment where samples are in relative motion, such as tribological and mechanical testing (i.e., fatigue, wear, fretting, and adhesion testing). Prior systems are limited in the temperatures they can achieve. Furthermore, the time required to reach these limiting temperatures can be 90 minutes or more, both of which consume more cryogen and limit the amount of testing that can be performed.

[0006] A more complete understanding of the subject matter of the present disclosure may be obtained by reference to the following detailed description when taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a cryogenic test chamber according to an aspect of the present disclosure. [Diagram 2] FIG. 2 is a close-up view of a cryogenic test chamber according to an aspect of the present disclosure. [Diagram 3] FIG. 2 is a cross-sectional side view of a cryogenic test chamber according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] It should be understood that the following disclosure provides many different embodiments or examples for implementing different functions of various embodiments. To simplify the disclosure, specific examples of components and arrangements are described below. These are, of course, merely examples and are not intended to be limiting. The section headings used herein are for organizational purposes and should not be considered as limiting the subject matter described. Reference is now made to more specific embodiments of the disclosure and data supporting such embodiments. However, it should be noted that the following disclosure is merely for illustrative purposes and is not intended to limit the scope of the claimed subject matter in any way.

[0009] The cryogenic chamber disclosed herein is for quenching a chamber (e.g., for mechanical testing equipment) to cryogenic environmental conditions without directly exposing the test sample to a cryogenic coolant (known as a dry test condition). Conventional cryogenic testing equipment cools the test chamber using a cryogen, such as liquid nitrogen, which acts as a heat exchanger within the chamber to reduce the ambient temperature by expansion and evaporation. The cryogenic chamber disclosed herein flows the cryogen through a series of unconnected channels in a non-sealed environmental chamber at positive pressure, allowing for high mass flow of cryogen and improved cooling performance without the need for significant insulation or sealing. The positive pressure prevents air and moisture from entering the chamber. The positive pressure is achieved by introducing room temperature cryogen liquid and high purity gas into the chamber through separate inlets. The high purity gas is introduced at room temperature in close proximity to the test sample using a sparger, while the cryogen liquid inlet is kept separate by a bulkhead and a series of diversion channels. The temperature of the chamber can be controlled by balancing these two flows.

[0010] The combination of separate gas and liquid flows, a series of fixed and floating channels, and a non-sealed chamber at positive pressure is a novel concept that allows rapid, efficient, and stable cooling to the entire theoretical temperature range (i.e., from -196°C to room temperature for liquid nitrogen). Liquid helium operations have been implemented, allowing test equipment to be cooled well below its current accurate measurement range (-200°C).

[0011] The cryogenic chambers disclosed herein are useful for multiple applications. Their utility has been directly demonstrated for cryogenic tribological testing on a tribometer. A tribometer is a machine used to measure the tribological performance of engineered systems, including the friction, wear, and lubrication properties of bearing materials and lubricants. Tribological testing using tribometers is very important in the research and development of any kind of bearing material or lubricant. A typical tribometer has a fixed part and a moving part that allows two test samples to be in contact with each other and to rub against each other. Most tribometers can only test materials and lubricants under ambient conditions. However, to more accurately examine tribological performance, the best approach is to use a tribometer that simulates the actual operating conditions of the material. State-of-the-art temperature-controlled commercial tribometers can reach test temperatures of -120°C to -160°C.

[0012] The cryogenic chamber disclosed herein has been shown to reduce typical tribometer test temperatures well below this limit using direct cooling of the test chamber by introduction of a cryogen liquid. Specifically, when using liquid nitrogen, quenching has been measured at multiple sampling points over the entire temperature range from room temperature to -196°C.

[0013] Second, the cryogenic chambers disclosed herein are highly relevant for industrial testing applications. Materials testing in cryogenic environments is an emerging possibility for liquefied natural gas (LNG) and refrigerant storage and distribution, superconductivity, and most space technologies. A few examples include cooling systems used in magnetic resonance imaging (MRI), liquefied hydrogen fueled engines, and mechanical components for future extraterrestrial NASA missions / commercial space applications. Numerous cryogenic material tests, such as sliding friction, wear, fatigue life, tensile, and fracture toughness, are in high demand from public and private R&D groups such as NASA, SpaceX, etc. The rapid and inexpensive testing capabilities provided by the cryogenic chambers disclosed herein are needed to develop new mechanisms, materials, and lubricants (solid, liquid, gas, or mixtures) under extreme temperatures and controlled atmospheres. The versatile nature of the cryogenic chambers disclosed herein allows for the performance of a variety of mechanical testing instruments (i.e., tensile, fatigue, fracture) where the test samples may be in relative motion.

[0014] By cooling all parts of the system in a non-sealed chamber, significantly higher coolant flow rates can be achieved and temperatures are stable and consistent. This is done without contacting the sample with the coolant. The setup is fully compatible with heated test chambers and allows for temperature sweep experiments (i.e., from cryogenic conditions to extremely high temperature conditions, e.g., 1000°C). The cryochambers disclosed herein do not require vacuum insulation or exotic materials, thereby reducing the cost, complexity, space required, and time required for each test. However, it is understood that such insulation can be added to further reduce the temperatures obtainable with the cryochambers disclosed herein.

[0015] The cryogenic chambers disclosed herein are extremely flexible for different testing requirements and are a dramatic improvement over state-of-the-art equipment in terms of both usability and availability. Most cryogenic mechanical testing equipment requires large, complex, and expensive insulated environmental chambers with indirect cooling, which reduces flexibility and usability.

[0016] Cryogen liquid is pumped from a pressurized liquid tank to the test equipment through a direct insulated line, allowing the test chamber to be at a positive pressure. The liquid feed line includes a vacuum insulated section where the cryogen remains in a liquid state and a non-vacuum insulated section where partial expansion and evaporation occurs. Partially evaporated cryogen is introduced into the chamber and into a fixed upper channel. The cryogen overflows from the upper channel and cascades into a lower channel in contact with the test sample holder. The lower channel is not fixed and is free to rotate and move with the sample holder about the axis of the test chamber.

[0017] FIG. 1 is a cross-sectional view of a cryogenic test chamber 100 according to an embodiment of the present disclosure. FIG. 2 is a close-up view of the cryogenic test chamber 100 with cryogen and gas flowing therethrough according to an embodiment of the present disclosure. With collective reference to FIGS. 1 and 2, the cryogenic test chamber 100 includes a housing 102 in which a test instrument 104 is housed. The test instrument 104 may be a tribometer or other piece of test instrument. The test instrument 104 resides in a chamber 106 that is temperature controlled and isolated from the housing 102. A tube 108 extends into the chamber 106 and delivers a gas (e.g., high purity gas at room temperature) to the volume surrounding the test instrument 104. The gas may be, for example, nitrogen, helium, methane, argon, etc. A tube 110 extends into the housing 102 and delivers a cryogen to an upper channel 112. The cryogen may be, for example, liquid nitrogen, liquid helium, liquid oxygen, liquefied natural gas, etc. The cryogen delivered to the upper channel 112 is kept separate from the chamber 106 to maintain a dry testing environment.

[0018] The upper channel 112 is ring-shaped and surrounds the chamber 106. An inner wall 118 of the upper channel 112 is spaced slightly from the outer wall of the chamber 106 to form an annular passage 120 therebetween, allowing the chamber 106 to rotate relative to the upper channel 112. Cryogen is supplied to the upper channel 112 via a tube 110 and spills down through the annular passage 120 into the lower channel 114. The upper channel 112 includes a top wall 116 that extends above the top of the wall 118 and is adjacent to but spaced from the exterior of the chamber 106, allowing the chamber 106 to rotate relative to the upper channel 112. The top wall 116 is adjacent to the exterior of the chamber 106 and helps direct the cryogen into the annular passage 120. Wall 118 is sized to extend almost all the way to top wall 116, leaving a small gap through which cryogen can exit upper channel 112 and enter annular passage 120. The cryogen flows through annular passage 120 and collects in lower channel 114 (see FIG. 2).

[0019] The lower channel 114 is ring-shaped and surrounds the chamber 106. In some embodiments, the lower channel 114 is attached to the chamber 106 and rotates or moves with it. In other embodiments, the lower channel 114, like the upper channel 112, is separate from the chamber 106. In such embodiments, it may be necessary to include a seal between the chamber 106 and the base of the housing 102 to prevent cryogen from exiting the housing 102 between the lower channel 114 and the chamber 106. A lower portion 124 of the lower channel 114 acts as a seal between the lower channel 114 and the chamber 106 to prevent the cryogen from escaping therefrom. Cryogen present in the lower channel 114 contacts the exterior of the chamber 106. The lower channel 114 includes a tapered edge 122 that helps to retain the cryogen within the lower channel 114 during operation of the test instrument 104 and directs any excess cryogen present on the top of the tapered edge 122 into the lower channel 114. In some embodiments, the lower channel 114 has a tapered profile with a diameter that increases from the top of the lower channel 114 towards the bottom of the lower channel 114 .

[0020] The upper and lower channels 112, 114 are designed such that the cryogen flowing therethrough contacts and cools a substantial portion of the exterior of the chamber 106. In comparison to prior systems, the cryogenic test chamber 100 prevents the cryogen from contacting the test equipment 104, allowing for more consistent test conditions within the chamber 106.

[0021] The cryogenic test chamber 100 allows for more rapid cooling compared to prior systems due to the increased cryogen mass flow rate allowed as a result of the open system design (i.e., compared to closed system designs). As the cryogen flows from the upper channel 112 to the lower channel 114, some cryogen is lost to evaporation. If too much cryogen enters the cryogenic test chamber 100, the excess cryogen is allowed to exit the lower channel 114 via the radial passage 126 formed between the upper channel 112 and the lower channel 114. During normal operation, the amount of cryogen supplied to the cryogenic test chamber 100 is balanced by the amount of cryogen that evaporates. This limits the amount of cryogen that spills out of the system. The increased mass flow rate provided by the cryogenic test chamber 100 increases the cooling efficiency of the system. The increased cooling efficiency reduces the time required to reach temperatures below -160°C, reduces the amount of cryogen required, and allows the system to reach lower temperatures than prior systems. The present system is also distinguished from prior systems in that it uses gravity driven flow and does not require a pump to move the cryogen through the system.

[0022] Injection of room temperature high purity gas into the chamber 106 provides several benefits over prior systems, including better temperature control of the system and improved control of the environmental conditions within the chamber 106 to prevent condensation.

[0023] In various embodiments, the upper and lower channels 112, 114 can be 3D printed from a variety of materials. The material only needs to be able to withstand the temperature of the cryogen being used. In contrast, the chamber 106 is made from a material that has good heat transfer properties, which cools the interior of the chamber 106 more efficiently.

[0024] 3 is a cross-sectional side view of a cryogenic test chamber 200 according to an embodiment of the disclosure. Cryogenic test chamber 200 is similar to cryogenic test chamber 100, and like parts have been given like part numbers where appropriate. Cryogenic test chamber 200 is designed for use with a test fixture 204, shown as a tensile tester. Cryogenic test chamber 200 includes a housing 202 configured to house a chamber 206, an upper channel 212, and a lower channel 214. Chamber 206 is configured to enclose test fixture 204. Tube 208 extends into chamber 206 and delivers gas (e.g., high purity gas at room temperature) to chamber 206. Tube 210 extends into housing 202 and delivers cryogen to upper channel 212. The upper channel 212 includes an upper wall 216 that helps retain the cryogen and direct the flow of cryogen from the upper channel 212 to the lower channel 214 via an annular passage 220 formed between a wall 218 of the upper channel 212 and an outer wall of the chamber 206. The lower channel 214 includes a tapered edge 222 that helps retain the cryogen within the lower channel 214 and direct any excess cryogen present on the top of the tapered edge 222 into the lower channel 214 during operation of the test instrument 204. In some embodiments, the lower channel 214 has a tapered profile with a diameter that increases from the top of the lower channel 214 to the bottom of the lower channel 214. If too much cryogen enters the cryogenic test chamber 200, the excess cryogen is allowed to exit the lower channel 214 via a radial passage 226 formed between the upper channel 212 and the lower channel 214. An important difference between chamber 100 and chamber 200 is the dimensions. In the embodiment of Figure 3, upper channel 212 and lower channel 214 are axially longer to accommodate the dimensions of chamber 206. Aside from the dimensional differences, chambers 100 and 200 are similar and operate in a similar manner.

[0025] Experimental Testing Tests using liquid nitrogen have demonstrated rapid cooling performance. Prior to the implementation of the cryogenic chamber disclosed herein, the tribometer was able to reach an equilibrium temperature of -150°C in 90 minutes using a metered nitrogen flow to avoid flooding the chamber. The present design allows the system to reach a temperature of -196°C after 7 minutes of nitrogen burst flow. This cooling performance has been reliably demonstrated using a cryoprobe configured to sample the chamber atmosphere, the proximity temperature, and the contact temperature. Besides the improved performance, the consumption of cryogen is also reduced due to the dramatic reduction in cooling time per test cycle. Since the introduced cryogen, e.g., nitrogen, is in liquid phase, ultra-fast cooling to cryogenic temperatures is achieved by an initial burst of cold nitrogen gas in the chamber until the chamber temperature is sufficiently cooled in a dry state (free of moisture or other contaminants from the ambient air, as determined by a gas detector). This liquid is kept separate from the test sample, but is brought into direct contact with the outer surface of the sample holder. Thus, heat absorption and evaporation can occur within the innermost test volume independent of phase change, resulting in further reduction in temperature. The continuous introduction of a mixed phase, or equilibrium of liquid and gas coolant, into the test environment and through the sample holder ensures that the test atmosphere is well controlled and that testing is performed in dry conditions, regardless of the use of a non-sealed chamber.

[0026] Example of working example Two identical specimens were tensile tested at room temperature and at -150°C using a cryogenic test chamber according to an embodiment of the present disclosure. The first specimen was loaded into the tensile tester and tensile tested at room temperature. The second specimen was loaded into the tensile tester and the cryogenic test chamber was used to cool the second specimen to -150°C, then tensile tested the second specimen. The cooling process took approximately 2 minutes and 29 seconds (compared to approximately 40 minutes for other machines). Table 1 below shows the results of the tensile tests. TIFF2025514332000002.tif69170

[0027] Although various embodiments of the present disclosure are illustrated in the accompanying drawings and described in the above detailed description, it is understood that the disclosure is not limited to the embodiments disclosed herein, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the disclosure as set forth herein.

[0028] The term "substantially" is defined as to a large extent, but not necessarily all, of what is specified, as understood by one of ordinary skill in the art. In any of the disclosed embodiments, the terms "substantially," "approximately," "generally," and "about" may be substituted with "within a [percentage] of what is specified," (where the percentages include 0.1, 1, 5, and 10).

[0029] The above outlines the functions of some embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should understand that they may readily use the present disclosure as a basis for designing or modifying other processes and structures to carry out the same purpose and / or achieve the same advantages of the embodiments introduced herein. Those skilled in the art should also recognize that such equivalent structures do not depart from the spirit and scope of the present disclosure, and that those skilled in the art may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. The scope of the present invention should be determined solely by the language of the claims that follow. The term "comprising" in the claims shall mean "including at least," such that the recited list of elements in the claims is an open group. The terms "a," "an," and other singular terms shall include their plural forms unless expressly excluded.

[0030] Conditional language used herein, including "can," "might," "could," "for example," and the like, is generally intended to convey that certain embodiments include certain features, elements, and / or states, but other embodiments do not, unless expressly stated otherwise or understood otherwise within the context in which it is used. Thus, such conditional language is not generally intended to imply that the features, elements, and / or states are somehow required in one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or states are included or implemented in any particular embodiment, with or without creator input or prompting.

[0031] Although the above detailed description shows, describes and points out novel features applied to various embodiments, it is understood that various omissions, substitutions and changes in the form and details of the illustrated devices or algorithms may be made without departing from the spirit of the present disclosure. As will be appreciated, the processes described herein may be embodied in forms that do not achieve all of the functions and benefits described herein, since some functions may be used or practiced separately from others. The scope of protection is determined by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalence of the claims are embraced within their scope.

[0032] While various embodiments of the method and apparatus of the present invention are illustrated in the accompanying drawings and described in the detailed description above, it is understood that the invention is not limited to the disclosed embodiments, but that numerous rearrangements, modifications, and substitutions are possible without departing from the spirit of the invention as described herein.

Claims

1. A chamber; an upper channel surrounding the chamber and configured to receive a cryogen; a lower channel surrounding said chamber; a cryogenic test chamber comprising:

2. The cryogenic testing chamber of claim 1 , wherein the upper channel is not connected to the chamber such that the chamber can move relative to the upper channel.

3. The cryogenic testing chamber of claim 1 , wherein the lower channel is connected to the chamber and rotates with the chamber.

4. The cryogenic testing chamber of claim 1 further comprising an annular passage formed between an inner wall of the upper channel and an outer wall of the chamber.

5. The cryogenic testing chamber of claim 4 , wherein the upper channel includes an upper wall extending above a top of the inner wall.

6. The cryogenic testing chamber of claim 1 , wherein the lower channel includes an upper wall having a tapered edge.

7. 10. The cryogenic testing chamber of claim 1 further comprising a first tube for supplying a cryogen and a second tube for supplying a gas.

8. The cryogenic testing chamber of claim 7 , wherein the first tube extends into the first channel.

9. The cryogenic testing chamber of claim 7 , wherein the second tube extends into the chamber.

10. The cryogenic testing chamber of claim 1 further comprising a test apparatus disposed within said chamber.

11. The cryogenic test chamber of claim 10 , wherein the test device is a tribometer.

12. The cryogenic testing chamber of claim 10 , wherein the testing device is a tensile testing machine.

13. The cryogenic testing chamber of claim 1 , wherein the upper and lower chambers are configured to allow cryogen delivered to the upper channel to directly contact sides of the chambers.

14. 1. A method of cooling a cryogenic testing chamber, comprising: supplying a cryogen to an upper channel surrounding the chamber; supplying a gas to the chamber; Including, the cryogen flows from the upper channel to the lower channel through an annular passage formed between an inner wall of the upper channel and the chamber; method.

15. The method of claim 14 , further comprising operating a test device disposed within the chamber.

16. The method of claim 14, wherein the chamber is cooled to a temperature below -160°C.

17. 15. The method of claim 14, wherein the chamber is cooled from room temperature to below -160°C in less than 8 minutes.

18. The method of claim 14 , wherein the gas comprises a high purity gas at room temperature.

19. The method of claim 14 , wherein the supplying of the gas maintains a positive pressure in the chamber.

20. 1. A method of cooling a cryogenic testing chamber, comprising: directing a flow of the cryogen through the first channel and the second channel such that the cryogen contacts an exterior wall of the chamber; directing a gas flow into the chamber to create a positive pressure in the chamber; Including, The chamber is not sealed. method.

21. The method of claim 20 , further comprising operating a test device disposed within the chamber.

22. 21. The method of claim 20, wherein the first channel is not connected to the chamber such that the chamber can rotate relative to the first channel.

23. 21. The method of claim 20, wherein the lower channel is connected to the chamber and rotates with the chamber.

24. 21. The method of claim 20, further comprising an annular passage formed between an inner wall of the upper channel and an outer wall of the chamber.

25. 25. The method of claim 24, wherein the upper channel includes an upper wall that extends above a top of the inner wall.

26. The method of claim 20 , wherein the lower channel includes an upper wall having a tapered edge.

27. 21. The method of claim 20, further comprising a first tube supplying a cryogen and a second tube supplying a gas.

28. 30. The method of claim 27, wherein the first tube extends into the first channel.

29. 28. The method of claim 27, wherein the second tube extends into the chamber.

30. The method of claim 20 , further comprising a test device disposed within the chamber.

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