System for controlled cooling of tribotest chamber to cryogenic temperatures

Abstract

The present invention relates to system for controlled cooling of tribotest chamber to cryogenic temperatures, wherein temperature inside enclosed chamber can be reduced to -150 °C through recirculation of filtered and dried compressed air throughout enclosed chamber, temperature inside tribotest chamber can be maintained throughout a test run, and comprises a compressor at least one pressure regulator (12) and pressure gauge (11) wherein pressure adjustment is made for a stream of air which was first pressurized in the compressor (14) and then conducted through air conduction tube (8) and open gate of solenoid valve (13), at least one radiator (7) immersed in liquid nitrogen inside liquid nitrogen tank (6) wherein pressure-adjusted air passed through air filter (10) and drying filter (9) is cooled by recirculation via heat conduction method, at least one tribotest chamber (1) where cooled compressed air is conveyed via at least one heat-insulated tube (5), at least one thermocouple probe (2) which measures ambient temperature inside tribotest chamber (1) instantaneously, a PLC unit which reads the temperature value measured by thermocouple probe (2) and adjusts temperature level.

Description

[0001] SYSTEM FOR CONTROLLED COOLING OF TRIBOTEST CHAMBER TO CRYOGENIC TEMPERATURES

[0002] Technological Field:

[0003] The present invention relates to a system for controlled cooling of tribotest chamber to cryogenic temperatures, wherein temperature inside enclosed chamber can be reduced to -150 °C through recirculation of filtered and dried compressed air throughout enclosed chamber and temperature inside tribotest chamber can be maintained throughout a test run.

[0004] State of Art:

[0005] Advancements and innovations in the high-tech fields including, without limitation, military, aerospace, superconductors and energy industries require equipment, devices or systems that are capable of operating at extremely low (<273,15 K, < 0 °C) and cryogenic (<120 K, < -150 °C) temperatures. For the components of said equipment, device or system that are physically in contact, tests for low temperature tribology are needed to predict wear behavior they exhibit over time at low temperatures. Tribotester devices have been developed to conduct wear tests at low ambient temperature. Key technologies used in the design and construction of low temperature tribotesters include the control of test ambient temperature, motion and loading, and measurement of friction and wear at low temperatures. To maintain low ambient temperatures, friction pair can be immersed directly into cryogenic liquids (77 K liquid nitrogen, 20 K liquid hydrogen, 4.2 K liquid helium, 90 K liquid oxygen, etc.) Also, low-temperature gas can be used as cooling medium. Continuous temperature control can be maintained through mixing of hot and gold gas, or intermittent injection of cryogenic liquids.

[0006] In the frequently applied current state of the technique, high-speed tribotests where tribotest medium is in a vacuum state can produce inaccurate results because of serious temperature rises caused by friction heat, and the lack of heat transfer medium. Furthermore, temperature rise in contact interface in vacuum environment mainly depends on the thermal conductivity of two rubbing objects. This can cause variations in the test results depending on the material of the sample. In another cooling application which uses direct or indirect contact of cryogenic liquids, the friction temperature occurred during tribology tests reaches boiling point on the friction interface of cryogenic liquids, causing a formation of a gas film which has a seriously lower thermal conductivity particularly in liquid helium medium. This leads to a significant reduction in cooling capability of cryogenic liquids. And preventing said disadvantage is only possible under limited test conditions where low friction heat will be released. Moreover, if cryogenic liquid is used as an immersion medium, it is inevitable that test ambient temperature is limited to a constant temperature. In this case, it is impossible to conduct tribotests at different low temperature values. In literature, there are many inventions for temperature control. One of them is described below.

[0007] In patent application Nr. US5267449A, "Method and System for Cryogenic Refrigeration Using Air" is described. This invention aims to obtain a cryogenic-temperature air for the purposes of increased efficiency, lower costs and maintenance time. For this, a stream of air passes through a particulate air filter in an insulated enclosed space. Filtered stream of air is then conducted to a compressor. Then, compressed stream of air is conducted to a dryer / particulate removal arrangement. Then, compressed stream of air is conducted from trap via a conduit to a heat exchanger where compressed stream of air is cooled to approximately -68 °C without loss of more than a negligible amount of pressure. Cooled compressed stream of air is conducted from heat exchanger via a conduit through a particulate strainer to a turbo expander. The cooled gas stream exits turbo expander via conduit 60 at approximately -157 °C.

[0008] The system described above uses heat exchanger which enable the air to reach cryogenic and near cryogenic temperatures. In the cited document, as the heat exchanger is incapable of bringing air temperature to cryogenic temperature, it is necessary to use a turbo expander. This causes a multitude of disadvantages, because of costs and complexity of the structure. As a result, a new technology is needed, which is capable of eliminating disadvantages described above, controlling temperature instantaneously, cooling tribobest chamber from room temperature to cryogenic temperature (-150° C), and eliminating contact effect cryogenic liquid directly by refrigerating filtered and dried air.

[0009] Description of Invention:

[0010] This invention is a system for controlled cooling of tribotest chamber to cryogenic temperatures, which is a new technology capable of eliminating disadvantages described above, controlling temperature instantaneously, cooling tribobest chamber from room temperature to cryogenic temperature (-150° C), and eliminating contact effect cryogenic liquid directly by refrigerating filtered and dried air.

[0011] To realize all purposes mentioned above and which will further be revealed in the detailed description below, invention enables cooling of the enclosed tribotest chamber to the cryogenic ambient temperature by the cold air produced by the filtered, dehumidified compressed air by passing it through conduits immersed in the liquid nitrogen via heat conduction. Invention is genuine in this aspect, and a first-in-its-kind application in terms of cooling method.

[0012] Thanks to this cooling system developed with this invention, it is possible to cool the Tribotest chamber from room temperature to cryogenic temperature (-150 °C) wherein temperature control can be realized instantaneously. By cooling filtered and dried stream of air, the direct cryogenic liquid contact effect is eliminated. Thus, chemical reactions caused by cryogenic coolant in the tribotest contact region is minimized. And this results in wear data that have high reliability and repeatability. Continuous feeding of cryogenic liquids into test chamber and therefore consumption of them in the form of consumables considerably drives up the test costs. As, with this invention, the compressed air which can be produced unlimitedly is cooled by passing it through a limited-capacity cryogenic liquid tank, liquid cryogenic coolant consumption is minimized and therefore test costs are significantly reduced. Thanks to the cooling system developed with the invention, it is possible to cool tribotest chamber at temperature values from room temperature (23 °C) up to the cryogenic temperatures (-150 °C) with a precision of ± 3 °C. Thanks to the system developed in the scope of invention, it is possible to use filtered and dried air as a coolant unlimitedly and with zero cost. Cooling system for tribotest chamber developed with the invention can be mass-produced as an industrial product with low cost.

[0013] The structural specifications and characteristics as well as all advantages of the invention will be understood more clearly by the drawings provided below, and detailed description provided below through references to these drawings, and therefore the assessment should be based on these drawings and detailed description.

[0014] Description of Drawings:

[0015] Invention will be described through references to appended drawings, and therefore specifications of the invention will be understood more clearly and appreciated, however, this is not intended to limit invention to these certain embodiments. On the contrary, it is intended to cover all alternatives, modifications, embodiments, and equivalences that can be included in the field of the invention defined by the appended claims. It should be understood that the details provided and / or shown is provided and / or shown in order to describe the preferred embodiments of the present invention, and facilitate the most useful and easier-to-under stand definition both for embodiments of the methods and rules and conceptual particulars of the invention. In these drawings;

[0016] Figure 1 An example schematic representation of the invention

[0017] While the figures that will help this innovation to be understood are enumerated as it is defined in annexed picture, they are presented below with their names.

[0018] Legend:

[0019] 1. Tribotest Chamber 2. Thermocouple Probe

[0020] 3. Transmission Wire

[0021] 4. PLC Unit

[0022] 5. Heat-Insulated Tube

[0023] 6. Li qui d Nitrogen T ank

[0024] 7. Radiator

[0025] 8. Air Conduction Tube

[0026] 9. Dryer Filter

[0027] 10. Air Filter

[0028] 11. Pressure Gauge

[0029] 12. Pressure Regulator

[0030] 13. Solenoid Valve

[0031] 14. Compressor

[0032] Description of Invention:

[0033] Invention comprises a compressor at least one pressure regulator (12) and pressure gauge (11) wherein pressure adjustment is made for a stream of air which was first pressurized in the compressor (14) and then conducted through air conduction tube (8) and open gate of solenoid valve (13), at least one radiator (7) immersed in liquid nitrogen inside liquid nitrogen tank (6) wherein pressure-adjusted air passed through air filter (10) and drying filter (9) is cooled by recirculation via heat conduction method, at least one tribotest chamber (1) where cooled compressed air is conveyed via at least one heat-insulated tube (5), at least one thermocouple probe (2) which measures ambient temperature inside tribotest chamber (1) instantaneously, a PLC unit which reads the temperature value measured by thermocouple probe (2) and adjusts temperature level.

[0034] Invention comprises a PLC unit (4) wherein desired temperature value is adjusted via digital or touch buttons provided on the display it comprises. Invention comprises a PLC unit (4) which sends a signal to solenoid valve (13) to change its position when ambient temperature inside the tribotest chamber (1) is outside a preset reference range of the value set on the display, and removes the air coming from compressor (14) out of the system. Invention comprises a PLC unit (4) which, when ambient temperature inside the tribotest chamber (1) reaches a value higher than the set value, sends a signal to solenoid value (13) to allow air coming from compressor (14) to be introduced into the cooling system, and, having cooled therein, cooled air to be fed to the tribotest chamber (1).

[0035] Detailed Description of Invention:

[0036] Invention aims to develop a cooling system which enable cooling of the inside of test chamber of tribotest device in a controlled way. Description of the general working principles including system elements used in the cooling system developed and their functions are as follows: stream of air pressurized in the compressor (14) passing through open gate of solenoid valve (13) via air conduction tube (8) and then adjusted with pressure regulator (12) and pressure gauge (11) to the desired pressure, and then passed through air filter (10) and drying filter (9). Then, filtered and dried compressed air passes through radiator (7) fully immersed in the liquid nitrogen inside the liquid nitrogen tank (6) during which it is cooled down via heat conduction. Cooled compressed air is conducted via heat-insulated tube (5) to the tribotest chamber (1). Ambient temperature inside tribotest chamber (1) is measured with a thermocouple probe (2) instantaneously and temperature value can be seen on the temperature gauge display present in the integrated PLC unit (4). It is possible to adjust desired temperature value to the desired value using the buttons present on the said display. When the ambient temperature inside tribotest chamber (1) is outside the preferably ± 3°C tolerance range of the set value, PLC unit (4) triggers solenoid valve (13) to change its position, and therefore removes air coming from compressor (14) out of the system. When ambient temperature inside the tribotest chamber (1) reaches a value higher than the set value, PLC unit (4) triggers the solenoid value (13) to allow air coming from compressor (14) to be introduced into the cooling system, and, having cooled therein, cooled air to be fed to the tribotest chamber (1).

[0037] A reference number follows technical and all other specifications mentioned in each claim, these reference numbers are only intended to make claims easier to understand, therefore, it should not be considered that these reference numbers limit the scope of any elements indicated with these reference numbers for illustrative purposes. Around these basic concepts, it is possible to develop a wide variety of embodiments of the invention, and the invention cannot be limited to the embodiments described herein, but is essentially as set forth in the claims.

[0038] It is clear that a person skilled in the art can also demonstrate the innovation described in the invention by using similar configurations and / or apply such configuration to other fields with similar purposes used in the relevant art. Therefore, it is evident that such configurations will lack the criterion of novelty and especially the criterion of exceeding the state of the art.

Claims

CLAIMS1- A system for controlled cooling of tribotest chamber to cryogenic temperatures, which comprises:at least one pressure regulator (12) and pressure gauge (11) wherein pressure adjustment is made for a stream of air which was first pressurized in the compressor (14) and then conducted through air conduction tube (8) and open gate of solenoid valve (13),at least one radiator (7) immersed in liquid nitrogen inside liquid nitrogen tank (6) wherein pressure-adjusted air passed through air filter (10) and drying filter (9) is cooled by recirculation via heat conduction method,at least one tribotest chamber (1) where cooled compressed air is conveyed via at least one heat-insulated tube (5),at least one thermocouple probe (2) which measures ambient temperature inside tribotest chamber (1) instantaneously,a PLC unit which reads the temperature value measured by the thermocouple probe (2) and adjusts temperature level.2- the system according to Claim 1 for controlled cooling of tribotest chamber to cryogenic temperatures, which is characterized by comprising a PLC unit (4) wherein the desired temperature value is adjusted using digital and touch buttons present on the display it comprises.3- the system according to Claim 1 for controlled cooling of tribotest chamber to cryogenic temperatures, which is characterized by comprising a PLC unit (4) which sends a signal to solenoid valve (13) to change its position when ambient temperature inside the tribotest chamber (1) is outside a preset reference range of the value set on the display, and removes the air coming from compressor (14) out of the system.4- the system according to Claim 1 for controlled cooling of tribotest chamber to cryogenic temperatures, which is characterized by comprising a PLC unit (4) which, when ambient temperature inside the tribotest chamber (1) reaches a value higher than the setvalue, sends a signal to solenoid value (13) to allow air coming from compressor (14) to be introduced into the cooling system, and, having cooled therein, cooled air to be fed to the tribotest chamber (1).

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