A closed liquid-free nitrogen consumption cryogenic waveguide cooling system and cooling method

Abstract

The application discloses a kind of full-closed liquid nitrogen consumption-free cryogenic wave oscillator cooling systems and cooling method.The system includes motor, refrigerator, cold sink, cooler, impeller, vacuum cylinder, flowmeter, bypass valve, liquid level meter, constant pressure tank, pressure stabilizing heater, cooling pipe, supply path, gas supply path, pressure relief path, backflow path, compensation heat source and the like.Cooled backflow liquid nitrogen is pressurized by impeller, enters heat exchanger and exchanges heat with cold head, temperature decreases after heat dissipation, enters cryogenic wave oscillator cooling channel again to take away heat of magnetic structure array, forming flow loop.Loop pressure can be adjusted, flow can be adjusted, temperature can be adjusted in the range of 65K-80K, and maximum output cooling capacity can vary between 400-500W.The application can realize permanent magnet array cooling of advanced light source mainstream cryogenic wave oscillator, does not need liquid nitrogen supply throughout, greatly reduces operation complexity, and has lower temperature, operation safety, wide application and other characteristics.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of low-temperature and permanent magnetic wave oscillators, and particularly relates to a fully-closed low-temperature wave oscillator cooling system without liquid nitrogen consumption and a cooling method. BACKGROUND

[0002] In the technical field of low-temperature permanent magnetic wave oscillators, a commonly used low-temperature obtaining method is a semi-open supercooled liquid nitrogen circulation, that is, normal-pressure liquid nitrogen is used as a cold source to provide cold energy for supercooled liquid nitrogen, and then the heat load at the end of the wave oscillator is taken away, so that the low-temperature state is maintained, however, this needs continuous liquid nitrogen supply, especially in the case that liquid nitrogen is inconvenient to obtain and liquid nitrogen storage tanks cannot be placed, which limits the development of the technology.

[0003] For a wave oscillator based on a permanent magnetic material praseodymium-iron-boron, a lower temperature can further improve the performance. The commonly used cooling system of the current wave oscillator is limited to the normal-pressure liquid nitrogen cold source, and the lowest temperature is about 80K.

[0004] In addition, for the conduction cooling method of the refrigerator, the refrigerator cannot be far away from the equipment, the temperature gradient of the permanent magnet array is difficult to control, and the wave oscillator main body structure becomes complex, and the vibration problem of the refrigerator is difficult to avoid. SUMMARY

[0005] In view of this, the application provides a fully-closed low-temperature wave oscillator cooling system without liquid nitrogen consumption and a cooling method, which are used to solve the problems in the background art.

[0006] The specific technical scheme is as follows:

[0007] A fully-closed low-temperature wave oscillator cooling system without liquid nitrogen consumption, characterized in that the system comprises a motor 01, a refrigerator 02, a supply path 14, a gas supply path 15, a pressure relief path 16, a backflow path 17 and a vacuum cylinder 06, the vacuum cylinder 06 is internally provided with a cold sink 03, a cooler 04, an impeller 05, a flow meter 07, a bypass valve 08, a liquid level meter 09, a flow control valve 10, a constant-pressure tank 11, a constant-pressure heat source 12, a cooling pipe 13 and a compensation heat source 18.

[0008] The refrigerator 02 is connected with the cooler 04, and is used to control the cooler 04 to cool and obtain liquid nitrogen from high-purity nitrogen gas input from the gas supply path 15; the cooler 04 delivers the obtained liquid nitrogen to a low-temperature wave oscillator to be cooled through the supply path 14, and delivers the obtained liquid nitrogen to the constant-pressure tank 11 through the bypass valve 08 and the cooling pipe 13.

[0009] The reflux path 17 is used to receive liquid nitrogen cooled by the low-temperature oscillator, and is connected with the inlet of the flow valve 10, the flow meter 07 and the impeller 05, the output port of the constant pressure tank 11 is connected with the inlet of the flow meter 07 and the impeller 05, the outlet of the impeller 05 is connected with the inlet of the cooler 04; the motor 01 is connected with the impeller 05, and is used to control the rotation of the impeller 05, so that the liquid nitrogen in the constant pressure tank 11 and the reflux liquid nitrogen received by the reflux path 17 are refluxed to the cooler 04 through the flow meter 07 and the impeller 05;

[0010] The pressure relief path 16 is connected with the constant pressure tank 11, and is used to relieve pressure when the constant pressure tank 11 is in an overpressure state;

[0011] The compensation heat source 18 is connected with the cold sink 03 and the cooler 04, and is used to control the temperature of the cooler 04 to be a set temperature;

[0012] The constant pressure heat source 12 is connected with the constant pressure tank 11, and is used to control the pressure in the constant pressure tank 11 to be a set pressure, so that the liquid nitrogen is kept in a liquid state;

[0013] The liquid level meter 09 is connected with the constant pressure tank 11, and is used to monitor the liquid level in the constant pressure tank 11.

[0014] Further, the cooler 04 adopts a counter-flow solid heat conduction form, the cooling channel adopts oxygen-free copper RRR>40, the fluid aperture is 15 mm, and the cooling channel is arranged in a layered manner; the total length of the cooling channel is 1.5-2.5 m. Wherein, Q represents the cooling capacity required by the cooler, k represents the thermal conductivity of the fluid, ΔT represents the allowable temperature difference, Re represents the Reynolds number, and Pr represents the Prandtl number.

[0015] Further, the cooling capacity K of the cooling pipe 13 to the constant pressure tank 11 is determined according to the formula Wherein, Q represents the cooling capacity of the cooler to nitrogen, k represents the thermal conductivity of the fluid, ΔT represents the allowable temperature difference, Re represents the Reynolds number, and Pr represents the Prandtl number. Wherein, Q represents the cooling capacity of the cooler to nitrogen, k represents the thermal conductivity of the fluid, ΔT represents the allowable temperature difference, Re represents the Reynolds number, and Pr represents the Prandtl number. C represents the cooling capacity of the cooler to nitrogen, ρ l represents the liquid density, h v represents the gaseous enthalpy, and h l represents the liquid enthalpy.

[0016] Further, the cooling capacity K of the cooling pipe 13 to the constant pressure tank 11 is determined according to the formula Wherein, h i represents the internal convective heat transfer coefficient of the cooling pipe 13, and h o represents the external convective heat transfer coefficient of the cooling pipe 13.

[0017] Further, the impeller 05 is a stable structure of a centrifugal full-flow type.

[0018] Further, the liquid level meter 09 is arranged on the top extension pipe of the constant pressure tank 11.

[0019] Further, the normal working liquid level in the constant pressure tank 11 is 35% of the height of the constant pressure tank.

[0020] Further, the impeller 05 is placed below the lowest point of the cooler 04, the high point of the impeller is lower than 60% of the height of the constant pressure tank 11, and the highest point of the cooling pipe 13 is at 30% of the height of the constant pressure tank.

[0021] A cooling method based on the cooling system of the low-temperature wave oscillator, the steps of which include:

[0022] Open the bypass valve 08, open the gas supply path 15 to input high-purity nitrogen into the cooler 04 for gradual cooling until condensation, and finally collect in the constant pressure tank 11; during the cooling process, the temperature of the cooler 04 is controlled by the compensation heat source 18 to be not lower than the set temperature;

[0023] When the liquid nitrogen in the constant pressure tank 11 accumulates to a set value higher than the normal working liquid level, close the gas supply path 15, increase the internal pressure of the constant pressure tank 11 to a set pressure through the pressure stabilizing heat source 12, start the motor 01, and determine the flow condition through the flow meter 07;

[0024] When the flow meter 07 shows that the flow is stable, open the flow control valve 10, gradually close the bypass valve 08, and gradually cool the low-temperature object; during the process, the backflow temperature is not higher than the saturation temperature of liquid nitrogen;

[0025] When the temperature of the low-temperature wave oscillator approaches the target temperature, adjust the opening degree of the bypass valve 08 to less than 5%, and increase the motor 01 speed to the target set flow; when the temperature of the low-temperature wave oscillator approaches the set temperature of the cooler 04 and is stable, it is determined that the cooling is completed.

[0026] The low-temperature wave oscillator cooling system of the present application is fully enclosed and consumes no liquid nitrogen, which includes a motor 01, a refrigerator 02, a cold sink 03, a cooler 04, an impeller 05, a vacuum cylinder 06, a flow meter 07, a bypass valve 08, a liquid level meter 09, a flow control valve 10, a constant pressure tank 11, a pressure stabilizing heat source 12, a cooling pipe 13, a supply path 14, a gas supply path 15, a pressure relief path 16, a backflow path 17, and a compensation heat source 18. The backflow path 17 is connected to the inlet of the flow meter 07 through the flow control valve 10, the inlet of the impeller 05 is connected to the outlet of the flow meter 07, the inlet of the cooler 04 is connected to the outlet of the impeller 05, the outlet of the cooler is connected to the inlet of the bypass valve 08, the supply path 14 and the gas supply path 15, the bottom of the constant pressure tank 11 is connected to the outlet of the cooling pipe 13 and the inlet of the flow meter 07, and the pressure relief path 16 is connected to the top of the constant pressure tank 11. The refrigerator 02 provides cold energy, liquefies normal temperature nitrogen gas before establishing a cycle, and this part of cold energy replaces the normal pressure liquid nitrogen as a cold source during continuous operation, thereby avoiding continuous supply of liquid nitrogen.

[0027] In a preferred embodiment of the present invention, the cooler 04 is a counter-current solid-state heat conduction type. The residual resistivity (RRR) of the oxygen-free copper used in the cooling channels is >40. The height of the cooler is less than 200 mm, the fluid orifice diameter of the cooling channels is 15 mm, and the cooling channels are arranged in layers. The required total channel length is calculated using the following formula:

[0028]

[0029] Where Q represents the cooling capacity required by the cooler, π is pi, k is the thermal conductivity of the fluid, ΔT is the allowable temperature difference, Re is the Reynolds number, and Pr is the Prandtl number.

[0030] In a preferred embodiment of the present invention, the compensating heat source 18 and the cooling sink 03 are in surface contact, the heat flux density is uniformly distributed, and the amount of heat is automatically controlled based on the temperature of the middle part of the cooling sink 03.

[0031] In a preferred embodiment of the present invention, the impeller 05 is not supported by a low-temperature bearing, is made of a low-temperature resistant material, and is a stable centrifugal full-flow structure.

[0032] In a preferred embodiment of the present invention, the bypass flow and the pressure vessel 11 are connected by a cooling pipe 13. The highest point of the cooling pipe 13 is at 30% of the height of the pressure vessel. The cooling capacity of the cooling pipe 13 to the pressure vessel per unit area can be calculated by the following formula: Where h i The value of h represents the convective heat transfer coefficient inside cooling tube 13. o This indicates the external convective heat transfer coefficient of cooling tube 13.

[0033] In a preferred embodiment of the present invention, the liquid nitrogen working fluid is replenished through nitrogen condensation via the gas supply line 15, omitting the liquid nitrogen replenishment. The condensation rate can be calculated using the following formula: Q C ρ represents the cooling capacity of the refrigeration unit for nitrogen. l h represents the density of the liquid. v enthalpy of gas, h l This represents the enthalpy of liquid.

[0034] In a preferred embodiment of the present invention, the liquid level gauge 09 is placed on the top extension tube of the pressure tank 11, extending to the highest point of the cooler, with a connecting hole.

[0035] In a preferred embodiment of the present invention, the pressure tank 11 operates at a liquid level of about 35%, and the pressure-stabilizing heat source 12 is installed in the outlet pipe on the side of the pressure tank 11, and the volatile gas flows back from the top.

[0036] In a preferred embodiment of the present invention, the impeller 05 is positioned below the lowest point of the cooler 04, and the highest point of the impeller is 60% below the position of the pressure tank 11.

[0037] In a preferred embodiment of the present application, the integrated vacuum insulation, normal temperature pressure pre-extraction 10Pa long-term self-sealing is maintained.

[0038] Compared with the prior art, the full-closed liquid nitrogen consumption-free cryogenic undulator cooling system has the following advantages:

[0039] First, the dependence on liquid nitrogen is eliminated, and the experimental application range is more extensive without relying on a liquid nitrogen cooling source.

[0040] Second, the temperature of the undulator magnetic array can be reduced to a lower temperature, and in principle, it can be reduced by more than 10K to improve performance.

[0041] Third, the safety is greatly improved, and the liquid nitrogen storage amount is greatly reduced, and even if all the liquid nitrogen is released, safety can be ensured.

[0042] Fourth, the temperature of the cooling object can be adjusted to meet the temperature requirements within a certain range of the load.

[0043] Fifth, the form of the load is less limited, and the load can be placed in a relatively distant place to reduce the interference with the experiment.

[0044] Sixth, the system structure is relatively compact, and the cooling source can be flexibly changed according to the laboratory requirements. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the present application, the embodiments of the present application will be further described below in combination with the drawings. Obviously, the embodiments in the following drawings are only some of the embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0046] Figure 1 It is a conceptual diagram of the full-closed liquid nitrogen consumption-free cryogenic undulator cooling system.

[0047] Figure 2 It is a structural diagram of the cooler.

[0048] Figure 3 It is a structural diagram of the impeller.

[0049] Among them, 01-motor, 02-refrigerator, 03-cold sink, 04-cooler, 05-impeller, 06-vacuum cylinder, 07-flow meter, 08-bypass valve, 09-liquid level meter, 10-flow control valve, 11-constant pressure tank, 12-stable pressure heat source, 13-cooling pipe, 14-supply path, 15-gas supply path, 16-pressure relief path, 17-backflow path, 18-compensation heat source. DETAILED DESCRIPTION

[0050] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] With reference to Figure 1 , the application provides a completely closed low-temperature wave oscillator cooling system without liquid nitrogen consumption, comprising a motor 01, a refrigerator 02, a cold sink 03, a cooler 04, an impeller 05, a vacuum cylinder 06, a flowmeter 07, a bypass valve 08, a liquid level meter 09, a flow control valve 10, a constant pressure tank 11, a constant pressure heat source 12, a cooling pipe 13, a supply path 14, a gas supply path 15, a pressure relief path 16, a return path 17, a compensation heat source 18, etc. The return path 17 is connected to the inlet of the flowmeter 07 through the flow control valve 10 to complete the return and flow regulation of the fluid, the inlet of the impeller 05 is connected to the outlet of the flowmeter 07 to complete the measurement of the flow, the inlet of the cooler 04 is connected to the outlet of the impeller 05 to complete the pressurization of the fluid, and the outlet of the cooler is connected to the inlet of the bypass valve 08, the supply path 14 and the gas supply path 15. After the fluid is cooled, the liquid supply of the cooling pipe 13, the flow of the supply path 14 and the input of the high-purity nitrogen gas of the gas supply path 15 are completed in turn to obtain liquid nitrogen and deliver it to the constant pressure tank 11. The bottom port of the constant pressure tank 11 is connected to the outlet of the cooling pipe 13 and the inlet of the flowmeter 07 to balance and control the pressure. The pressure relief path 16 is connected to the top port of the constant pressure tank 11 to complete the pressure relief protection in the overpressure state. The cooling pipe 13 uses the lower-temperature liquid nitrogen output by the cooler to cool the constant pressure tank. During the cooling and condensation, the flow direction of the nitrogen gas is from the outlet to the inlet of the cooler. During the operation, the liquid nitrogen flows from the inlet to the outlet of the cooler. That is, the inlet and outlet of the cooler are defined according to the operation state.

[0052] In this embodiment, with reference to Figure 1 , the bypass valve 08 is opened, the gas supply path 15 is connected to the high-purity nitrogen gas, and the gas is gradually cooled and condensed in the cooler 04 until it is finally collected in the constant pressure tank 11. The condensation rate of the nitrogen gas in the cooler 04 can be calculated by the following formula: where Q C represents the cooling capacity of the refrigerator for nitrogen, ρ l represents the liquid density, h v represents the gaseous enthalpy, and h l represents the liquid enthalpy. During the process, the temperature of the cooler 04 is controlled by the compensation heat source 18 to be not lower than 65K; Qc is a single-valued function of the temperature of the cold sink 03, which can be measured by independent operation of the refrigerator.

[0053] In this embodiment, with reference to Figure 1 , when the liquid nitrogen in the constant pressure tank 11 accumulates to 60%, the gas supply path 15 is closed, the internal pressure of the constant pressure tank 11 is increased to about 3 bara by the constant pressure heat source 12, the liquid nitrogen is controlled in a supercooled state to avoid the occurrence of cavitation at the inlet of the pump and to improve the cooling potential; then the motor 01 is started and the flow condition is determined by the flowmeter 07.

[0054] In this embodiment, reference is made to Figure 1 When the flow meter 07 shows that the flow is stable, the flow control valve 10 is opened, and the bypass valve 08 is gradually closed, so as to gradually cool the object to be cooled (i.e. the cryogenic oscillator). During the process, the backflow temperature of the liquid nitrogen after the cryogenic oscillator is transported through the cooler 04 and the supply path 14, and is not higher than the saturation temperature of the liquid nitrogen.

[0055] In this embodiment, reference is made to Figure 1 When the temperature of the cryogenic oscillator approaches 90K, the bypass valve 08 is closed to about 5%, the rotating speed of the motor 01 is increased to the target set flow, the temperature of the cooler 04 is controlled to the set temperature (less than 80K) by adjusting the compensation heat source 18, and the pressure of the constant pressure tank 11 is controlled to the set pressure by adjusting the constant pressure heat source 12. The temperature gradient of the cooling object is realized by the target set flow, the set temperature is determined according to the demand of the cooling object (i.e. the cryogenic oscillator), and the set pressure ensures that the liquid nitrogen is always in a pure liquid state, is not gasified, and is greater than the saturation pressure of the highest temperature.

[0056] In this embodiment, reference is made to Figure 1 When the temperature of the cryogenic oscillator approaches the set temperature of the cooler 04, and the change rate in one hour is less than 1K, it is determined that the cooling is ended, the states of the units are kept unchanged, and the running state is entered.

[0057] In this embodiment, reference is made to Figure 1 After the stable running, the liquid level height in the constant pressure tank 11 is in the normal working liquid level (the liquid level height is about 35%), and specifically, it can be determined according to the power of the constant pressure heat source 12. If the power of the constant pressure heat source 12 is too large, the liquid level needs to be increased. If it is intended to increase the liquid level, the gas supply path 15 is opened to gradually accumulate liquid to reach the target liquid level; if it is intended to reduce the liquid level, the pressure relief path 16 is opened to slowly exhaust gas, so as to gradually reduce the liquid level to the target height. In this embodiment, reference is made to Figure 2 The cooler 04 is in a counter-flow solid heat conduction form, the oxygen-free copper RRR>40, the height is less than 200mm, the fluid aperture is 15mm, and the cooling channel is in a layered arrangement.

[0058] In this embodiment, reference is made to Figure 3 The impeller 05 is not supported by the cryogenic bearing, is made of a low-temperature resistant material, is a centrifugal full-flow type stable structure, and the rotation of the impeller 05 is controlled by the motor 01.

[0059] The above description is only used for explaining the technical solutions of the present application, and does not limit the present application. Although the above embodiment is described in detail, those skilled in the art can replace, modify and simply change it without departing from the scope of the present technical solutions, and the replacement, modification and simple change cannot make the essence of the corresponding technical solutions deviate from the scope of the present application.

Claims

1. A completely closed, liquid-free, and nitrogen consumption-free cryogenic oscillator cooling system, characterized by, It comprises: A motor (01), a refrigerator (02), a supply path (14), a gas supply path (15), a pressure relief path (16), a return path (17) and a vacuum cylinder (06), wherein the vacuum cylinder (06) is provided with a cold sink (03), a cooler (04), an impeller (05), a flow meter (07), a bypass valve (08), a liquid level meter (09), a flow control valve (10), a constant pressure tank (11), a stable heat source (12), a cooling pipe (13) and a compensation heat source (18); The refrigerator (02) is connected with the cooler (04) for controlling the cooler (04) to cool the high-purity nitrogen gas input from the gas supply path (15) to obtain liquid nitrogen; the cooler (04) delivers the cooled liquid nitrogen to the cryogenic oscillator to be cooled through the supply path (14), and to the constant pressure tank (11) through the bypass valve (08) and the cooling pipe (13); The return path (17) is used for receiving the liquid nitrogen cooled in the cryogenic oscillator; the return path (17) is connected with the inlet of the impeller (05) through the flow control valve (10) and the flow meter (07), the output port of the constant pressure tank (11) is connected with the inlet of the impeller (05) through the flow meter (07), and the outlet of the impeller (05) is connected with the inlet of the cooler (04); the motor (01) is connected with the impeller (05) for controlling the rotation of the impeller (05), so that the liquid nitrogen in the constant pressure tank (11) and the return liquid nitrogen received by the return path (17) are returned to the cooler (04) through the flow meter (07) and the impeller (05); The pressure relief path (16) is connected with the constant pressure tank (11) for pressure relief protection when the constant pressure tank (11) is in an overpressure state; The compensation heat source (18) is connected with the cooler (04) through the cold sink (03) for controlling the temperature of the cooler (04) to be a set temperature; The stable heat source (12) is connected with the constant pressure tank (11) for controlling the pressure in the constant pressure tank (11) to be a set pressure, so that the liquid nitrogen remains in a liquid state; The liquid level meter (09) is connected with the constant pressure tank (11) for monitoring the liquid level in the constant pressure tank (11).

2. The cryogenic waveguide cooler system of claim 1, wherein, The cooler (04) adopts the counterflow solid heat conduction form, the cooling channel adopts oxygen-free copper with RRR>40, the fluid aperture is 15mm, and the cooling channel is arranged in layers; the total length of the cooling channel is 1.5m Wherein, Q represents the cooling capacity required to be reached by the cooler, k represents the thermal conductivity coefficient of the fluid, ΔT is the allowable temperature difference, Re represents the Reynolds number, and Pr represents the Prandtl number.

3. The cryogenic waveguide cooler system of claim 1 or 2, wherein, According to the formula determining the condensation rate of nitrogen by the cooler (04) where Q C represents the cooling capacity of the nitrogen by the refrigeration machine, p l represents the liquid density, h v gaseous enthalpy, h l represents the liquid enthalpy.

4. The cryogenic waveguide cooler system of claim 1, wherein, According to the formula Determine the cooling capacity K of the cooling pipe (13) per unit area of the constant pressure tank (11); wherein h i The convection heat transfer coefficient inside the cooling pipe (13) is h o The convection heat transfer coefficient outside the cooling pipe (13) is h 5. The cryogenic waveguide cooler system of claim 1, wherein, The impeller (05) is a stable structure of a centrifugal full-flow type.

6. The cryogenic waveguide cooler system of claim 1, wherein, The liquid level meter (09) is arranged on the top extension pipe of the constant pressure tank (11).

7. The cryogenic waveguide cooler system of claim 1, wherein, The normal working liquid level height in the constant pressure tank (11) is 35% of the height of the constant pressure tank.

8. The cryogenic waveguide cooler system of claim 7, wherein, The impeller (05) is arranged below the lowest point of the cooler (04), and the highest point of the cooling pipe (13) is at 30% of the height of the constant pressure tank.

9. A cooling method based on the cryogenic oscillator cooling system of claim 1, comprising the following steps: opening the bypass valve (08) and opening the gas supply path (15) to input high-purity nitrogen gas into the cooler (04) to gradually cool and condense until the liquid nitrogen is collected in the constant pressure tank (11); during the cooling process, the temperature of the cooler (04) is controlled by the compensation heat source (18) to be not lower than a set temperature; when the liquid nitrogen in the constant pressure tank (11) accumulates to a set value higher than the normal working liquid level, the gas supply path (15) is closed, the internal pressure of the constant pressure tank (11) is increased to a set pressure by the stable heat source (12), and then the motor (01) is started and the flow condition is determined by the flow meter (07); When the flow meter (07) shows that the flow is stable, open the control valve (10), gradually close the bypass valve (08), and gradually cool the low-temperature object. During the process, the backflow temperature is not higher than the saturation temperature of liquid nitrogen. When the temperature of the low-temperature wave oscillator approaches the target temperature, adjust the opening of the bypass valve (08) to less than 5%, and increase the speed of the motor (01) to the target set flow. When the temperature of the low-temperature wave oscillator approaches the set temperature of the cooler (04) and is stable, it is determined that the cooling is completed.

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