CN117723327A - 2K negative pressure visual heat exchanger test platform, system and use method - Google Patents
2K negative pressure visual heat exchanger test platform, system and use method Download PDFInfo
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- 239000007788 liquid Substances 0.000 claims abstract description 222
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims abstract description 192
- 239000001307 helium Substances 0.000 claims abstract description 189
- 229910052734 helium Inorganic materials 0.000 claims abstract description 189
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- 238000001816 cooling Methods 0.000 claims description 35
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Abstract
The invention discloses a 2K negative pressure visual heat exchanger test platform, a system and a use method, wherein the 2K negative pressure visual heat exchanger test platform comprises a vacuum cover, a 4K normal pressure liquid helium tank, a 2K negative pressure heat exchanger to be tested and a 2K negative pressure superfluid helium tank, a cold screen arranged on the inner wall of the vacuum cover is arranged in the vacuum cover, the 4K normal pressure liquid helium tank, the 2K negative pressure heat exchanger to be tested and the 2K negative pressure superfluid helium tank are arranged in the cold screen, and the test system comprises a low-temperature test valve box, a measurement and control controller and the 2K negative pressure visual heat exchanger test platform. The invention can be used for researching the flow and heat transfer characteristics of the heat exchanger under different heat exchanger types, fin types, geometric dimensions and mass flow under deep low temperature environment with high precision, evaluating the flow pressure drop and heat transfer coefficient change relation of different fin units along with Reynolds number, measuring the speed distribution of the core body and the internal channel of the end enclosure by an optical test technology, and providing data support for the design of negative pressure heat exchanger in a larger refrigerator in the future.
Description
Technical Field
The invention relates to the technical field of refrigeration and deep low temperature, in particular to a 2K negative pressure visualization heat exchanger test platform, a system and a use method.
Background
Helium cryogenic systems are an indispensable infrastructure in large scientific facilities. The 2K negative pressure heat exchanger is a heat exchanger working in a 4K liquid helium and 2K superfluid helium temperature area, and can be used for recovering cold energy of a deep low temperature system and improving the generation rate of superfluid helium. The 2K negative pressure heat exchanger operates in a deep low temperature and negative pressure environment, and the heat exchange temperature difference is small. The physical properties of helium in a deep low-temperature environment change drastically, and there is a transition between two physical states of 4K liquid helium and 2K superfluid helium.
The heat transfer, pressure drop performance and volume of the 2K negative pressure heat exchanger have important influence on the performance, construction and operation cost of a deep low temperature system. At present, when designing heat exchangers at home and abroad, heat transfer and flow relational expressions obtained through space division experiments are directly adopted, or heat transfer and flow relational expressions of a certain type of heat exchanger are directly applied to heat exchangers under another type or new working conditions, but larger errors exist when the relational expressions are directly applied to ultralow temperature systems. In addition, the speed distribution of helium in opaque channels cannot be measured with high accuracy and over a wide range using conventional invasive speed measurement methods.
Disclosure of Invention
The invention aims at: aiming at the defects in the prior art, the 2K negative pressure heat exchanger testing platform, the system and the using method are provided, the system and the method can be used for researching the flow and heat transfer characteristics of heat exchangers under different heat exchanger types, fin types, geometric dimensions and mass flow in a deep low-temperature environment with high precision, evaluating the change relation of flow pressure drop and heat exchange coefficients of different fin units along with Reynolds numbers, measuring the speed distribution of the internal channels of a core body and an end socket by an optical testing technology, and providing data support for the design of negative pressure heat exchanger selection in a larger refrigerator in the future.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the invention provides a 2K negative pressure visualization heat exchanger test platform, which comprises a vacuum cover, a 4K normal pressure liquid helium tank, a 2K negative pressure heat exchanger to be tested and a 2K negative pressure superfluid helium tank, wherein a cold screen arranged on the inner wall of the vacuum cover is arranged in the vacuum cover, an air inlet pipeline and an air return pipeline arranged on the outer side of the cold screen are respectively connected with a first air inlet pipeline and a first air return pipeline, the vacuum cover is also connected with a first vacuum pump, a normal temperature switch valve is arranged on a connecting pipeline of the vacuum cover and the first vacuum pump, and the 4K normal pressure liquid helium tank, the 2K negative pressure heat exchanger to be tested and the 2K negative pressure superfluid helium tank are arranged in the cold screen;
the vacuum cover is provided with a 4K liquid inlet pipeline, the 4K liquid inlet pipeline is divided into a first branch, a second branch and a third branch after entering the vacuum cover, the first branch is connected with a cold side inlet pipeline of the 4K normal pressure liquid helium tank through a low-temperature throttle valve, the second branch is connected with a hot side inlet of the 4K normal pressure liquid helium tank through a low-temperature regulating valve, the third branch is connected with the 2K negative pressure superfluid helium tank, a low-temperature regulating valve is arranged on a connecting pipeline of the third branch and the 2K negative pressure superfluid helium tank, a cold side outlet of the 4K normal pressure liquid helium tank is connected with a second return pipeline, a hot side outlet of the 4K normal pressure liquid helium tank is connected with a hot side inlet of the 2K negative pressure heat exchanger to be tested, a low-temperature stop valve and a flowmeter are arranged on a pipeline of the hot side outlet of the 4K normal pressure liquid helium tank and the hot side inlet of the 2K negative pressure heat exchanger to be tested, a side outlet of the 2K negative pressure heat exchanger is connected with the 2K negative pressure superfluid helium tank to be tested, and a cold side outlet of the 2K negative pressure heat exchanger to be tested is connected with the cold side inlet of the 2K negative pressure heat exchanger to be tested;
The temperature sensor and the pressure sensor are arranged on the first air inlet pipe, the temperature sensor and the pressure sensor are arranged on the first air return pipe, the temperature sensor and the pressure sensor are arranged on the 4K liquid inlet pipe, the temperature sensor and the 4K normal pressure liquid level meter are arranged on the 4K normal pressure liquid helium tank, the pressure sensor is arranged on the cold side outlet pipe of the 4K normal pressure liquid helium tank, the temperature sensor and the pressure sensor are respectively arranged on the hot side inlet pipe, the hot side outlet pipe, the cold side inlet pipe and the cold side outlet pipe of the 2K negative pressure heat exchanger to be tested, the flowmeter, the pressure sensor and the temperature sensor are arranged on the first liquid return pipe, the differential pressure sensor is respectively connected between the two ends of the hot side and the two ends of the cold side of the 2K negative pressure heat exchanger to be tested, and the temperature sensor, the 4K negative pressure liquid level meter and the 2K negative pressure liquid level meter are arranged on the 2K negative pressure overflow helium tank;
the components of the 2K negative pressure heat exchanger to be tested are made of high light transmission materials, the vacuum cover and the cold screen are provided with a speed measuring area corresponding to the 2K negative pressure heat exchanger to be tested, and the speed measuring area is made of high light transmission materials.
Preferably, the connecting pipeline of the hot side outlet of the 4K normal pressure liquid helium tank and the hot side inlet of the 2K negative pressure heat exchanger to be tested comprises a plurality of connecting branches which are arranged in parallel, each connecting branch is respectively provided with a low-temperature stop valve and a flowmeter, and the types of the flowmeters on each connecting branch are different.
Preferably, the connecting pipeline of the hot side outlet of the 4K normal pressure liquid helium tank and the hot side inlet of the 2K negative pressure heat exchanger to be tested comprises a plurality of connecting branches which are arranged in parallel, each connecting branch is respectively provided with a low-temperature stop valve and a flowmeter, and the types of the flowmeters on each connecting branch are different.
Preferably, pressure sensors are respectively arranged on a hot side inlet pipeline, a hot side outlet pipeline, a cold side inlet pipeline and a cold side outlet pipeline of the 2K negative pressure heat exchanger to be tested, and two pressure sensors with different measuring ranges are respectively arranged on the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger to be tested.
Preferably, heaters are respectively arranged at the bottom of the 2K negative pressure superfluid helium tank and the bottom of the outer side of the cold screen.
Preferably, the first liquid return pipeline is provided with a low-temperature stop valve which is arranged at two ends of the upper flowmeter in parallel.
In a second aspect, the invention provides a 2K negative pressure visualized heat exchanger test system, which comprises a low-temperature test valve box, a measurement and control controller and the 2K negative pressure visualized heat exchanger test platform in the first aspect, wherein a measurement and control program is loaded in the measurement and control controller;
the low temperature test valve box is internally provided with a cold screen air return pipeline, a heat exchanger liquid return pipeline, a cooling air return pipeline, a heat exchanger liquid inlet pipeline, a cold screen air inlet pipeline, a first mixer and a second mixer respectively, the cold screen air return pipeline is connected with the first air return pipeline, the heat exchanger liquid return pipeline is connected with the first liquid return pipeline, the cooling air return pipeline is connected with the second air return pipeline, the cold screen air return pipeline, the heat exchanger liquid return pipeline and the cooling air return pipeline are respectively provided with a low temperature regulating valve, the heat exchanger liquid return pipeline is also provided with a heater, a normal temperature switching valve and a second vacuum pump which are positioned at the downstream of the low temperature regulating valve, a first branch pipe is arranged between the cold screen air return pipeline and the cooling air return pipeline, a second branch pipe is arranged between the heat exchanger liquid return pipeline and the cooling air return pipeline, the first branch pipe and the second branch pipe are respectively provided with a low-temperature regulating valve, the first mixer is respectively connected with the 4K liquid inlet pipeline and the heat exchanger liquid inlet pipeline, the second mixer is respectively connected with the first air inlet pipeline and the cold screen air inlet pipeline, the heat exchanger liquid inlet pipeline and the cold screen air inlet pipeline are respectively provided with low-temperature regulating valves, the low-temperature test valve box is also provided with an evacuation return temperature air return pipeline and a replacement return temperature air inlet pipeline, the evacuation return temperature air return pipeline is provided with a third vacuum pump and a normal-temperature switching valve, the evacuation return temperature air return pipeline is provided with three connecting branch pipes, the connecting branch pipes are provided with normal-temperature switching valves, the cold screen return air pipeline, the heat exchanger liquid return pipeline and the cooling return air pipeline are respectively connected with the evacuation return temperature return air return pipeline through one connecting branch pipe, the connecting branch pipe is respectively connected to the cold screen air return pipeline, the heat exchanger liquid return pipeline and the upstream of the low-temperature regulating valve on the cooling air return pipeline, the replacement temperature return air inlet pipeline is respectively connected with the first mixer and the second mixer, the normal-temperature regulating valve and the one-way valve are arranged on the connecting pipelines of the replacement temperature return air inlet pipeline and the first mixer, and the normal-temperature regulating valve is arranged on the connecting pipelines of the replacement temperature return air inlet pipeline and the second mixer;
And the measurement and control controller is respectively in communication connection with each valve and each sensor of the vacuum cover and the low-temperature test valve box.
Preferably, the 4K liquid inlet pipeline, the hot side outlet pipeline of the 4K normal pressure liquid helium tank, the hot side inlet pipeline of the 2K negative pressure heat exchanger to be tested and the connecting branch pipes are respectively provided with an exhaust branch pipe, and the exhaust branch pipes are respectively provided with a safety valve and a rupture disk.
Preferably, the exhaust branch pipe of the hot side inlet pipeline of the 2K negative pressure heat exchanger to be tested is also provided with a one-way valve.
In a third aspect, the present invention provides a method for using the 2K negative pressure visualized heat exchanger test system as described in the second aspect, which is characterized by comprising the following steps:
s1, closing a vacuum removing cover and a first vacuumAll valves except normal temperature switch valves on the connecting pipeline of the pump are started to continuously carry out continuous vacuumizing treatment on the vacuum cover by the first vacuum pump, so that the vacuum degree in the vacuum cover is maintained to be 1 multiplied by 10 -3 Pa or less;
s2, respectively opening valves on all pipelines in a vacuum cover and normal temperature switch valves on an evacuating return temperature return air pipeline and all connecting branch pipes, starting a third vacuum pump to carry out vacuumizing treatment on a 4K normal pressure liquid helium tank, a 2K negative pressure heat exchanger to be tested, a 2K negative pressure superfluid helium tank and all pipelines, closing the normal temperature switch valves on the evacuating return temperature return air pipeline and all connecting branch pipes and stopping the third vacuum pump when the display pressure of pressure sensors on the first air inlet pipeline and the 4K liquid inlet pipeline is 10-100Pa, opening normal temperature regulating valves on connecting pipelines of a replacement return temperature air inlet pipeline and a first mixer and a second mixer, respectively inputting 300K helium gas into the first air inlet pipeline and the 4K liquid inlet pipeline, and closing the normal temperature regulating valves on the replacement return temperature air inlet pipeline and the connecting pipelines of the first mixer and the second mixer for 5-10 minutes when the display pressure of pressure sensors on the first air inlet pipeline and the 4K liquid inlet pipeline is about 1-2bara, so as to complete a gas replacement process;
S3, repeating the step S2 for 2 times;
s4, respectively opening valves on all pipelines in the vacuum cover, the evacuation return temperature return air pipeline and normal temperature switch valves on all connecting branch pipes, starting a third vacuum pump to carry out vacuumizing treatment on the 4K normal pressure liquid helium tank, the 2K negative pressure heat exchanger to be tested, the 2K negative pressure superfluid helium tank and all pipelines, and when the display pressure of pressure sensors on the first air inlet pipeline and the 4K liquid inlet pipeline is 10-100Pa, firstly closing the evacuation return temperature return air pipeline and the normal temperature switch valves on all connecting branch pipes, closing the third vacuum pump and then closing the valves on all pipelines of the vacuum cover;
s5, opening low-temperature regulating valves on the first branch pipe and the cold screen air inlet pipe, inputting 50K helium into the spiral winding pipe at the outer side of the cold screen for cooling, opening the low-temperature regulating valve on the cold screen air return pipe and closing the low-temperature regulating valve on the first branch pipe after the display temperature of the temperature sensor on the first air return pipe is about 75K, and continuously inputting 50K helium into the cold screen through the cold screen air inlet pipe for cooling for 2-3 hours, so that radiation heat leakage is reduced;
s6, respectively opening a low-temperature throttle valve on a first branch pipeline and a low-temperature regulating valve on a cooling return pipeline and a liquid inlet pipeline of a heat exchanger, inputting pressurized liquid helium (4.7K, 3 bara) into the 4K liquid inlet pipeline, synchronously opening a low-temperature regulating valve on a third branch pipeline and a second branch pipeline, injecting the pressurized liquid helium (4.7K, 3 bara) into a 2K negative pressure superfluid helium tank for precooling, setting the opening of the low-temperature throttle valve on the first branch pipeline to 5% -8% when the display temperature of a temperature sensor of the 4K normal pressure liquid helium tank is 4.7K, reducing the pressure of the pressurized liquid (4.7K, 3 bara) on the first branch pipeline to normal pressure liquid helium (4.2K, 1 bara), and keeping the display pressure of the low-temperature throttle valve on the first branch pipeline and the pressure sensor on the second return pipeline to be always at 1.1K by using a measurement and control program, keeping the display pressure on the second gas pipeline at 1.2K negative pressure sensor on the left branch pipeline and constant pressure liquid helium tank at the side of the 2K, and keeping the temperature of the low-temperature sensor on the second branch pipeline at the side of the 2K normal pressure liquid helium tank at the 2K, and at the 2K constant temperature and at the side of the 2.4.4 bara constant temperature inlet side of the low-pressure liquid helium tank and the low-pressure sensor on the low-pressure liquid helium tank;
S7, opening a low-temperature throttle valve on a hot side outlet of a 2K negative pressure heat exchanger to be detected and a connecting pipeline of a 2K negative pressure superfluid helium tank to be detected, inputting pressurized liquid helium (4.2K, 2.92 bara) to the hot side of the 2K negative pressure heat exchanger to be detected, reducing the pressure and the temperature of the pressurized liquid helium (4.2K, 2.92 bara) flowing out of the 2K negative pressure heat exchanger to be detected to 2.2K superfluid helium (3130 Pa) by setting the opening of the low-temperature throttle valve on the hot side outlet of the 2K negative pressure heat exchanger to be detected and the connecting pipeline of the 2K negative pressure superfluid helium tank to be detected to 5% -10% when the display temperature and the display liquid level of a temperature sensor of the 2K negative pressure superfluid helium tank and a 4K normal pressure liquid level gauge are about 4.7K and 50% -80% respectively, simultaneously, a low-temperature regulating valve and a normal-temperature switching valve on a liquid return pipeline of the heat exchanger are opened, a second vacuum pump is started to take away vaporization heat of 4K liquid helium in the 2K negative pressure superfluid helium tank, when the display pressure of a pressure sensor on a cold side inlet pipeline of the 2K negative pressure heat exchanger to be tested is about 3100Pa, a low-temperature throttling valve on a hot side outlet of the 2K negative pressure heat exchanger to be tested and a pressure sensor on a cold side inlet pipeline of the 2K negative pressure heat exchanger to be tested are interlocked through a measurement and control program, so that the display pressure of the pressure sensor on the cold side inlet pipeline of the 2K negative pressure heat exchanger to be tested is always kept at about 3100 Pa;
S8, closing low-temperature regulating valves on the third branch, the first branch and the second branch, opening low-temperature regulating valves on a cold screen return air pipeline and a heat exchanger return liquid pipeline, waiting for display parameters of temperature sensors on a hot side inlet pipeline and a cold side inlet pipeline of a 2K negative pressure heat exchanger to be tested, a 4K normal pressure liquid level meter of a 4K normal pressure liquid helium tank and a 2K negative pressure liquid level meter of the 2K negative pressure overflow helium tank to reach the following test working conditions and maintain for more than 10 minutes: the temperature sensors on the hot side inlet pipeline and the cold side inlet pipeline of the 2K negative pressure heat exchanger to be tested show temperatures of about 4.2K and 2.2K respectively, and the 4K normal pressure liquid level meter of the 4K normal pressure liquid helium tank and the 2K negative pressure liquid level meter of the 2K negative pressure overflow helium tank show liquid levels of about 70-90% respectively;
s9, keeping the flow rates of a hot side inlet and a cold side inlet of a 2K negative pressure heat exchanger to be measured equal, measuring the temperature and pressure drop of the cold side and the hot side of the 2K negative pressure heat exchanger to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of flow rates in the range of 1.0-5.0g/s at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors, wherein the expression of the J-F factors is as follows:
Wherein: nu is the nussel number; re is the Reynolds number; pr is the Plandter number; Δp is the pressure drop, pa; d is the hydraulic diameter, m; ρ is density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the v is the velocity, m/s, l is the flow length, m;
s10, fixing the flow rate of a hot side inlet of a 2K negative pressure heat exchanger to be measured to be a certain value, measuring the temperature and pressure drop of a cold side inlet of the 2K negative pressure heat exchanger to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of cold side measuring flow rates within the range of 1.0-5.0g/s at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
s11, fixing the flow of a cold side inlet of a 2K negative pressure heat exchanger to be measured to be a certain value, measuring the temperature and pressure drop of a hot side inlet of the 2K negative pressure heat exchanger to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of hot side measuring flow ranges from 1.0 g/s to 5.0g/s at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
S12, after the test is finished, closing a normal temperature switch valve on a connecting pipeline of a vacuum cover and a first vacuum pump, closing a first vacuum pump, opening a low temperature regulating valve on a first branch pipe and a second branch pipe, closing a cold screen air return pipeline, a heat exchanger liquid inlet pipeline and a low temperature regulating valve on a cold screen air inlet pipeline, stopping injecting 50K helium gas and pressurized liquid helium (4.7K, 3 bara) into the cold screen and the 4K liquid inlet pipeline respectively, regulating the opening of the first branch pipeline, a hot side outlet of a 2K negative pressure heat exchanger to be tested and a low temperature throttling valve on a connecting pipeline of a 2K negative pressure superfluid helium tank to be tested to 100%, opening the low temperature regulating valve on a third branch pipeline, opening the normal temperature switch valve on each connecting branch pipe, inputting 300K to the cold screen and the 4K liquid inlet pipeline by replacing the normal temperature regulating valve between the temperature return air inlet pipeline and the first mixer and the second mixer, and regulating valve so that the display pressure of the first air inlet pipeline and the 4K liquid inlet pipeline is about 2-3bara;
s13, after the temperature and the pressure in each pipeline and equipment of the 2K negative pressure visual heat exchanger test system are respectively restored to normal temperature and normal pressure, closing all valves and equipment of the 2K negative pressure visual heat exchanger test system;
S14, separating the 2K negative pressure visualization heat exchanger testing platform from the low-temperature testing valve box, replacing the 2K negative pressure heat exchanger to be tested with 2K negative pressure heat exchangers of other fin types and geometric dimensions, and repeating the steps to perform performance testing.
Compared with the prior art, the invention has the beneficial effects that:
the 2K negative pressure heat exchanger test platform provided by the invention can be used for researching the flow and heat transfer characteristics of heat exchangers under different heat exchanger types, fin types, geometric dimensions and mass flow under deep low temperature environment with high precision, evaluating the change relation of flow pressure drop and heat exchange coefficients of different fin units along with Reynolds number, measuring the speed distribution of the core body and the internal channel of the end enclosure by an optical test technology, and providing data support for the design selection of the negative pressure heat exchanger in a larger refrigerator in the future.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described. It should be noted that in all the drawings, each element or portion is not necessarily drawn to actual scale.
Fig. 1 is a schematic diagram of an overall structure of a 2K negative pressure heat exchanger test system according to an embodiment of the invention.
In the figure:
1. a vacuum cover; 11. a cold screen; 12. a first air intake line; 13. a first return air line; 14. a first vacuum pump; 15. 4K liquid inlet pipeline; 151. a first branch; 152. a second branch; 153. a third branch; 16. a second return air line; 17. a first liquid return line; 18. a connection branch; 2. a 4K normal pressure liquid helium tank; 3. a 2K negative pressure heat exchanger to be tested; 4. 2K negative pressure superfluid helium tank; 5. a low temperature test valve box; 51. a cold screen return air pipeline; 52. a liquid return pipeline of the heat exchanger; 521. a second vacuum pump; 53. a cooling return air pipeline; 531. a first branch pipe; 532. a second branch pipe; 54. a liquid inlet pipeline of the heat exchanger; 55. a cold screen air inlet pipeline; 56. a first mixer; 57. a second mixer; 58. a vacuumizing and temperature-returning air return pipeline; 581. a third vacuum pump; 582. a connecting branch pipe; 59. replacing a temperature return air inlet pipeline; 6. an exhaust branch pipe; 71. a low temperature throttle valve; 72. a low temperature regulating valve; 73. a low temperature shut-off valve; 74. normal temperature switch valve; 75. a normal temperature regulating valve; 76. a one-way valve; 77. a safety valve; 81. a temperature sensor; 82. a pressure sensor; 83. 4K normal pressure liquid level meter; 84. a differential pressure sensor; 85. a 4K negative pressure liquid level meter; 86. 2K negative pressure liquid level meter; 87. a venturi flow meter; 88. an emerson flowmeter; 89. a turbine flowmeter; 9. a heater.
Wherein only one point is labeled in the figures for the same type of valve, sensor and flowmeter.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Moreover, the use of the terms first, second, etc. to define elements is merely for convenience in distinguishing the elements from each other, and the terms are not specifically meant to indicate or imply relative importance unless otherwise indicated.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
At present, when designing heat exchangers at home and abroad, heat transfer and flow relational expressions obtained through space division experiments are directly adopted, or heat transfer and flow relational expressions of a certain type of heat exchanger are directly applied to heat exchangers under another type or new working conditions, but larger errors exist when the relational expressions are directly applied to ultralow temperature systems. Therefore, the invention provides a 2K negative pressure heat exchanger test platform, a system and a using method thereof, which can be used for researching the flow and heat transfer characteristics of heat exchangers under different heat exchanger types, fin types, geometric dimensions and mass flow in a deep low-temperature environment with high precision, evaluating the flow pressure drop and heat transfer coefficient change relation of different fin units along with Reynolds numbers, measuring the speed distribution of the internal channels of a core body and an end socket by an optical test technology, and providing data support for the design of negative pressure heat exchangers in larger refrigerators in the future.
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Example 1
As shown in fig. 1, the embodiment of the invention provides a 2K negative pressure heat exchanger test platform, which comprises a vacuum cover 1, a 4K normal pressure liquid helium tank 2, a 2K negative pressure heat exchanger 3 to be tested and a 2K negative pressure superfluid helium tank 4, wherein a cold screen 11 is arranged on the inner wall of the vacuum cover 1, an air inlet pipeline and an air return pipeline at the outer side of the cold screen 11 are respectively connected with a first air inlet pipeline 12 and a first air return pipeline 13, the vacuum cover 1 is also connected with a first vacuum pump 14, a normal temperature switch valve 74,4K normal pressure liquid helium tank 2, a 2K negative pressure heat exchanger 3 to be tested and the 2K negative pressure superfluid helium tank 4 are arranged on the connecting pipeline of the vacuum cover 1 and the first vacuum pump 14, and are arranged in the cold screen 11;
the vacuum cover 1 is provided with a 4K liquid inlet pipeline 15,4K, a liquid inlet pipeline 15 is divided into a first branch 151, a second branch 152 and a third branch 153 after entering the vacuum cover 1, the first branch 151 is connected with a cold side inlet pipeline of a 4K normal pressure liquid helium tank 2 through a low-temperature throttle valve 71, the second branch 152 is connected with a hot side inlet of the 4K normal pressure liquid helium tank 2 through a low-temperature regulating valve 72, the third branch 153 is connected with a 2K negative pressure superfluid helium tank 4, a cold side outlet of the third branch 153 and the 2K negative pressure superfluid helium tank 4 are provided with a low-temperature regulating valve 72,4K, a hot side outlet of the second return pipeline 16,4K of the normal pressure liquid helium tank 2 is connected with a hot side inlet of the 2K negative pressure heat exchanger 3 to be tested, a low-temperature stop valve 73 and a flowmeter are arranged on a connecting pipeline of the hot side outlet of the 4K normal pressure liquid helium tank 2 and the hot side inlet of the 2K negative pressure heat exchanger 3 to be tested, a side outlet of the 2K negative pressure heat exchanger 3 is connected with the 2K negative pressure superfluid helium tank 4 to be tested, a cold side outlet of the 2K negative pressure heat exchanger 3 is connected with the cold side inlet of the 2K negative pressure heat exchanger 3 to be tested, and the cold side outlet of the 2K negative pressure heat exchanger 3 is connected with the cold side inlet of the 2K negative pressure heat exchanger 3 to be tested;
The first air inlet pipeline 12 is provided with a temperature sensor 81 and a pressure sensor 82, the first air return pipeline 13 is provided with a temperature sensor 81,4K, the liquid inlet pipeline 15 is provided with a temperature sensor 81 and a pressure sensor 82,4K, the normal pressure liquid helium tank 2 is provided with the temperature sensor 81 and a pressure sensor 82, the cold side outlet pipeline of the normal pressure liquid helium tank 2 is provided with the pressure sensor 83,4K, the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be tested are respectively provided with the temperature sensor 81 and the pressure sensor 82, the first liquid return pipeline 17 is provided with a flowmeter, the pressure sensor 82 and the temperature sensor 81, the differential pressure sensor 84,2K negative pressure overflow helium tank 4 is respectively connected between the hot side two ends and between the cold side two ends of the 2K negative pressure heat exchanger 3 to be tested, and the temperature sensor 81, the 4K negative pressure liquid level meter 85 and the 2K negative pressure liquid level meter 86 are respectively arranged. The measurement accuracy of the negative pressure level gauge 86 under 2K conditions is higher than that of the 4K negative pressure level gauge 85,2K.
Preferably, the first branch 151 and the low-temperature throttle valve 71 on the hot side outlet of the 2K negative pressure heat exchanger 3 to be tested and the connecting pipeline of the 2K negative pressure superfluid helium tank 4 are joule-thomson throttle expansion valves (J-T valves), the 4K normal pressure liquid helium tank 2 is an immersion type coil heat exchanger, and the minimum allowable volume of the 4K normal pressure liquid helium tank 2 is a liquid fully immersed type coil heat exchanger. Of course, in other embodiments of the present invention, other types of cryogenic throttle valves 71 and 4K atmospheric liquid helium tank 2 may be used.
Specifically, the 2K negative pressure heat exchanger 3 to be measured is fixedly installed through 4 lead screws, and is fixed and leveled by using bolts in the horizontal direction and the vertical direction, so that the heat exchangers of different types and sizes can be replaced more conveniently.
Further, the first vacuum pump 14 is a combination of a molecular pump and a mechanical pump.
The 2K negative pressure heat exchanger test platform provided by the embodiment can be used for researching the flow and heat transfer characteristics of heat exchangers under different heat exchanger types, fin types, geometric dimensions and mass flow under a deep low-temperature environment with high precision, evaluating the change relation of flow pressure drops and heat exchange coefficients of different fin units along with Reynolds numbers, measuring the speed distribution of the internal channels of the core body and the end socket by an optical test technology, and providing data support for the design selection of the negative pressure heat exchanger in a future larger refrigerator.
Further, the first liquid return pipeline 17 is provided with a low-temperature stop valve 73 connected in parallel with two ends of the upper flowmeter, when the vacuum pump is just started to vacuumize the pipeline of the test platform, the low-temperature stop valve 73 can be opened, the pressure in the loop is rapidly reduced, and when the display pressure of the pressure sensor 82 on the cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be tested is reduced to 3000-5000Pa, the low-temperature stop valve 73 is closed.
Preferably, the flowmeter on the first liquid return pipeline 17 is a venturi flowmeter 87, and a differential pressure sensor 84 for detecting pressure drops at two sides of an inlet and an outlet of the venturi flowmeter 87 is arranged between the inlet and the outlet.
Further, the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested are connected through a plurality of connecting branches 18, each connecting branch 18 is provided with a low-temperature stop valve 73 and a flowmeter, and the types of the flowmeters on each connecting branch 18 are different.
The existing 2K negative pressure heat exchanger test platform is generally only provided with one type of flowmeter for measuring the helium medium flow injected into the hot side of the 2K negative pressure heat exchanger 3 to be tested, however, the heat exchanger test platform is generally required to test various different flow working conditions, and a single type of flowmeter cannot monitor the helium medium flow injected into the hot side of the 2K negative pressure heat exchanger 3 to be tested with high precision under certain flow working conditions, so that the measurement precision of the test platform is affected to a certain extent. According to the embodiment, the plurality of connection branches 18 are arranged between the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested, the low-temperature stop valve 73 and different types of flowmeters are arranged on each connection branch 18, the adaptive flowmeters can be selected according to different flow test working conditions during testing, and the connection branch 18 where the adaptive flowmeters are located is started to be communicated with the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested, so that the high-precision measurement of helium medium flow input by the hot side of the 2K negative pressure heat exchanger 3 to be tested can be guaranteed under each flow test working condition of a test platform, the risk that the measurement precision of a single type of flowmeters is low under certain flow test working conditions is reduced, and the test precision of the test platform can be guaranteed.
Specifically, the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested are connected through two connecting branches 18, wherein the flowmeter on one connecting branch 18 is a venturi flowmeter 87, and the flowmeter on the other connecting branch 18 is an emerson flowmeter 88. Because the venturi flowmeter 87 needs to combine the temperature, pressure and pressure drop of the inlet fluid and the pressure drop of the outlet fluid when measuring, the connecting branch 18 where the venturi flowmeter 87 is positioned is also provided with a temperature sensor 81 and a pressure sensor 82 for detecting physical properties of the inlet fluid of the flowmeter and a differential pressure sensor 84 for detecting pressure drop of the inlet fluid and the pressure drop of the outlet fluid of the flowmeter.
In addition, in the present embodiment, when cooling, the low-temperature stop valves 73 on all the connection branches 18 need to be opened completely, so that the whole cooling is performed, and the cooling uniformity is ensured.
It should be noted that, the connection between the hot side outlet pipe of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipe of the 2K negative pressure heat exchanger 3 to be tested through the two connection branches 18 is not to be construed as limiting the present invention, and in other embodiments of the present invention, more connection branches 18 may be disposed between the hot side outlet pipe of the 4K normal pressure liquid helium tank 2 and the hot side inlet pipe of the 2K negative pressure heat exchanger 3 to be tested according to actual requirements.
Further, a pressure sensor 82 is arranged at the downstream of the low-temperature throttle valve 71 of the connecting pipeline of the hot side outlet of the 2K negative pressure heat exchanger 3 to be tested and the 2K negative pressure superfluid helium tank 4, and the pressure sensor 82 is used for displaying the pressure at the rear end of the low-temperature throttle valve 71 on the connecting pipeline of the hot side outlet of the 2K negative pressure heat exchanger 3 to be tested and the 2K negative pressure superfluid helium tank 4 and monitoring the throttling effect.
Further, the inner side and the outer side of the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be tested are respectively provided with a temperature sensor 81.
Specifically, two temperature sensors 81 and one temperature sensor 81 are respectively arranged on the inner side and the outer side of the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be tested, wherein the temperature sensor 81 on the inner side is used as a standby, and the reliability of measurement in the embodiment can be further improved. Wherein, the temperature sensors 81 outside the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be measured are uniformly distributed in a radiation shield (not shown in the figure), and the radiation shield is used for reducing the influence of heat radiation on the measurement accuracy of the temperature sensors 81.
Two pressure sensors 82 with different measuring ranges are respectively arranged on a cold side inlet pipeline and a cold side outlet pipeline of the 2K negative pressure heat exchanger 3 to be measured and are respectively used for measuring under positive pressure working conditions and negative pressure working conditions, and when the pressure in the cold side inlet pipeline of the 2K negative pressure heat exchanger is reduced to 0.1bar, the pressure is converted to the negative pressure sensor 82.
Further, the pressure sensor 82 and the differential pressure sensor 84 on the cold side of the 2K negative pressure heat exchanger 3 to be measured are both disposed in a container (not shown in the figure) into which micro-positive pressure normal temperature helium gas is injected, which can reduce the risk of air leakage into the sensor to affect the measurement accuracy.
Further, heaters 9 are respectively arranged at the tank bottom of the 2K negative pressure superfluid helium tank 4 and the bottom outside the cold screen 11. In this embodiment, after the test is completed, the heater 9 may be started to adjust the cold measurement flow of the 2K negative pressure heat exchanger 3 to be tested and accelerate the temperature return rate of the test platform.
Preferably, the power of the electric heater on the 2K negative pressure superfluid helium tank 4 is 500W and is provided with a programmable direct current stabilized voltage supply.
Preferably, an electric heater for adjusting the temperature return rate in the vacuum cover 1 is arranged at the bottom of the outer side of the cold screen 11. Alternatively, the electric heater has an electric power of 100W and is provided with a programmable DC regulated power supply.
Further, the components of the 2K negative pressure heat exchanger 3 to be tested are made of high light transmission materials such as organic glass, and the vacuum cover 1 is provided with a speed measuring area corresponding to the 2K negative pressure heat exchanger 3 to be tested, and the speed measuring area is made of high light transmission materials such as organic glass.
At present, when the heat exchanger is tested at home and abroad, the speed distribution of helium medium in the heat exchange channel of the 2K negative pressure heat exchanger 3 to be tested is mainly measured by adopting a traditional invasive speed measuring method. However, the conventional immersion type velocity measurement method cannot realize high-precision and large-scale measurement of the velocity distribution of helium medium in an opaque heat exchange medium channel. In the embodiment, the 2K negative pressure heat exchanger 3 to be tested is made of a high light transmission material, and the test areas which are also made of the high light transmission material are arranged on the vacuum cover 1 and the cold screen 11, so that the speed distribution of helium medium in a heat exchange medium channel of the 2K negative pressure heat exchanger 3 to be tested can be measured in a high-precision and large-scale manner through an optical velocimetry instrument during heat exchanger test.
In summary, the 2K negative pressure heat exchanger test platform provided in this embodiment may be used for: (1) A new type or low leakage rate, low pressure drop, high heat exchange efficiency, high mechanical strength and small volume of the heat exchanger applied under the new working condition is developed so as to reduce the volume and manufacturing cost of the low-temperature test valve box 5 and the matched device; (2) Study the heat exchanger performance under different types of heat exchangers, type fins, geometry, mass flow and thermal load; (3) Evaluating the applicability of the relation of the flow pressure drop and the heat exchange coefficient of different fin units along with the change of the Reynolds number, and correcting by using experimental data; (4) High-precision measuring equipment such as a temperature sensor 81, a pressure sensor 82, a flowmeter, a liquid level meter and the like are developed; (5) The speed distribution of the heat exchanger core and the flow channel inside the end socket is measured by using an optical test technology, and data support is provided for the design of 2K negative pressure heat exchanger in a refrigerator with larger refrigerating capacity in future.
Example two
The embodiment of the invention provides a 2K negative pressure heat exchanger test system, which comprises a low-temperature test valve box 5, a measurement and control controller and a 2K negative pressure heat exchanger test platform as in the first embodiment, wherein the measurement and control controller is internally provided with a measurement and control program;
the low temperature test valve box 5 is respectively provided with a cold screen air return pipeline 51, a heat exchanger liquid return pipeline 52, a cooling air return pipeline 53, a heat exchanger liquid inlet pipeline 54, a cold screen air inlet pipeline 55, a first mixer 56 and a second mixer 57, the cold screen air return pipeline 51 is connected with the first air return pipeline 13, the heat exchanger liquid return pipeline 52 is connected with the first liquid return pipeline 17, the cooling air return pipeline 53 is connected with the second air return pipeline 16, the cold screen air return pipeline 51, the heat exchanger liquid return pipeline 52 and the cooling air return pipeline 53 are respectively provided with a low temperature regulating valve 72, the heat exchanger liquid return pipeline 52 is also provided with a heater 9, a normal temperature switch valve 74 and a second vacuum pump 521 which are positioned at the downstream of the low temperature regulating valve 72, a first branch pipe 531 is arranged between the cold screen air return pipeline 51 and the cooling air return pipeline 53, a second branch pipe 532 is arranged between the heat exchanger liquid return pipeline 52 and the cooling air return pipeline 53, the first branch pipe 531 and the second branch pipe 532 are respectively provided with a low-temperature regulating valve 72, the first mixer 56 is respectively connected with the 4K liquid inlet pipeline 15 and the heat exchanger liquid inlet pipeline 54, the second mixer 57 is respectively connected with the first air inlet pipeline 12 and the cold screen air inlet pipeline 55, the heat exchanger liquid inlet pipeline 54 and the cold screen air inlet pipeline 55 are respectively provided with the low-temperature regulating valve 72, the low-temperature test valve box 5 is also provided with an evacuation return-temperature air inlet pipeline 58 and a replacement return-temperature air inlet pipeline 59, the evacuation return-temperature return-air pipeline 58 is provided with a third vacuum pump 581 and a normal-temperature switching valve 74, the evacuation return-temperature return-air pipeline 58 is provided with three connecting branch pipes 582, the connecting branch pipe 582 is provided with the normal-temperature switching valve 74, the cold screen return-air pipeline 51, the heat exchanger return-liquid pipeline 52 and the cooling return-air pipeline 53 are respectively connected with the evacuation return-temperature return-air pipeline 58 through one connecting branch pipe 582, the connecting branch pipes 582 are respectively connected with the cold screen return-air pipeline 51, the heat exchanger liquid return pipeline 52 and the cooling air return pipeline 53 are respectively connected with the first mixer 56 and the second mixer 57 at the upstream of the low-temperature regulating valve 72, the normal-temperature regulating valve 75 and the one-way valve 76 are arranged on the connecting pipeline of the replacement liquid return pipeline 59 and the first mixer 56, and the normal-temperature regulating valve 75 is arranged on the connecting pipeline of the replacement liquid return pipeline 59 and the second mixer 57;
The measurement and control controller is respectively in communication connection with each valve and each sensor of the vacuum cover 1 and the low-temperature test valve box 5.
The heat exchanger liquid inlet pipeline 54, the cold screen air inlet pipeline 55 and the replacement temperature return air inlet pipeline 59 can respectively input helium media with different temperatures into the first mixer 56 and the second mixer 57, and during testing, a tester can adjust the opening degree of each valve connected with the first mixer 56 and the second mixer according to testing requirements to control the input quantity of the helium media with different temperatures in the first mixer 56 and the second mixer 57, so that helium media with required temperatures are obtained in the first mixer 56 and the second mixer 57 and are input into a 2K negative pressure heat exchanger testing platform.
Further, the 4K liquid inlet pipeline 15, the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2, the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested and each connecting branch pipe 582 are respectively provided with an exhaust branch pipe 6, and the exhaust branch pipes 6 are respectively provided with a safety valve 77 and a rupture disk, so that gas in each pipeline can be timely discharged under emergency conditions such as water cut-off, power failure and the like, and the pressure safety of each pipeline and a testing platform is ensured.
Preferably, the exhaust branch pipe 6 of the connection branch pipe 582 of the heat exchanger liquid return pipeline 52 and the evacuating and temperature returning air pipeline 58 is also provided with a backup safety valve 77, and the backup safety valve 77 is arranged in a negative pressure protection device (not shown in the figure).
Preferably, the exhaust branch pipe 6 of the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested is also provided with a one-way valve 76 so as to reduce or eliminate the influence of thermo-acoustic oscillation.
Further, the heat exchanger return line 52 also has a turbine flow meter 89 downstream of the second vacuum pump 521, the turbine flow meter 89 being operable to check the venturi flow meter 87 on the first return line 17 at ambient temperature and pressure conditions.
Example III
The embodiment of the invention provides a use method of the 2K negative pressure heat exchanger test system as described in the second embodiment, which comprises the following steps:
s1, all valves except a normal temperature switch valve 74 on a connecting pipeline of the vacuum cover 1 and the first vacuum pump 14 are closed, and the first vacuum pump 14 is started to continuously vacuumize the vacuum cover 1, so that the vacuum degree in the vacuum cover 1 is maintained to be 1 multiplied by 10 -3 Pa or less;
s2, respectively opening valves on all pipelines in the vacuum cover 1 and normal temperature switch valves 74 on the evacuating and tempering air return pipelines 58 and all connecting branch pipes 582, starting a third vacuum pump 581 to vacuumize the 4K normal pressure liquid helium tank 2, the 2K negative pressure heat exchanger 3 to be tested, the 2K negative pressure superfluid helium tank 4 and all pipelines, closing the normal temperature switch valves 74 on the evacuating and tempering air return pipelines 58 and all connecting branch pipes 582 and stopping the third vacuum pump 581 when the display pressure of the pressure sensor 82 on the first air inlet pipeline 12 and the 4K liquid inlet pipeline 15 is 10-100Pa, opening the normal temperature regulating valves 75 on the connecting pipelines of the evacuating and tempering air inlet pipeline 59 and the first mixer 56 and the second mixer 57, respectively inputting 300K to the first air inlet pipeline 12 and the 4K liquid inlet pipeline 15, and closing the normal temperature regulating valves 75 on the connecting pipelines of the replacing and the first air inlet pipeline 59 and the second mixer 57 when the display pressure of the pressure sensor 82 on the first air inlet pipeline 12 and the 4K liquid inlet pipeline 15 is about 1-2bara, and completing the normal temperature regulating valve 5-5 minutes of the replacing and the normal temperature regulating process;
S3, repeating the step S2 for 2 times;
s4, respectively opening valves on all pipelines in the vacuum cover 1 and normal temperature switch valves 74 on the evacuating and temperature return air pipelines 58 and all connecting branch pipes 582, starting a third vacuum pump 581 to vacuumize the 4K normal pressure liquid helium tank 2, the 2K negative pressure heat exchanger 3 to be tested, the 2K negative pressure superfluid helium tank 4 and all pipelines, when the display pressure of pressure sensors 82 on the first air inlet pipeline 12 and the 4K liquid inlet pipeline 15 is 10-100Pa, firstly closing the normal temperature switch valves 74 on the evacuating and temperature return air pipelines 58 and all connecting branch pipes 582, closing the third vacuum pump 581, and then closing the valves on all pipelines of the vacuum cover 1;
s5, opening the low-temperature regulating valves 72 on the first branch pipe 531 and the cold screen air inlet pipeline 55, inputting 50K helium into the spiral winding pipe outside the cold screen 11 for cooling, opening the low-temperature regulating valve 72 on the cold screen air return pipeline 51 and closing the low-temperature regulating valve 72 on the first branch pipe 531 after the display temperature of the temperature sensor 81 on the first air return pipeline 13 is about 75K, and inputting 50K helium into the cold screen 11 through the cold screen air inlet pipeline 55 for continuously cooling for 2-3 hours, so that radiation heat leakage is reduced;
s6, respectively opening a low-temperature throttle valve 71 on a first branch 151 and a low-temperature regulating valve 72 on a cooling return air pipeline 53 and a heat exchanger liquid inlet pipeline 54, inputting pressurized liquid helium (4.7K, 3 bara) into a 4K liquid inlet pipeline 15, synchronously opening the low-temperature regulating valve 72 on a third branch 153 and a second branch 532, injecting the pressurized liquid helium (4.7K, 3 bara) into a 2K negative pressure superfluid helium tank 4 for precooling, setting the opening of the low-temperature throttle valve 71 on the first branch 151 to 5% -8% when the display temperature of a temperature sensor 81 of the 4K normal pressure liquid helium tank 2 is 4.7K, reducing the pressure of the pressurized liquid helium (4.7K, 3 bara) on the first branch 151 to normal pressure liquid helium (4.2K, 1 bara), and keeping the display pressure of a pressure sensor 82 on the second return air pipeline 16 at about 1.1bara constant pressure by using a low-temperature throttle valve 71 on the first branch 153 and the second branch 16 of a measurement and control program, and keeping the display pressure sensor 82 on the second branch 16 at the 2.82 side of the normal pressure liquid helium tank 2.2K constant at the low pressure side of the heat exchanger liquid inlet pipeline 2, and keeping the temperature of the pressurized liquid helium tank at 2.82 at the 2K constant pressure side of the normal pressure liquid inlet side of the heat exchanger liquid helium tank 2;
S7, opening a low-temperature throttle valve 71 on a connecting pipeline of a hot side outlet of a 2K negative pressure heat exchanger 3 to be detected and a 2K negative pressure superfluid helium tank 4, inputting pressurized liquid helium (4.2K, 2.92 bara) to the hot side of the 2K negative pressure heat exchanger 3 to be detected, reducing the pressure of the pressurized liquid helium (4.2K, 2.92 bara) flowing out of the 2K negative pressure heat exchanger 3 to be detected to 2.2K superfluid helium (3130 Pa) by setting the opening of the low-temperature throttle valve 71 on the connecting pipeline of the hot side outlet of the 2K negative pressure heat exchanger 3 to be detected and the 2K negative pressure superfluid helium tank 4 to be detected to 5-10 when the display temperatures and the display liquid levels of a temperature sensor 81 and a 4K normal pressure liquid level gauge 83 of the 2K negative pressure superfluid helium tank 4 are about 4.7K and 50-80% respectively, simultaneously opening a low-temperature regulating valve 72 and a normal-temperature switching valve 74 on a heat exchanger liquid return pipeline 52, starting a second vacuum pump 521 to take away vaporization heat of 4K liquid helium in a 2K negative pressure superfluity helium tank 4, and when the display pressure of a pressure sensor 82 on a cold side inlet pipeline of a 2K negative pressure heat exchanger 3 to be tested is about 3100Pa, interlocking the low-temperature regulating valve 71 on a hot side outlet of the 2K negative pressure heat exchanger 3 to be tested and the pressure sensor 82 on a cold side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested through a measurement and control program, so that the display pressure of the pressure sensor 82 on the cold side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested is always kept at about 3100 Pa;
S8, closing the low-temperature regulating valves 72 on the third branch 153, the first branch 531 and the second branch 532, opening the low-temperature regulating valves 72 on the cold screen return air pipeline 51 and the heat exchanger return liquid pipeline 52, waiting for the display parameters of the temperature sensors 81 on the hot side inlet pipeline and the cold side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested, the 4K normal pressure liquid level gauge 83 of the 4K normal pressure liquid helium tank 2 and the 2K negative pressure liquid level gauge 86 of the 2K negative pressure superfluid helium tank 4 to reach the following test working conditions and maintain for more than 10 minutes: the temperature sensors 81 on the hot side inlet pipeline and the cold side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested show temperatures of about 4.2K and 2.2K respectively, and the 4K normal pressure liquid level meter 83 of the 4K normal pressure liquid helium tank 2 and the 2K negative pressure liquid level meter 86 of the 2K negative pressure overflow helium tank 4 show liquid levels of about 70-90% respectively;
s9, keeping the flow rates of a hot side inlet and a cold side inlet of the 2K negative pressure heat exchanger 3 to be measured equal, measuring the temperature and pressure drop of the cold side and the hot side of the 2K negative pressure heat exchanger 3 to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing method (PIV), measuring the flow rate range to be 1.0-5.0g/s, measuring a group at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors, wherein the expression of the J-F factors is as follows:
Wherein: nu is the nussel number; re is the Reynolds number; pr is the Plandter number; Δp is the pressure drop, pa; d is the hydraulic diameter, m; ρ is density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the v is the velocity, m/s, l is the flow length, m;
s10, fixing the flow rate of a hot side inlet of a heat exchanger to be a certain value, measuring the temperature and pressure drop of a cold side inlet of a 2K negative pressure heat exchanger 3 to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of cold side measuring flow rates within the range of 1.0-5.0g/s at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
s11, fixing the flow rate of a cold side inlet of a heat exchanger to be measured to be a certain value, measuring the temperature and pressure drop of a hot side inlet of a 2K negative pressure heat exchanger 3 to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of hot side measuring flow rates within the range of 1.0-5.0g/s at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
S12, after the test is finished, closing a normal temperature switch valve 74 on a connecting pipeline of the vacuum cover 1 and the first vacuum pump 14, closing the first vacuum pump 14, opening a low temperature regulating valve 72 on a first branch pipe 531 and a second branch pipe 532, closing a cold screen air return pipeline 51, a heat exchanger liquid return pipeline 52, a heat exchanger liquid inlet pipeline 54 and a low temperature regulating valve 72 on a cold screen air inlet pipeline 55, stopping inputting 50K helium gas and pressurized liquid helium (4.7K and 3 bara) into the cold screen 11 and the 4K liquid inlet pipeline 15 respectively, regulating the opening of the first branch pipe 151 and a low temperature throttling valve 71 on a connecting pipeline of the 2K negative pressure heat exchanger 3 to be tested and the 2K negative pressure overflow helium tank 4 to be 100%, opening the low temperature regulating valve 72 on a third branch pipe 153, opening the normal temperature switch valve 74 on each connecting branch pipe 582, inputting 300K helium gas into the cold screen 11 and the 4K liquid inlet pipeline 15 through a replacement temperature return air inlet pipeline 59, and regulating valves 12-82 bara between the replacement temperature air inlet pipeline 59 and the first mixer 56 and the second mixer 57 to enable the opening of the first pressure sensor 82 to be about 2-82 bara;
s13, adjusting the power of an electric heater at the bottom of the outer side of the cold screen 11 and the bottom of the 2K negative pressure overflow helium tank 4 so as to accelerate the temperature return progress;
S14, after the temperature and the pressure in each pipeline and equipment of the 2K negative pressure visual heat exchanger test system are respectively restored to normal temperature and normal pressure, closing all valves and equipment of the 2K negative pressure visual heat exchanger test system;
s15, separating the 2K negative pressure visualization heat exchanger testing platform from the low-temperature testing valve box 5, replacing the 2K negative pressure heat exchanger 3 to be tested with 2K negative pressure heat exchangers of other fin types and geometric dimensions, and repeating the steps to perform performance testing.
The method for adjusting the flow rate of the hot side inlet and the cold side inlet of the heat exchanger in the steps S9-S11 comprises the following steps: the heat exchanger hot side inlet flow is regulated by adjusting the opening of the low temperature regulating valve 72 on the heat exchanger feed line 54 and the second leg 152, and the power of the second vacuum pump 521 is regulated to regulate the heat exchanger cold side inlet flow.
Further, the steps S9-S11 can select an adaptive flowmeter according to the flow condition during each test and enable the connecting branch 18 to communicate the hot side outlet pipeline of the 4K normal pressure liquid helium tank 2 with the hot side inlet pipeline of the 2K negative pressure heat exchanger 3 to be tested, so as to ensure that the flow input by the hot side inlet of the 2K negative pressure heat exchanger 3 to be tested can be accurately measured.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The utility model provides a visual heat exchanger test platform of 2K negative pressure, its characterized in that includes vacuum cover (1), 4K ordinary pressure liquid helium tank (2), awaits measuring 2K negative pressure heat exchanger (3) and 2K negative pressure superfluid helium tank (4), cold screen (11) on its inner wall have in vacuum cover (1), inlet tube and return air pipeline that cold screen (11) outside set up connect first inlet tube way (12) and first return air pipeline (13) respectively, vacuum cover (1) still is connected with first vacuum pump (14), be provided with normal atmospheric temperature ooff valve (74) on vacuum cover (1) and the connecting tube way of first vacuum pump (14), 4K ordinary pressure liquid helium tank (2), await measuring 2K negative pressure heat exchanger (3) and 2K negative pressure superfluid helium tank (4) set up in cold screen (11);
the vacuum cover (1) is provided with a 4K liquid inlet pipeline (15), the 4K liquid inlet pipeline (15) enters the vacuum cover (1) and is divided into a first branch (151), a second branch (152) and a third branch (153), the first branch (151) is connected with a cold side inlet pipeline of the 4K normal pressure liquid helium tank (2) through a low-temperature throttle valve (71), the second branch (152) is connected with a hot side inlet of the 4K normal pressure liquid helium tank (2) through a low-temperature regulating valve (72), the third branch (153) is connected with a 2K negative pressure superfluid helium tank (4), the connecting pipeline of the third branch (153) and the 2K negative pressure superfluid helium tank (4) is provided with a low-temperature regulating valve (72), the cold side outlet of the 4K liquid helium tank (2) is connected with a second return air pipeline (16), the hot side outlet of the 4K normal pressure liquid helium tank (2) is connected with a hot side inlet of the 2K negative pressure heat exchanger (2), the hot side of the 4K normal pressure liquid helium tank (2) is connected with a hot side heat exchanger (3) of the 2K negative pressure heat exchanger (3), the hot side of the 2K normal pressure liquid helium tank (2) is connected with the hot side heat exchanger (3), a low-temperature throttle valve (71) is arranged on a connecting pipeline between a hot side outlet of the 2K negative pressure heat exchanger (3) to be tested and the 2K negative pressure superfluid helium tank (4), a cold side inlet of the 2K negative pressure heat exchanger (3) to be tested is connected with the 2K negative pressure superfluid helium tank (4), and a cold side outlet of the 2K negative pressure heat exchanger (3) to be tested is connected with a first liquid return pipeline (17);
The system comprises a first air inlet pipeline (12), a first air return pipeline (13), a first pressure gauge (83), a second air inlet pipeline (13), a first pressure gauge (82), a second pressure gauge (84), a negative pressure gauge (81) and a differential pressure sensor (86), wherein the first air inlet pipeline (12) is provided with a temperature sensor (81) and a pressure sensor (82), the first air return pipeline (13) is provided with a temperature sensor (81) and a pressure sensor (82), the 4K normal pressure liquid helium tank (2) is provided with a temperature sensor (81) and a pressure gauge (83), the cold side outlet pipeline of the 4K normal pressure liquid helium tank (2) is provided with a pressure sensor (82), the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger (3) are respectively provided with a temperature sensor (81) and a pressure sensor (82), the first liquid return pipeline (17) is provided with a flowmeter, a pressure sensor (82) and a temperature sensor (81), a differential pressure sensor (84) is respectively connected between the hot side and the cold side two ends of the 2K negative pressure heat exchanger (3), and a negative pressure gauge (85) is provided with a negative pressure gauge (84);
the components of the 2K negative pressure heat exchanger (3) to be tested are made of high light transmission materials, and the vacuum cover (1) and the cold screen (11) are provided with a speed measuring area which corresponds to the 2K negative pressure heat exchanger (3) to be tested, and the speed measuring area is made of high light transmission materials.
2. The 2K negative pressure visualization heat exchanger test platform according to claim 1, wherein the connection pipeline of the hot side outlet of the 4K normal pressure liquid helium tank (2) and the hot side inlet of the 2K negative pressure heat exchanger to be tested (3) comprises a plurality of connection branches (18) which are arranged in parallel, and each connection branch (18) is provided with a low-temperature stop valve (73) and a flowmeter respectively, and the types of the flowmeters on each connection branch (18) are different.
3. The 2K negative pressure visualization heat exchanger test platform according to claim 1, wherein two temperature sensors (81) and one temperature sensor (81) are respectively arranged on the inner side and the outer side of the hot side inlet pipeline, the hot side outlet pipeline, the cold side inlet pipeline and the cold side outlet pipeline of the 2K negative pressure heat exchanger (3) to be tested.
4. A 2K negative pressure visualized heat exchanger test platform according to claim 3, wherein pressure sensors (82) are respectively arranged on a hot side inlet pipeline, a hot side outlet pipeline, a cold side inlet pipeline and a cold side outlet pipeline of the 2K negative pressure heat exchanger (3) to be tested, and two pressure sensors (82) with different measuring ranges are respectively arranged on a cold side inlet pipeline and a cold side outlet pipeline of the 2K negative pressure heat exchanger (3) to be tested.
5. The 2K negative pressure visualization heat exchanger test platform as claimed in claim 1, wherein heaters (9) are respectively arranged at the tank bottom of the 2K negative pressure superfluid helium tank (4) and the bottom outside the cold screen (11).
6. The 2K negative pressure visualization heat exchanger test platform of claim 1, wherein the first liquid return pipeline (17) is provided with a low-temperature stop valve (73) which is arranged at two ends of the upper flowmeter in parallel.
7. A 2K negative pressure visualized heat exchanger test system, which is characterized by comprising a low-temperature test valve box (5), a measurement and control controller and a 2K negative pressure visualized heat exchanger test platform according to any one of claims 1-6, wherein the measurement and control controller is loaded with a measurement and control program;
the low-temperature test valve box (5) is respectively provided with a cold screen return air pipeline (51), a heat exchanger return air pipeline (52), a cooling return air pipeline (53), a heat exchanger inlet air pipeline (54), a cold screen inlet air pipeline (55), a first mixer (56) and a second mixer (57), the cold screen return air pipeline (51) is connected with the first return air pipeline (13), the heat exchanger return air pipeline (52) is connected with the first return air pipeline (17), the cooling return air pipeline (53) is connected with the second return air pipeline (16), the cold screen return air pipeline (51), the heat exchanger return air pipeline (52) and the cooling return air pipeline (53) are respectively provided with a low-temperature regulating valve (72), the heat exchanger return air pipeline (52) is also provided with a heater (9), a normal-temperature switching valve (74) and a second vacuum pump (521) which are positioned at the downstream of the low-temperature regulating valve (72), the cold screen return air pipeline (51) and the cooling return air pipeline (53) are connected with the second return air pipeline (53), a first return branch pipe (532) and a second return air pipeline (532) are respectively provided with a cooling branch pipe (532), the first mixer (56) is respectively connected with the 4K liquid inlet pipeline (15) and the heat exchanger liquid inlet pipeline (54), the second mixer (57) is respectively connected with the first air inlet pipeline (12) and the cold screen air inlet pipeline (55), the heat exchanger liquid inlet pipeline (54) and the cold screen air inlet pipeline (55) are provided with a low-temperature regulating valve (72), the low-temperature test valve box (5) is also provided with an evacuation return air pipeline (58) and a replacement return air inlet pipeline (59), the evacuation return air pipeline (58) is provided with a third vacuum pump (581) and a normal-temperature switching valve (74), the evacuation return air pipeline (58) is provided with three connecting branch pipes (582), the connecting branch pipes (582) are provided with normal-temperature switching valves (74), the cold screen return air pipeline (51), the heat exchanger return air pipeline (52) and the cooling return air pipeline (53) are respectively connected with the cold screen air return pipeline (52) through one of the connecting branch pipes (58) and the cooling return air pipeline (582) respectively, the replacement tempering air inlet pipeline (59) is respectively connected with the first mixer (56) and the second mixer (57), a normal temperature regulating valve (75) and a one-way valve (76) are arranged on the connecting pipeline of the replacement tempering air inlet pipeline (59) and the first mixer (56), and a normal temperature regulating valve (75) is arranged on the connecting pipeline of the replacement tempering air inlet pipeline (59) and the second mixer (57);
And the measurement and control controller is respectively in communication connection with each valve and each sensor of the vacuum cover (1) and the low-temperature test valve box (5).
8. The 2K negative pressure visualized heat exchanger test system according to claim 7, wherein the 4K liquid inlet pipeline (15), the hot side outlet pipeline of the 4K normal pressure liquid helium tank (2), the hot side inlet pipeline of the 2K negative pressure heat exchanger (3) to be tested and each of the connecting branch pipes (582) are respectively provided with an exhaust branch pipe (6), and the exhaust branch pipes (6) are respectively provided with a safety valve (77) and a rupture disk.
9. The 2K negative pressure visualized heat exchanger test system according to claim 8, wherein the exhaust branch pipe (6) of the hot side inlet pipeline of the 2K negative pressure heat exchanger (3) to be tested is further provided with a one-way valve (76).
10. A method of using the 2K negative pressure visualization heat exchanger test system of claim 7, comprising the steps of:
s1, all valves except a normal temperature switch valve (74) on a connecting pipeline of a vacuum cover (1) and a first vacuum pump (14) are closed, and the first vacuum pump (14) is started to continuously perform continuous vacuumizing treatment on the vacuum cover (1), so that the vacuum degree in the vacuum cover (1) is maintained to be 1 multiplied by 10 -3 Pa or less;
s2, respectively opening valves on all pipelines in a vacuum cover (1) and normal temperature switch valves (74) on an evacuating and temperature return air pipeline (58) and all connecting branch pipes (582), starting a third vacuum pump (581) to vacuumize a 4K normal pressure liquid helium tank (2), a 2K negative pressure heat exchanger (3) to be tested, a 2K negative pressure superfluid helium tank (4) and all pipelines, closing the normal temperature switch valves (74) on the evacuating and temperature return air pipeline (58) and all connecting branch pipes (582) when the display pressure of a pressure sensor (82) on a first air inlet pipeline (12) and a 4K liquid inlet pipeline (15) is 10-100Pa, closing a third vacuum pump (581), opening the normal temperature switch valves (75) on connecting pipelines of a temperature return air inlet pipeline (59) and a first mixer (56) and a second mixer (57), respectively inputting 300K helium gas to the first air inlet pipeline (12) and the 4K liquid inlet pipeline (15), and closing the normal temperature switch valves (74) on the first air inlet pipeline (12) and the pressure sensor (15) when the display pressure of the first air inlet pipeline (12) and the 4K liquid inlet pipeline (15) is about 10-100Pa, and the normal temperature switch valves (75) on the first air inlet pipeline (57) and the second mixer (57) are closed, and the normal temperature switch valves (75) is closed, and the normal temperature switch is about 5-5 m and the normal temperature switch valves is replaced;
s3, repeating the step S2 for 2 times;
s4, respectively opening valves on all pipelines in a vacuum cover (1) and normal temperature switch valves (74) on an evacuating and tempering air return pipeline (58) and all connecting branch pipes (582), starting a third vacuum pump (581) to vacuumize a 4K normal pressure liquid helium tank (2), a 2K negative pressure heat exchanger (3) to be tested, a 2K negative pressure superfluid helium tank (4) and all pipelines, and when the display pressure of a pressure sensor (82) on a first air inlet pipeline (12) and a 4K liquid inlet pipeline (15) is 10-100Pa, firstly closing the evacuating and tempering air return pipeline (58) and the normal temperature switch valves (74) on all connecting branch pipes (582), closing the third vacuum pump (581), and then closing the valves on all pipelines of the vacuum cover (1);
S5, opening low-temperature regulating valves (72) on the first branch pipe (531) and the cold screen air inlet pipeline (55), inputting 50K helium into the spiral winding pipe at the outer side of the cold screen (11) for cooling, opening the low-temperature regulating valve (72) on the cold screen air return pipeline (51) and closing the low-temperature regulating valve (72) on the first branch pipe (531) after the display temperature of a temperature sensor (81) on the first air return pipeline (13) is about 75K, and inputting 50K helium into the cold screen (11) through the cold screen air inlet pipeline (55) for continuously cooling for 2-3 hours, so that radiation heat leakage is reduced;
s6, respectively opening a low-temperature throttle valve (71) on a first branch (151) and a low-temperature regulating valve (72) on a cooling return air pipeline (53) and a heat exchanger liquid inlet pipeline (54), inputting pressurized liquid helium (4.7K, 3 bara) to a 4K liquid inlet pipeline (15), synchronously opening a low-temperature regulating valve (72) on a third branch (153) and a second branch (532), injecting the pressurized liquid helium (4.7K, 3 bara) to a 2K negative pressure superfluid helium tank (4), precooling until the display temperature of a temperature sensor (81) of a 4K normal-pressure liquid helium tank (2) is 4.7K, setting the opening of the low-temperature throttle valve (71) on the first branch (151) to be 5% -8% so as to decompress and cool the pressurized liquid helium (4.7K, 3 bara) on the first branch (151) into normal-pressure liquid helium (4.2K, 1 bara), and keeping the pressure of a pressure sensor (82) on the second return air pipeline (16) at a level of 1.82 until the display temperature sensor (82) on the second branch (16) is 1.82, and always keeping the opening of the low-pressure sensor (82) on the second branch (16) at the same time when the display temperature sensor (81) is 1.82) A low-temperature stop valve (73) on a connecting pipeline between a hot side outlet of the 4K normal pressure liquid helium tank (2) and a hot side inlet of the 2K negative pressure heat exchanger (3) to be tested, and pre-cooling pressurized liquid helium (4.7K, 3 bara) on the hot side of the 4K normal pressure liquid helium tank (2) into pressurized liquid helium (4.2K, 2.92 bara) through normal pressure liquid helium (4.2K, 1 bara) on the cold side of the 4K normal pressure liquid helium tank (2) and keeping the pressure and the temperature of the pressurized liquid helium (4.7K, 3 bara) stable;
S7, opening a low-temperature throttle valve (71) on a connecting pipeline of a hot side outlet of a 2K negative pressure heat exchanger (3) to be detected and a 2K negative pressure superfluid helium tank (4) to be detected, inputting pressurized liquid helium (4.2K, 2.92 bara) to the hot side of the 2K negative pressure heat exchanger (3), opening a low-temperature throttle valve (71) on the connecting pipeline of the 2K negative pressure superfluid helium tank (4) to be detected to 5% -10% when the display temperature and the display liquid level of a temperature sensor (81) and a 4K normal pressure liquid level meter (83) of the 2K negative pressure superfluid helium tank (4) are about 4.7K and 50% -80% respectively, simultaneously opening a low-temperature regulating valve (72) and a normal-temperature switch valve (74) on a circuit (52) of the heat exchanger to be detected, taking away the heat of the 2K negative pressure heat exchanger (3) to be detected from the 2K negative pressure heat exchanger (3) to be detected to the pressure side by a low-temperature throttle valve (71) on the connecting pipeline of the 2K negative pressure superfluid helium tank (4) to be detected to be 2.2K, opening a low-temperature regulating valve (82) on the circuit (52) to be detected to be 2.2K superfluid helium (3130 Pa), and taking away the heat of the 2K negative pressure superfluid helium (521) flowing from the heat exchanger to be detected to the cold side through the cold valve (82) on the cold side of the connecting pipeline of the pipeline to be detected, the display pressure of a pressure sensor (82) on the cold side inlet pipeline of the 2K negative pressure heat exchanger (3) to be tested is always kept at about 3100 Pa;
S8, closing low-temperature regulating valves (72) on a third branch (153), a first branch (531) and a second branch (532), opening low-temperature regulating valves (72) on a cold screen return air pipeline (51) and a heat exchanger return liquid pipeline (52), waiting for display parameters of temperature sensors (81) on a hot side inlet pipeline and a cold side inlet pipeline of a 2K negative pressure heat exchanger (3) to be tested, a 4K normal pressure liquid level meter (83) of a 4K normal pressure liquid helium tank (2) and a 2K negative pressure liquid level meter (86) of a 2K negative pressure overflow helium tank (4) to reach the following test working conditions and maintain for more than 10 minutes: the temperature sensors (81) on the hot side inlet pipeline and the cold side inlet pipeline of the 2K negative pressure heat exchanger (3) to be tested show that the temperatures are about 4.2K and 2.2K respectively, and the liquid levels of a 4K normal pressure liquid level meter (83) of the 4K normal pressure liquid helium tank (2) and a 2K negative pressure liquid level meter (86) of the 2K negative pressure overflow helium tank (4) are about 70-90% respectively;
s9, keeping the flow rates of a hot side inlet and a cold side inlet of a 2K negative pressure heat exchanger (3) to be measured equal, measuring the temperature and pressure drop of the cold side and the hot side of the 2K negative pressure heat exchanger (3) to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring the flow rate range to be 1.0-5.0g/s, measuring a group at intervals of 0.5g/s, analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors, wherein the expression of the J-F factors is as follows:
Wherein: nu is the nussel number; re is the Reynolds number; pr is the Plandter number; Δp is the pressure drop, pa; d is the hydraulic diameter, m; ρ is density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the v is the velocity, m/s, l is the flow length, m;
s10, fixing the flow rate of a hot side inlet of a 2K negative pressure heat exchanger (3) to be measured to be a certain value, measuring the temperature and pressure drop of a cold side inlet of the 2K negative pressure heat exchanger (3) to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of cold side measuring flow rates within the range of 1.0-5.0g/s at intervals of 0.5g/s, then analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
s11, fixing the flow rate of a cold side inlet of a 2K negative pressure heat exchanger (3) to be measured to be a certain value, measuring the temperature and pressure drop of a hot side inlet of the 2K negative pressure heat exchanger (3) to be measured under different flow rates, measuring the speed distribution in different flow channels of the heat exchanger by using a particle image testing (PIV), measuring a group of hot side measuring flow rates within the range of 1.0-5.0g/s at intervals of 0.5g/s, then analyzing the change relation of the heat exchange efficiency, the flow pressure drop and the speed distribution of a certain heat exchanger under different Reynolds numbers along with the Reynolds numbers, and evaluating the change relation of J-F factors;
S12, after the test is finished, a normal temperature switch valve (74) on a connecting pipeline of the vacuum cover (1) and the first vacuum pump (14) is closed, a low temperature regulating valve (72) on a first branch pipe (531) and a second branch pipe (532) is opened, a cold screen return air pipeline (51), a heat exchanger liquid return pipeline (52), a heat exchanger liquid inlet pipeline (54) and a cold screen air inlet pipeline (55) are closed, the normal temperature switch valve (74) on each connecting branch pipe (55) is opened, 50K helium and pressurized liquid helium (4.7K, 3 bara) are stopped being respectively injected into the cold screen (11) and the 4K liquid inlet pipeline (15), the opening of the first branch pipe (151) and the low temperature regulating valve (71) on the connecting pipeline of the 2K negative pressure heat exchanger (3) to be tested and the 2K negative pressure overflow helium tank (4) is adjusted to 100%, the normal temperature switch valve (74) on each connecting branch pipe (153) is opened, the cold screen return air inlet pipeline (11) and the 4K liquid inlet pipeline (582) are respectively opened, the opening degree of a normal temperature regulating valve (75) between the temperature-returning air inlet pipeline (59) and the first mixer (56) and the second mixer (57) is regulated so that the display pressure of a pressure sensor (82) on the first air inlet pipeline (12) and the 4K liquid inlet pipeline (15) is about 2-3bara;
s13, after the temperature and the pressure in each pipeline and equipment of the 2K negative pressure visual heat exchanger test system are respectively restored to normal temperature and normal pressure, closing all valves and equipment of the 2K negative pressure visual heat exchanger test system;
S14, separating the 2K negative pressure visualization heat exchanger testing platform from the low-temperature testing valve box (5), replacing the 2K negative pressure heat exchanger (3) to be tested with 2K negative pressure heat exchangers of other fin types and geometric dimensions, and repeating the steps to perform performance testing.
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