CN115753883A - Energy-conserving test platform of adiabatic performance of liquid hydrogen equipment material - Google Patents
Energy-conserving test platform of adiabatic performance of liquid hydrogen equipment material Download PDFInfo
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- CN115753883A CN115753883A CN202211507255.8A CN202211507255A CN115753883A CN 115753883 A CN115753883 A CN 115753883A CN 202211507255 A CN202211507255 A CN 202211507255A CN 115753883 A CN115753883 A CN 115753883A
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Abstract
The invention relates to an energy-saving test platform for the thermal insulation performance of a liquid hydrogen equipment material, which comprises a calorimeter, and a liquid nitrogen Dewar, a computer, a leak detection system, a vacuum unit, a rewater and a helium liquefaction circulation recovery system which are connected with the calorimeter.
Description
Technical Field
The invention relates to the technical field of low-temperature heat insulation/liquefaction, in particular to a heat insulation performance energy-saving test platform for a liquid hydrogen equipment material.
Background
In order to meet the requirement of efficient sustainable development of domestic liquid hydrogen storage and transportation, a precise test platform for the heat insulation performance of the multilayer heat insulation material at the liquid hydrogen temperature region is designed and researched, and the vacancy of the heat insulation performance of the test material in the ultralow temperature environment can be made up.
The existing low-temperature heat insulation material test method can be divided into a wet calorimetry method based on low-temperature liquid evaporation and a dry calorimetry method based on a refrigerator according to the difference between the cold end temperature and the calorimetry method, wherein the wet calorimetry method uses low-temperature liquid to maintain relatively stable cold end temperature, the heat leakage quantity of a system is obtained by measuring the evaporation quantity of the liquid, the test result is more accurate, but the cold end temperature is limited, and the test cost is higher; in the latter, a refrigerator is used for replacing low-temperature liquid to control the temperature of the cold end, so that the experimental steps are simplified, the problems of cost and safety are avoided, and the error of the test result is larger. The method can be divided into a cylindrical type, a flat type and an ellipsoidal type according to different modes of wrapping multiple layers of materials, wherein the flat type has a simple structure, but small measurement area and large error; the ellipsoid type accords with the actual application scene, but the processing is difficult and the wrapping is complex; the cylindrical shape can effectively reduce unnecessary axial heat transfer, thereby improving the testing precision, and is more commonly used. In addition, most of the multi-layer heat-insulating material test platforms can only measure the heat insulating performance of the liquid nitrogen temperature zone material, only a few of the platforms cover the liquid hydrogen temperature zone test, but the feasibility and the accuracy are not verified, and the method for recovering the cold energy of the low-temperature liquid and reducing the energy consumption of a test system is still a great problem aiming at the wet-type calorimetry with higher precision. Therefore, it is necessary to further develop the design and development work of the platform for testing the thermal insulation performance of the multilayer thermal insulation material in the liquid hydrogen temperature zone.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the energy-saving test platform for the thermal insulation performance of the liquid hydrogen equipment material is provided.
The technical scheme adopted by the invention for solving the technical problems is as follows: a liquid hydrogen equipment material thermal insulation performance energy-saving test platform comprises a calorimeter, and a liquid nitrogen Dewar, a computer, a leak detection system, a vacuum unit, a rewarming device and a helium liquefaction cycle recovery system which are connected with the calorimeter;
the calorimeter is of a cylindrical structure and comprises a vacuum shell, a liquid nitrogen cold screen, a liquid nitrogen inlet, a liquid nitrogen outlet and an inner container, wherein the liquid nitrogen cold screen, the liquid nitrogen inlet, the liquid nitrogen outlet and the inner container are arranged in the vacuum shell, the inner container is wrapped with a heat insulating material and comprises a measuring section, a measuring section inlet pipe and a measuring section outlet pipe are arranged on the measuring section, an upper protection section and a lower protection section are respectively arranged at the upper end and the lower end of the measuring section, an upper protection section liquid inlet pipe and an upper protection section gas outlet pipe are also arranged in the upper protection section, and the upper protection section is communicated with the lower protection section through a communicating pipe;
and the upper protection section and the lower protection section are filled with liquid helium for absorbing heat from the upper part and the lower part of the measurement section, so that the liquid helium in the measurement section is evaporated only due to the heat transmitted by the multilayer composite heat insulation material in the circumferential direction. Go up the protection section, protect the section down and link to each other through middle communicating pipe, become the space that links to each other, liquid helium in this space is through last protection section feed liquor pipe feed liquor, through last protection section outlet duct (sheltered from by the feed liquor pipe in this view) exhaust.
The helium liquefaction circulation recovery system comprises a recovery air bag, a helium compressor, a high-pressure dirty helium container, a helium purifier and a helium liquefier according to the connection sequence, the output end of the helium liquefier is connected to the calorimeter, the exhaust end of the calorimeter is connected with the recovery air bag, and the helium purifier is connected with a liquid nitrogen dewar.
By adopting the technical scheme, the helium liquefaction cycle recovery system is system equipment used for recovering the cold quantity in the helium gas as much as possible and reducing the test cost, the liquefaction capacity, the helium gas loss and the power consumption cost of the helium liquefaction cycle recovery system are calculated and evaluated, the technical economy analysis is carried out on the system and a liquid helium Dewar direct liquid supply method in the whole life cycle, and the energy-saving potential of the test platform is further explored.
Furthermore, the upper end of the vacuum shell is also provided with an outer cavity flange and an aerial insertion interface, so that the vacuum shell is convenient to connect.
Furthermore, a hot end temperature sensor and a cold end temperature sensor are arranged in the vacuum shell;
the outer surface of the whole liner is wrapped with a plurality of layers of heat insulating materials according to the method of GB/T31480-2015 high vacuum multi-layer heat insulating material for the deep cooling container. And a 4K platinum resistance thermometer is respectively arranged at the inner side and the outer side of the middle part of the outer wall surface of the measurement section, and a 4K platinum resistance thermometer is respectively distributed at the 90% liquid level and the 50% liquid level of the upper protection section so as to detect the consumption level of the liquid helium in the protection section and timely supplement a proper amount of the liquid helium. The thermometer precision is +/-0.1K.
Further, a vacuum valve and a liquid nitrogen pump are arranged between the liquid nitrogen Dewar and the calorimeter.
Further, a multimeter is arranged between the computer and the calorimeter.
Furthermore, the output end of the rewarming device is connected with the outlet pipe of the measuring section, and the output end of the rewarming device is connected to the recovery air bag after being connected with the gas pressure sensor, the gas temperature sensor and the gas mass flowmeter.
Further, the liquid nitrogen cooling screen is made of copper, and a liquid nitrogen coil is wound on the liquid nitrogen cooling screen;
by adopting the technical scheme, the temperature of the cold shield is ensured to be at the temperature of liquid nitrogen. The liquid nitrogen cold shield can absorb heat radiation from the shell on one hand and also provides a stable hot end temperature boundary for the measuring section on the other hand. And a 77K thermometer is respectively arranged at a liquid nitrogen inlet and a liquid nitrogen outlet of the liquid nitrogen cold screen to ensure that the temperature of the liquid nitrogen cold screen is monitored to be constant. And when the temperature control system detects that the temperature of the outlet of the liquid nitrogen cooling screen rises, the liquid nitrogen circulation volume is increased, and the temperature range of the hot boundary is ensured to be (77 +/-2) K.
The invention has the advantages of solving the defects in the background technology, being suitable for measuring the apparent thermal conductivity of the high-vacuum multilayer heat-insulating material under the condition of ultralow temperature (liquid helium temperature zone-269 ℃) and using a helium liquefaction cycle recovery system for the cold recovery of the device, thereby improving the economy and having the following advantages:
1. the liquid nitrogen cold shield is used for cold insulation, so that heat transfer from an external heat source is reduced, and the consumption of liquid helium in the test process is reduced;
2. liquid helium is used for maintaining a stable cold end temperature, the heat leakage quantity of the system is obtained by measuring the evaporation quantity of the liquid helium, and the test result is more accurate;
3. the cylindrical calorimeter can effectively reduce unnecessary axial heat transfer, thereby improving the test precision;
4. the helium liquefaction circulation recovery system can recover the cold quantity in the helium as much as possible by applying the helium liquefaction circulation recovery system in the device, and the test cost is reduced.
Drawings
FIG. 1 is a schematic structural diagram of a preferred embodiment of the present invention;
FIG. 2 is a block diagram of the helium liquefaction cycle recovery system of the present invention;
FIG. 3 is a schematic diagram of the construction of the calorimeter of the invention.
Detailed Description
The invention will now be described in further detail with reference to the drawings and preferred embodiments. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
The energy-saving testing platform for the thermal insulation performance of the liquid hydrogen equipment material shown in fig. 1 to fig. 3 comprises a calorimeter 1, and a liquid nitrogen dewar 2, a computer 3, a leak detection system 4, a vacuum unit 5, a reheater 6 and a helium liquefaction cycle recovery system 7 which are connected with the calorimeter 1;
the calorimeter 1 is a cylindrical structure and comprises a vacuum shell 11, a liquid nitrogen cold screen 12, a liquid nitrogen inlet 121, a liquid nitrogen outlet 122 and an inner container 13 wrapping heat insulation materials, wherein the liquid nitrogen cold screen 12, the liquid nitrogen inlet 121, the liquid nitrogen outlet 122 and the inner container 13 are arranged in the vacuum shell 11;
the helium liquefaction circulation recovery system 7 comprises a recovery air bag, a helium compressor, a high-pressure sewage helium container, a helium purifier and a helium liquefier according to the connection sequence, the output end of the helium liquefier is connected to the calorimeter 1, the exhaust end of the calorimeter 1 is connected with the recovery air bag, and the helium purifier is connected with a liquid nitrogen dewar.
Wherein, the upper end of the vacuum casing 11 is further provided with an outer cavity flange 111 and an aerial insertion interface 112, which are convenient for connection.
A hot end temperature sensor and a cold end temperature sensor are also arranged in the vacuum shell 11; the outer surface of the whole liner is wrapped with a multi-layer heat-insulating material according to the method of GB/T31480-2015 high-vacuum multi-layer heat-insulating material for the deep cooling container. A4K platinum resistance thermometer is respectively arranged inside and outside the multilayer heat insulating material at the middle part of the outer wall surface of the measuring section 131, and a 4K platinum resistance thermometer is respectively distributed at the 90% liquid level and the 50% liquid level of the upper protection section 134 so as to detect the liquid helium consumption level of the protection section and timely supplement a proper amount of liquid helium. The thermometer precision is +/-0.1K.
A vacuum valve 8 and a liquid nitrogen pump 9 are arranged between the liquid nitrogen Dewar 2 and the calorimeter 1. A multimeter 10 is also provided between the computer 3 and the calorimeter 1.
The output end of the rewarming device 6 is connected with the outlet pipe 133 of the measuring section, and the output end of the rewarming device is connected to the recovery air bag after being connected with the gas pressure sensor 61, the gas temperature sensor 62 and the gas mass flowmeter 63.
The liquid nitrogen cold shield 12 is made of copper, and a liquid nitrogen coil is wound on the liquid nitrogen cold shield.
Description of the principle:
the calorimeter is a key device for testing the heat insulation performance of the multilayer heat-insulating material in the liquid helium temperature region, the calorimeter adopts a cylindrical structure and a wet-type calorimetry testing principle, and strength check is carried out on structural design parameters such as material selection, wall thickness, volume and the like of each container in the calorimeter through mechanical analysis, so that the mechanical structure reliability of the calorimeter is ensured; theoretical heat leakage calculation analysis is carried out on the calorimeter from 3 heat transfer ways of solid heat conduction, gas heat transfer and radiation heat transfer so as to ensure the accuracy of a test result. The system can calculate and obtain the apparent thermal conductivity of the material under the given test working condition by measuring the gas flow evaporated by the calorimeter with liquid helium as a working medium and according to the thickness of the tested multilayer heat-insulating material and the temperature of cold and hot boundaries, and the specific formula is as follows:
in the formula:
λ -apparent thermal conductivity, W/(m.K);
phi-flow meter correction factor, given according to flow meter specifications;
qm-average mass flow of evaporated helium over 1h, kg/s;
h-latent heat of vaporization of liquid helium at test ambient pressure, J/kg;
th-mean value of thermal boundary temperature within 1h after the system reaches steady state, K;
tc-the average value of the cold boundary temperature within 1h after the system has reached steady state, K;
r is the inner cylinder outer radius of the calorimeter, m;
delta-multilayer insulation sample thickness, m;
l-length of multilayer insulation measurement section, m.
The system can measure the thermal insulation performance of the composite multilayer thermal insulation material under the temperature difference from liquid helium/liquid hydrogen temperature to liquid nitrogen temperature or the temperature difference from liquid helium/liquid hydrogen temperature to room temperature by measuring the heat flow entering the calorimeter through the thermal insulation material and combining the relationship between the heat flow and the low-temperature liquid evaporation rate and the law of Fourier She Daore to calculate the apparent effective thermal conductivity and the heat flow density of the composite multilayer thermal insulation material. The system comprises a calorimeter (comprising a hoisting device), a vacuum pumping system, a data acquisition system and an auxiliary system, and can be reasonably designed on site according to the requirement of Party A. The experiment table calculates and obtains the apparent thermal conductivity coefficient lambda of the tested heat-insulating material under the specified test condition by measuring the gas flow qm of the liquid helium evaporation caused by heat leakage between the liquid helium temperature 4K and the liquid nitrogen temperature 77K.
In order to meet the use condition of the vacuum multilayer heat-insulating material, the space between the inner container and the outer shell is a vacuum interlayer, the vacuum interlayer maintains the vacuum degree below 1 x 10 < -3 > Pa, and the ultimate vacuum of a corresponding vacuum unit is more than one order of magnitude of the vacuum degree, namely 1 x 10 < -4 > Pa; the effective pumping speed of the vacuum unit needs to meet the gas load requirement of a vacuum interlayer of the calorimeter in the maximum design sample test; if the rubber sealing vacuum gauge pipe joint is regulated according to JB/T8105.1, the metal sealing vacuum gauge pipe joint is regulated according to JB/T8105.2; the type and measurement range of the vacuum gauge and the matched vacuum gauge need to meet the requirement of interlayer vacuum degree, and the uncertainty of vacuum measurement should be less than 20%. The width of the sample is 5mm greater than the length of the inner cylinder of the calorimeter; the total number of units of the sample is 30 units; the cleanness of the sample meets the national standard requirement; sealing the top surface of the upper protection section and the bottom surface of the lower protection section by using a sample same type of heat insulation material to prevent axial heat radiation and heat leakage; the length of the sample is reserved with 50mm of allowance according to the calculation result of the outer diameter of the inner cylinder of the calorimeter; the samples were oven dried at (105. + -. 5) ℃ for 24h before testing.
The liquid helium evaporated in the measuring section is changed into helium, the helium is discharged through an outlet pipe of the measuring section, the helium passes through a rewarming device for rewarming heat exchange and returns to the room temperature, the pressure and the temperature are measured through a gas pressure sensor and a gas temperature sensor, the current gas state is confirmed, wherein the thermometer measuring error of the gas temperature is +/-1K, and the gas temperature can reach +/-0.1K after calibration. The helium then re-enters the gas mass flow meter to measure its flow value. Further, the current atmospheric pressure was measured by an atmospheric pressure gauge, and the measurement error of the atmospheric pressure gauge was ± 50Pa.
While particular embodiments of the present invention have been described in the foregoing specification, various modifications and alterations to the previously described embodiments will become apparent to those skilled in the art from this description without departing from the spirit and scope of the invention.
Claims (7)
1. The utility model provides a liquid hydrogen equipment material thermal insulation performance energy-conserving test platform which characterized in that: the system comprises a calorimeter (1), and a liquid nitrogen Dewar (2), a computer (3), a leak detection system (4), a vacuum unit (5), a rewarming device (6) and a helium liquefaction cycle recovery system (7) which are connected with the calorimeter (1);
the calorimeter (1) is of a cylindrical structure and comprises a vacuum shell (11), a liquid nitrogen cooling screen (12), a liquid nitrogen inlet (121), a liquid nitrogen outlet (122) and a liner (13) wrapping heat-insulating materials, wherein the liquid nitrogen cooling screen (12), the liquid nitrogen inlet (121), the liquid nitrogen outlet (122) and the liner (13) are arranged in the vacuum shell (11), the liner (13) comprises a measuring section (131), a measuring section inlet pipe (132) and a measuring section outlet pipe (133) are arranged on the measuring section (131), an upper protecting section (134) and a lower protecting section (135) are respectively arranged at the upper end and the lower end of the measuring section (131), an upper protecting section liquid inlet pipe (136) and an upper protecting section gas outlet pipe are also arranged in the upper protecting section (134), and the upper protecting section (134) is communicated with the lower protecting section (135) through a communicating pipe (137);
helium liquefaction circulation recovery system (7) include recovery gasbag, helium compressor, high pressure dirty helium collection grid, helium purifier and helium liquefier according to the connection sequence, the output of helium liquefier be connected to the calorimeter, the exhaust end of calorimeter (1) with retrieve the gasbag and be connected, helium purifier connect the liquid nitrogen dewar.
2. The energy-saving testing platform for the thermal insulation performance of liquid hydrogen equipment materials according to claim 1, characterized in that: the upper end of the vacuum shell (11) is also provided with an outer cavity flange (111) and an aerial insertion interface (112).
3. The energy-saving testing platform for the thermal insulation performance of liquid hydrogen equipment materials according to claim 1, characterized in that: and a hot end temperature sensor and a cold end temperature sensor are also arranged in the vacuum shell (11).
4. The energy-saving testing platform for the thermal insulation performance of liquid hydrogen equipment materials according to claim 1, characterized in that: a vacuum valve (8) and a liquid nitrogen pump (9) are arranged between the liquid nitrogen Dewar (2) and the calorimeter (1).
5. The energy-saving testing platform for the thermal insulation performance of the liquid hydrogen equipment material as claimed in claim 1, characterized in that: a universal meter (10) is also arranged between the computer (3) and the calorimeter (1).
6. The energy-saving testing platform for the thermal insulation performance of liquid hydrogen equipment materials according to claim 1, characterized in that: the output end of the rewarming device (6) is connected with the outlet pipe (133) of the measuring section, and the output end of the rewarming device is connected to the recycling air bag after being connected with the gas pressure sensor (61), the gas temperature sensor (62) and the gas mass flowmeter (63).
7. The energy-saving testing platform for the thermal insulation performance of liquid hydrogen equipment materials according to claim 1, characterized in that: the liquid nitrogen cold screen (12) is made of copper, and a liquid nitrogen coil is wound on the liquid nitrogen cold screen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211507255.8A CN115753883A (en) | 2022-11-29 | 2022-11-29 | Energy-conserving test platform of adiabatic performance of liquid hydrogen equipment material |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211507255.8A CN115753883A (en) | 2022-11-29 | 2022-11-29 | Energy-conserving test platform of adiabatic performance of liquid hydrogen equipment material |
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| CN115753883A true CN115753883A (en) | 2023-03-07 |
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