Liquid hydrogen temperature zone material mechanical testing platform based on low-temperature refrigerator and refrigerant circulation

Abstract

The invention relates to the technical field of material mechanical testing, and aims to provide a liquid hydrogen temperature zone material mechanical testing platform based on a low-temperature refrigerator and a refrigerant circulation. The testing platform comprises a universal testing machine, a vacuum insulated dewar cavity, a refrigerant circulation system and a low-temperature refrigeration system. The refrigerant circulation system comprises a nozzle, a secondary cold end heat exchanger, a secondary convection type heat exchanger, a primary cold end heat exchanger, a primary convection type heat exchanger, and a high-pressure gas storage tank, a circulating pump, a low-pressure gas storage tank and a helium bottle arranged outside the universal testing machine. A closed circulation loop is formed through a pipeline, and helium is taken as a refrigerant. According to the liquid hydrogen thermal zone material mechanical testing platform based on low-temperature refrigerator andrefrigerant circulation, the testing of various mechanical properties such as isothermal stretching, compression, bending, shearing, fatigue and fracture toughness of materials in the temperature range of the liquid hydrogen to the room temperature can be realized, the temperature range of the material mechanical test is expanded, and the temperature control precision and stability are improved. Meanwhile, a large amount of waste of helium is avoided, the test cost is greatly reduced, and the use of liquid hydrogen is avoided to improve the safety of the system.

Description

technical field [0001] The invention relates to the technical field of material mechanics testing, in particular to a material mechanics testing platform in a liquid hydrogen temperature zone based on a low-temperature refrigerator and a refrigerant cycle. The platform can measure quasi-static mechanical properties such as tensile, fatigue, bending, and fracture toughness of structural materials under the environment of liquid hydrogen temperature (-253°C) to normal temperature (20°C). Background technique [0002] As an efficient and clean energy source, hydrogen energy is one of the important long-term solutions to current energy problems. How to store and transport safely and efficiently is a key technical challenge for the large-scale application of hydrogen energy. With the increasing maturity of cryogenic, adiabatic and vacuum technologies, the storage and transportation of cryogenic liquid hydrogen has higher storage density and lower operating pressure, which reduce...

AI Technical Summary

Problems solved by technology

However, liquid helium is expensive (about 150 yuan / L), and each test requires at least hundreds of liters of liquid helium to cool the sample, which is impossible for users who do not have a liquid helium circulation preparation system. Recycling will make the test cost very high; the latent heat of vaporization per unit volume of liquid hydrogen is low (only 3.18×10 4 kJ / m 3 , about 1 / 7 of liquefied natural gas) so it is easy to vaporize and cause the system pressure to rise rapidly, hydrogen has low ignition energy (0.017mJ), large flammable range (4-75%), and large detonation range (18.3-59%), so it is extremely Inflammable and explosive, hydrogen molecules are small in size and density, easy to leak and spread, and hydrogen is also easy to cause hydrogen embrittlement of materials, so the use of liquid hydrogen requires very expensive safety protection equipment and strict operating procedures

In addition, by using liquid helium or liquid hydrogen to immerse the sample, a more accurate and stable temperature control can be obtained at the corresponding boiling point temperature (liquid helium boiling point -269°C; liquid hydrogen boiling point -253°C) by means of boiling heat exchange; To realize the test above the boiling point of liquid helium or liquid hydrogen, it is necessary to suspend the sample above the liquid helium or liquid hydrogen, and use the flashed helium (or liquid hydrogen) vapor to heat the sample through natural convection heat exchange. Cooling, this heat transfer method has a limited heat transfer coefficient, and it is difficult to achieve a small heat transfer temperature difference and high temperature control accuracy and stability, that is, it is impossible to carry out effective isothermal mechanical performance tests

[0005] Therefore, in order to test the temperature of liquid hydrogen, the existing material mechanical property test system must use liquid helium or liquid hydrogen as the cold source and refrigerant, which has technical problems of high test operation cost, complicated operation, and poor safety, and it is difficult to test liquid helium. Or isothermal mechanical performance test in the temperature zone above the liquid hydrogen temperature

Images