38 results about "Liquid nitrogen" patented technology

The invention belongs to the technical field of low-temperature facility environment testing, and discloses a temperature and pressure environment test chamber and a test method thereof. The main body of the temperature and pressure environment test chamber is a test chamber body, and an external gas inlet branch on the test chamber body is used for conveying gas to the test chamber body; the air pressure adjusting branch is used for adjusting the pressure of the air inlet branch; the exhaust branch is used for exhausting gas in the test cabin body; the circulating gas branch is used for gas circulation in the test cabin body; the liquid nitrogen injection branch comprises a liquid nitrogen injection branch and a liquid nitrogen discharge branch, the liquid nitrogen injection branch is used for injecting liquid nitrogen into the test cabin, and the liquid nitrogen discharge branch is used for discharging nitrogen of the liquid nitrogen buffer tank. The test method comprises an air temperature and pressure environment test method and a nitrogen temperature and pressure environment test method. The temperature and pressure environment test chamber and the test method thereof are applied to the field of large low-temperature facilities and the field of temperature and pressure test such as aerospace exploration, plateau environment and high-altitude environment, and have practical value.

The present invention discloses a method for determining an on-orbit calibration nonlinear coefficient of a satellite-borne microwave radiometer before launch. The method comprises: sequentially observing three calibration blackbodies by the satellite-borne microwave radiometer to be measured within a scanning cycle to obtain observation voltages and brightness temperatures corresponding to three different temperatures; the three calibration blackbodies comprise: a cold calibration blackbody at the boiling point of liquid nitrogen, a hot calibration blackbody at ambient temperature, and a calibration blackbody at an intermediate temperature between the cold and ambient temperatures; obtaining a secondary calibration curve from the observation voltages and brightness temperatures at the three different temperatures; determining virtual cold space data from the secondary calibration curve through virtual cold space observation; if observation data at an intermediate value between the virtual cold space data and the hot calibration blackbody data can be determined from the virtual cold space data and the hot calibration blackbody data, calculating the nonlinear coefficient from the virtual cold space data and the hot calibration blackbody data; otherwise, calculating the nonlinear coefficient from the virtual cold space data, the hot calibration blackbody data, and the intermediate temperature blackbody data.

The application provides a kind of detection method and system for liquid nitrogen liquid level, it is related to liquid level measurement technical field, including with the first data information of liquid nitrogen environment that is obtained by real-time acquisition using pre-set target sensor;Based on the first data information and the evaporation characteristics of liquid nitrogen in the present environment, after obtaining the empirical equation corresponding to the relationship between liquid nitrogen level and time, temperature, the target state equation and observation equation are constructed;Introduce Kalman filtering algorithm, and combine the target state equation and observation equation to estimate the real-time liquid level state of liquid nitrogen.Combined with Kalman filtering algorithm, the corresponding evaporation characteristics of the environment based on the storage of liquid nitrogen is used to obtain the empirical equation corresponding to the relationship between liquid nitrogen level and time, temperature, and then the sensor liquid level meter is used to realize the accurate estimation of the continuous real-time liquid level state of liquid nitrogen.

The liquid nitrogen testing Dewar comprises a cold end cold head, a variable-temperature cold head, a variable-temperature rotating block, a transition block, a loading cold head, the large-area-array detector, an optical window, a liquid nitrogen storage cavity and a shell. The cold energy of the liquid nitrogen storage cavity forms a solid conduction path through the cold-end cold head, the variable-temperature cold head and the loading cold head, and the variable-temperature cold head and the loading cold head adopt a low-heat-conduction hollow structure to construct a basic temperature difference; the variable-temperature rotating block is connected with the variable-temperature cold head and the transition block in a threaded fit mode, and the cooling capacity obtaining degree of the object carrying cold head is changed by means of position adjustment. According to the invention, flexible and accurate temperature control within the range of 80K-180K can be realized, the cooling capacity transmission is efficient, the use is convenient, and the device is suitable for testing and screening of large-area-array detectors with different temperature requirements.

The present application relates to a kind of sensor thermal shock and thermal response characteristic testing device and use method, the testing device includes lifting control unit, lifting unit, test unit and temperature control unit;The lifting control unit is electrically connected with lifting unit, the test unit is set in one side of lifting unit, the test unit is connected with temperature control unit;The test unit includes liquid nitrogen dewar, the liquid nitrogen dewar is connected to lifting unit, sample rod is provided above the liquid nitrogen dewar, support mechanism is connected above the sample rod, and the support mechanism is fixedly connected to workbench.The device of the present application can realize fast temperature switching between liquid nitrogen temperature zone (77 K) and room temperature, while automatically controlling to execute thermal shock cycle, and measure response dynamic behavior and record analysis data.

The invention discloses a method for quickly reducing the cooling temperature of a sample in a low-temperature impact test, which is characterized by comprising the following steps of: putting the sample into a low-temperature tank of an impact testing machine, adding alcohol to submerge the sample by more than 25mm, opening an air valve, slowly introducing liquid nitrogen, and keeping for a certain time after the temperature is reached, so as to ensure that the temperature is uniform. The invention aims to provide the method for quickly reducing the cooling temperature of the sample in the low-temperature impact test, and the method has the characteristics of high cooling rate, simplicity in operation, easiness in popularization and the like, and can meet the requirements of daily urgent test, completion of the test in a short time and provision of a test result.

The invention discloses a cleanliness detection method and device suitable for a long-distance refrigeration pipeline, and relates to the related technical field of cleanliness detection.The method comprises the steps that the injection gas type and injection pulse signals of a to-be-detected long-distance pipeline are determined; a liquid nitrogen vaporization device is connected, a pulse injection valve is controlled by injecting pulse signals to inject gas into an inlet, an infrared thermal imaging array is adopted to collect the temperature of the outer surface, and real-time response data of the temperature of the outer surface are output; constructing a heat transfer abnormal area identification model through a pipeline three-dimensional transient heat transfer equation, and marking an abnormal area to obtain a heat transfer abnormal area; and analyzing the heat transfer abnormity response data of the heat transfer abnormity area, and generating a cleanliness detection result. The technical problems that in the prior art, the cleanliness detection efficiency of a long-distance refrigeration pipeline is low, real-time dynamic monitoring cannot be achieved, and a local pollution area is difficult to accurately recognize are solved, and the technical effects that the heat transfer abnormal area is accurately positioned, and high-efficiency and high-precision cleanliness detection is conducted on the pipeline are achieved.

The invention discloses a system and method for testing water-ice phase change frost heaving force in liquid nitrogen cold impact coal rock, a liquid nitrogen injection device accurately controls the cooling rate of a sample, and it is ensured that stable temperature change is maintained in the freezing process; the sample testing device monitors flow, temperature, deformation quantity and frost heaving force parameters of a sample in the freezing process in real time, and the data acquisition and control device is responsible for synchronously collecting data; through cooperative work of multiple devices, high precision and synchronism of the measurement process are guaranteed, multi-parameter synchronous measurement at any moment in the freezing process is achieved, and therefore complete and accurate experimental data are provided for research of complex physical phenomena such as water-ice phase change frost heaving force in the liquid nitrogen environment. Besides, through real-time dynamic monitoring of the cooling process, frost heaving deformation of the sample can be accurately evaluated, and generation of measurement errors and time delay in the traditional technology is avoided. The device is not only suitable for static measurement, but also can meet dynamic experiment requirements, and the accuracy and efficiency of experiments are greatly improved.

The invention provides sample cooling equipment, a sample cooling method and a freezing observation treatment device. The sample cooling equipment comprises a gas supply assembly; the cooling assembly comprises a cooling generation bottle and a heat exchange tube; the transmission assembly comprises a protection pipe, a stop pipe and an air supply pipe, the stop pipe and the inner wall of the protection pipe are arranged at an interval, so that a vacuum heat insulation space is defined by the stop pipe and the protection pipe, and the air supply pipe communicates with the heat exchange pipe; and the cooling table assembly comprises a cooling table. Normal-temperature nitrogen is input into the heat exchange pipe through the gas supply assembly and then cooled through liquid nitrogen, and then the cooled nitrogen is input into the cooling table assembly through the conveying assembly, so that cooling and caching of samples are achieved. In the process, due to the arrangement of the heat insulation space in the transmission assembly, the loss of cooling capacity of the gas in the transmission process is reduced to the maximum extent, the stability of the low-temperature environment of the cooling table assembly is ensured, and therefore the cooling table assembly has the advantages of being stable in temperature, convenient to operate and adjust, flexible to use, wide in application range and the like.

The application discloses a kind of low-temperature injection type accumulator test devices of multiple parameter adjustable, comprising: delivery pipe, accumulator, gas supply assembly, accumulator inflation and exhaust assembly, delivery pipe pressurization and pressure relief assembly, liquid nitrogen heat exchanger, constant temperature water bath, gas component measurement airtight container, vacuum pump, measurement control system.The application can be applicable to the performance parameter influence study of large-volume low-temperature injection type accumulator, can be realized but not limited to the delivery pipe pressure intensity change rate is adjusted in the range of 0~30kPa / s, effectively assesses the working performance of injection type accumulator under different inflation flow, inflation temperature, exhaust aperture, environmental back pressure and other parameters under variable back pressure condition, simultaneously obtains the loss flow, loss total amount of low-temperature liquid in injection type accumulator and the liquid level fluctuation in injection type accumulator during working process.

The invention belongs to the technical field of tunnel excavation, and particularly relates to a tunnel excavation gushing water rapid plugging construction method which comprises the following steps: (1) temporary plugging preparation; (2) quickly freezing water to form an ice plug layer; and (3) performing permanent plugging construction. The tunnel excavation gushing water rapid blocking construction method has the remarkable beneficial effects of being high in blocking efficiency, environmentally friendly, high in adaptability, good in economical efficiency and safe to operate. According to the method, the extremely low temperature characteristic of liquid nitrogen is utilized, gushing water can be quickly frozen within 30-60 minutes to form a stable ice plug layer, the plugging time is shortened by 80% or above compared with a traditional method, and the emergency treatment speed is greatly increased.

The invention relates to the technical field of automatic control of an aquatic product quick-freezing process, in particular to a liquid nitrogen flow automatic adjusting system and application thereof in abalone preservation, and the system comprises a data acquisition module which is used for acquiring physical parameters of a target aquatic product in real time; the thermophysical property resolving module is used for determining the instantaneous thermal conductivity of the aquatic product; the state prediction module is used for predicting and obtaining a next-moment system state including the next-moment core temperature and the next-moment surface temperature; the risk prediction module is used for determining a predicted heat stress risk index at the next moment; the control decision module is used for solving the minimum value of a preset cost function to determine the optimal liquid nitrogen injection intensity by combining the deviation, predicted by the state prediction module, between the core temperature at the next moment and the preset target temperature and the predicted heat stress risk index determined by the risk prediction module; the method gets rid of dependence on an immobilized cooling procedure, and ensures the stability and high quality of the quick-freezing fresh-keeping effect.

The application discloses a method for regulating the rejuvenation degree by low-temperature thermal cycle treatment, and steps of the method comprise the following: preparing a La-based amorphous alloy sample with a smooth mirror surface; performing low-temperature thermal cycle treatment on the sample, first placing the sample in liquid nitrogen (77K) and keeping the sample in the liquid nitrogen for a period of time, then quickly transferring the sample to boiling water and keeping the sample in the boiling water, and the time of the two processes is equal, and the total time is one cycle period, the time of each single cycle is controlled and the total keeping time is kept the same to obtain the sample after different cycle frequencies; analyzing the sample after the cycle by means of a nanoindenter, a differential scanning calorimeter and a dynamic thermal mechanical analyzer to obtain hardness, activation volume, relaxation enthalpy and beta relaxation activation energy respectively. The sample with different rejuvenation degrees can be obtained by regulating the cycle frequency, and the rejuvenation degree can reach the maximum at a certain cycle frequency, and the application also provides a new idea and scheme for regulating the rejuvenation degree of the amorphous alloy and improving the mechanical properties of the amorphous alloy.

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

The present invention discloses a test system and control method for ultra-low temperature impact testing. The test system comprises a liquid nitrogen storage device, a delivery system, and a closed test chamber. The liquid nitrogen storage device includes a liquid nitrogen storage tank with an evaporation device at its bottom and a stirring device at its center. The delivery system includes a delivery pipeline, the upper end of the liquid nitrogen storage tank being connected to the test chamber via the delivery pipeline, and a temperature control device being provided at its center. The control method includes steps S1-S10. The device of the present invention utilizes a cryogenic gaseous working fluid to control the ambient temperature of a local area of ​​the equipment. Adjustment to different ambient temperature requirements is achieved by varying the power of the thermal evaporation device and the stirring rate of the stirring device. The device has the advantages of wide temperature coverage, automated parameter adjustment, and reliable operation.

The utility model relates to a temperature control device for an ultralow-temperature impact test. The temperature control device comprises a box body, and a feeding bin, a first auxiliary bin, a reaction bin and a second auxiliary bin which are arranged in the box body and distributed from one end of the box body to the other end of the box body, a transfer part is slidably connected to the bottom of the box body and penetrates through the feeding bin, the first auxiliary bin, the reaction bin and the second auxiliary bin; the temperature piece is respectively connected with the first auxiliary bin, the reaction bin and the second auxiliary bin. The technical scheme of the application has the beneficial technical effects that when cooling treatment needs to be performed, the temperature piece firstly controls the first auxiliary bin and the second auxiliary bin to perform cooling to the required test temperature of the to-be-tested object. Immediately, the temperature part controls the reaction bin to cool, and meanwhile, the first auxiliary bin and the second auxiliary bin are communicated with the reaction bin, so that the temperature can be more accurately and quickly controlled. The problem that in the prior art, cooling is conducted in a liquid nitrogen spraying mode, but the cooling temperature cannot be well controlled, and consequently test data are not accurate is solved.

The present invention discloses a temperature control method for a cooling system of a high-temperature superconducting cable. For the existing temperature control methods, the regulation of the temperature of the coolant liquid nitrogen is relatively lagging, unable to respond promptly to the change of the system's heat load, and during the regulation process, the temperature change range is large, the stable period is short, and seriously, the temperature of the coolant liquid nitrogen will reach its vaporization temperature. The technical solution adopted by the present invention is that the circulating liquid nitrogen temperature of the cooling system adopts an adjustment method mainly based on the cable energization current value and supplemented by the liquid nitrogen temperature value at the cable outlet. This adjustment method is completed by a current temperature control unit, a temperature difference control unit, a cooling capacity adjustment unit, and a command output module. The present invention adopts a mixed adjustment method mainly based on the cable energization current value and supplemented by the liquid nitrogen temperature value at the cable outlet, which increases the timeliness of the temperature adjustment of the cooling system, reduces the fluctuation of the cooling system temperature with the change of the energization current, shortens the temperature adjustment time, and increases the stability of the system.

The application discloses a burst needle valve testing device, and belongs to the technical field of petroleum chemical industry, oil and gas storage and transportation. The burst needle valve testing device comprises a storage tank, a first material conveying pipe and a first control valve group, a second material conveying pipe and a second control valve group, and a third material conveying pipe; a bubble detector is arranged to detect the bubble amount of the output end of the third material conveying pipe; under the condition that the bubble amount is a first preset value, the pressure value detected by a pressure detector is a sealing pressure value of the burst needle valve; and under the condition that the bubble amount is a second preset value, the pressure value detected by the pressure detector is an opening pressure value of the burst needle valve. Before the burst needle valve is tested, liquid nitrogen is introduced into the storage tank, so that the temperature value of the whole burst needle valve testing device can be kept in a low temperature range, the test temperature of the burst needle valve can be approximately the same as the actual working temperature, and therefore the accuracy and reliability of the burst needle valve testing can be improved.

The invention belongs to the technical field of superconducting cooling cold energy recovery, and particularly discloses a cold energy recovery system suitable for a high-temperature superconducting cable, which is characterized in that a cold box and a liquid nitrogen tank are separately arranged, and a circulating pipeline and a first one-way pipeline are respectively used for circulating backflow liquid nitrogen and supplementing high-temperature liquid nitrogen; in the cold box, the liquid supplementing pipeline, the superconducting terminal and the external cold supply device are sequentially provided with multiple stages of heat exchange parts, and the multiple stages of heat exchange parts are matched with a cold nitrogen inlet located in the cold box and a second one-way pipeline communicated with the cold nitrogen inlet to uniformly lead out low-temperature nitrogen generated by evacuation and decompression, sequentially exchange heat according to the temperature gradient and then discharge the low-temperature nitrogen; the device has the following advantages that low-temperature nitrogen cascade recovery is achieved, backflow and liquid supplementing pre-cooling, dewar heat leakage reduction and external cooling are considered, and the energy efficiency and the operation stability are improved.

The invention provides a low-temperature in-situ sample rod utilizing a high-pressure nitrogen throttling effect. The low-temperature in-situ sample rod comprises a shell, a gas path pipeline, a throttling unit and a sample table, wherein the gas path pipeline and the throttling unit are arranged in the shell; the gas path pipeline is used for supplying high-pressure nitrogen to the throttling unit and conveying low-pressure nitrogen discharged by the throttling unit; the throttling unit is subjected to Joule-Thomson expansion through a throttling structure so as to generate cold energy of a liquid nitrogen temperature zone; and the sample table is thermally coupled with the cold end of the throttling unit to provide a required low-temperature environment for the sample. The device does not depend on a liquid working medium, is compact in structure, low in vibration, free of posture dependence, easy to operate and suitable for refrigeration in a small-cooling-capacity liquid nitrogen temperature zone, and can meet the requirements of in-situ microscopic imaging and spectroscopy equipment.

This invention provides a vacuum testing device and method, relating to the technical field of vacuum sealing. The vacuum testing device includes: a housing with a vacuum chamber inside; a liquid nitrogen transmission assembly, including: a mounting base installed on the side of the housing; a liquid nitrogen transmission pipeline inserted into the vacuum chamber through the mounting base, both ends of the liquid nitrogen transmission pipeline including connecting sections extending through the mounting base and out of the housing, the connecting sections being suitable for receiving or discharging liquid nitrogen introduced from the outside; a stage installed on the liquid nitrogen transmission pipeline to hold the sample to be tested, the temperature of the stage being adjusted by the flow of liquid nitrogen in the liquid nitrogen transmission pipeline; and two sets of first sealing assemblies respectively fitted onto the connecting sections and pressed between the outer side of the connecting sections and the mounting base. The first sealing assemblies are configured to create a sealed testing environment in the vacuum chamber by expanding or contracting different parts when the temperature inside the vacuum chamber changes to above or below a predetermined temperature.

The application discloses a frozen sample protection device and a protection method. The frozen sample protection device comprises a shell and a gas seal assembly. The shell has an inner cavity and a placing opening. The gas seal assembly comprises an air outlet piece. The air outlet piece has an air outlet slit. The air outlet piece is used for forming an air curtain between the placing opening and a workstation, so that the air curtain shields the placing opening. When an article is taken out or placed into the workstation, the air outside the shell cannot enter the workstation through the placing opening due to the air curtain formed by the gas seal assembly, so that moisture cannot be mixed into the preparation space of the sample (such as liquid nitrogen). The generation of ice crystals during the preparation and transmission of the sample can be reduced, and the pollution of the ice crystals to the frozen sample can be reduced.

The invention discloses a liquid nitrogen splashing prevention cofferdam for an ultralow temperature test, a system and a using method, and the cofferdam comprises a base which is of a square frame structure and is flatly laid on the ground. And the vertical plate protection plate is rotatably connected with the two parallel side edges of the base, and the vertical plate protection plate can rotate to form an included angle of 0-90 degrees with the base by taking a connecting point as an axis. The base and the vertical plate protection plate are made of ultra-low temperature resistant materials. And the locking mechanism is arranged on the base and used for locking the base and the vertical plate protection plate when the base rotates to a certain angle. The modularized detachable cofferdam capable of preventing liquid nitrogen from splashing is arranged within a certain range of the ultralow-temperature liquid nitrogen test area, the ultralow-temperature test area isolated from the outside is formed, meanwhile, the cofferdam can be flexibly arranged according to test requirements, enclosing and sealing are achieved, test protection is facilitated, the area where low-temperature liquid nitrogen is possibly splashed in the specific test area is isolated, and the test efficiency is improved. The effectiveness of test protection can be greatly improved, and the safety of personnel and equipment instruments is protected.

This application discloses a precision control method for liquid nitrogen cryogenic testing, comprising: deploying primary and secondary temperature sensors and a triaxial accelerometer in the near field of the specimen and synchronizing them with a Hopkinson bar system to predict the stress wave interference time window; calculating vibration intensity in real time, arbitrating and identifying spurious temperature sensor signals caused by impact vibration, and switching to a reliable virtual true temperature value; simultaneously, defining a cold energy health index by monitoring liquid nitrogen storage and system status, and dynamically switching control modes based on this index; and implementing a special strategy of locking and smooth recovery during impact transients. This invention effectively shields measurement distortion caused by dynamic interference and achieves a balance between control precision and system safety under resource constraints, significantly improving the environmental stability and process controllability of cryogenic impact testing.

The utility model discloses a detection sampling pipeline for a low-temperature environment, which relates to the detection sampling field of the low-temperature environment and comprises a detection sampling pipeline main body, an intelligent heating assembly is arranged in the detection sampling pipeline main body, and a sampling pipeline cleaning assembly is arranged on one side of the intelligent heating assembly. According to the utility model, the prior art is improved, and in actual use, through the intelligent heating assembly, the problems that under the low-temperature condition (such as the temperature range of liquid nitrogen), the material of a common sampling pipeline becomes brittle, the sealing performance is reduced, leakage is easily caused, and the sampling accuracy is influenced are solved. And the condition that the sampling difficulty is increased due to the fact that the formation of condensed water or ice crystals hinders the flow of fluid is avoided.

The invention belongs to the technical field of isotope separation, and relates to a fluoride quantitative taking device. The device comprises an evacuation line, a purging line and a material taking line. The device can be configured with different container connection modes according to material taking objects, and the containers comprise a 8L container and a 3m < 3 > container. In the material taking process of the 8L container, an operator only needs to ensure that the container has enough liquid nitrogen for freezing, the liquid level of the liquid nitrogen does not need to be recorded and maintained, and quantitative material taking of the container can be achieved according to mass accumulation of the thermal mass flow meter. In the calibration process of the material taking metering tool of the 3m < 3 > container, the 3m < 3 > container does not need to be disassembled and assembled, and the calibration workload is reduced. The electric control valve is placed in front of the thermal gas mass flow meter, so that the measurement error of the mass flow meter is reduced, the inlet pressure of the material taking container is ensured to be at the level required by the process, and condensation and accumulation of a product medium at the inlet of the container cannot be caused.

This application provides a rapid cooling device for a temperature chamber, comprising: a temperature chamber body; a first cooling assembly, the first cooling assembly including a compressor and a condenser disposed outside the temperature chamber body and connected by a first pipe, and an evaporator disposed in an air duct area inside the temperature chamber body; the compressor's inlet is connected to a second pipe for introducing refrigerant into it, the condensate outlet of the condenser is connected to the evaporator's liquid inlet through a third pipe, and the evaporator's outlet is connected to the second pipe through a fourth pipe, the third pipe being equipped with an expansion valve; and a second cooling assembly, the second cooling assembly including a nitrogen supply pipe and a liquid nitrogen storage tank; one end of the nitrogen supply pipe is connected to the top of the temperature chamber body, and the other end is connected to the liquid nitrogen storage tank. This application uses a combination of a compressor and liquid nitrogen to simultaneously cool the temperature chamber body, enabling a rapid decrease in the temperature inside the temperature chamber body, thereby improving the cooling efficiency of the temperature chamber body.

According to the technology for recycling the low-temperature nitrogen of the normal-pressure liquid nitrogen storage tank, thermal load calculation is conducted according to the temperature, pressure and flow values of the low-temperature nitrogen in the normal-pressure flat-bottom liquid nitrogen storage tank and nitrogen filled in a cold box, the low-temperature nitrogen emptied by the normal-pressure flat-bottom liquid nitrogen storage tank is reheated, depressurized and input into a nitrogen filled pipeline of the cold box to serve as the nitrogen filled in the cold box, and the nitrogen filled in the cold box is recycled. And the matching rate of the low-temperature nitrogen discharge amount of the normal-pressure liquid nitrogen storage tank and the nitrogen filling amount of the cold box is calculated, the cooling capacity of the low-temperature nitrogen discharged from the atmosphere by the liquid nitrogen storage tank is recycled to the maximum extent, the emptied nitrogen product is fully utilized, and the purpose of reducing the energy consumption of the air separation device is achieved.

The application discloses a method for estimating liquid nitrogen flow of a low-temperature wind tunnel test state, belongs to the field of experimental aerodynamics, and aims to solve the problem that the proportional-integral-derivative closed loop control is adopted to adjust system output in the current low-temperature wind tunnel operation, the space difference between the total temperature measurement position and the liquid nitrogen injection position is limited, and the mixing heat transfer process leads to serious hysteresis of the total temperature control, greatly increases the liquid nitrogen consumption, and reduces the test efficiency. In combination with the high-speed airflow convection heat exchange and gas dynamics, the application aims at the liquid nitrogen flow estimation problem of the low-temperature wind tunnel, proposes a calculation method of the liquid nitrogen flow based on the target values of the total pressure, the total temperature and the Mach number, and can calculate the required liquid nitrogen flow according to the test state before the test, greatly improves the low-temperature wind tunnel test efficiency, and reduces the operation cost. The application can be quickly applied to other similar wind tunnels, has good engineering applicability, high application value and good application prospect.

The invention discloses a wide temperature zone gas-liquid phase change measuring device, which comprises a channel steel substrate and a phase change measuring container, a radiation bottom shell, a temperature control system and a material conveying system are arranged on the channel steel substrate in parallel, and the top of the radiation bottom shell is detachably connected with a radiation end shell, the phase change measuring container is arranged in the middle of a closed space defined by a radiation bottom shell and a radiation end shell, a welding structure of a copper pipe and a copper plate is used as a heat sink directly surrounding the container, the heat conductivity coefficient is high, the heat capacity is large, the temperature response is fast, the cooling capacity / heat of a refrigerant (liquid nitrogen at the temperature of-173 DEG C or other low-temperature liquefied gas) can be evenly spread to the outer wall of the whole container, and the measurement accuracy is high. The vacuum interlayer thoroughly cuts off gas heat conduction, the columnar structure defined by the copper plates is similar to a suspension structure, thermal contact resistance is eliminated, long-term constant temperature can be achieved in low-temperature and high-temperature states, and extremely low-temperature accessibility and wide-temperature-range stability are really considered.