CN106441636B - Method and device for detecting heat productivity of high-temperature superconducting block - Google Patents
Method and device for detecting heat productivity of high-temperature superconducting block Download PDFInfo
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Abstract
The invention discloses a method and a device for detecting the heat productivity of a high-temperature superconducting block material. The method comprises the following steps: under a stable magnetic field in advance, calculating to obtain a first liquid nitrogen loss of the container within a preset time according to temperature data measured by a sensor arranged at the top in the container; when the container is in the variable magnetic field, calculating to obtain a second liquid nitrogen loss amount of the container within the preset time according to temperature data measured by a sensor arranged at the inner top of the container; and calculating the heat productivity of the high-temperature superconductor block which is arranged in the container, soaked in the liquid nitrogen and under the changing magnetic field within the preset time according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount. By using the method and the device for detecting the calorific value of the high-temperature superconducting block material, the calorific value of the high-temperature superconducting block material which is arranged in a container, soaked in liquid nitrogen and under a variable magnetic field can be accurately estimated.
Description
Technical Field
The invention relates to a high-temperature superconducting magnetic levitation technology, in particular to a method and a device for detecting the heat productivity of a high-temperature superconducting block.
Background
Compared with electromagnetic levitation (EMS) and electric levitation (EDS) technologies based on electromagnetic attraction and electromagnetic repulsion, the high-temperature superconducting magnetic levitation technology realizes passive self-stabilization levitation by means of magnetic flux pinning between a high-temperature superconductor block and an external magnetic field. The high-temperature superconducting magnetic suspension technology is characterized in that a superconducting block is soaked in liquid nitrogen, so that the temperature of the superconducting block is reduced to enter a superconducting state, and the superconducting block entering the superconducting state can be stably suspended under the action of an external magnetic field. The technology does not need active control and has a simple structure, so the technology becomes one of ideal choices of practical magnetic levitation technology.
The first manned high-temperature superconducting magnetic levitation test vehicle in the world was successfully developed by the southwest university of transportation in 2000, and a great deal of research work aiming at the aspects of levitation, guidance and driving is carried out later, so that the practical development of the high-temperature superconducting magnetic levitation train is greatly promoted. In the high-temperature superconducting magnetic suspension technology, the suspension force is an important characteristic quantity for reflecting the suspension characteristic of the high-temperature superconductor, and is also one of key parameters in the design of a magnetic suspension system. In practical application, the surface of the permanent magnetic track has certain unevenness, and the magnetic field of the track also has certain unevenness, so that when the high-temperature superconducting magnetic suspension train runs on the track at high speed, the vehicle-mounted superconductor is in a changing magnetic field environment. The changing external magnetic field can aggravate the movement of magnetic force lines in the superconductor, thereby causing the local temperature rise of the superconductor to be larger, reducing the critical current density, and finally influencing the suspension performance of the superconductor or even causing the quench. Once the superconductor is quenched, the train loses suspension force, and the rail rubs and even derails. Therefore, it is necessary to study the heat generation of the high-temperature superconductor in a variable external magnetic field environment.
However, since the high-temperature superconductor block is completely immersed in liquid nitrogen when put into use, a method of directly measuring the surface temperature of the block using a temperature sensor to obtain the calorific value of the high-temperature superconductor block cannot be realized.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for detecting the heat generation of a high temperature superconductor block, so that the heat generation of the high temperature superconductor block, which is immersed in liquid nitrogen and is in a changing magnetic field, can be accurately estimated.
The technical scheme of the invention is realized in the following way:
a method for detecting the calorific value of a high-temperature superconducting bulk material comprises the following steps:
under a stable magnetic field in advance, calculating to obtain a first liquid nitrogen loss amount of the container within a preset time according to temperature data measured by a sensor arranged at the top in the container;
when the container is in the variable magnetic field, calculating to obtain a second liquid nitrogen loss amount of the container within the preset time according to temperature data measured by a sensor arranged at the inner top of the container;
and calculating the heat productivity of the high-temperature superconductor block which is arranged in the container, soaked in the liquid nitrogen and under the changing magnetic field within the preset time according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount.
Preferably, the calculating the first liquid nitrogen loss amount or the second liquid nitrogen loss amount of the container within the preset time includes:
calculating in real time to obtain the current liquid level height in the container according to the current temperature data measured by a sensor arranged at the top in the container, thereby respectively obtaining the liquid level heights at the starting time and the ending time of the preset time length;
calculating to obtain a liquid level drop value in the container within the preset time according to the liquid level heights at the starting time and the ending time of the preset time;
and calculating to obtain the first liquid nitrogen loss amount or the second liquid nitrogen loss amount according to the liquid level drop value.
Preferably, the calculating in real time the current liquid level height in the container according to the current temperature data measured by the sensor disposed at the top of the container includes:
A. establishing a state space model in advance according to actual experimental measurement data, and generating a particle set which comprises a group of particles with distribution characteristics meeting liquid level prior probability distribution;
B. measuring current temperature data by a sensor arranged at the top in a container filled with liquid nitrogen;
C. calculating to obtain an estimated value of the current liquid level height in the container according to the state space model, the particle set and the current temperature data;
D. and correcting the estimated value of the current liquid level height obtained by calculation through a particle filter algorithm to obtain the corrected current liquid level height.
Preferably, after the step D, the method further includes:
when the current sampling point is not the last sampling point, resampling and weighting the particle set according to the corrected current liquid level height, and returning to execute the step B; and when the current sampling point is the last sampling point, ending the process.
Preferably, the establishing a state space model in advance according to actual experimental measurement data includes:
obtaining a liquid nitrogen evaporation empirical formula in advance according to liquid nitrogen evaporation characteristic data of a static evaporation experiment under different working conditions, and establishing a system state transfer equation according to the liquid nitrogen evaporation empirical formula;
carrying out a simulation oscillation test and an actual measurement oscillation test on a container filled with liquid nitrogen in advance, analyzing test data, counting a test noise distribution model, and establishing a system observation equation;
and establishing a state space model according to the system state transition equation and the system observation equation.
Preferably, the system state transition equation is:
h k ＝h k-1 +Δh+ξ k-1 ；
h is the distance from a sensor arranged at the top of a container filled with liquid nitrogen to the liquid level of the liquid nitrogen in the container, and subscripts k and k-1 respectively represent variable sequences at different times; Δ h is the falling speed of the liquid level of the liquid nitrogen, ξ k-1 Is the system noise.
Preferably, the system state transition equation is:
T k ＝T LN +a·h k +η k ；
wherein, T k Temperature, T, measured at the kth instant by a sensor arranged on top of a container filled with liquid nitrogen LN Is the temperature of the liquid nitrogen, a is the temperature distribution coefficient, eta k To observe the noise.
Preferably, the calorific value of the high-temperature superconductor block within the preset time is calculated by the following formula:
Q＝r LN *(m c -m uc )；
wherein Q is the heat productivity of the high-temperature superconductor block material within the preset time, and r is LN M is the latent heat of vaporization parameter of liquid nitrogen c M is the second liquid nitrogen loss uc First loss of liquid nitrogenConsumption amount.
Preferably, the sensor arranged at the top of the container filled with liquid nitrogen is a platinum resistance temperature sensor.
The invention also provides a device for detecting the heat productivity of the high-temperature superconducting block, which comprises: the device comprises at least two sensors, a signal acquisition unit, a data transmission unit, a heating value estimation unit and a memory;
the sensors are respectively arranged at the top and the bottom in the container filled with liquid nitrogen;
the signal acquisition unit is used for receiving current temperature data measured by a sensor arranged at the top in a container filled with liquid nitrogen, storing the received temperature data in a memory and sending the temperature data to the data sending unit;
the data sending unit is used for sending the temperature data to the calorific value estimation unit;
the calorific value estimation unit is used for calculating and obtaining a first liquid nitrogen loss amount of the container within a preset time length according to temperature data measured by a sensor arranged at the top in the container in a stable magnetic field in advance; when the container is in the variable magnetic field, calculating to obtain a second liquid nitrogen loss amount of the container within the preset time according to temperature data measured by a sensor arranged at the inner top of the container; calculating to obtain the calorific value of the high-temperature superconductor block which is arranged in the container, soaked in the liquid nitrogen and is under the changing magnetic field within the preset time according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount;
the memory is used for storing temperature data.
Preferably, the heat generation amount estimation unit further includes: the liquid level height estimation module and the heating value calculation module;
the liquid level height estimation module is used for calculating the current liquid level height in the container in real time according to the current temperature data measured by the sensor arranged at the top in the container, so as to respectively obtain the liquid level heights at the starting time and the ending time of the preset time length;
the heating value calculation module is used for calculating and obtaining a liquid level drop value in the container within the preset time length according to the liquid level heights at the starting time and the ending time of the preset time length; and calculating to obtain the first liquid nitrogen loss amount or the second liquid nitrogen loss amount according to the liquid level drop value.
Preferably, the liquid level estimating module further comprises: the model generation submodule, the calculation submodule and the correction submodule;
the model generation submodule is used for establishing a state space model in advance according to actual experimental measurement data and generating a particle set which comprises a group of particles with distribution characteristics meeting liquid level prior probability distribution;
the calculation submodule is used for calculating to obtain an estimated value of the current liquid level height according to the state space model, the particle set and the current temperature data;
and the correction submodule is used for correcting the calculated estimated value of the current liquid level height through a particle filter algorithm to obtain the corrected current liquid level height.
Preferably, the sensor is a platinum resistance temperature sensor.
Preferably, the data sending unit is a wireless transmission device or a wired transmission device.
As can be seen from the above, in the method and apparatus for detecting heat generation of a high-temperature superconductor block provided by the present invention, since the temperature sensor is used as a temperature measuring element to measure the temperature change condition in the container filled with liquid nitrogen, the difference between the liquid nitrogen loss amounts in the container under a stable magnetic field and the container under a variable magnetic field is obtained according to the temperature data, and the heat generation amount of the high-temperature superconductor block under the variable magnetic field in the preset time period is calculated according to the difference between the liquid nitrogen loss amounts, the change of the liquid nitrogen level can be obtained by measuring the change of the top temperature of the container, so as to calculate the liquid nitrogen consumption amount within a certain time period, and then the difference between the liquid nitrogen loss amounts in the container under the stable magnetic field and the container under the variable magnetic field in the time period is compared to obtain the liquid nitrogen loss caused by the heat generation of the high-temperature superconductor block, and finally, the heat generation amount of the high-temperature superconductor block within the time can be calculated according to the liquid nitrogen loss, so that the heat generation amount of the high-temperature superconductor block which is arranged in the container and soaked in the liquid nitrogen and under the variable magnetic field can be accurately estimated. The detection method and the detection device can be used for the requirement of the research on the calorific value of the high-temperature superconducting bulk material, and are beneficial to understanding the influence of a changing magnetic field on a suspension system.
Drawings
Fig. 1 is a schematic structural view of a device for detecting the calorific value of a high-temperature superconducting bulk material according to an embodiment of the present invention.
Fig. 2 is a schematic flow chart of a method for detecting the calorific value of the high-temperature superconducting bulk material in the embodiment of the present invention.
Fig. 3 is a schematic flow chart of a method for calculating the current liquid level height according to an embodiment of the present invention.
Fig. 4 is a schematic flow chart of a method for calculating the current liquid level height according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples.
When the superconducting bulk material is under a changing magnetic field, the movement of magnetic lines of force in the high-temperature superconducting bulk material is intensified, so that the local temperature rise of the superconductor is larger. The invention provides a method for detecting the heat productivity of a high-temperature superconducting block material, which adopts a mode of comparing the evaporation capacity of liquid nitrogen under a variable magnetic field and a stable magnetic field to indirectly measure and obtain the heating condition of the high-temperature superconducting block material under the variable magnetic field. Based on the characteristic that the stable evaporation capacity of the liquid nitrogen is not changed in unit time, the difference value of the evaporation capacity of the liquid nitrogen under the changing magnetic field and the stable magnetic field in a period of time is compared, and the liquid nitrogen loss caused by the heating of the superconducting blocks in the period of time can be obtained.
Fig. 1 is a schematic structural view of a device for detecting the calorific value of a high-temperature superconducting bulk material according to an embodiment of the present invention. As shown in fig. 1, the apparatus for detecting the calorific value of the high-temperature superconducting bulk material in the embodiment of the present invention mainly includes: at least two sensors 11, a signal acquisition unit 12, a data transmission unit 13, a calorific value estimation unit 14 and a memory 15;
the sensors 11 are respectively arranged at the top and the bottom in the container filled with liquid nitrogen;
the signal acquisition unit 12 is used for receiving current temperature data measured by a sensor 11 arranged at the top in a container filled with liquid nitrogen, storing the received temperature data in a memory 15 and sending the temperature data to the data sending unit 13;
the data sending unit 13 is configured to send the temperature data to the heating value estimation unit 14;
the calorific value estimation unit 14 is configured to calculate, in advance, a first liquid nitrogen loss amount of the container within a preset time according to temperature data measured by a sensor arranged at the top of the container in a stable magnetic field; when the container is in the variable magnetic field, calculating to obtain a second liquid nitrogen loss amount of the container within the preset time according to temperature data measured by a sensor arranged at the top in the container; calculating to obtain the calorific value of the high-temperature superconductor block which is arranged in the container, soaked in the liquid nitrogen and is under the changing magnetic field within the preset time according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount;
the memory 15 is used for storing temperature data.
In addition, preferably, in an embodiment of the present invention, the heating value estimation unit 14 may further include: a liquid level height estimation module 141 and a heat generation amount calculation module 142;
the liquid level height estimation module 141 is configured to calculate in real time to obtain a current liquid level height in the container according to current temperature data measured by a sensor disposed at the top of the container, so as to obtain liquid level heights at the start time and the end time of the preset time period, respectively;
the heating value calculating module 142 is configured to calculate a liquid level drop value in the container within the preset time according to the liquid level heights at the starting time and the ending time of the preset time; and calculating to obtain the first liquid nitrogen loss amount or the second liquid nitrogen loss amount according to the liquid level drop value.
Preferably, in an embodiment of the present invention, the liquid level estimating module 141 may further include: a model generation sub-module, a calculation sub-module and a modification sub-module (not shown in FIG. 1);
the model generation submodule is used for establishing a state space model in advance according to actual experimental measurement data and generating a particle set which comprises a group of particles with distribution characteristics meeting liquid level prior probability distribution;
the calculation submodule is used for calculating to obtain an estimated value of the current liquid level height according to the state space model, the particle set and the current temperature data;
and the correction submodule is used for correcting the calculated estimated value of the current liquid level height through a particle filter algorithm to obtain the corrected current liquid level height.
Preferably, in the embodiment of the present invention, the sensor 31 is a platinum resistance temperature sensor. Compared with a platinum resistance liquid level meter, the platinum resistance temperature sensor used in the invention has the advantages of less quantity, more stable performance and higher measurement precision.
Preferably, in an embodiment of the present invention, the data sending unit 33 may be a wireless transmission device or a wired transmission device, which is not limited in the present invention.
Preferably, in an embodiment of the present invention, the heating value estimation unit may be a computing device such as a personal computer, a server, or another form of computer.
In addition, the invention also provides a method for detecting the heat productivity of the high-temperature superconducting bulk material.
Fig. 2 is a schematic flow chart of a method for detecting calorific value of a high-temperature superconducting bulk material in an embodiment of the present invention. As shown in fig. 2, the method for detecting the calorific value of the high-temperature superconducting bulk material in the embodiment of the present invention mainly includes the following steps:
and 21, calculating to obtain a first liquid nitrogen loss of the container within a preset time according to temperature data measured by a sensor arranged at the inner top of the container in a stable magnetic field in advance.
In this step, it is first necessary to calculate in advance the first liquid nitrogen loss in the container within a preset time period when in the steady magnetic field.
For example, in a preferred embodiment of the present invention, when the container is in the stable magnetic field, the liquid level drop value in the container within a preset time period can be calculated according to the temperature data measured by the sensor disposed at the top of the container, and then the first liquid nitrogen loss amount can be calculated according to the liquid level drop value.
In addition, in the technical scheme of the invention, the length of the preset duration can be preset according to the requirements of actual application conditions. For example, the preset time period may be 10 minutes, 30 minutes, 1 hour, 2 hours, or the like.
in this step, the second liquid nitrogen loss amount of the container within the preset time period when the container is in the stable magnetic field can be calculated in real time.
For example, in an embodiment of the present invention, when the container is in the steady magnetic field, the liquid level drop value in the container within a preset time period can be calculated according to the current temperature data measured by a sensor arranged at the top of the container, and then the second liquid nitrogen loss value can be calculated according to the liquid level drop value.
And 23, calculating the heat productivity of the high-temperature superconductor block which is arranged in the container, soaked in the liquid nitrogen and under the variable magnetic field within the preset time according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount.
The liquid nitrogen stable evaporation amount is not changed in unit time, the high-temperature superconductor block is arranged in the container and soaked in the liquid nitrogen, and the liquid nitrogen evaporation speed is accelerated due to the heating of the high-temperature superconductor block under a changing magnetic field, so that the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount is the liquid nitrogen loss amount caused by the heating of the high-temperature superconductor block in the preset time. That is, the above difference is the portion of the liquid nitrogen which is consumed more than the stable evaporation under the stable magnetic field, and the heat absorbed by the evaporation is the heat generation of the high temperature superconductor block within the preset time period. Therefore, the calorific value of the high-temperature superconductor block material in the preset time period can be calculated according to the difference value of the first liquid nitrogen loss amount and the second liquid nitrogen loss amount.
For example, in an embodiment of the present invention, the heat generation amount of the high-temperature superconductor block within the preset time period may be calculated by the following formula:
Q＝r LN *(m c -m uc )
wherein Q is the heat productivity of the high-temperature superconductor block material within the preset time, and r is LN M is a latent heat of vaporization parameter of liquid nitrogen c M is the evaporation capacity (i.e. the second liquid nitrogen loss) of liquid nitrogen under the change of magnetic field uc The evaporation amount of liquid nitrogen (i.e. the first liquid nitrogen loss) under the stable magnetic field is obtained.
In addition, in the technical solution of the present invention, the steps 21 and 22 can be implemented in various ways, and a specific way of the steps will be taken as an example to describe the technical solution of the present invention in detail.
For example, in a preferred embodiment of the present invention, calculating the first liquid nitrogen loss amount or the second liquid nitrogen loss amount of the container within a preset time period according to the temperature data measured by the sensor disposed at the top of the container may include the following steps:
and step 31, calculating in real time to obtain the current liquid level height in the container according to the current temperature data measured by the sensor arranged at the top in the container, so as to respectively obtain the liquid level heights at the starting time and the ending time of the preset time.
Step 32, calculating to obtain a liquid level drop value in the container within the preset time according to the liquid level heights at the starting time and the ending time of the preset time;
and step 33, calculating to obtain the first liquid nitrogen loss amount or the second liquid nitrogen loss amount according to the liquid level drop value.
In the technical solution of the present invention, the step 31 can be implemented in various ways, and one of the specific ways is taken as an example to describe the technical solution of the present invention in detail.
Fig. 3 is a schematic flow chart of a method for calculating the current liquid level height according to an embodiment of the present invention. For example, preferably, as shown in fig. 3, in an embodiment of the present invention, the step 31 of calculating in real time the current liquid level in the container according to the current temperature data measured by the sensor disposed at the top of the container may include the following steps:
In the technical scheme of the invention, before calculating the current liquid level height, a state space model needs to be established in advance, and a particle set comprising a group of particles with distribution characteristics meeting the liquid level prior probability distribution is generated, namely the particle set is initialized.
In the technical solution of the present invention, there may be a plurality of specific implementation manners to implement the step 41. The technical solution of the present invention will be described in detail below by taking one specific implementation manner as an example.
For example, in the technical solution of the present invention, the establishing a state space model in advance according to actual experimental measurement data includes:
step 411, obtaining a liquid nitrogen evaporation empirical formula in advance according to liquid nitrogen evaporation characteristic data of the static evaporation experiment under different working conditions (for example, different environmental temperatures and different containers), and establishing a system state transfer equation according to the liquid nitrogen evaporation empirical formula.
Step 412, performing a simulated oscillation test and an actual measurement oscillation test on a container (for example, a vehicle-mounted Dewar) filled with liquid nitrogen in advance, analyzing test data, counting a test noise distribution model, and establishing a system observation equation.
And 413, establishing a state space model according to the system state transition equation and the system observation equation.
In addition, preferably, in the technical solution of the present invention, the system state transition equation may be:
h k ＝h k-1 +Δh+ξ k-1
wherein h is the distance from a temperature sensor arranged at the top of a container (such as a vehicle-mounted Dewar) filled with liquid nitrogen to the liquid level of the liquid nitrogen in the container, and the subscripts k and k-1 respectively show variable sequences at different times, namely show different moments, such as h k Denotes the value of h at the kth time, h k-1 A value of h representing the (k-1) th time; Δ h is the falling speed of the liquid level of the liquid nitrogen, ξ k-1 Is the system noise.
In addition, preferably, in the technical solution of the present invention, the system state transition equation may be:
T k ＝T LN +a·h k +η k
wherein, T k The temperature, T, measured at the k-th instant by a temperature sensor arranged on top of a container (e.g. a Dewar on board a vehicle) filled with liquid nitrogen LN Is the temperature of liquid nitrogen, a is the temperature distribution coefficient, eta k To observe the noise.
In the technical scheme of the invention, a liquid nitrogen liquid level change model (namely a state space model) containing interference noise and linear variables can be established based on the characteristic that liquid nitrogen evaporation is basically linear in an approximate environment, so that the liquid level can be predicted according to the state space model.
Therefore, through the above steps 411 to 413, a state space model can be established according to the above system state transition equation and system observation equation. Of course, values of various parameters (e.g., dewar size, ambient temperature, etc.) in the state space model may change according to changes of the actual application environment, and are not described herein again.
In addition, preferably, in the technical solution of the present invention, when initializing the particle set, each particle in the particle set is generated according to a liquid level prior probability distribution, so that a distribution characteristic of each particle in the particle set satisfies the liquid level prior probability distribution.
Preferably, in the technical scheme of the invention, the liquid level prior probability distribution can be obtained in advance through actual experimental measurement data.
And step 42, measuring current temperature data through a sensor arranged at the top in the container filled with the liquid nitrogen.
In addition, in the technical solution of the present invention, the sensor disposed on the top of the container filled with liquid nitrogen (e.g., vehicle-mounted dewar) may be a platinum resistance temperature sensor, or may be another temperature sensor.
And 43, calculating to obtain an estimated value of the current liquid level height in the container according to the state space model, the particle set and the current temperature data.
In the technical solution of the present invention, since the state space model is already established in step 41, the particle set is initialized, and the current temperature data is obtained by measurement in step 42, in this step, the estimated value of the current liquid level in the container can be calculated by using a particle filtering method according to the state space model, the particle set, and the current temperature data.
And step 44, correcting the estimated value of the current liquid level height obtained by calculation through a particle filter algorithm to obtain the corrected current liquid level height.
Since the particle filter algorithm is a method for performing weighted correction on the deviation signal, in this step, the estimated value of the current liquid level height obtained by calculation may be corrected by the particle filter algorithm to obtain the corrected current liquid level height.
Through the steps 41 to 44, the estimated value of the corrected current liquid level height can be obtained, so that the real-time liquid level height with higher precision can be obtained. Therefore, by the method, the oscillation interference of the container filled with the liquid nitrogen (such as a vehicle-mounted Dewar on a high-temperature superconductor maglev train) in the running process can be well eliminated, the liquid nitrogen level of the container filled with the liquid nitrogen is accurately detected, and the liquid nitrogen level which is closer to a true value is obtained.
In addition, fig. 4 is a schematic flow chart of a method for calculating the current liquid level height according to another embodiment of the present invention. For example, as shown in fig. 4, in another embodiment of the present invention, the step 44 may further include:
45, when the current sampling point is not the last sampling point, resampling and weighting the particle set according to the corrected current liquid level height, and returning to execute the step 42; and when the current sampling point is the last sampling point, ending the process.
In this step, the particle set is resampled and weighted according to the corrected current liquid level height (that is, the particle set is screened according to the calculated value of the corrected current liquid level height, for example, the weight of the particle of the small probability event is made small by a weighting method, so as to reduce the influence of the particle of the small probability event on the final result), the particle set is updated, and then the step 42 is executed again to sample the next time point, that is, the resampled particle set is used to combine the temperature data of the next time measured by the sensor, so as to calculate the current liquid level height of the next time point. And repeating the calculation once every time the particle set is updated to obtain a calculated value of the current liquid level until the last sampling point is finished, namely, all the sampling points are calculated, so that the liquid level can be accurately monitored in real time, and the current liquid level in the container can be obtained in real time.
In summary, in the method and the device for detecting heat productivity of the high-temperature superconductor block provided by the invention, the temperature change condition in the container filled with liquid nitrogen is measured by using the temperature sensor as the temperature measuring element, the difference value of the liquid nitrogen loss amounts in the container under the stable magnetic field and the container under the variable magnetic field is obtained according to the temperature data, and the heat productivity of the high-temperature superconductor block under the variable magnetic field in the preset time period is calculated according to the difference value of the liquid nitrogen loss amounts, so that the change of the liquid nitrogen liquid level can be obtained by measuring the change of the top temperature of the container, the liquid nitrogen consumption in a period of time can be calculated, then the difference value of the liquid nitrogen loss amounts in the container under the stable magnetic field and the container under the variable magnetic field in the time period is compared, the liquid nitrogen loss caused by the heat productivity of the high-temperature superconductor block is obtained, and the heat productivity of the high-temperature superconductor block in the time can be calculated according to the liquid nitrogen loss, so that the heat productivity of the high-temperature superconductor block which is arranged in the container and soaked in the liquid nitrogen and under the variable magnetic field can be accurately estimated. The detection method and the detection device can be used for the requirement of the research on the calorific value of the high-temperature superconducting bulk material, and are beneficial to understanding the influence of a changing magnetic field on a suspension system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A method for detecting the calorific value of a high-temperature superconducting bulk is characterized by comprising the following steps:
under a stable magnetic field in advance, calculating to obtain a first liquid nitrogen loss amount of the container within a preset time according to temperature data measured by a sensor arranged at the top in the container;
when the container is in the variable magnetic field, calculating to obtain a second liquid nitrogen loss amount of the container within the preset time according to temperature data measured by a sensor arranged at the top in the container;
and calculating to obtain the calorific value of the high-temperature superconductor blocks which are arranged in the container, soaked in the liquid nitrogen and under the changing magnetic field within the preset time according to the difference value of the first liquid nitrogen loss and the second liquid nitrogen loss.
2. The method of claim 1, wherein the calculating the first or second amount of liquid nitrogen loss for the container over a preset time period comprises:
calculating the current liquid level height in the container in real time according to the current temperature data measured by a sensor arranged at the top in the container, so as to respectively obtain the liquid level heights at the starting time and the ending time of the preset time length;
calculating to obtain a liquid level drop value in the container within the preset time according to the liquid level heights at the starting time and the ending time of the preset time;
and calculating to obtain the first liquid nitrogen loss amount or the second liquid nitrogen loss amount according to the liquid level drop value.
3. The method of claim 2, wherein calculating in real time a current liquid level in the vessel based on current temperature data measured by a sensor disposed at a top of the vessel comprises:
A. establishing a state space model in advance according to actual experimental measurement data, and generating a particle set which comprises a group of particles with distribution characteristics meeting liquid level prior probability distribution;
B. measuring current temperature data by a sensor arranged at the top in a container filled with liquid nitrogen;
C. calculating to obtain an estimated value of the current liquid level height in the container according to the state space model, the particle set and the current temperature data;
D. and correcting the estimated value of the current liquid level height obtained by calculation through a particle filter algorithm to obtain the corrected current liquid level height.
4. The method of claim 3, further comprising, after step D:
when the current sampling point is not the last sampling point, resampling and weighting the particle set according to the corrected current liquid level height, and returning to execute the step B; and when the current sampling point is the last sampling point, ending the process.
5. The method of claim 3, wherein the pre-establishing a state space model from actual experimental measurement data comprises:
obtaining a liquid nitrogen evaporation empirical formula in advance according to liquid nitrogen evaporation characteristic data of a static evaporation experiment under different working conditions, and establishing a system state transfer equation according to the liquid nitrogen evaporation empirical formula;
carrying out a simulation oscillation test and an actual measurement oscillation test on a container filled with liquid nitrogen in advance, analyzing test data, counting a test noise distribution model, and establishing a system observation equation;
and establishing a state space model according to the system state transition equation and the system observation equation.
6. The method of claim 5, wherein the system state transition equation is:
wherein, the first and the second end of the pipe are connected with each other,
a foot mark for measuring the distance from a sensor arranged on the top of a container filled with liquid nitrogen to the liquid level of the liquid nitrogen in the container
And
respectively showing variable sequences at different times;
is the falling speed of liquid nitrogen level
Is the system noise.
7. The method of claim 6, wherein the system state transition equation is:
wherein, the first and the second end of the pipe are connected with each other,
for the sensor arranged on the top of the container filled with liquid nitrogen
The temperature measured at each of the time points is,
is the temperature of the liquid nitrogen and is,
in order to be a temperature distribution coefficient,
to observe the noise.
8. The method according to claim 1, wherein the heat generation amount of the high-temperature superconductor block material in the preset time period is calculated by the following formula:
wherein Q is the calorific value of the high-temperature superconductor block within the preset time period,
is a latent heat of vaporization parameter of the liquid nitrogen,
as the second amount of liquid nitrogen lost,
is the first liquid nitrogen loss.
9. The method of claim 1, wherein:
the sensor arranged at the top of the container filled with liquid nitrogen is a platinum resistance temperature sensor.
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