CN117110364A - Hydrogen specific heat measurement device and method - Google Patents

Hydrogen specific heat measurement device and method Download PDF

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Publication number
CN117110364A
CN117110364A CN202310987116.8A CN202310987116A CN117110364A CN 117110364 A CN117110364 A CN 117110364A CN 202310987116 A CN202310987116 A CN 202310987116A CN 117110364 A CN117110364 A CN 117110364A
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sample
hydrogen
temperature
standard container
sample cavity
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张春伟
郭嘉翔
魏金莹
齐向阳
杨晓阳
王静
崔皓玉
陈永
杨括
陈静
李山峰
杨思锋
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Beijing Institute of Aerospace Testing Technology
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Beijing Institute of Aerospace Testing Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity

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Abstract

The invention discloses a device and a method for measuring specific heat of hydrogen. According to the invention, the hydrogen specific heat measuring device based on the principle of an adiabatic calorimeter method is designed, and a continuous deflation measuring method is designed according to the device, so that the high-efficiency measurement of the multi-state hydrogen specific heat physical property is successfully realized. The interior of the sample cavity is designed into a thin-wall round bottle spherical structure, and outside the pressure measurement range of the lifting device, the influence of the self heat capacity of the sample cavity on the temperature rising process can be reduced, and the measurement accuracy is improved.

Description

Hydrogen specific heat measurement device and method
Technical Field
The invention relates to the field of hydrogen physical property testing, in particular to a device and a method for measuring specific heat of hydrogen.
Background
Conventional specific heat measurement mainly includes differential thermal analysis, pulse heating, flow calorimetry, thermal relaxation, and the like. When the measured object and the reference object are loaded with the same heat in the differential thermal analysis method, the temperature rising curves respectively show differences because of different heat absorption capacities, and the specific heat capacity of the measured object is determined by measuring the temperature difference between the measured object and the reference object, but the differential thermal analysis method is mostly used for measuring the specific heat of the solid, and has no better reference object aiming at the hydrogen working medium, and the stability and the repetition rate of the test result are poor. The measurement principle of the pulse heating method is that a sample to be measured is heated by pulse current, and the temperature change of the sample is represented by the change of resistivity in the pulse heating time, but the pulse heating method is only applicable to solids with good electric conduction and heat conduction, and cannot be applicable to hydrogen physical property measurement. The flow calorimeter is characterized in that working medium is heated when flowing through a calorimeter (heating device and power meter) at a certain flow, and the specific heat of the working medium is obtained according to the temperature rise of the fluid, but the method is influenced by the flow measurement precision, and the temperature uniformity in the fluid is poor, so that the test precision is low. The thermal relaxation method loads heat to a container and a test sample through heat conduction, records the time from the beginning of temperature rising to the temperature stabilization and the final temperature of a working medium, obtains the thermal diffusion coefficient of a substance, calculates the average specific heat capacity of the working medium in the temperature rising process, but the method has higher requirement on the uniformity of the temperature of the test sample and the temperature of the container and has poorer precision. Therefore, how to design a high-precision hydrogen specific heat measuring device suitable for gas hydrogen, liquid hydrogen, supercritical hydrogen, and the like is important.
Disclosure of Invention
The invention aims to provide a high-precision and simple-structure hydrogen specific heat measuring device and method, which are used for providing heat for a certain amount of hydrogen samples in an adiabatic environment, then measuring the temperature rise of the samples, calculating the specific heat of the samples, designing a specific test structure according to the principle and realizing specific heat tests of low-temperature liquid hydrogen, high-temperature gas hydrogen and supercritical hydrogen.
The invention adopts the following technical scheme to realize the aim of the invention:
in a first aspect, the present invention provides a hydrogen specific heat measurement apparatus comprising a low temperature dewar, a hydrogen source tank and a hot water bath;
a sample cavity for containing a hydrogen sample to be measured is arranged in the inner cavity of the low-temperature Dewar, and radiation heat exchange between the sample cavity and the low-temperature Dewar is reduced by sequentially coating the inner cold screen and the outer cold screen outside the sample cavity;
the sample cavity is of a thin-wall spherical bottle structure, and the outside of the sample cavity is wrapped with a heat insulation shell; a sample cavity pressure sensor and a sample cavity temperature sensor are arranged in the sample cavity and are respectively used for measuring pressure and temperature data corresponding to the hydrogen sample in the cavity; the heat insulation shell outside the sample cavity is provided with a first electric heating component, the inside of the sample cavity is provided with a second electric heating component, and when the sample cavity is heated by the second electric heating component, the heat insulation shell is heated by the first electric heating component and synchronously heats up along with the sample cavity;
The top of the sample cavity extends out of the heat insulation shell, a sample cavity plug is arranged at the outlet, one end of the stainless steel capillary tube penetrates through the sample cavity plug to be communicated with the inside of the sample cavity, and the other end of the stainless steel capillary tube extends out of the low-temperature Dewar and is sequentially connected with the electromagnetic valve and the hydrogen gas vent valve; the part of the stainless steel capillary tube in the low-temperature Dewar is provided with a plurality of radiation-proof cold screens which are horizontally arranged;
the sample filling pipeline is sequentially connected with the hydrogen source tank and the sample filling valve, and then is connected with a stainless steel capillary tube between the electromagnetic valve and the hydrogen emptying valve, and is used for transferring a hydrogen sample in the hydrogen source tank into the sample cavity when the electromagnetic valve and the sample filling valve are opened;
the constant-temperature water bath is used for providing a constant-temperature environment, and the standard container is arranged in the constant-temperature water bath and exchanges heat with a medium in the bath; the standard container is connected to a stainless steel capillary tube between the electromagnetic valve and the hydrogen gas vent valve through a standard container air inlet valve; the standard container is internally provided with a standard container pressure sensor and a standard container temperature sensor which are used for measuring the pressure and the temperature of the hydrogen sample in the standard container in real time.
As a preferable mode of the first aspect, the system further comprises a controller, wherein the first electric heating component, the second electric heating component, the sample cavity pressure sensor, the sample cavity temperature sensor, the electromagnetic valve, the standard container pressure sensor and the standard container temperature sensor are all connected to the controller through signals and power lines, so that automatic measurement of pressure and temperature parameters and opening control of the electromagnetic valve are realized.
Preferably, in the first aspect, a water bath circulation line with a circulation pump is provided on the constant temperature water bath.
As a preferred aspect of the first aspect, the sample chamber temperature sensor and the standard container temperature sensor are both lasesshore Cernox temperature sensors, and the sensor signal line is a low-thermal conductivity phosphor copper wire.
As a preferable aspect of the first aspect, the first electric heating element is a polyimide electric heating film, and the second electric heating element is an electric heating wire.
As a preferable aspect of the first aspect, the sample filling line is a vacuum insulated pipe.
As a preferable mode of the first aspect, the stainless steel capillary tube is externally and fixedly sleeved with a copper sleeve, and the radiation-proof cold screen is welded on the copper sleeve; the electric equipment in the hydrogen specific heat measuring device adopts an explosion-proof design.
As a preferable mode of the first aspect, a plurality of vacuum standard containers are provided in the constant temperature water bath, and each of the standard containers is connected to the stainless steel capillary in parallel via the capillary, and the communicating relationship between the standard containers can be controlled by the valve.
In a second aspect, the present invention provides a method as described in any one of the first aspects above Method for measuring the specific heat of hydrogen of a device for measuring the specific heat of hydrogen, for measuring a temperature T s Pressure is P s Specific heat coefficient C of hydrogen sample at single target state point v The measurement mode is as follows:
s101, opening an electromagnetic valve and a sample filling valve, conveying a liquid hydrogen sample from a hydrogen source tank to a sample cavity of a low-temperature Dewar, filling the sample cavity, and reading a pressure sensor of the sample cavity to be higher than P s Filling is completed, and the electromagnetic valve and the sample filling valve are closed;
s102, opening a hydrogen gas vent valve, and enabling the temperature measured by a sample cavity temperature sensor to be stabilized at T by controlling the power of the first electric heating component and the opening of the electromagnetic valve by the controller s The pressure measured by the sample cavity pressure sensor is stabilized at P s Then closing the hydrogen gas vent valve; the redundant hydrogen sample generated in the adjustment process is discharged through a hydrogen vent valve;
s103, the controller applies a constant heating amount to the hydrogen sample in the sample cavity by controlling the voltage U and the application time t applied to the second electric heating assemblyL is the resistance of the second electric heating component, so that the temperature of the hydrogen sample is slightly increased, and the temperature of the hydrogen sample after the heating quantity Q is applied is measured to be T by a sample cavity temperature sensor s1 ；
S104, the temperature of the hydrogen sample in the sample cavity falls back to T again s Then, the air inlet valve of the standard container is opened, the electromagnetic valve is opened by the controller to exhaust, and after the hydrogen exhausted by the sample cavity completely enters the standard container which is at room temperature through the air inlet valve of the standard container, the pressure P in the standard container is measured by the pressure sensor of the standard container and the temperature sensor of the standard container respectively g And temperature T g ；
S105, after the hydrogen sample in the sample cavity is emptied, controlling the second electric heating assembly to restart the sample cavity from T through the controller s Heated to T s1 Calculating the corresponding heating quantity Q according to the voltage and the application time applied to the second electric heating component in the heating process 0 And finally obtaining the specific heat coefficient C of the hydrogen sample of the target state point v ：
Wherein: v (V) c 、V g The calibration volume of the stainless steel capillary tube and the standard container between the sample cavity and the electromagnetic valve respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen; t (T) s Is the temperature of the sample cavity, P s And θ is the capillary mass correction coefficient for the sample chamber pressure.
In a third aspect, the present invention provides a method for measuring specific heat of hydrogen using the apparatus for measuring specific heat of hydrogen according to any one of the first aspect, for measuring a temperature T s The pressure is P from high to low u 、P m 、P d Specific heat coefficient C of hydrogen sample of three target state points v1 、C v2 、C v3 The measurement mode is as follows:
s201, opening an electromagnetic valve and a sample filling valve, conveying a liquid hydrogen sample from a hydrogen source tank to a sample cavity of a low-temperature Dewar, filling the sample cavity, and reading a pressure sensor of the sample cavity to be higher than P u Filling is completed, and the electromagnetic valve and the sample filling valve are closed;
s202, opening a hydrogen gas vent valve, and enabling the temperature measured by a sample cavity temperature sensor to be stabilized at T by controlling the power of the first electric heating component and the opening of the electromagnetic valve by the controller s The pressure measured by the sample cavity pressure sensor is stabilized at P u Then closing the hydrogen gas vent valve; the redundant hydrogen sample generated in the adjustment process is discharged through a hydrogen vent valve;
s203, the controller controls the voltage U applied to the second electric heating component u And application time t u Applying a constant heating amount to the hydrogen sample in the sample chamberL is the resistance of the second electric heating componentThe temperature of the hydrogen sample is slightly increased, and the heating quantity Q is measured by a sample cavity temperature sensor u The temperature of the hydrogen sample after the application is T su ；
S204, the temperature of the hydrogen sample in the sample cavity falls back to T again s Then, the air inlet valve of the standard container is opened, the electromagnetic valve is opened by the controller to discharge the vaporized hydrogen into the standard container which is at room temperature, and the pressure detected by the pressure sensor of the sample cavity is defined by P u Reduced to P m Closing the electromagnetic valve to complete the first stage of exhaust, and synchronously adjusting the power of the first electric heating component through the controller in the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor is stabilized at T s The method comprises the steps of carrying out a first treatment on the surface of the The controller then controls the voltage U applied to the second electrical heating assembly m And application time t m Applying a constant heating amount to the hydrogen sample in the sample chamberThe temperature of the hydrogen sample is slightly increased, and the heating quantity Q is measured by a sample cavity temperature sensor m The temperature of the hydrogen sample after the application is T sm ；
S205, the temperature of the hydrogen sample in the sample cavity falls back to T again s Then, the air inlet valve of the standard container is opened, the electromagnetic valve is opened by the controller to discharge the vaporized hydrogen into the standard container which is at room temperature, and the pressure detected by the pressure sensor of the sample cavity is defined by P m Reduced to P d Closing the electromagnetic valve to complete the second stage of exhaust, and synchronously adjusting the power of the first electric heating component through the controller in the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor is stabilized at T s The method comprises the steps of carrying out a first treatment on the surface of the The controller then controls the voltage U applied to the second electrical heating assembly d And application time t d Applying a constant heating amount to the hydrogen sample in the sample chamber The temperature of the hydrogen sample is slightly increased, and the heating quantity Q is measured by a sample cavity temperature sensor d The temperature of the hydrogen sample after the application is T sd ；
S206, the temperature of the hydrogen sample in the sample cavity falls back to T again s Then, the air inlet valve of the standard container is opened, the electromagnetic valve is opened by the controller to gasify and discharge hydrogen into the standard container which is at room temperature, the electromagnetic valve is closed after the complete discharge to complete the third-stage discharge, and the power of the first electric heating component is synchronously regulated by the controller in the discharge process, so that the temperature measured by the temperature sensor of the sample cavity is stabilized at T s ；
S207, respectively acquiring three groups of pressures P in the standard container after the first-stage exhaust, the second-stage exhaust and the third-stage exhaust are finished according to real-time measurement results of the standard container pressure sensor and the standard container temperature sensor in the exhaust process g1 、P g2 、P g3 And temperature T g1 、T g2 、T g3 ；
S208, after the hydrogen sample in the sample cavity is emptied, controlling the second electric heating assembly to restart the sample cavity from T through the controller s Heated to T su From T s Heated to T sm From T s Heated to T sd Calculating the corresponding heating quantity Q according to the voltage and the application time applied to the second electric heating assembly in the three groups of heating processes u0 、Q m0 、Q d0 And finally obtaining the specific heat coefficient C of the hydrogen sample at three target state points v1 、C v2 、C v3 ：
Wherein: m is m i For the total mass of hydrogen sample discharged into standard container in the ith stage and before stage,m c is the mass of hydrogen in a stainless steel capillary tube between a sample cavity and an electromagnetic valveθ is the capillary mass correction coefficient, V c 、V g The calibration volume of the stainless steel capillary tube and the standard container between the sample cavity and the electromagnetic valve respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen.
Compared with the prior art, the invention has the following outstanding and beneficial technical effects: the invention designs a hydrogen specific heat measuring device based on the principle of an adiabatic calorimeter method, and designs a continuous deflation measuring method according to the device, so that the high-efficiency measurement of the multi-state hydrogen specific heat physical property is successfully realized. The inside design of sample chamber becomes thin wall round bottle spherical structure, outside hoisting device's pressure measurement scope, can also reduce the influence of sample chamber self heat capacity to the temperature rising process, improves measuring accuracy.
The conception, specific structure, and technical effects of the present invention will be further described with reference to the accompanying drawings so as to fully understand the objects, features, and effects of the present invention.
Drawings
FIG. 1 is a schematic diagram of a hydrogen specific heat measuring apparatus according to the present invention.
FIG. 2 is a schematic diagram of another hydrogen specific heat measuring device according to the present invention.
The reference numerals in the drawings are: the low-temperature Dewar 1, a sample cavity 2, a first electric heating component 3, a sample cavity plug 4, a second electric heating component 5, a sample cavity pressure sensor 6, a sample cavity temperature sensor 7, an inner cold screen 8, an outer cold screen 9, a stainless steel capillary tube 10, a radiation-proof cold screen 11, a signal and power line 12, a controller 13, an electromagnetic valve 14, a hydrogen vent valve 15, a sample filling pipeline 16, a sample filling valve 17, a hydrogen source tank 18, a constant-temperature water bath 19, a standard container 20, a standard container air inlet valve 21, a standard container pressure sensor 22, a standard container temperature sensor 23, a water bath circulation pipeline 24 and a circulating pump 25.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below. The technical features of the embodiments of the invention can be combined correspondingly on the premise of no mutual conflict.
In the description of the present invention, it will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected with intervening elements present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.
In the description of the present invention, it should be understood that the terms "first" and "second" are used solely for the purpose of distinguishing between the descriptions and not necessarily for the purpose of indicating or implying a relative importance or implicitly indicating the number of features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.
Referring to fig. 1, in a preferred embodiment of the present invention, there is provided a hydrogen specific heat measuring apparatus comprising components of a cryogenic dewar 1, a sample chamber 2, a first electric heating element 3, a sample chamber plug 4, a second electric heating element 5, a sample chamber pressure sensor 6, a sample chamber temperature sensor 7, an inner cold screen 8, an outer cold screen 9, a stainless steel capillary tube 10, a radiation-proof cold screen 11, a signal and power line 12, a controller 13, an electromagnetic valve 14, a hydrogen vent valve 15, a sample filling line 16, a sample filling valve 17, a hydrogen source tank 18, a thermostatic water bath 19, a standard container 20, a standard container air inlet valve 21, a standard container pressure sensor 22, a standard container temperature sensor 23, a water bath circulation line 24, a circulation pump 25, and the like. The specific assembly form and the working principle of each component in the device are described in detail below.
The low-temperature Dewar 1 is used for providing a specific heat coefficient testing environment for a hydrogen sample at a specific temperature and a specific pressure (called a state point), a sample cavity 2 for containing the hydrogen sample to be subjected to specific heat measurement is arranged in the inner cavity of the low-temperature Dewar 1, and the radiation heat exchange between the sample cavity 2 and the low-temperature Dewar 1 can be reduced by sequentially coating an inner cold screen 8 and an outer cold screen 9 outside the sample cavity 2. The low-temperature Dewar 1 is a constant-temperature and constant-pressure low-temperature Dewar, and the outer wall of the low-temperature Dewar can reduce heat exchange with the environment through vacuum heat insulation.
The sample cavity 2 is of a thin-wall spherical bottle structure, so that the influence of the self heat capacity of the sample cavity 2 on the temperature rising process can be reduced under the condition of ensuring the bearing capacity, and the measuring accuracy is improved. The outside of the sample cavity 2 is wrapped with an insulating shell, and the sample cavity 2 is completely wrapped. A sample cavity pressure sensor 6 and a sample cavity temperature sensor 7 are arranged in the sample cavity 2 and are respectively used for measuring pressure and temperature data corresponding to the hydrogen sample in the cavity. A first electric heating component 3 is arranged on the heat insulation shell outside the sample cavity 2, and a second electric heating component 5 is arranged inside the sample cavity 2. Because the specific heat coefficient of the hydrogen sample needs to be accurately measured, when the temperature of the sample cavity 2 is increased, the heat insulation shell is synchronously increased along with the sample cavity, so that no heat leakage of the sample cavity is ensured. This can be achieved by synchronously controlling the heating of the second electric heating assembly 5 and the first electric heating assembly 3, i.e. when the sample chamber 2 is heated by the second electric heating assembly 5, the outside of the insulating housing is also heated by the first electric heating assembly 3 to synchronously heat up with the sample chamber 2, the heating amplitude of which can be precisely controlled by the heating power.
The top of the sample cavity 2 extends out of the heat insulation shell through a pipe section, and a sample cavity plug 4 is arranged at the outlet. The sample cavity plug 4 also needs to be made of heat insulation materials, so that heat leakage is avoided. One end of the stainless steel capillary tube 10 penetrates through the sample cavity plug 4 to be communicated with the inside of the sample cavity 2, and the other end of the stainless steel capillary tube extends out of the low-temperature Dewar 1 and is sequentially connected with the electromagnetic valve 14 and the hydrogen gas vent valve 15. The connection position of the stainless steel capillary tube 10 and the sample cavity plug 4 and the low-temperature Dewar 1 are required to be kept airtight. The part of the stainless steel capillary tube 10 inside the low-temperature dewar 1 is provided with a plurality of radiation-proof cold screens 11 which are horizontally arranged. The radiation-proof cold screen 11 may be made of a material capable of insulating heat radiation, such as stainless steel. The stainless steel capillary 10 is fixedly sleeved with a copper sleeve, and the radiation-proof cold screen 11 can be welded on the copper sleeve to avoid damage to the stainless steel capillary 10 in the fixing process.
The sample filling pipeline 16 is connected with a hydrogen source tank 18 and a sample filling valve 17 in sequence, and then is connected with the stainless steel capillary 10 between the electromagnetic valve 14 and the hydrogen gas vent valve 15, and is used for transferring the hydrogen sample in the hydrogen source tank 18 into the sample cavity 2 when the electromagnetic valve 14 and the sample filling valve 17 are opened. The solenoid valve 14 needs to adopt a high-precision solenoid valve, so that the measurement accuracy is improved.
The constant temperature water bath 19 is used for providing a constant temperature environment, and the standard container 20 is arranged in the constant temperature water bath 19 and exchanges heat with the medium in the bath. The standard reservoir 20 is connected to the stainless steel capillary tube 10 between the solenoid valve 14 and the hydrogen purge valve 15 by a standard reservoir inlet valve 21. The standard container 20 is a container for storing vaporized hydrogen, the volume of the inside of the container is accurately calibrated, and after the hydrogen is discharged into the standard container 20, the mass of the hydrogen can be obtained through conversion of an ideal gas state equation by measuring the temperature and the pressure of the inside. Depending on the mass invariance, the mass of this portion of hydrogen gas can correspond to the mass of the liquid hydrogen sample in the sample chamber 2, between which only a partial loss is possible, which can be compensated further later.
In an embodiment of the present invention, a water bath circulation line 24 may be provided on the thermostatic water bath 19, on which a circulation pump 25 is installed, to promote temperature uniformity inside the thermostatic water bath 19 by circulation of internal water. The standard container 20 is placed in the thermostatic water bath 19, and the hydrogen sample discharged into the standard container 20 can be maintained in a low-pressure constant-temperature state, so that the quality of the internal hydrogen can be estimated through an ideal gas state equation. The standard container 20 can be communicated with the stainless steel capillary 10 in the state that the standard container air inlet valve 21 is opened, so that the air inlet and outlet states of the sample cavity 2 are controlled. A standard container pressure sensor 22 and a standard container temperature sensor 23 are provided in the standard container 20 for measuring the hydrogen sample pressure and temperature inside the standard container 20 in real time. The double-layer heat-preservation inner container and the double-layer heat-preservation cover plate can be further arranged in the hot water bath, so that the temperature stability is guaranteed, and the hot water bath has a function of preventing dry burning. The standard container is preferably made of 316L stainless steel.
From the ideal gas state equation pv=nrt, the corresponding molar amount can be converted by measuring the hydrogen sample pressure P and the temperature T inside the standard container 20 with the volume V fixed, and the mass of hydrogen can be calculated from the molar mass of hydrogen. Therefore, when a fixed amount of liquid hydrogen sample is inputted into the sample chamber 2, the determination of the specific heat coefficient of the hydrogen sample can be realized by applying a fixed amount of heat thereto, then measuring the amount of change in the temperature of the sample after the application of heat, and then calculating the mass of the sample in the sample chamber 2 by the conversion of the standard container 20.
The loss of the hydrogen sample from the sample chamber 2 to the standard container 20 is mainly due to the sample chamber 2 and the stainless capillary 10 serving as the intermediate transfer path, and the loss volumes of these two parts may be theoretically considered. Considering that the length of the stainless steel capillary tube 10 tends to be long, with the vast majority of the length being inside the cryogenic dewar 1, the length of the tube segment that connects to the standard vessel 20 after the solenoid valve 14 is short; secondly, the hydrogen sample flowing in the stainless steel capillary 10 may be in a partially liquid state before the solenoid valve 14 and may become substantially gaseous after the solenoid valve 14; finally, the sample chamber 2 is generally small in volume due to the stored liquid hydrogen sample, and is substantially negligible relative to the total volume of the stainless steel capillary 10. Thus, in embodiments of the present invention, only the volume of the stainless steel capillary 10 between the sample chamber 2 and the solenoid valve 14 may be considered when calculating the above-described losses, while the volume of the sample chamber 2 and the volume of the stainless steel capillary 10 after the solenoid valve 14 are negligible.
In the measurement of the specific heat coefficient of the hydrogen sample, it is necessary to switch each valve repeatedly and to record time domain signals of various sensors, so that the controller 13 is provided as a central control and processing device in the present invention. The controller 13 can be implemented by any single-chip microcomputer, PLC, MCU, DCS and other devices. The first electric heating component 3, the second electric heating component 5, the sample cavity pressure sensor 6, the sample cavity temperature sensor 7, the electromagnetic valve 14, the standard container pressure sensor 22 and the standard container temperature sensor 23 are all connected to the controller 13 through the signal and power line 12, so that automatic measurement of pressure and temperature parameters and opening control of the electromagnetic valve 14 are realized. Before the signal and power line 12 is led out of the low-temperature Dewar 1, the signal and power line can exchange heat with the radiation-proof cold screen, and perform temperature compensation, so that heat leakage loss is reduced.
In addition, the specific model of each sensor and heating element in the present invention is not limited, but the higher the accuracy should be. In the embodiment of the invention, the sample cavity temperature sensor 7 and the standard container temperature sensor 23 are both Lakeshore Cernox temperature sensors, and the sensor signal wire adopts a low-heat-conductivity phosphor copper wire, so that the heat leakage of the signal wire is reduced. In addition, the first electric heating element 3 may take the form of an electric heating film, preferably a polyimide electric heating film, while the second electric heating element 5 takes the form of an electric heating wire. The electrically heated membrane may be wrapped outside the insulating housing of the sample chamber 2, while the electrically heated wire may be built into the sample chamber 2. In addition, the sample filling line 16 employs a vacuum insulated pipe to reduce hydrogen sample loss.
Meanwhile, because of the inflammability and explosiveness of hydrogen, in order to ensure the safety of experiments, the electric equipment in the whole hydrogen specific heat measuring device adopts an explosion-proof design, a nitrogen fire-fighting system is arranged on an experiment site and is linked with a hydrogen concentration monitoring host, and the externally discharged hydrogen is diluted by nitrogen when necessary.
In addition, since the present invention converts the hydrogen gas quality depending on the ideal gas state equation, it is preferable that the inside of the standard container 20 be maintained at normal temperature and pressure, thereby ensuring the accuracy of the conversion. Therefore, if the invention is only used for single-state point specific heat test, the effective volume of the inside of the standard container 20 can be ensured to be basically similar to the total volume after the vaporization of the hydrogen sample in the sample cavity 2 through the model selection of the standard container 20, so that the conversion of the quality can be realized in the standard container 20 by measuring the pressure and the temperature. However, there is also a need in the present invention for a multiple state point specific heat test that is performed continuously by one hydrogen sample charge. In this process, hydrogen is continuously purged into standard vessels 20 in stages, and it is difficult for a single standard vessel 20 to meet the requirements of ensuring that the internal pressure is at normal pressure for each point of condition.
Therefore, in order to meet the requirement of the multi-state point specific heat test, referring to fig. 2, in another embodiment of the present invention, a plurality of standard containers 20 are provided in a constant temperature water bath, each of which is connected to the stainless steel capillary 10 in parallel through a capillary, and can be in communication relationship with each other through a valve control. Specifically, in the embodiment of the present invention, a plurality of standard containers 20 are connected to each other by an inter-container capillary tube with an inter-container control valve, which may also be connected to the controller 11 and controlled by the controller 13. In the initial state, only 1 standard vessel 20 is connected to the stainless steel capillary 10, and the other standard vessel 20 is not connected to the standard vessel 20 connected to the stainless steel capillary 10. The standard container pressure sensor 22 and the standard container temperature sensor 23 may be provided only in the 1 st standard container 20, and may be provided separately in each standard container 20. In the use process, the pressure in the standard container 20 communicated with the stainless steel capillary tube 10 can be monitored in real time through the standard container pressure sensor 22, and whenever the internal pressure monitored by the controller 13 exceeds the normal pressure, the inter-container control valve at the front end of the next standard container 20 is newly opened to be communicated with the stainless steel capillary tube 10. For example, when it is detected that the internal pressure of the standard container 20 which is in communication with the stainless steel capillary 10 in the initial state exceeds the normal pressure, the inter-container control valve at the front end of the second standard container 20 may be opened so that the first standard container 20 and the second standard container 20 are in communication through the inter-container capillary. All the standard containers 20 are pumped to a vacuum state in advance, so that after capillary communication between the containers, the interiors of the two standard containers 20 are communicated, the pressure is reduced, and at the moment, hydrogen can be stored under normal pressure again. When the internal pressure monitored by the controller 13 through the standard container pressure sensor 22 exceeds the normal pressure, the next standard container 20 may be continuously opened. Only three standard containers 20 are shown in fig. 2, but in fact more standard containers 20 may be provided, which in turn are connected by inter-container capillaries with inter-container control valves.
It should be noted that when a plurality of standard containers 20 are provided in the constant temperature water bath 19, the volume of the single standard container 20 should not be excessively large, so that an excessive drop in the overall internal pressure after newly opening one standard container 20 is avoided. The specific volume of a single standard container 20 may be reasonably optimized according to actual testing requirements, without limitation. The standard container 20 is preferably made of 316L stainless steel.
Based on the above-mentioned hydrogen specific heat measuring device shown in fig. 2, in another preferred embodiment of the present invention, a hydrogen specific heat measuring method is provided, which includes a single-state point specific heat test mode after one hydrogen sample filling and a multi-state point specific heat test mode after one hydrogen sample filling. Specific implementations of these two modes are described below.
It should be noted that all valves in the initial state are in the closed state in the two modes; the cryogenic dewar 1 provides a suitable test environment in which the circulation pump 25 operates normally, maintaining the temperature within the constant temperature water bath 19 at room temperature.
1. Single state point C after one hydrogen sample filling v (T s 、P s ) Specific heat test mode
This mode is used to measure a temperature T s Pressure is P s Specific heat coefficient C of hydrogen sample at single target state point v The specific measurement mode is as follows:
s101, calibrating the volumes of the sample cavity 2, the stainless steel capillary 10 section between the sample cavity 2 and the electromagnetic valve 14 and the standard container 20, and respectively marking as V s 、V c And V g . The solenoid valve 14 and the sample filling valve 17 are opened, the liquid hydrogen sample from the hydrogen source tank 18 is fed into the sample chamber 2 of the cryogenic dewar 1, the sample chamber 2 is filled and the reading of the sample chamber pressure sensor 6 is higher than P s Filling is completed at this time, and the solenoid valve 14 and the sample filling valve 17 are closed.
S102, opening the hydrogen gas vent valve 15, and enabling the controller 13 to enable the temperature of the sample cavity by controlling the power of the first electric heating assembly 3 and the opening of the electromagnetic valve 14The temperature measured by the sensor 7 reaches T s The pressure measured by the sample cavity pressure sensor 6 reaches P s The excess hydrogen sample produced by this conditioning process is vented through a hydrogen vent valve 15. To stabilize the internal state of the sample chamber 2, i.e. the temperature measured by the sample chamber temperature sensor 7 is stabilized at T s The pressure measured by the sample cavity pressure sensor 6 is stabilized at P s After that, the hydrogen vent valve 15 is closed.
S103, the controller 13 controls the power of the second electric heating assembly 5 through the signal and the power line 12 to apply a constant value tiny heating quantity Q to the hydrogen sample in the sample cavity 2 u The temperature of the hydrogen sample is then increased, and the specific heat coefficient of the hydrogen sample at the current state point can be reflected by the temperature change. The controller 13 applies a constant heating amount to the hydrogen sample in the sample chamber 2 by controlling the voltage U and the application time T applied to the second electric heating assembly 5, so that the temperature of the hydrogen sample is slightly raised, and the temperature T of the hydrogen sample after the heating amount Q is applied is measured by the sample chamber temperature sensor 7 s1 。
The above Q is calculated by the following formula:
wherein U is the measured voltage of the second electric heating component 5, L is the resistance of the second electric heating component 5, and t is the applied time of the voltage.
S104, the temperature of the hydrogen sample in the sample cavity 2 falls back to T again s After the standard container air inlet valve 21 is opened, the electromagnetic valve 14 is opened by the controller 13 to exhaust, and the hydrogen exhausted by the sample cavity 2 completely enters the standard container 20 which is at room temperature through the standard container air inlet valve 21, and then the pressure P in the standard container 20 is measured by the standard container pressure sensor 22 and the standard container temperature sensor 23 respectively g And temperature T g 。
Since the low-pressure normal-temperature hydrogen gas in the standard container 20 is close to the ideal gas state, the total mass m of hydrogen gas in the standard container 20 is calculated by the following formula:
P g (V c +V g )＝ZnRT g (2)
m＝nM H (3)
wherein Z is hydrogen compression factor at normal temperature and pressure, and the value is 1.000599.
The total hydrogen mass m is corrected to exclude the hydrogen mass m in the stainless steel capillary 10 between the sample cavity 2 and the electromagnetic valve 14 c ：
Wherein θ is the capillary mass correction coefficient, so the original hydrogen mass in the sample cavity 2 is m+m c 。
S105, after the hydrogen sample in the sample cavity 2 is emptied, the controller 13 controls the second electric heating assembly 5 to restart the sample cavity 2 from T s Heated to T s1 According to the voltage U applied to the second electric heating element 5 during the heating process 0 And application time t 0 Thereby calculating the corresponding heating amount Q 0 To eliminate the influence of the sample chamber 2 itself on the measurement, Q 0 Calculated by the following formula:
wherein U is 0 For the heating voltage, t, of the second electric heating element 5 0 For heating the cavity, i.e. voltage U 0 Is applied for a period of time.
Summarizing the substitution of the above formula into hydrogen specific heat C v The specific heat coefficient C of the hydrogen sample at the target state point can be finally obtained by a calculation formula v ：
Of course, in practical application, the formulas (1) - (6) are combined, and the formulas are integrated by skipping the deduction processes, and then the formulas can be directly passed throughCalculating hydrogen specific heat C corresponding to target state point v ：
Wherein: v (V) c 、V g The calibration volumes of the stainless steel capillary 10 and the standard container 20 between the sample cavity 2 and the electromagnetic valve 14 respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen; t (T) s Is the temperature of the sample cavity at the target state point, P s For the pressure of the sample chamber at the target state point, θ is the capillary mass correction coefficient (i.e., capillary factor, which is related to different temperatures and pressures, and can be determined by table look-up or experimentation).
2. Multi-state point C after one-time filling of hydrogen sample v1 (T s 、P u )、C v2 (T s 、P m )、C v3 (T s 、P d ) Specific heat test mode
In this mode, three status points, C respectively, can be measured simultaneously v1 (T s 、P u )、C v2 (T s 、P m )、C v3 (T s 、P d ) Wherein P is u >P m >P d . Therefore, the measured temperatures of the multi-state point specific heat test mode are T s The pressure is P from high to low u 、P m 、P d The specific heat measurement mode of the hydrogen sample of the three target state points is specifically as follows:
s201, calibrating the volumes of the sample cavity 2, the stainless steel capillary 10 (the section between the sample cavity 2 and the electromagnetic valve 14) and the standard container 20, and respectively marking as V s 、V c And V gi (volume V of Standard container 20 with multiple venting) gi For variation and gradual increase, the volume of a single standard container 20 may be calibrated first, followed by a subsequent determination of the total volume based on the number of standard containers 20 that are open together, i.e., in communication with the stainless steel capillary 10). The solenoid valve 14 and the sample filling valve 17 are opened and the liquid from the hydrogen source tank 18 is suppliedSample chamber 2 of low temperature Dewar 1 for transporting hydrogen sample in state is filled in sample chamber 2, and reading of pressure sensor 6 in sample chamber is higher than P u Filling is completed at this time, and the solenoid valve 14 and the sample filling valve 17 are closed.
S202, opening the hydrogen gas vent valve 15, and enabling the controller 13 to stabilize the temperature measured by the sample cavity temperature sensor 7 at T by controlling the power of the first electric heating component 3 and the opening of the electromagnetic valve 14 s The pressure measured by the sample cavity pressure sensor 6 is stabilized at P u Then the hydrogen purge valve 15 is closed; the excess hydrogen sample produced by the conditioning process is vented through a hydrogen vent valve 15.
S203, the controller 13 controls the voltage U applied to the second electric heating assembly 5 u And application time t u Applying a constant heating amount to the hydrogen sample in the sample cavity 2 to slightly raise the temperature of the hydrogen sample, and measuring the heating amount Q by the sample cavity temperature sensor 7 u The temperature of the hydrogen sample after the application is T su 。
Q is as described above u Can be calculated by the following formula:
wherein U is u To maintain pressure P u The corresponding measured voltage of the second electric heating component 5 is L which is the resistance of the second electric heating component 5, t u Is the pressure P u Corresponding to the measured voltage application time period.
Similar to the single-state-point specific heat test mode, the multi-state-point specific heat test mode also requires that the liquid hydrogen sample is vaporized and discharged into the standard container 20 for mass conversion, but since other state points need to be measured later, all the hydrogen sample cannot be directly discharged into the standard container 20, and staged gas discharge is required to be performed, which will be described in detail below.
S204, the temperature of the hydrogen sample in the sample cavity 2 falls back to T again s After that, the standard container air inlet valve 21 is opened, the controller 13 opens the electromagnetic valve 14 to discharge the vaporized hydrogen gas into the constantIn a standard container 20 at room temperature, the pressure detected by the sample cavity pressure sensor 6 is defined by P u Reduced to P m Closing the electromagnetic valve 14 to complete the first stage of exhaust, and synchronously adjusting the power of the first electric heating component 3 by the controller 13 during the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor 7 is stabilized at T s . When the first stage of the exhaust is completed, the pressure P in the standard container 20 is acquired according to the standard container pressure sensor 22 and the standard container temperature sensor 23 g1 And temperature T g1 。
After the first stage of the exhaust is completed, the controller 13 then controls the voltage U applied to the second electric heating assembly 5 m And application time t m Applying a constant heating amount to the hydrogen sample in the sample cavity 2 to slightly raise the temperature of the hydrogen sample, and measuring the heating amount Q by the sample cavity temperature sensor 7 m The temperature of the hydrogen sample after the application is T sm 。
Q is as described above m Can be calculated by the following formula:
wherein U is m To maintain pressure P m The corresponding measured voltage of the second electric heating component 5 is L which is the resistance of the second electric heating component 5, t m Is the pressure P m Corresponding to the measured voltage application time period.
S205, the temperature of the hydrogen sample in the sample cavity 2 falls back to T again s After that, the standard container air inlet valve 21 is opened, the controller 13 opens the electromagnetic valve 14 to discharge the vaporized hydrogen gas into the standard container 20 which is at room temperature, and the pressure detected by the sample cavity pressure sensor 6 is defined by P m Reduced to P d Closing the electromagnetic valve 14 to complete the second stage of exhaust, and synchronously adjusting the power of the first electric heating component 3 through the controller 13 during the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor 7 is stabilized at T s . When the second stage of venting is completed, the pressure P in the standard container 20 needs to be obtained according to the standard container pressure sensor 22 and the standard container temperature sensor 23 g2 And temperature T g2 。
After the second stage of the exhaust is completed, the controller 13 then controls the voltage U applied to the second electric heating assembly 5 d And application time t d Applying a constant heating amount to the hydrogen sample in the sample cavity 2 to slightly raise the temperature of the hydrogen sample, and measuring the heating amount Q by the sample cavity temperature sensor 7 d The temperature of the hydrogen sample after the application is T sd 。
Q is as described above 3 Can be calculated by the following formula:
wherein U is d To maintain pressure P d The corresponding measured voltage of the second electric heating component 5 is L which is the resistance of the second electric heating component 5, t d Is the pressure P d Corresponding to the measured voltage application time period.
S206, the temperature of the hydrogen sample in the sample cavity 2 falls back to T again s After that, the air inlet valve 21 of the standard container is opened, the electromagnetic valve 14 is opened by the controller 13 to gasify and discharge hydrogen into the standard container 20 which is at room temperature, the electromagnetic valve 14 is closed to complete the third-stage air discharge after the whole discharge is finished, and the power of the first electric heating component 3 is synchronously regulated by the controller 13 in the air discharge process, so that the temperature measured by the temperature sensor 7 of the sample cavity is stabilized at T s . In the third stage, the pressure in the sample cavity gradually changes from P along with the total vaporization of the internal liquid hydrogen d Reducing to normal pressure. When the third-stage venting is completed, the pressure P in the standard container 20 needs to be obtained according to the standard container pressure sensor 22 and the standard container temperature sensor 23 g3 And temperature T g3 。
S207, after the hydrogen gas discharged from the sample cavity enters the standard container 20 through the standard container air inlet valve 21, the temperature is restored to 300K at room temperature, and the pressure of the hydrogen gas entering the sample cavity gradually rises. And in order to ensure that the pressure in the standard container 20 is maintained at substantially normal pressure, the controller 13 is used to switch on again each time the pressure detected by the standard container pressure sensor 22 exceeds normal pressureThe inter-vessel control valve at the front end of the next standard vessel 20 is opened to allow it to also communicate with the stainless steel capillary 10. And as new standard containers 20 open, the internal pressure drops causing the temperature to also slightly fluctuate. Therefore, although the pressure and temperature in the standard container 20 are maintained substantially around the normal pressure and the normal temperature in the first stage exhaust, the second stage exhaust, and the third stage exhaust, there may be a certain deviation, and it is necessary to record three sets of pressures P in the standard container 20 when the first stage exhaust, the second stage exhaust, and the third stage exhaust are completed, respectively, based on the real-time measurement results of the standard container pressure sensor 22 and the standard container temperature sensor 23 in the exhaust process g1 、P g2 、P g3 And temperature T g1 、T g2 、T g3 These three sets of pressure and temperature values can be used to accurately scale the corresponding hydrogen sample mass according to the ideal gas equation.
It should be noted that the ideal gas equation is converted by considering the total volume of the standard container 20 connected to the stainless steel capillary 10 at the end of the first, second and third stages of gas exhaustion, but the volume may be changed, and is denoted as V g1 、V g2 、V g3 . V at this time g1 、V g2 、V g3 Can be respectively based on the number n of standard containers 20 communicated with the stainless steel capillary 10 at the end of the exhaust of the first stage, the second stage and the third stage 1 、n 2 、n 3 The calculation is performed in combination with the volume of a single standard container 20.
Since the low-pressure normal-temperature hydrogen in the system is close to the ideal gas state, the hydrogen mass is calculated by the following formula.
P gi (V c +V gi )＝Zn i RT gi (10)
m i ＝n i M H (11)
Wherein m is i The value of m in this example increases gradually 3 The total mass is that Z is the compression factor of hydrogen at normal temperature and normal pressure, and the value is 1.000599. For the total mass m of the hydrogen 3 Make corrections taking into account sample chamber 2 andmass m of hydrogen in stainless steel capillary 10 between solenoid valves 14 c ：
Where θ is the capillary mass correction coefficient.
S208, after the hydrogen sample in the sample cavity 2 is emptied, the controller 13 controls the second electric heating assembly 5 to restart the sample cavity 2 from T s Heated to T su From T s Heated to T sm From T s Heated to T sd The heating time t of each of the three phases is recorded u0 、t m0 、t d0 Calculating the corresponding heating amount Q according to the voltage and the application time applied to the second electric heating assembly 5 in the three groups of heating processes u0 、Q m0 、Q d0 ，Q u0 、Q m0 、Q d0 Calculated by the following formula respectively:
wherein U is u0 、U m0 、U d0 Respectively from T s Heated to T su From T s Heated to T sm From T s Heated to T sd The heating voltage applied to the second electric heating assembly 5 is applied in three stages. U (U) u0 、U m0 、U d0 Respectively from T s Heated to T su From T s Heated to T sm From T s Heated to T sd Three-stage heating voltage is applied to the second electric heating element 5Is a time period of (2).
What is needed is the self-T s Heated to T su From T s Heated to T sm From T s Heated to T sd After each heating phase is completed, isothermal reversion to T is required s 。
Thus, the above formula is summarized and substituted into the hydrogen specific heat C v The specific heat coefficient C of the hydrogen sample of the three target state points can be finally obtained by a calculation formula v1 、C v2 、C v3 ：
Wherein: m is m i For the total mass of hydrogen sample discharged into standard container in the ith stage and before stage,m c is the mass of hydrogen in the stainless steel capillary 10 between the sample cavity 2 and the electromagnetic valve 14θ is the capillary mass correction coefficient, V c 、V g The calibration volumes of the stainless steel capillary 10 and the standard container 20 between the sample cavity 2 and the electromagnetic valve 14 respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen.
Therefore, the invention designs a continuous deflation measuring method based on the hydrogen specific heat measuring device of the adiabatic calorimeter principle shown in fig. 2, and successfully realizes the efficient measurement of the multi-state hydrogen specific heat physical property.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

1. The hydrogen specific heat measuring device is characterized by comprising a low-temperature Dewar (1), a hydrogen source tank (18) and a constant-temperature water bath (19);
a sample cavity (2) for containing a hydrogen sample to be measured is arranged in the inner cavity of the low-temperature Dewar (1), and the radiation heat exchange between the sample cavity (2) and the low-temperature Dewar (1) is reduced by sequentially coating an inner cold screen (8) and an outer cold screen (9) outside the sample cavity (2);
the sample cavity (2) is of a thin-wall spherical bottle structure, and the heat insulation shell is wrapped outside the sample cavity (2); a sample cavity pressure sensor (6) and a sample cavity temperature sensor (7) are arranged in the sample cavity (2) and are respectively used for measuring pressure and temperature data corresponding to the hydrogen sample in the cavity; a first electric heating component (3) is arranged on the heat-insulating shell outside the sample cavity (2), a second electric heating component (5) is arranged inside the sample cavity (2), and when the sample cavity (2) is heated by the second electric heating component (5), the heat-insulating shell is heated by the first electric heating component (3) to synchronously heat up along with the sample cavity (2);
A sample cavity plug (4) is arranged at the outlet of the insulating shell, one end of a stainless steel capillary tube (10) penetrates through the sample cavity plug (4) to be communicated with the inside of the sample cavity (2), and the other end of the stainless steel capillary tube extends out of the low-temperature Dewar (1) and is sequentially connected with an electromagnetic valve (14) and a hydrogen gas vent valve (15); the part of the stainless steel capillary tube (10) in the low-temperature Dewar (1) is provided with a plurality of radiation-proof cold screens (11) which are horizontally arranged;
the sample filling pipeline (16) is sequentially connected with the hydrogen source tank (18) and the sample filling valve (17) and then connected with the stainless steel capillary tube (10) between the electromagnetic valve (14) and the hydrogen gas vent valve (15), and is used for transferring a hydrogen sample in the hydrogen source tank (18) into the sample cavity (2) when the electromagnetic valve (14) and the sample filling valve (17) are opened;
the constant temperature water bath (19) is used for providing a constant temperature environment, and the standard container (20) is arranged in the constant temperature water bath (19) and exchanges heat with a medium in the bath; the standard container (20) is connected to the stainless steel capillary tube (10) between the electromagnetic valve (14) and the hydrogen gas vent valve (15) through the standard container air inlet valve (21); a standard container pressure sensor (22) and a standard container temperature sensor (23) are arranged in the standard container (20) and are used for measuring the pressure and the temperature of a hydrogen sample in the standard container (20) in real time.
2. The hydrogen specific heat measurement device according to claim 1, further comprising a controller (13), wherein the first electric heating component (3), the second electric heating component (5), the sample cavity pressure sensor (6), the sample cavity temperature sensor (7), the electromagnetic valve (14), the standard container pressure sensor (22) and the standard container temperature sensor (23) are connected to the controller (13) through signals and power lines (12), so that automatic measurement of pressure and temperature parameters and opening control of the electromagnetic valve (14) are realized.
3. The hydrogen specific heat measurement device according to claim 1, characterized in that a water bath circulation line (24) with a circulation pump (25) is provided on the thermostatic water bath (19).
4. The hydrogen specific heat measurement device according to claim 1, wherein the sample chamber temperature sensor (7) and the standard container temperature sensor (23) are both lasesshore Cernox temperature sensors, and the sensor signal line is a low-thermal conductivity phosphor copper wire.
5. The hydrogen specific heat measurement device according to claim 1, wherein the first electric heating component (3) employs a polyimide electric heating film, and the second electric heating component (5) employs an electric heating wire.
6. The hydrogen specific heat measurement device according to claim 1, wherein the sample filling line (16) employs a vacuum insulated pipe.
7. The hydrogen specific heat measuring device according to claim 1, wherein a copper sleeve is fixedly sleeved outside the stainless steel capillary tube (10), and the radiation-proof cold screen (11) is welded on the copper sleeve; the electric equipment in the hydrogen specific heat measuring device adopts an explosion-proof design.
8. The hydrogen specific heat measuring device according to claim 1, wherein a plurality of vacuum standard containers are arranged in the constant temperature water bath (19), and each standard container is connected to the stainless steel capillary (10) in parallel through the capillary and can be communicated with each other through a valve control.
9. A method for measuring specific heat of hydrogen using the device for measuring specific heat of hydrogen according to any one of claims 1 to 8, wherein the measurement temperature is T s Pressure is P s Specific heat coefficient C of hydrogen sample at single target state point v The measurement mode is as follows:
s101, opening an electromagnetic valve (14) and a sample filling valve (17), conveying a liquid hydrogen sample from a hydrogen source tank (18) to a sample cavity (2) of the low-temperature Dewar (1), filling the sample cavity (2) and reading a sample cavity pressure sensor (6) higher than P s When filling is completed, the electromagnetic valve (14) and the sample filling valve (17) are closed;
s102, opening a hydrogen gas vent valve (15), and enabling the controller (13) to stabilize the temperature measured by the sample cavity temperature sensor (7) at T by controlling the power of the first electric heating assembly (3) and the opening of the electromagnetic valve (14) s The pressure measured by the sample cavity pressure sensor (6) is stabilized at P s Then closing the hydrogen vent valve (15); the redundant hydrogen sample generated in the adjustment process is discharged through a hydrogen gas vent valve (15);
s103, the controller (13) applies a constant heating amount to the hydrogen sample in the sample cavity (2) by controlling the voltage U and the application time t applied to the second electric heating assembly (5)L is the resistance of the second electric heating component (5) to make the hydrogen sample warmThe temperature of the hydrogen sample after the heating quantity Q is applied is measured to be T by a sample cavity temperature sensor (7) after the temperature is slightly increased s1 ；
S104, the temperature of the hydrogen sample in the sample cavity (2) falls back to T again s After the standard container air inlet valve (21) is opened, the electromagnetic valve (14) is opened by the controller (13) to exhaust, and the hydrogen exhausted by the sample cavity (2) completely enters the standard container (20) at room temperature through the standard container air inlet valve (21), and then the pressure P in the standard container (20) is measured by the standard container pressure sensor (22) and the standard container temperature sensor (23) respectively g And temperature T g ；
S105, after the hydrogen sample in the sample cavity (2) is emptied, the controller (13) controls the second electric heating component (5) to restart the sample cavity (2) from T s Heated to T s1 Calculating the corresponding heating quantity Q according to the voltage and the application time applied to the second electric heating component (5) in the heating process 0 And finally obtaining the specific heat coefficient C of the hydrogen sample of the target state point v ：
Wherein: v (V) c 、V g The calibration volumes of the stainless steel capillary tube (10) and the standard container (20) between the sample cavity (2) and the electromagnetic valve (14) are respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen; t (T) s Is the temperature of the sample cavity, P s And θ is the capillary mass correction coefficient for the sample chamber pressure.
10. A method for measuring specific heat of hydrogen using the device for measuring specific heat of hydrogen according to any one of claims 1 to 8, wherein the measurement temperature is T s The pressure is P from high to low u 、P m 、P d Specific heat coefficient C of hydrogen sample of three target state points v1 、C v2 、C v3 The measurement mode is as follows:
s201 opening the electromagnetic valve (14)) And a sample filling valve (17) for feeding a liquid hydrogen sample from a hydrogen source tank (18) into the sample chamber (2) of the cryogenic dewar (1), filling the sample chamber (2) and reading the sample chamber pressure sensor (6) above P u When filling is completed, the electromagnetic valve (14) and the sample filling valve (17) are closed;
s202, opening a hydrogen gas vent valve (15), and enabling the controller (13) to stabilize the temperature measured by the sample cavity temperature sensor (7) at T by controlling the power of the first electric heating assembly (3) and the opening of the electromagnetic valve (14) s The pressure measured by the sample cavity pressure sensor (6) is stabilized at P u Then closing the hydrogen vent valve (15); the redundant hydrogen sample generated in the adjustment process is discharged through a hydrogen gas vent valve (15);
s203, the controller (13) controls the voltage U applied to the second electric heating component (5) u And application time t u Applying a constant heating amount to the hydrogen sample in the sample chamber (2)L is the resistance of the second electric heating component (5) to slightly increase the temperature of the hydrogen sample, and the heating quantity Q is measured by the sample cavity temperature sensor (7) u The temperature of the hydrogen sample after the application is T su ；
S204, the temperature of the hydrogen sample in the sample cavity (2) falls back to T again s After that, the standard container air inlet valve (21) is opened, the controller (13) opens the electromagnetic valve (14) to discharge the vaporized hydrogen into the standard container (20) which is at room temperature, and the pressure detected by the sample cavity pressure sensor (6) is defined by P u Reduced to P m Closing the electromagnetic valve (14) to complete the first-stage exhaust, and synchronously adjusting the power of the first electric heating component (3) through the controller (13) in the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor (7) is stabilized at T s The method comprises the steps of carrying out a first treatment on the surface of the The controller (13) then controls the voltage U applied to the second electric heating assembly (5) m And application time t m Applying a constant heating amount to the hydrogen sample in the sample chamber (2)The temperature of the hydrogen sample is slightly increased, and the heating quantity Q is measured by a sample cavity temperature sensor (7) m The temperature of the hydrogen sample after the application is T sm ；
S205, the temperature of the hydrogen sample in the sample cavity (2) falls back to T again s After that, the standard container air inlet valve (21) is opened, the controller (13) opens the electromagnetic valve (14) to discharge the vaporized hydrogen into the standard container (20) which is at room temperature, and the pressure detected by the sample cavity pressure sensor (6) is defined by P m Reduced to P d Closing the electromagnetic valve (14) to complete the second-stage exhaust, and synchronously adjusting the power of the first electric heating component (3) through the controller (13) in the exhaust process to ensure that the temperature measured by the sample cavity temperature sensor (7) is stabilized at T s The method comprises the steps of carrying out a first treatment on the surface of the The controller (13) then controls the voltage U applied to the second electric heating assembly (5) d And application time t d Applying a constant heating amount to the hydrogen sample in the sample chamber (2)The temperature of the hydrogen sample is slightly increased, and the heating quantity Q is measured by a sample cavity temperature sensor (7) d The temperature of the hydrogen sample after the application is T sd ；
S206, the temperature of the hydrogen sample in the sample cavity (2) falls back to T again s Then, an air inlet valve (21) of the standard container is opened, an electromagnetic valve (14) is opened by a controller (13) to gasify and discharge hydrogen into the standard container (20) which is at room temperature, the electromagnetic valve (14) is closed after the complete discharge to complete the third-stage discharge, and the power of the first electric heating component (3) is synchronously regulated by the controller (13) in the discharge process, so that the temperature measured by the temperature sensor (7) of the sample cavity is stabilized at T s ；
S207, respectively acquiring three groups of pressures P in the standard container (20) when the first-stage exhaust, the second-stage exhaust and the third-stage exhaust are completed according to real-time measurement results of the standard container pressure sensor (22) and the standard container temperature sensor (23) in the exhaust process g1 、P g2 、P g3 And temperature T g1 、T g2 、T g3 ；
S208, in the cavity (2) to be sampledAfter the hydrogen sample in the part is emptied, the second electric heating assembly (5) is controlled by the controller (13) to restart the sample cavity (2) from the T s Heated to T su From T s Heated to T sm From T s Heated to T sd Calculating the corresponding heating quantity Q according to the voltage and the application time applied to the second electric heating component (5) in the three groups of heating processes u0 、Q m0 、Q d0 And finally obtaining the specific heat coefficient C of the hydrogen sample at three target state points v1 、C v2 、C v3 ：
Wherein: m is m i For the total mass of hydrogen sample discharged into standard container in the ith stage and before stage,m c is the hydrogen mass in the stainless steel capillary (10) between the sample cavity (2) and the electromagnetic valve (14)>θ is the capillary mass correction coefficient, V c 、V g The calibration volumes of the stainless steel capillary tube (10) and the standard container (20) between the sample cavity (2) and the electromagnetic valve (14) are respectively; z is hydrogen compression factor at normal temperature and pressure; r represents a gas constant; m is M H Represents the molar mass of hydrogen.
CN202310987116.8A 2023-08-07 2023-08-07 Hydrogen specific heat measurement device and method Pending CN117110364A (en)

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