CN110346404A - A kind of measuring device that balances each other suitable for 80K-400K warm area - Google Patents

Abstract

The invention relates to a phase balance measuring device suitable for a temperature range of 80K-400K, comprising: a pressure chamber forming a thermal switch; the pressure chamber is located in a constant temperature chamber; a resonant cavity is arranged in the pressure chamber; The machine provides cooling capacity for the constant temperature liquid in the constant temperature chamber through the first heat exchanger connected to it; the first heater adjusts the temperature of the pressure chamber to realize a stable temperature environment of the resonant cavity in the 80K-400K temperature range. The invention adopts the weighing method to configure the gas to be measured, based on advanced microwave detection means, can accurately distinguish the gas liquefaction phase transition point, and obtain high-precision phase balance characteristics of pure substance and/or mixture; according to the thermal physical property parameters and microwave resonance frequency With specific mathematical relations, the phase balance measuring device can also be used for the measurement of multiple thermophysical parameters such as gas refraction, dielectric constant, density, and virial coefficient.

Description

A phase balance measuring device suitable for 80K-400K temperature range

technical field

The invention relates to a measuring device, in particular to a phase balance measuring device suitable for a temperature range of 80K-400K.

Background technique

Thermophysical properties such as fluid phase equilibrium are the basic properties of fluids, which can provide information for the development of equations of state such as cubic equations, virial equations, and Helmholtz equations, as well as fluid theories and methods such as molecular dynamics and quantum "ab initio calculation". Basic data and inspection standards; especially, accurate measurement of thermophysical properties such as phase equilibrium characteristics of substances in the 80K-400K temperature range is crucial to system design and unit optimization in the fields of low temperature, refrigeration, energy, chemical industry, etc., and is also a related industry standard foundation and key basis.

Usually, in the phase balance measurement device, the composition of the mixture is determined by the analysis of the gas chromatograph. The accuracy of the composition depends on the measurement repeatability and the measurement accuracy of the gas chromatograph. The uncertainty of the composition measurement is difficult to break through 0.001. However, based on the weighing method (currently the highest precision of the mixture ratio) to configure a certain proportion of the mixture, when using the synthetic method to measure, there is no need for a gas chromatograph to analyze the components, so the components have higher accuracy (uncertainty is usually lower than 0.001) , but it is difficult to accurately observe the initial formation of the dew point with the eyes through the viewing window; in addition, in the traditional thermal physical property measurement device, due to the different measurement methods of different thermal physical properties, it is difficult to integrate multiple measurement devices to achieve multiple measurements of the same device. High-precision measurement of thermophysical parameters. Therefore, new technical means are needed to detect the phase transition point of the mixture and correlate multiple thermophysical parameters with a certain physical parameter. The traditional phase balance and other thermophysical property measurement devices mostly use throttling refrigerators, and the design of the matching vacuum insulation structure is unreasonable, the structure is complex, the system load is heavy, and the heat leakage from the room temperature environment is increased; The use of mechanical stirrers has high noise, large fluid disturbance, poor temperature distribution uniformity, and poor temperature control accuracy; in addition, the inherent working temperature range limitations of the measurement methods used by different measurement devices lead to the actual temperature and physical property measurement devices such as phase balance. The effective working range is small.

To sum up, in order to achieve high-precision thermophysical properties (phase balance) measurement in the temperature range of 80K-400K, it is necessary to explore new measurement methods and find a parameter associated with multiple thermophysical parameters in order to realize multiple thermophysical properties of a device. Measurement of physical parameters; at the same time, actively develop and design compact and efficient adiabatic structures and temperature control algorithms to achieve 80K-400K continuously adjustable high-precision temperature control.

Contents of the invention

The purpose of the invention is to solve the problems of the traditional phase balance measuring device, such as small effective temperature range for measurement, poor temperature control accuracy at low temperature, low measurement accuracy of mixture components, single measurement physical properties and the like. The invention provides a phase balance measurement device suitable for the temperature range of 80K-400K based on advanced microwave detection technology, composite heat insulation structure and gas "thermal switch" structure design and efficient multi-point temperature control algorithm.

The invention provides a phase balance measurement device suitable for the temperature range of 80K-400K, comprising: a pressure chamber forming a thermal switch; the pressure chamber is located in a constant temperature chamber; a resonant cavity is arranged in the pressure chamber; the characteristic is that : The first refrigerator provides cooling capacity for the constant temperature liquid in the constant temperature chamber through the first heat exchanger connected to it; the first heater adjusts the temperature of the pressure chamber to achieve a stable temperature environment for the resonant cavity in the temperature range of 80K-400K .

Wherein, the pressure chamber and the resonance chamber maintain consistent or approximately equal pressures.

Wherein, the resonant cavity is a quasi-spherical structure.

Wherein, the resonant cavity is filled with a certain proportion of mixed gas or pure substance configured by weighing method.

Wherein, the cavity material of the resonant cavity is selected from metal materials such as high-conductivity oxygen-free copper or stainless steel; or non-metallic materials such as sapphire, plexiglass, tempered glass; materials; or a composite structure composed of metal materials, non-metal materials, and superconducting materials; the inner wall of the metal material resonator can also be plated with high-conductivity metal layers such as gold and silver.

Wherein, the constant temperature liquid in the constant temperature layer is selected from pure substances such as water, mineral oil, alkanes and their derivatives, olefins and their derivatives, alcohols and their derivatives, ethers and their derivatives, and mixtures of the above substances. .

Wherein, a jet mixer is used to stir the constant temperature liquid.

Among them, the device can measure multiple thermophysical properties such as pure substance or mixture phase equilibrium, density, dielectric coefficient, refractive index, density virial coefficient, and dielectric virial coefficient.

Wherein, the number of the first refrigerator is one or more than one group, and a throttling refrigerator using a single-stage compressor is used, and its refrigeration working medium is selected from pure substances such as alkanes and their derivatives, olefins and their derivatives, or a mixture of the above substances.

Wherein, the number of the first heat exchanger is one or more than one group, and the material is selected from metal materials with high conductivity such as high-conductivity oxygen-free copper or red copper. The heat exchange structure and heat exchange form of the heat exchanger.

The invention adopts the weighing method to configure the gas to be measured, based on advanced microwave detection means, can accurately distinguish the gas liquefaction phase transition point, and obtain high-precision phase balance characteristics of pure substances and/or mixtures; The mathematical relationship of the phase balance measurement device can also be used for the measurement of multiple thermophysical parameters such as gas refraction, dielectric constant, density, and virial coefficient; the jet stirring design can reduce noise and obtain a more uniform temperature field distribution. Reduce the disturbance of constant temperature liquid to physical property measurement; adopt high-efficiency heat insulation measures such as composite vacuum cover, multi-layer hollow radiation protection screen, hollow or hollow suspender, based on "thermal switch" rapid adjustment and advanced multi-point temperature control algorithm, can realize liquid Continuously adjustable high-precision temperature control from the nitrogen temperature zone to the medium and high temperature zone (80K-400K).

Description of drawings

Fig. 1 is a schematic diagram of a phase balance measurement device in the 80K-400K temperature zone of the present invention.

Detailed ways

In order to facilitate the understanding of the present invention, the embodiments of the present invention will be described below in conjunction with the accompanying drawings. Those skilled in the art should understand that the following description is only for the convenience of explaining the present invention, not as a specific limitation on its scope.

Fig. 1 is a schematic diagram of a phase balance measuring device suitable for a temperature range of 80K-400K according to the present invention. As shown in Figure 1, the phase balance measuring device of the present invention includes: a first molecular pump group 1, a first valve 2, a second valve 3, a cryogenic valve 4, a third valve 5, a pressure gauge 6, a vacuum cover 7, a Radiation screen 8, constant temperature liquid outlet 9, constant temperature chamber 10, constant temperature liquid 11, first refrigerator 12, first heat exchanger 13, pressure chamber 14, thermometer 15, microwave antenna 16, first heater 17, second molecule Pump group 18, fourth valve 19, resonance chamber 20, fifth valve 21, third molecular pump group 22, second heater 23, sixth valve 24, tee pipe 25, pressure reducing valve 26, jet agitator 27 , the second refrigerator 28, the second heat exchanger 29, the constant temperature liquid inlet 30, the constant temperature liquid return pipe 31, and the gas source 32. Wherein: the first refrigerating machine 12 provides stable cooling capacity for the resonant cavity 20 , and the second refrigerating machine 28 provides stable cooling capacity for the outermost thermostatic layer of the vacuum cover 7 .

As shown in Figure 1, the first refrigerator 12 is a throttling refrigerator, which provides cooling capacity for the constant temperature liquid 11 in the constant temperature chamber 10 through the first heat exchanger 13 connected thereto, and together with the first heater 17 Real-time adjustment of the temperature control system realizes a stable temperature environment of the resonant cavity in the temperature range of 80K-400K, and the first heater 17 heats the pressure chamber 14 to adjust the temperature of the resonant cavity. According to the actual needs of the system, multi-stage refrigerators and/or multi-stage first heat exchangers can be used. The number of the first refrigerating machine is one or a group of more, using a throttling refrigerating machine including but not limited to a single-stage compressor, and its refrigerating working medium includes but not limited to alkanes and their derivatives, olefins and their derivatives and other pure substances, and mixtures of the above-mentioned substances; the number of the first heat exchanger is one or a group of multiples, and the material is a metal material with high conductivity including but not limited to high-conductivity oxygen-free copper and red copper. Including but not limited to the heat exchange structure and heat exchange form of the sleeve heat exchanger. The liquid level of the constant temperature liquid 11 submerges the entire first heat exchanger 13, and the liquid level height can be monitored in real time by the liquid level device. When the liquid level of the constant temperature liquid 11 is lower than the top of the first heat exchanger 13, the constant temperature liquid is replenished in time to ensure Maintain a stable temperature environment. The constant temperature liquid 11 includes but not limited to pure substances such as mineral oil, alkanes and their derivatives, olefins and their derivatives, alcohols and their derivatives, ethers and their derivatives, and mixtures of the above substances. The constant temperature liquid 11 is stirred by the jet stirrer 27 , the noise is lower, and a more uniform temperature field can be obtained. The number of stirrers is not less than one, and the distribution positions include but are not limited to those shown in FIG. 1 . Other forms of agitators can also be used according to specific needs.

As shown in FIG. 1 , the second refrigerating machine 28 is a throttling type refrigerating machine, and provides cooling capacity for the constant temperature liquid in the outermost constant temperature layer of the vacuum cover 7 through the second heat exchanger 29 connected thereto. The vacuum cover 7 is a multi-layer composite structure, the outermost layer of which is a constant temperature layer, and at least one constant temperature liquid inlet 30 and a constant temperature liquid outlet 9 are distributed on the constant temperature layer of the vacuum cover 7, and the constant temperature liquid inlet 30 and the constant temperature liquid outlet are 9 is connected to the second heat exchanger 29 through a constant temperature liquid return pipe 31; the inside of the vacuum cover 7 includes at least one layer of vacuum layer, which not only maintains the stability of the external temperature, but also reduces the impact of room temperature fluctuations, and is more conducive to building A uniform and stable temperature environment also reduces the payload. The number of the second refrigerating machine is one or more than one group, and a throttling refrigerating machine including but not limited to a single-stage compressor is adopted, and its refrigerating working medium includes but not limited to alkanes and their derivatives, olefins and their derivatives and other pure substances, and mixtures of the above-mentioned substances; the number of the second heat exchanger is one or more than one group, and the material is a metal material with high conductivity including but not limited to high-conductivity oxygen-free copper and red copper. Including but not limited to the heat exchange structure and heat exchange form of the sleeve heat exchanger. The constant temperature liquid in the constant temperature layer includes but not limited to water, mineral oil, alkanes and their derivatives, olefins and their derivatives, alcohols and their derivatives, ethers and their derivatives, etc., and mixtures of the above substances . As a further modified embodiment, the vacuum cover 7 may not include a constant temperature layer, but at least one vacuum layer is included at this time. In this case, the second refrigerating machine 28, the second heat exchanger 29, and the constant temperature liquid inlet 30 can be omitted. Liquid outlet 9 and constant temperature liquid return pipe 31. The material of the vacuum cover can be 316 stainless steel, 304 stainless steel, aluminum alloy and other low-density and high-strength metal materials. The constant temperature liquid return pipe 31 needs to take appropriate insulation measures, preferably using a foaming agent for foaming insulation, and/or wrapping insulation cotton on it, so as to reduce heat leakage along the way and reduce cooling capacity consumption.

As shown in FIG. 1 , the second molecular pump group 18 is connected to the vacuum layer of the vacuum cover 7 through the fourth valve 19 to maintain a high vacuum degree of the vacuum layer and reduce convection and radiation heat transfer. The anti-radiation screen 8 adopts a single-layer or multi-layer (including two layers) hollow gold-plated structure, which can greatly reduce the radiation heat leakage of the system and reduce the system load. The vacuum cover 7, the radiation shield 8 and the outer surface of the thermostatic chamber 10 form a closed space together, and the closed space is connected to the first molecular pump group 1 through the valve 2. As a further preference, the second molecular pump group 18 and The first molecular pump unit 1 can be combined with a set of high-flow molecular pump unit to maintain a high vacuum degree in the space where the molecular pump unit 18 and the molecular pump unit 1 are connected.

As shown in Figure 1, the gas circuit system mainly includes: gas source 32, pressure reducing valve 26, sixth valve 24, third molecular pump unit 22, fifth valve 21, second valve 3, pressure chamber 14, three-way pipe 25. Cryogenic valve 4, resonant cavity 20, etc. The gas source 32 is a high-purity working fluid or a certain proportion of mixed gas configured according to the weighing method. The gas enters through the pressure reducing valve 26, the sixth valve 24, the second valve 3, the three-way pipe 25, and the low temperature valve 4. Pressure chamber 14 and resonance chamber 20 . A resonant cavity 20 is provided in the pressure cavity 14, and the resonant cavity 20 is connected to the pressure cavity 14 through a heat-insulating suspender. It has the advantages of simple structure, convenient installation and disassembly, and good heat insulation performance. By adopting the connection structure of the three-way pipe 25, the pressure chamber 14 and the resonance chamber 20 maintain the same or approximately equal pressure, which can effectively reduce the pressure deformation of the resonance chamber and simplify the correction of non-ideal factors.

The resonant cavity 20 adopts a quasi-spherical structure, and the cavity satisfies the equation x ² /R _x ² +y ² /R _y ² +z ² /R _z ² =1, and its longest radius in the three-axis directions of x, y, and z ( Denoted as R _max ) is 1-1.01 times of the shortest radius (denoted as R _min ), the second longest radius (denoted as R _mid ) is 1-1.01 times of the shortest radius R _min , and the shortest radius R _min can be 1cm-25cm Any value between; the resonant cavity 20 adopts metal materials including but not limited to high-conductivity oxygen-free copper, stainless steel, sapphire, plexiglass, tempered glass and other non-metallic materials; type material; the inner wall of the metal material resonator can also be plated with high conductivity metal layers such as gold and silver.

As shown in Figure 1, the pressure chamber 14 also acts as a "thermal switch". By adjusting the openings of the second valve 3, the fifth valve 21, the sixth valve 24, the low temperature valve 4, and the pressure reducing valve 26, different The on and off states of the "hot switch" are used to turn on and off. When the pressure chamber 14 is filled with gas, it is in the open state of the "thermal switch". At this time, the pressure chamber 14 and the resonance chamber 20 mainly rely on the convection of the internal working gas to achieve the purpose of heat exchange. If the temperature of the resonance chamber 20 reaches the target temperature, use The third molecular pump group 22 quickly pumps away the working medium inside the pressure chamber 20, that is, closes the "heat switch". Due to the good thermal insulation performance of the boom, the convective heat exchange and conduction heat exchange between the pressure chamber 14 and the resonance chamber 20 are eliminated. There is only a small amount of radiation heat exchange, and the temperature control system can timely adjust the heating capacity of the second heater 23 based on the readings of thermometers such as the thermometer 15 to achieve a stable temperature control effect. The working medium of the "thermal switch" is helium, neon, argon, nitrogen and other non-flammable gases, which can be freely selected according to different temperature ranges, and the working pressure covers 0-10MPa. Combined with the advanced multi-point temperature control algorithm, a continuously adjustable temperature control environment within 80K-400K can be realized through the opening and closing of the gas "heat switch".

In the embodiment shown in FIG. 1 , the microwave antenna 16 is used to transmit or receive microwave signals, and the microwave antenna is preferably a pair. Fill the resonant cavity 20 with a certain proportion of mixed gas or pure substance configured by weighing method (currently the method with the highest accuracy for determining the components of the mixed gas), and close the cryogenic valve after the pressure in the resonant cavity 20 is balanced with the pressure in the pressure chamber 14 4. After the temperature and pressure in the resonant cavity 20 are balanced, microwave signals are transmitted and received through the microwave antenna to obtain the resonant frequency in the current state; after that, the temperature of the resonant cavity is lowered to the next target temperature, and after the temperature and pressure are rebalanced, the resonant frequency is obtained by scanning Frequency measurement to obtain the resonant frequency in the new state; in this way, continuous cooling-equilibrium-sweeping measurement can detect the liquefaction of the gas by detecting the change of the resonant frequency with the temperature of the resonant cavity in real time, and determine the dew point temperature and dew point pressure of the mixed gas through cross calculation , so as to complete the phase equilibrium characteristic measurement of known components. It should be noted that, based on the device and the quantitative relationship between the resonant frequency and other physical properties, other thermal physical property parameters of pure substances and mixtures can also be determined.

The device uses the microwave resonance method. In addition to the high-precision measurement of the phase equilibrium characteristics of pure substances or mixtures, it can also be used for the measurement of other thermal physical properties. The measurement method is as follows: 1) The refractive index of the gas, by measuring The ratio of the resonant frequency in the vacuum and the pressurized state can obtain the gas refractive index in the pressurized state at this temperature; 2) complex permittivity, by measuring the resonant frequency and half width of the resonant cavity vacuum and pressurized state, it can be obtained by Mathematical relational formula to calculate its complex dielectric constant; 3) Based on the mathematical relationship between molar susceptibility and density and dielectric constant, combined with certain mixing rules, the density of the mixture under the component can be measured; 4) By measuring the same temperature and different pressure The gas density and/or dielectric constant under the condition can be extrapolated to the vacuum state to obtain the gas density virial coefficient and/or dielectric virial coefficient. Any appropriate modification based on this device for the measurement of other physical properties such as isothermal compressibility coefficient and specific heat still falls within the protection scope of the technical solution of the present invention.

The invention adopts the weighing method to configure the gas to be measured, based on advanced microwave detection means, can accurately distinguish the gas liquefaction phase transition point, and obtain high-precision phase balance characteristics of pure substances and/or mixtures; The mathematical relationship of the phase balance measurement device can also be used for the measurement of multiple thermophysical parameters such as gas refraction, dielectric constant, density, and virial coefficient; the jet stirring design can reduce noise and obtain a more uniform temperature field distribution. Reduce the disturbance of constant temperature liquid to physical property measurement; adopt high-efficiency heat insulation measures such as composite vacuum cover, multi-layer hollow radiation protection screen, hollow or hollow suspender, based on "thermal switch" rapid adjustment and advanced multi-point temperature control algorithm, can realize liquid Continuously adjustable high-precision temperature control from the nitrogen temperature zone to the medium and high temperature zone (80K-400K).

It can be understood that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or be modified to be equivalent to equivalent changes. Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. a kind of measuring device that balances each other suitable for 80K-400K warm area, comprising: form the pressure chamber of thermal switch；The pressure Chamber is located in thermostatic chamber；Resonant cavity is provided in the pressure chamber；It is attached thereto it is characterized by: first refrigeration machine passes through First Heat Exchanger provides cooling capacity for the constant temperature liquid in thermostatic chamber；The temperature of pressure chamber is adjusted in primary heater, realizes The stable temperature environment of resonant cavity between 80K-400K warm area.

2. balance each other measuring device as described in claim 1, it is characterised in that: pressure chamber resonant cavity is consistent or approximation Equal pressure.

3. balance each other measuring device as described in claim 1, it is characterised in that: the resonant cavity is torispherical structure.

4. balance each other measuring device as described in claim 1, it is characterised in that: the resonant cavity is filled with to use is matched with weight method The a certain proportion of mixed gas or pure matter set.

5. balance each other measuring device as described in claim 1, it is characterised in that: the cavity material of the resonant cavity is led selected from height Oxygen-free copper or stainless steel and other metal materials；Or the nonmetallic materials such as sapphire, organic glass, tempered glass；Or copper oxidation is closed The superconductors such as object, iron (nickel) base；Or the compound material being composed of metal material, nonmetallic materials, superconductor；Gold The inner wall for belonging to material resonances chamber can also plate that gold, silver are contour to lead metal layer.

6. balance each other measuring device as described in claim 1, it is characterised in that: the constant temperature liquid in thermostat layer is selected from water, mineral The pure matter such as oil, alkane hydrocarbons and their derivates, olefin and its derivatives, alcohols and its derivative, ethers and its derivative and above-mentioned The mixture of material composition.

7. balance each other measuring device as described in claim 1, it is characterised in that: stirred using jet stirrer constant temperature liquid It mixes.

8. balance each other measuring device as described in claim 1, it is characterised in that: described device can be equal to pure matter or mixture The measurement of multiple hot physical property such as weighing apparatus, density, dielectric coefficient, refractive index, density virial coefficient, dielectric virial coefficient.

9. balance each other measuring device as described in claim 1, it is characterised in that: the first refrigeration machine quantity is one or one Group is multiple, using the throttle-type refrigeration machine of single-stage compressor, refrigerant working fluid be selected from alkane hydrocarbons and their derivates, alkene and its The mixture of the pure matter such as derivative or above-mentioned substance composition.

10. balancing each other measuring device as described in claim 1, it is characterised in that: the First Heat Exchanger quantity be one or One group is multiple, material be selected from oxygen-free high conductivity type copper or red copper etc. with high-conductivity can metal material, using double pipe heat exchanger or The heat exchange structure and heat transfer form of wound tube heat exchanger.