Device and method for measuring the enthalpy of evaporation of a mixture of fluids

Abstract

The present application relates to the technical field of thermophysical property measurement, and provides a kind of mixed fluid evaporation enthalpy measuring device and method, device includes: calorimetric mechanism, with the measuring cell suitable for containing sample to be measured;Main pipeline, one end of main pipeline is communicated with measuring cell, and the other end of main pipeline extends to the side away from measuring cell;Injection pump, communicated with main pipeline, suitable for extracting vaporized sample to be measured;Chromatograph, suitable for analyzing the component of vaporized sample to be measured.The present application extracts vaporized sample from measuring cell using injection pump, so that the whole phase change process and its energy exchange occur within the thermodynamic boundary of calorimetric system, avoiding the system error of traditional injection condensation method;At the same time, by configuring chromatograph at vapor phase outlet, the extracted steam can be analyzed for component, combined with calorimetric data and steam composition at corresponding time, effectively suppress and quantify the component drift influence caused by rectification effect, to obtain high-precision evaporation enthalpy data.

Description

Technical Field

[0001] This invention relates to the field of thermophysical property measurement technology, and in particular to a device and method for measuring the enthalpy of vaporization of a mixed fluid. Background Technology

[0002] Enthalpy of vaporization (also known as vaporization enthalpy) is a key thermodynamic parameter describing the energy required for a substance to transform from a liquid phase to a vapor phase, and it plays an important role in chemical process design. Especially in the design and simulation of core units in liquefied natural gas (LNG) plants—such as main cryogenic heat exchangers, throttling flash evaporators, and cryogenic distillation columns—accurate enthalpy of vaporization data is the foundation for heat balance calculations, equipment selection, and process optimization.

[0003] However, accurately measuring enthalpy of vaporization faces significant challenges under the low-temperature and high-pressure conditions commonly encountered in LNG processes. Currently, there are two main types of methods: The first type is the injection condensation method: room temperature high-pressure gas is injected into a low-temperature calorimetric cell via an injection pump for condensation, and the enthalpy of vaporization is inferred by measuring the released heat. The main drawback of this method is that the compression work done by the pump on the gas during the injection process occurs outside the calorimetric system and cannot be captured by the heat flux sensor, resulting in a significantly lower measured heat and introducing a non-negligible systematic error. The second type is vaporization calorimetry: under controlled conditions, a trace amount of liquid is vaporized at low temperature and high pressure, and the heat absorbed is measured. Although this method avoids the problem of external work, it can lead to serious deviations in multi-component mixtures due to the "distillation effect"—the more volatile components preferentially vaporize, causing the composition of the remaining liquid to change continuously. If the composition of the vapor cannot be measured in real time at every moment, the obtained total enthalpy change corresponds to a system with unknown composition and dynamic drift, making it difficult to use for engineering calculations.

[0004] Therefore, there is an urgent need in the field for a method that can overcome the above-mentioned defects, especially the problems of pump work error and mixture component drift, and can accurately measure enthalpy of evaporation under low temperature and high pressure. Summary of the Invention

[0005] This invention provides a device and method for measuring the enthalpy of vaporization of a mixed fluid, thereby solving the technical problems of high difficulty and high error in obtaining the enthalpy of vaporization of a mixed fluid in the prior art.

[0006] This invention provides a device for measuring the enthalpy of vaporization of a mixed fluid, comprising: The calorimeter has a measuring cell suitable for holding the sample to be tested; A main pipeline, one end of which is connected to the measuring pool, and the other end of which extends away from the measuring pool; An injection pump, connected to the main pipeline, is adapted to extract the vaporized sample to be tested; A chromatograph suitable for analyzing the components of a vaporized sample to be tested.

[0007] According to the present invention, a measuring device for the enthalpy of vaporization of a mixed fluid is provided, wherein the calorimetric mechanism further includes: The calorimetric cell body comprises a reference cell and the measuring cell; A heating element is disposed in at least a portion of the reference pool and the measuring pool; The calorimetric pool includes an inner wall and an outer wall surrounding the outer side of the inner wall, with an interlayer space formed between the inner wall and the outer wall; The interlayer space is suitable for filling with a refrigerant.

[0008] According to the present invention, a measuring device for the enthalpy of vaporization of a mixed fluid is provided, wherein the calorimetric mechanism further includes: A heat sensor is located at the center of the calorimetric tank. The first temperature sensor is located at the center of the calorimetric cell. A second temperature sensor is disposed in the heating element.

[0009] The measuring device for the enthalpy of evaporation of a mixed fluid provided by the present invention further includes: A first refrigeration mechanism is connected to the interlayer space, and the two form a circulation loop for the refrigerant.

[0010] The measuring device for the enthalpy of evaporation of a mixed fluid provided by the present invention further includes: The second refrigeration mechanism is connected to the interlayer space and is adapted to output the refrigerant into the interlayer space.

[0011] The measuring device for the enthalpy of evaporation of a mixed fluid provided by the present invention further includes: A first vacuum pump is connected to the main pipeline; The second vacuum pump is connected to the interlayer space.

[0012] The measuring device for the enthalpy of evaporation of a mixed fluid provided by the present invention further includes: A mass flow meter is installed on the main pipeline; A pressure sensor is installed in the main pipeline; The mass flow meter and the pressure sensor are both located upstream of the injection pump.

[0013] The measuring device for the enthalpy of evaporation of a mixed fluid provided by the present invention further includes: The data acquisition mechanism is electrically connected to the calorimeter, the mass flow meter, the pressure sensor, and the chromatograph, respectively.

[0014] The present invention also provides a method for measuring the enthalpy of vaporization of a mixed fluid, using the above-mentioned measuring device for the enthalpy of vaporization of a mixed fluid, comprising at least the following steps: Sample loading: At least two samples to be tested are loaded into a measuring cell pre-cooled to a preset temperature; the temperature and pressure of the samples to be tested are detected, and the phase state and saturation point of the mixed fluid during phase transition are determined by combining phase equilibrium data; Controlled vaporization and heat flow measurement: The syringe pump performs a back-pull operation from the main pipeline at a preset volume rate, causing the pressure in the measuring cell to drop and induce the sample to be tested in the measuring cell to vaporize at a constant temperature; the calorimeter simultaneously measures the endothermic heat flow signal corresponding to the sample during the vaporization process. Repeat and calculate: Repeat the controlled vaporization and heat flow measurement steps until all the samples to be tested in the measurement cell have been vaporized; add up the endothermic peak areas measured in all the heat flow measurement steps to obtain the total enthalpy of vaporization; When the sample to be tested is set to be supercooled or superheated, after determining the saturation state, the supercooled heat or superheated heat is subtracted to ensure that the phase change heat is the heat change from saturated liquid phase to saturated gas phase.

[0015] The method for measuring the enthalpy of evaporation of a mixed fluid according to the present invention further includes: After completing one of the controlled vaporization and heat flow measurement steps, immediately close the valve connected to the measurement cell to isolate the vaporized gaseous sample in the main pipeline and the syringe pump. Open the valve of the syringe pump and inject all the gaseous sample in the syringe pump into the sample vial; Remove the sample vial and analyze the molar composition of the sample using chromatography or other methods; Repeat the above steps to obtain a series of sample component data that correspond one-to-one with the endothermic heat flux peaks.

[0016] The above-mentioned technical solutions provided by this invention have at least the following beneficial technical effects: By integrating the calorimetric mechanism, main pipeline, syringe pump, and chromatograph system, the key problems existing in the prior art for measuring the enthalpy of vaporization of mixed working fluids under low temperature and high pressure conditions are effectively solved. This device uses a syringe pump to extract the vaporized sample from the measuring cell, ensuring that the entire phase change process and its energy exchange occur within the thermodynamic boundary of the calorimetric system. This fundamentally avoids the systematic errors caused by the failure of the external compression work to be captured by the calorimetric system in the traditional injection condensation method. Simultaneously, by configuring a chromatograph at the vapor phase outlet, real-time or near-real-time component analysis of the extracted vapor can be performed. By combining the calorimetric data with the vapor composition at the corresponding time, the enthalpy change and specific physical properties are accurately correlated, effectively suppressing and quantifying the component drift effect caused by the distillation effect, and obtaining high-precision enthalpy of vaporization data with clear thermodynamic definitions that can be used for engineering simulation. This device has a reasonable structure and stable operation, and is particularly suitable for determining the enthalpy of vaporization of multi-component low-temperature mixed systems under real process conditions. It provides reliable data support for the design and process optimization of related core equipment, demonstrating significant technological progress and good industrial application value. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the device for measuring the enthalpy of evaporation of a mixed fluid provided in an embodiment of the present invention.

[0019] Figure label: 1. Calorimetric mechanism; 11. Measuring cell; 12. Reference cell; 13. Heating unit; 14. Interlayer space; 15. Heat sensor; 16. First temperature sensor; 17. Second temperature sensor; 2. Main pipeline; 3. Injection pump; 4. Chromatograph; 51. First refrigeration mechanism; 52. Second refrigeration mechanism; 6. First vacuum pump; 7. Second vacuum pump; 8. Mass flow meter; 9. Pressure sensor; 10. Data acquisition mechanism. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] The following is combined Figure 1 This invention describes an apparatus and method for measuring the enthalpy of vaporization of a mixed fluid according to embodiments of the present invention.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a measuring device for the enthalpy of vaporization of a mixed fluid, comprising: a calorimetric mechanism 1 having a measuring cell 11 suitable for holding a sample to be tested; a main pipeline 2 having one end connected to the measuring cell 11 and the other end extending away from the measuring cell 11; an injection pump 3 connected to the main pipeline 2 and suitable for extracting vaporized sample to be tested; and a chromatograph 4 suitable for analyzing the components of the vaporized sample to be tested.

[0023] It should be understood that the embodiments of the present invention effectively solve the key problems existing in the measurement of the enthalpy of vaporization of mixed working fluids under low temperature and high pressure conditions by integrating the calorimetric mechanism 1, the main pipeline 2, the syringe pump 3, and the chromatograph 4. The device uses the syringe pump 3 to extract the vaporized sample from the measuring cell 11, ensuring that the entire phase change process and its energy exchange occur within the thermodynamic boundary of the calorimetric system. This fundamentally avoids the systematic errors caused by the failure of the external compression work to be captured by the calorimetric system in the traditional injection condensation method. Simultaneously, by configuring the chromatograph 4 at the vapor phase outlet, real-time or near-real-time component analysis of the extracted vapor can be performed. By combining the calorimetric data with the vapor composition at the corresponding time, the enthalpy change and specific physical properties can be accurately correlated, effectively suppressing and quantifying the component drift effect caused by the "distillation effect," and obtaining high-precision enthalpy of vaporization data with clear thermodynamic definitions that can be used for engineering simulation. The device has a reasonable structure and stable operation, and is particularly suitable for the determination of the enthalpy of vaporization of multi-component low-temperature mixed systems under real process conditions. It provides reliable data support for the design and process optimization of related core equipment, demonstrating significant technological advancement and good industrial application value.

[0024] In some possible implementations, the calorimetric mechanism 1 can be a differential scanning calorimeter; the syringe pump 3 is a high-precision micro-syringe pump or a diaphragm metering pump, with its inlet connected to the main pipeline 2 and its outlet connected to the collection container. During the measurement process, the syringe pump 3 extracts the vaporized sample from the measuring cell 11 at a controllable low flow rate, allowing the liquid phase to continuously and steadily vaporize under constant pressure. Since the vaporization process occurs entirely within the measuring cell 11, and the extraction action only removes the vapor phase products without performing additional compression work on the system, the heat absorption recorded by the calorimetric mechanism 1 is the true enthalpy change corresponding to the vaporization process, effectively avoiding the systematic error caused by the failure to account for external work in the traditional injection method.

[0025] In some possible implementations, the sample to be tested is stored in a sample material tank, including at least two types of sample material tanks, with at least one of each type, and the pressure of the different types of sample material tanks is different; the sample material tank is connected to the main pipeline 2 and is controlled by valves V2 and V3 to transport the sample to the measuring cell 11.

[0026] like Figure 1 As shown, according to an embodiment of the present invention, a measuring device for the enthalpy of vaporization of a mixed fluid is provided. The calorimetric mechanism 1 further includes: a calorimetric cell body forming a reference cell 12 and a measuring cell 11; a heating part 13 surrounding at least a portion of the reference cell 12 and the measuring cell 11; the calorimetric cell body includes an inner wall and an outer wall surrounding the outer side of the inner wall, and an interlayer space 14 is formed between the inner wall and the outer wall; wherein the interlayer space 14 is adapted to be filled with a refrigerant.

[0027] In some possible implementations, the calorimetric cell has a dual-cell structure, internally forming a mutually isolated but thermally symmetrical reference cell 12 and a measuring cell 11. The measuring cell 11 is used to hold the mixed fluid sample to be tested, while the reference cell 12 is either empty or filled with an inert medium (such as high-purity nitrogen or vacuum) and serves as a reference for heat flux measurement. By employing differential calorimetry, the system can effectively counteract environmental disturbances and background thermal drift, significantly improving the resolution of minute phase change thermal signals.

[0028] The heating element 13 is typically composed of a thin-film heater or resistance wire with high response speed and low thermal inertia, and each is independently temperature controlled.

[0029] Furthermore, the interlayer space 14 of the calorimeter tank is used to fill refrigerants (such as ethanol or ethylene glycol) or liquid nitrogen. The entire calorimeter tank can be precisely controlled at any set point within the range of -196°C to room temperature through a programmed temperature control system, meeting the testing requirements of LNG and related cryogenic mixed working fluids under real process conditions.

[0030] In addition, the inner and outer walls of the calorimeter pool are made of materials with low thermal conductivity, high mechanical strength and good low-temperature toughness (such as stainless steel or titanium alloy), and thermal insulation support structures are set at key interfaces to minimize radial heat leakage and ensure the sealing reliability of the structure under high pressure differential.

[0031] like Figure 1 As shown, according to an embodiment of the present invention, a measuring device for the enthalpy of vaporization of a mixed fluid is provided. The calorimetric mechanism 1 further includes: a heat sensor 15 disposed at the center of the calorimetric pool; a first temperature sensor 16 disposed at the center of the calorimetric pool; and a second temperature sensor 17 disposed at the heating part 13.

[0032] It should be understood that the heat sensor 15 is located in the geometric center region of the calorimetric cell, preferably on the plane of symmetry between the measuring cell 11 and the reference cell 12, or integrated into the heat flow sensing element at the bottom of the cell. This heat sensor 15 can be a high-sensitivity thermopile, a thin-film heat flow meter, or a differential heat flow sensor based on a microelectromechanical system (MEMS), used to detect in real time the heat flow change in the measuring cell 11 caused by sample vaporization, and output an electrical signal proportional to the phase change enthalpy. Simultaneously, a first temperature sensor 16 is located at the center of the calorimetric cell to accurately monitor the real-time temperature of the medium inside the measuring cell 11. A second temperature sensor 17 is located on the heating element 13 to monitor the temperature state of the surface of the heating element or its adjacent area. Its function is to provide feedback on the operating temperature of the heating element 13, cooperating with the control system to achieve closed-loop regulation of the heating power, thereby maintaining thermal balance between the measuring cell 11 and the reference cell 12 or operating according to a preset temperature control program. Through the coordinated configuration of the above-mentioned multi-point temperature measurement and heat flow sensing, the system can accurately identify the start and end times of vaporization, correct errors introduced by the heat capacity of the pool, thermal hysteresis and environmental disturbances, and combine the extraction rate of the injection pump 3 and the component analysis results of the chromatograph 4 to realize the dynamic correlation calculation of instantaneous enthalpy of vaporization and corresponding vapor phase composition.

[0033] like Figure 1 As shown, a measuring device for the enthalpy of evaporation of a mixed fluid provided according to an embodiment of the present invention further includes: a first refrigeration mechanism 51, which is connected to the interlayer space 14, and a circulation loop of the refrigerant is formed between the two.

[0034] In some possible implementations, the first refrigeration mechanism 51 may employ a vapor compression refrigeration device. This device includes a compressor, a condenser, a throttling device, and an evaporator connected in sequence, forming a standard vapor compression refrigeration cycle. In this device, cooling of the calorimetric unit 1 is achieved by delivering cooling energy to the refrigerant bath medium through a vapor compression refrigeration device. This method is highly efficient and convenient when the required refrigeration temperature is not high.

[0035] like Figure 1As shown, a measuring device for the enthalpy of evaporation of a mixed fluid provided according to an embodiment of the present invention further includes: a second refrigeration mechanism 52, which is connected to the interlayer space 14 and is adapted to output a refrigerant into the interlayer space 14.

[0036] In some possible implementations, the second refrigeration unit 52 may employ a liquid nitrogen supply device. This device typically includes a liquid nitrogen storage tank, a pressurization system, a flow control valve, and cryogenic delivery pipelines, capable of injecting liquid nitrogen into the interlayer space 14 as needed. In actual operation, liquid nitrogen can be directly used as a refrigerant to fill the interlayer space 14, achieving rapid cooling of the calorimeter pool and maintenance of extremely low temperatures through its high latent heat of vaporization.

[0037] like Figure 1 As shown, a measuring device for the enthalpy of evaporation of a mixed fluid provided according to an embodiment of the present invention further includes: a first vacuum pump 6, connected to the main pipeline 2; and a second vacuum pump 7, connected to the interlayer space 14.

[0038] It should be understood that the first vacuum pump 6 is connected to the main pipeline 2 and is mainly used to perform high-vacuum pretreatment on the main pipeline 2 and the vapor phase passage connected to it before the experiment. By removing residual air, moisture or other impurities in the pipeline, contamination of the vapor phase sample by non-target components can be effectively avoided, ensuring the accuracy of chromatographic analysis results. At the same time, eliminating background gases in the dead volume of the pipeline also helps to prevent them from condensing at low temperatures, causing changes in flow resistance or interference from component adsorption / desorption, thereby ensuring the compositional fidelity and flow stability of the vaporized sample during transport.

[0039] The second vacuum pump 7 is connected to the interlayer space 14 and is used to evacuate the interlayer space 14 before the refrigerant is injected or during equipment maintenance. When using cryogenic liquids such as liquid nitrogen as the refrigerant, pre-evacuating the air and water vapor in the interlayer can prevent them from freezing at low temperatures, blocking the flow channels, or forming a thermal resistance layer, thus affecting the heat transfer efficiency.

[0040] like Figure 1 As shown, a measuring device for the enthalpy of evaporation of a mixed fluid provided according to an embodiment of the present invention further includes: a mass flow meter 8, disposed on the main pipeline 2; and a pressure sensor 9, disposed on the main pipeline 2; wherein the mass flow meter 8 and the pressure sensor 9 are both located upstream of the injection pump 3.

[0041] It should be understood that the mass flow meter 8 is preferably a mass flow meter suitable for low temperature and low pressure conditions, capable of directly and continuously measuring the mass flow rate of the mixed steam vaporized and flowing out from the measuring cell 11, unaffected by changes in composition, temperature fluctuations, or pressure fluctuations. By obtaining the mass of sample vaporized per unit time, the total heat absorption measured by the calorimeter 1 can be accurately normalized to the enthalpy of vaporization per unit mass, significantly improving the quantitative accuracy of thermodynamic data.

[0042] Simultaneously, a pressure sensor 9 is installed near the mass flow meter 8 to monitor the absolute pressure of the vapor phase before entering the syringe pump 3 in real time. Since the enthalpy of vaporization is a function of temperature and pressure, accurately determining the system pressure at the time of vaporization is crucial for subsequent thermodynamic state correlation and property model verification. Furthermore, this pressure signal can also serve as a feedback variable to adjust the pumping rate of the syringe pump 3, maintaining a constant pressure within the measuring cell 11, thereby enabling the determination of the enthalpy of vaporization under isobaric vaporization conditions.

[0043] In addition, the mass flow meter 8 and the pressure sensor 9 are both arranged upstream of the injection pump 3. On the one hand, this can avoid interference from the measurement signal caused by the pulsating flow or local pressure disturbance that may be generated during the operation of the injection pump 3. On the other hand, it ensures that the measured flow and pressure truly reflect the state of the vapor phase at the outlet of the measuring cell 11, rather than the non-equilibrium state after the pump has done work, thereby ensuring the thermodynamic consistency of the data.

[0044] like Figure 1 As shown, a device for measuring the enthalpy of evaporation of a mixed fluid according to an embodiment of the present invention further includes: a data acquisition mechanism 10, which is electrically connected to a calorimeter 1, a mass flow meter 8, a pressure sensor 9 and a chromatograph 4, respectively.

[0045] It should be understood that the data acquisition mechanism 10 is used to synchronously acquire and process multi-source signals during the experiment. This data acquisition mechanism 10 typically includes a multi-channel data acquisition module and a control computer, capable of acquiring in real time the heat flow and temperature signals output by the calorimeter 1, the vapor mass flow rate measured by the mass flow meter 8, the system pressure recorded by the pressure sensor 9, and the vapor phase composition data provided by the chromatograph 4. All signals are time-aligned through hardware synchronization or high-precision timestamps to ensure that the heat, mass, pressure, and composition information correspond strictly in a thermodynamic sense. Using this synchronized dataset, the enthalpy of vaporization corresponding to a specific vapor phase composition and operating conditions (temperature, pressure) can be accurately calculated. Simultaneously, the data acquisition mechanism 10 can also be used for closed-loop control, such as adjusting the flow rate of the syringe pump 3 or the heating power based on pressure or temperature feedback to maintain stable isothermal or isobaric vaporization conditions.

[0046] This invention also provides a method for measuring the enthalpy of vaporization of a mixed fluid, using the aforementioned measuring device for the enthalpy of vaporization of a mixed fluid, comprising at least the following steps: Sample loading: At least two samples to be tested are loaded into the measuring cell 11, which has been pre-cooled to a preset temperature; the sample can be connected to the main pipeline 2, and the low-pressure sample is loaded into the measuring cell 11 first through the valve, and then the high-pressure sample is loaded into the measuring cell 11; the measuring cell 11 has been stabilized at the preset temperature by the first refrigeration mechanism 51 and / or the second refrigeration mechanism 52 before loading, and is in a sealed state to avoid environmental moisture or air pollution.

[0047] Controlled vaporization and heat flow measurement: Valve V4 of syringe pump 3 is opened, and syringe pump 3 performs a back-pull operation from main pipeline 2 at a preset volume rate, causing the pressure in measuring cell 11 to drop and induce the sample to be tested in measuring cell 11 to vaporize at a constant temperature; calorimeter 1 simultaneously measures the endothermic heat flow signal corresponding to the sample to be tested during the vaporization process; during this process, calorimeter 1 monitors and records the heat flow signal generated by the endothermic phase change in real time; at the same time, mass flow meter 8 and pressure sensor 9 located upstream of syringe pump 3 simultaneously collect the mass flow rate of the vapor phase and the system pressure, and chromatograph 4 performs periodic or continuous component analysis on the extracted vapor, or a balance can be used to weigh the extracted sample.

[0048] Repeat and Calculation: Repeat the controlled vaporization and heat flow measurement steps until all samples in the measurement cell 11 have vaporized. Sum the endothermic peak areas measured in all heat flow measurement steps to obtain the total enthalpy of vaporization. That is, each vaporization stage corresponds to a distinguishable endothermic peak, the peak area of ​​which is proportional to the heat absorbed in that stage. After all samples have vaporized, integrate and sum the endothermic peak areas measured in each stage to obtain the total heat absorbed by the sample from the initial liquid state to the gaseous state. Combined with the total mass of the sample, the total enthalpy of vaporization of the mixed fluid at the specified temperature and average pressure can be calculated.

[0049] A method for measuring the enthalpy of evaporation of a mixed fluid according to an embodiment of the present invention further includes: (a) Before the formal measurement, test and calibrate the heating power signal and the fluid enthalpy change signal to ensure that the heat loss of the heating amount is within the acceptable range of the experiment; detect the temperature and pressure of the mixed fluid in the sample cell by the first temperature sensor 16 and the pressure sensor 9, and determine the phase state and saturation point when the mixed fluid undergoes phase change by combining the phase equilibrium data; when the fluid is set to be supercooled or superheated, after determining the saturation state by the first temperature sensor 16 and the pressure sensor 9 and combining the phase equilibrium data, subtract the supercooled heat or superheated heat to ensure that the phase change heat is the heat change from saturated liquid phase to saturated gas phase; (b) After completing one controlled vaporization and heat flow measurement step, immediately close the valve (V1) connected to the measuring cell 11 to isolate the vaporized gaseous sample in the main pipeline 2 and the injection pump 3, so as to completely isolate it from the remaining liquid phase in the measuring cell 11 and prevent the components from backmixing or continuing phase change. (c) Open the valve of the syringe pump 3 and inject all the gaseous sample in the syringe pump 3 into the sample bottle. The sample bottle is pre-vacuumed or filled with inert gas for protection, and has good airtightness and low temperature compatibility to ensure that the sample components are stable and leak-free during storage and transportation. (d) Remove the sample vial and analyze the molar composition of the sample using a chromatograph or similar method; Repeat steps (b)-(d) above to obtain a series of sample component data corresponding one-to-one with the endothermic heat flow peaks; repeat the above steps in each micro-step vaporization cycle to obtain a series of vapor phase component data with a clear time / process sequence corresponding one-to-one with each endothermic heat flow peak recorded by calorimeter 1.

[0050] In summary, this equipment can perform calorimetry under both isochoric and isobaric conditions. By correlating the integrated heat of each endothermic peak with the composition of the vapor phase captured concurrently, the local enthalpy of vaporization corresponding to a specific vapor phase composition can be calculated, thereby reconstructing the functional relationship between the enthalpy of vaporization and composition evolution throughout the unsteady vaporization process. This strategy effectively overcomes the compositional drift problem caused by the "distillation effect" in mixed fluids, giving the measured thermodynamic data clear physical property definitions, which can be directly used for multi-component phase equilibrium model correction, process simulation, and equipment design.

[0051] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the enthalpy of vaporization of a mixed fluid, characterized in that, include: The calorimeter (1) has a measuring cell (11) suitable for holding the sample to be tested. Main pipeline (2), one end of which is connected to the measuring pool (11), and the other end of which extends away from the measuring pool (11); The syringe pump (3) is connected to the main pipeline (2) and is suitable for extracting the vaporized sample to be tested; A chromatograph (4) is suitable for analyzing the components of the vaporized sample to be tested.

2. The measuring device for the enthalpy of evaporation of a mixed fluid according to claim 1, characterized in that, The calorimetric mechanism (1) further includes: The calorimetric cell body has a reference cell (12) and the measuring cell (11). A heating element (13) is disposed in at least a portion of the reference pool (12) and the measuring pool (11); The calorimetric pool includes an inner wall and an outer wall surrounding the outer side of the inner wall, and an interlayer space (14) is formed between the inner wall and the outer wall. The interlayer space (14) is suitable for filling with refrigerant.

3. The measuring device for the enthalpy of evaporation of a mixed fluid according to claim 2, characterized in that, The calorimetric mechanism (1) further includes: A heat sensor (15) is disposed at the center of the calorimetric pool body; The first temperature sensor (16) is located at the center of the calorimetric cell. A second temperature sensor (17) is disposed on the heating part (13).

4. The measuring device for the enthalpy of evaporation of a mixed fluid according to claim 2, characterized in that, Also includes: The first refrigeration mechanism (51) is connected to the interlayer space (14), and the two form a circulation loop for the refrigerant.

5. The measuring device for the enthalpy of evaporation of a mixed fluid according to claim 2, characterized in that, Also includes: The second refrigeration mechanism (52) is connected to the interlayer space (14) and is adapted to output the refrigerant into the interlayer space (14).

6. The measuring device for the enthalpy of evaporation of a mixed fluid according to claim 2, characterized in that, Also includes: The first vacuum pump (6) is connected to the main pipeline (2); The second vacuum pump (7) is connected to the interlayer space (14).

7. The measuring device for the enthalpy of vaporization of a mixed fluid according to any one of claims 1-6, characterized in that, Also includes: Mass flow meter (8) is installed on the main pipeline (2); Pressure sensor (9) is installed on the main pipeline (2); The mass flow meter (8) and the pressure sensor (9) are both located upstream of the injection pump (3).

8. The measuring device for the enthalpy of vaporization of a mixed fluid according to claim 7, characterized in that, Also includes: The data acquisition mechanism (10) is electrically connected to the calorimeter (1), the mass flow meter (8), the pressure sensor (9) and the chromatograph (4), respectively.

9. A method for measuring the enthalpy of vaporization of a mixed fluid, characterized in that, The measuring device for the enthalpy of evaporation of a mixed fluid as described in any one of claims 1-8 is characterized by comprising at least the following steps: Sample loading: At least two samples to be tested are loaded into a measuring cell (11) pre-cooled to a preset temperature; the temperature and pressure of the samples to be tested are detected, and the phase state and saturation point of the mixed fluid during phase change are determined by combining phase equilibrium data; Controlled vaporization and heat flow measurement: The injection pump (3) performs a back-pull operation from the main pipeline (2) at a preset volume rate to reduce the pressure in the measuring cell (11) to induce the sample to be tested in the measuring cell (11) to vaporize; the calorimeter (1) simultaneously measures the endothermic heat flow signal corresponding to the sample to be tested during the vaporization process. Repeat and calculate: Repeat the steps of controlled vaporization and heat flow measurement until all the samples to be tested in the measuring cell (11) have been vaporized; add up the endothermic peak areas measured in all the heat flow measurement steps to obtain the total enthalpy of vaporization; When the sample to be tested is set to be supercooled or superheated, after determining the saturation state, the supercooled heat or superheated heat is subtracted to ensure that the phase change heat is the heat change from saturated liquid phase to saturated gas phase.

10. The method for measuring the enthalpy of evaporation of a mixed fluid according to claim 9, characterized in that, Also includes: After completing one controlled vaporization and heat flow measurement step, immediately close the valve connecting the measurement cell (11) to isolate the vaporized gaseous sample in the main pipeline (2) and the injection pump (3); Open the valve of the syringe pump (3) and inject all the gaseous sample in the syringe pump (3) into the sample bottle; Remove the sample vial and analyze the molar composition of the sample using a chromatograph (4) and other methods; Repeat the above steps to obtain a series of sample component data that correspond one-to-one with the endothermic heat flux peaks.

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