A method and device for measuring and drawing phase diagram of hydrocarbon fuel

Abstract

The application discloses a method for measuring boiling point and pseudo-critical parameter of hydrocarbon fuel and drawing phase diagram, which comprises the following steps: delivering target substance to a calorimeter and heating to a target temperature; monitoring related parameters in real time; obtaining the boiling point of the target substance based on heat transfer characteristics in the fluid phase change process according to the real-time monitored parameters; obtaining the function of the heat sink of the target substance changing with temperature based on the energy transfer model between the calorimeter and the fuel; after the calorimeter is cooled to room temperature, adjusting the pressure, and continuing to perform the above steps to obtain the boiling point of the target substance and the function of the heat sink of the target substance changing with temperature under different pressures; obtaining the pseudo-critical parameter of the target substance and drawing the P-T phase diagram of the target substance based on the pseudo-critical parameter measurement method. The application further discloses a device for measuring boiling point and pseudo-critical parameter of hydrocarbon fuel and drawing phase diagram. The method and the device can realize accurate measurement of the boiling point and the pseudo-critical parameter and accurate drawing of the phase diagram.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermodynamics, calorimetry and supercritical fluid of hydrocarbon fuel, and particularly relates to a method and device for measuring boiling point and pseudo-critical parameters of hydrocarbon fuel and drawing phase diagram. BACKGROUND

[0002] Active cooling technology is a commonly used cooling method in the cooling system of hypersonic vehicles. Endothermic hydrocarbon fuel, which has the dual functions of cooling and propulsion, is the main cooling working medium of the active cooling thermal protection system. In the cooling channel of the vehicle, the hydrocarbon fuel is in a supercritical state at high temperature and high pressure, and its flow heat exchange, cracking and combustion processes have significant particularity and complexity. To essentially study the flow heat exchange law, cracking mechanism and combustion mechanism of the hydrocarbon fuel, it is necessary to obtain its thermophysical parameters under different pressures, temperatures and components. Since the thermophysical parameters of the hydrocarbon fuel near the critical temperature will change dramatically, it is necessary to accurately determine the critical parameters. The derived fuel phase diagram further reflects the relationship between the composition of the phase equilibrium system and the temperature and pressure, effectively verifies the internal consistency between the thermochemical data and the phase diagram data, and has important significance for the study of hydrocarbon fuel.

[0003] Currently, experimental measurement combined with model calculation is the main method to obtain the critical parameters of fluids. Common experimental methods include constant volume method, variable volume method, flow method, pulse heating method, density straight line diameter law method, and quasi-static thermal analysis method, etc. Eugene D. et al. used the pulse heating method to measure the critical pressure and critical temperature of thermally unstable compounds, and gave the critical temperature and pressure of diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol and hexaethylene glycol, respectively. (Eugene D. Nikitin, Alexander P. Popov. Critical temperatures and pressures of ethylene glycols [J]. Fluid Phase Equilibria, 2018, 472, 56-61.) Although the pulse heating method has the advantages of simplicity, reliability and high experimental efficiency, the determination of the critical point still needs to rely on subjective judgment, and the uniform mixing and flow of the fluid to be measured must be ensured during the measurement process. Yiran Wang et al. used the flow method to measure the critical temperature and critical pressure of isopropanol, isobutanol and gasoline component mixtures, and the results showed that isopropanol and isobutanol significantly improved the critical temperature and critical pressure of gasoline, and were verified by the Redlich-Kister equation. (Yiran Wang, Tian Lan, Raza Ali. Maogang He, Measurement of the critical temperature and critical pressure of isopropanol and isobutanol blended with gasoline components [J]. The Journal of Supercritical Fluids, 2022, 182, 8435-8446.) However, the flow method for measuring critical parameters still has the problem that the data in the near-critical region are greatly affected by subjective observation, and the fitting accuracy of the subsequent fitting equation is relatively low. Zhirong Chen et al. used the critical opalescence in a fused silica capillary to determine the critical temperature, and measured the critical pressure by heating the acetone-water solution to its critical temperature in an autoclave. In addition, they studied the P-V-T-X relationship of acetone-water solution by combining Peng-Robinson and Soave-Redlich-Kwong state equations.(Zhirong Chen, Yang Yao, Shenfeng Yuan. Measurement of Critical Temperatures, Critical Pressures and Densities of Acetone-Water Solutions for Simulation [J]. Journal of Solution Chemistry, 2023, 52, 1331-1351.) Critical opalescence is a light scattering phenomenon that occurs when a light beam is shone on a fluid near the critical point, which strongly scatters the light beam. This method still relies on subjective judgment to determine the critical point, and the P-V-T-X relationship requires a large amount of fitting data, resulting in low fitting efficiency. Rao Huoyu developed QSPR models for calculating the critical temperature and pressure of cycloalkanes based on quantitative structure-property relationship. Among them, the multiple linear regression (MLR) coefficients of QSPR-Tc and QSPR-Pc models reached 0.9984 and 0.9979, respectively, and the standard deviations of the two models were 3.40 K and 0.496 bar, respectively (Huoyu Rao, Zhiqiang Zhu, Zhanggao Le. QSPR Models for the Critical Temperature and Pressure of Cycloalkanes [J]. Chemical Physics Letters, 2022, 808, 1400-1421.). However, the experimental value uncertainty of such models is closely related to the number of carbon atoms in cycloalkanes, and fewer carbon atoms in cycloalkanes may lead to abnormal prediction results. Maogang He et al. used a fast estimation method to establish a prediction model for the critical temperature and critical pressure of multi-component mixtures based on the Chueh-Prausnitz equation, which requires the establishment of binary interaction coefficients τ to describe the non-ideal contribution of binary mixtures in advance. ij and k ij (Maogang He, Yang Liu, Xiangyang Liu. Prediction of critical temperature and critical pressure of multi-component mixtures [J]. Fluid Phase Equilibria, 2017, 441, 2-8.). This method requires a large number of empirical or semi-empirical correlations, but due to the type of mixture and the small amount of data, it results in low accuracy when calculating other unknown mixtures.

[0004] In summary, the existing experimental measurement method is significantly affected by subjective observation in the near critical region, and the existing calculation model faces the problems of numerous fitting data requirements and low data fitting accuracy and efficiency. SUMMARY

[0005] The present application aims to provide a method and device for measuring the boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams.

[0006] The present application provides the following technical solutions:

[0007] A method for measuring the boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams, the method comprising:

[0008] (1) delivering the target substance to the calorimeter and heating it to the target temperature;

[0009] (2) monitoring the temperature of the target substance at the inlet and outlet of the calorimeter, the temperature distribution of the calorimeter wall, the system pressure at both ends of the calorimeter, the current and voltage applied to both ends of the calorimeter, and the resistance of the calorimeter itself in real time;

[0010] (3) based on the heat transfer characteristics in the fluid phase change process, obtaining the boiling point of the target substance according to the parameters monitored in real time in step (2); at the same time, based on the energy transfer model between the calorimeter and the fuel, obtaining the function of the heat sink of the target substance with temperature change online;

[0011] (4) after the calorimeter is cooled to room temperature, adjusting the pressure, and continuing to perform the above steps (1) to (3) to obtain the boiling point of the target substance and the function of the heat sink of the target substance with temperature change under different pressures;

[0012] (5) based on the pseudo-critical parameter measurement method, obtaining the pseudo-critical parameters of the target substance: pseudo-critical temperature and pseudo-critical pressure, and drawing the P-T phase diagram thereof.

[0013] To avoid the problems of the existing experimental measurement method being significantly affected by subjective observation in the near critical region, and the existing calculation model facing numerous fitting data requirements and low data fitting accuracy and efficiency, the present application provides the above method. The technical concept of the present application is that the present application establishes the function relationship between temperature and enthalpy of hydrocarbon fuels under different pressures based on the calorimeter model; the present application establishes accurate boiling point and pseudo-critical temperature criteria based on the development trend of the heat sink of the fuel with temperature change; the present application determines the pseudo-critical pressure by fitting the intersection of the pseudo-critical temperature straight line and the boiling point curve of the fuel; the present application constructs the gas-liquid equilibrium line and the supercritical region according to the boiling point and the pseudo-critical parameters, and draws the P-T phase diagram of the fuel. The present application verifies the internal consistency between the thermochemical data and the phase diagram data, which is of great significance for the development of hydrocarbon fuels.

[0014] The measuring method provided by the application is flow calorimetry.

[0015] In step (1), the target substance is selected from one or a combination of at least two of alkanes, alkenes, cycloalkanes, cycloalkenes or aromatic hydrocarbons.

[0016] Further, in step (1), the flow rate of the target substance pumped into the calorimeter is 0.1-10 g / s or 1-1000 ml / s; the target temperature is 298-873 K, and the temperature rise rate is 1-5 K / min.

[0017] Further, in step (3), the heat transfer characteristics of the fluid phase change process are that the outlet temperature of the target substance and the outlet end wall temperature of the calorimeter tend to be stable values as the energy transfer between the calorimeter and the fuel continues to increase; when the temperature of the target substance is at the boiling point, the energy transferred by the calorimeter is used for its own phase change; the outlet temperature of the target substance is recorded as the boiling point T boiling .

[0018] Further, in step (3), the energy transfer model is used to calculate the temperature rise ΔT fuel of the hydrocarbon fuel with a mass of m fuel , which covers the calorimeter energy input model, the calorimeter energy transfer model to the environment, and the copper electrode energy transfer model to the environment.

[0019] The calorimeter energy input model is obtained by calculating the energy input into the calorimeter according to the voltage and current values applied to the two ends of the calorimeter, denoted as Q total .

[0020] The calorimeter energy transfer model to the environment is obtained by pre-calibrating the functions of the heat convection and thermal radiation energy of the calorimeter surfaces with lengths of 2xm and xm and the copper electrode surfaces used to hold the calorimeter to the environment with respect to the respective surface temperatures, denoted as Q 2x and Q x ; the energy transferred by the calorimeter to the environment is Q 2x -Q x , denoted as Q loss .

[0021] The copper electrode energy transfer model to the environment is obtained by the heat transferred by the copper electrode to the environment being Q x -Q loss , denoted as Q electrode .

[0022] The energy transfer model between the calorimeter and the fuel is obtained by Q fuel = Q total -Q lossQ electrode .

[0023] Further, in step (3), the target substance heat sink calculation formula is H p = Q fuel / m, and the function of heat sink change with temperature is denoted as H p (T).

[0024] Further, in step (4), the system pressure is 0.1-12 MPa, and the system pressure growth step is 0.05-1 MPa.

[0025] Further, in step (5), as an implementation manner:

[0026] The critical parameter measurement method comprises the first and second derivatives of the function of fuel heat sink change with temperature H p (T), the fitting function of fuel boiling point change with pressure T boiling (P), and the fitting function of fuel pseudo-critical temperature change with pressure T critical (P).

[0027] The fuel pseudo-critical temperature is determined as the average of the temperature points corresponding to the maximum values of the first and second derivatives of H p (T).

[0028] The fuel pseudo-critical pressure is determined as the pressure value corresponding to the intersection of the fitting functions T boiling (P) and T critical (P).

[0029] Further, in step (5), as another implementation manner:

[0030] The measurement method of pseudo-critical temperature is: based on the function of target substance heat sink change with temperature obtained online, gradually increasing the system pressure, and monitoring the temperature corresponding to the growth inflection point of the heat sink function H p (T), which is denoted as pseudo-critical temperature T critical .

[0031] The measurement method of pseudo-critical pressure is: based on the function of target substance heat sink change with temperature obtained online, gradually increasing the system pressure, and monitoring the pressure corresponding to the disappearance of boiling point T boiling or phase transition enthalpy ΔH vap , which is denoted as pseudo-critical pressure P critical .

[0032] Further, in step (5), the phase diagram drawing method is: obtaining the fuel gas-liquid equilibrium line through the fuel pressure-boiling point fitting curve; determining the fuel supercritical region through the fuel pseudo-critical temperature and pseudo-critical parameter; and drawing the fuel P-T phase diagram.

[0033] The application also provides a device for measuring the boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams, which comprises the above method.

[0034] The high-pressure constant-flow pump is used to pump the target substance into the calorimeter; the liquid gear flow meter is used to detect the stable state of the flow; the direct-current stabilized power supply is used to provide stable energy to the calorimeter; the calorimeter is used for fluid flow heat exchange platform; the back pressure valve is used to adjust the system pressure; the K-type thermocouple is used to monitor the fluid temperature; the infrared thermal imager is used to monitor the calorimeter wall temperature change; the pressure gauge is used to monitor the system pressure change; and the industrial computer is used to store and process the monitored parameters.

[0035] The industrial computer is used to store and process the monitored parameters, which specifically includes: recording the monitored parameters in real time, including the temperature of the target substance at the inlet and outlet positions of the calorimeter, the calorimeter wall temperature distribution, the system pressure at both ends of the calorimeter, the current and voltage applied to both ends of the calorimeter, and the resistance of the calorimeter itself; obtaining the boiling point of the target substance based on the heat transfer characteristics in the fluid phase change process; simultaneously, obtaining the function of the target substance heat sink changing with temperature based on the energy transfer model between the calorimeter and the fuel; obtaining the pseudo-critical parameters of the target substance based on the pseudo-critical parameter measurement method, the pseudo-critical parameters including the pseudo-critical temperature and the pseudo-critical pressure, and drawing the P-T phase diagram.

[0036] Compared with the prior art, the application has the following beneficial effects:

[0037] (1) The application measures the boiling point and pseudo-critical parameters of hydrocarbon fuels based on the flow calorimetry combined with the flow heat transfer characteristics and the pseudo-critical parameter criterion, effectively avoids the subjective interference in the boiling point and pseudo-critical parameter determination process, and improves the reliability and accuracy of the boiling point and pseudo-critical parameters.

[0038] (2) Based on the reliable boiling point and pseudo-critical parameter data of hydrocarbon fuels, the fuel gas-liquid equilibrium line and the fuel supercritical region are determined, and the internal consistency between the thermochemical data and the phase diagram data is constructed.

[0039] (3) The method provided by the application provides data support for studying the fuel flow heat transfer mechanism and the chemical thermodynamic mechanism, and provides a test and evaluation method for developing new fuels. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The flow chart for measuring the boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams;

[0041] Figure 2 The structure diagram of the measuring device;

[0042] Figure 3 The flow heat transfer characteristics of toluene at the boiling point;

[0043] Figure 4 Infrared thermal image of the calorimeter and copper electrode;

[0044] Figure 5 Fitting function of heat transfer from copper electrode to environment;

[0045] Figure 6 Toluene temperature trend with time (working condition: 3 MPa, 1 g / s);

[0046] Figure 7 Toluene heat sink trend with temperature increase (working condition: 3 MPa, 1 g / s);

[0047] Figure 8 Toluene heat sink first-order derivative trend with temperature increase (working condition: 5 MPa, 1 g / s);

[0048] Figure 9 Toluene heat sink second-order derivative trend with temperature increase (working condition: 5 MPa, 1 g / s);

[0049] Figure 10 Toluene pseudo-critical pressure measurement chart;

[0050] Figure 11 Toluene P-T phase diagram. DETAILED DESCRIPTION

[0051] The following examples can make the professional personnel more fully understand the present application, but do not limit the present application in any way.

[0052] The flow chart of the method for measuring boiling point and pseudo-critical parameter of hydrocarbon fuel and drawing phase diagram provided by the present application is shown in Figure 1 , and the structural schematic diagram of the measuring device is shown in Figure 2 .

[0053] The method for measuring boiling point and pseudo-critical parameter of hydrocarbon fuel and the method for drawing phase diagram provided by the present application using the measuring device include:

[0054] (1) The target substance is pumped into the calorimeter by a high-pressure constant-flow pump and heated to the target temperature by a direct-current stabilized power supply; during the pumping process, the liquid gear flow meter monitors the fluid flow in real time.

[0055] (2) The K-type thermocouple is used to monitor the fluid temperature in real time; the infrared thermal imager monitors the calorimeter wall temperature in real time; the pressure gauge monitors the system pressure in real time; and the direct-current stabilized power supply monitors the output current and output voltage in real time.

[0056] (3) The industrial computer records and processes the parameters monitored in real time in step (2), and obtains the boiling point of the target substance based on the heat transfer characteristics in the fluid phase change process; at the same time, the function of the heat sink of the target substance with temperature change is obtained online based on the energy transfer model between the heat pipe and the fuel.

[0057] (4) After the heat pipe is cooled to room temperature, the pressure is adjusted through the back pressure valve, and steps (1) to (3) are continuously executed to obtain the boiling point of the target substance and the function of the heat sink of the target substance with temperature change under different pressures.

[0058] (5) The industrial computer obtains the pseudo-critical parameters of the target substance based on the pseudo-critical parameter measurement method, and draws a P-T phase diagram thereof.

[0059] Example 1

[0060] In this embodiment, toluene is taken as an example, toluene is pumped into the heat pipe at 1 g / s and 3 MPa under high-pressure constant-flow pump, and the direct-current stabilized power supply outputs energy to gradually heat toluene from 298 K to 1073 K at a step of 10 K / min, and toluene is kept in a stable flow heat exchange state.

[0061] In this embodiment, the heat transfer characteristics in the fluid phase change process used are as follows:

[0062] As shown in Figure 3 , when toluene is at 570.6 K, the energy transferred by the heat pipe is used for its own phase change, at this time, the toluene temperature and the outlet end wall temperature of the heat pipe tend to be stable values with the continuous enhancement of the energy transfer between the heat pipe and the fuel, at this time, the wall temperature is 573.7 K, and the toluene outlet temperature is 570.6 K, which is recorded as the boiling point of toluene at 3 MPa; the relative error of the boiling point measurement is 2.5%.

[0063] In this embodiment, the energy transfer model used includes:

[0064] Heat pipe energy input model: the direct-current stabilized power supply applies stable current I and voltage U to both ends of the heat pipe; the heat pipe energy input Q total = UI.

[0065] As shown in Figure 4 , the heat pipe wall temperature T w and the copper electrode surface temperature T electrode can be read therefrom.

[0066] Heat pipe energy transfer model to the environment: the heat pipes with lengths of 2x and x without fluid are heated, and the energy conservation equations are established, which are recorded as Q 2x and Q x respectively; in order to exclude the interference of copper electrode heat loss, the heat pipe energy transfer model to the environment with a length of x is recorded as Q loss = Q2x -Q x The empirical formula obtained by fitting the experimental data is:

[0067] Q loss =10.30×10 -4 ×T w -1.82×10 -6 ×T w 2 +1.61×10 -9 ×T w 3 -11.83×10 -14 ×T w 4 .

[0068] Model of heat transfer from copper electrode to environment: For heating calorimeter tubes of lengths 2x and x without fluid, establish energy conservation equations, denoted as Q. 2x and Q x The energy transfer model of a calorimeter tube of length x to the environment is denoted as Q. loss =Q 2x -Q x The heat transferred from the copper electrode to the environment is denoted as Q. electrode =Q x -Q loss ;like Figure 5 As shown, the empirical formula obtained by fitting the experimental data is:

[0069] Q electrode = -9811.93 + 125.29 × T electrode -0.58×T electrode 2 +0.0012×T electrode 3 -8.83×T electrode 4

[0070] Energy transfer model between calorimeter tube and fuel: Establish the heat conservation equations between the various models, i.e., Q fuel =Q total -Q loss -Q electrode .

[0071] As the DC power input energy is further increased, the fuel temperature continues to rise, such as... Figure 6 As shown.

[0072] In this embodiment, the function of fuel heat sink change with temperature is H(T) = Q. fluid / m, where m is the mass of toluene, such as Figure 7Further, toluene was pumped into the heat pipe at 1 g / s and 5 MPa, and the output energy of the direct-current stabilized power source was used to gradually increase the temperature of toluene from 298 K to 1073 K at a step of 10 K / min, so as to maintain a stable flow heat exchange state of toluene.

[0073] In this embodiment, the function of the fuel heat sink changing with temperature is H(T) = Q fluid / m, m is the mass of toluene; the fuel temperature along the path is T = H -1 (T);

[0074] In this embodiment, the curves of the first derivative of the toluene heat sink and the second derivative of the heat sink changing with temperature are calculated, as shown in Figure 8 and Figure 9 The temperature corresponding to the time when the first derivative of the toluene heat sink starts to rapidly increase is recorded as T1, and the temperature corresponding to the time when the second derivative of the toluene heat sink starts to rapidly increase is recorded as T2,

[0075] The determination formula of the time when the first derivative of the heat sink starts to rapidly increase is

[0076] (dH p,x / dT x ) / (dH p,x-1 / dT x-1 )>10 (1-1)

[0077] The determination formula of the time when the second derivative of the heat sink starts to rapidly increase is

[0078] (dH p,x / dT x 2 ) / (d 2 H p,x-1 / dT x-1 2 )>10 (1-2)

[0079] In this embodiment, the pseudo-critical temperature determination formula is:

[0080] T c =(T1+T2) / 2 (1-3)

[0081] Based on the determination formula, the pseudo-critical temperature of toluene is calculated to be 589.5 K; combined with the NIST standard database, it can be known that the theoretical critical temperature of toluene is 591.75 K; and the measurement error is 0.38%.

[0082] In this embodiment, the pseudo-critical pressure measurement method is as follows: Figure 10As shown in the figure, the industrial computer draws toluene pressure-boiling point fitting curve and toluene pressure-critical temperature fitting straight line respectively, and the two fitting lines are extrapolated to intersect at a specific temperature-pressure point, and the pressure point is the toluene pseudo-critical pressure. Based on the intersection of the two fitting lines, the toluene pseudo-critical pressure is calculated to be 4.08 MPa; combined with the NIST standard database, it can be known that the theoretical critical pressure of toluene is 4.11 MPa; the measurement error is 0.73%.

[0083] In the embodiment, the hydrocarbon fuel phase diagram drawing step is: taking toluene as an example, the boiling point of toluene under different pressures, the pseudo-critical temperature and the pseudo-critical pressure of toluene under different pressures are obtained respectively. Based on the definition of phase diagram gas-liquid equilibrium line and supercritical region, the industrial computer draws an accurate toluene P-T phase diagram, as shown in the figure. Figure 11

[0084] In summary, the application avoids the influence of subjective measurement factors in the past pseudo-critical parameter measurement method and the disadvantage that the prediction model needs a large number of semi-empirical and empirical correlation expressions, and proposes a pseudo-critical parameter criterion based on the relationship between temperature, heat sink and heat sink derivative, and an accurate fuel phase diagram is drawn accordingly.​

Claims

1. A method for carbon-hydrogen fuel boiling point, near-critical parameter measurement and phase diagram plotting, characterized by, The method comprises: (1) delivering the target substance to the calorimeter and heating to a target temperature; (2) monitoring the temperature of the target substance at the inlet and outlet positions of the calorimeter, the wall surface temperature distribution of the calorimeter, the system pressure at both ends of the calorimeter, the current and voltage applied to both ends of the calorimeter, and the resistance of the calorimeter itself in real time; (3) obtaining the boiling point of the target substance based on the heat transfer characteristics in the phase change process of the fluid according to the parameters monitored in real time in step (2); at the same time, obtaining the function of the heat sink of the target substance with temperature change online based on the energy transfer model between the calorimeter and the fuel; (4) after the calorimeter is cooled to room temperature, adjusting the pressure, and continuing to perform steps (1) to (3) above to obtain the boiling point of the target substance and the function of the heat sink of the target substance with temperature change under different pressures; (5) obtaining the pseudo-critical parameters of the target substance, including the pseudo-critical temperature and the pseudo-critical pressure, based on the pseudo-critical parameter measurement method, and drawing the P-T phase diagram thereof. In step (3), the heat transfer characteristics in the fluid phase change process are as follows: the target substance outlet temperature and the calorimeter outlet end wall temperature tend to be stable values as the energy transfer between the calorimeter and the fuel continues to increase; when the target substance temperature is at the boiling point, the energy transferred by the calorimeter is used for its own phase change; the outlet temperature of the target substance is recorded as the boiling point T boiling . In step (3), the energy transfer model between the calorimeter and the fuel is used to calculate the temperature rise ΔT of the hydrocarbon fuel with mass m fuel The required energy Q fuel , which includes the calorimeter energy input model, the calorimeter energy transfer model to the environment, and the copper electrode heat transfer model to the environment; the calorimeter energy input model is obtained by calculating the energy input into the calorimeter according to the voltage and current values applied to the two ends of the calorimeter, denoted as Q total ; the calorimeter energy transfer model to the environment is obtained by pre-calibrating the functions of the heat convection and heat radiation energy of the surfaces of the calorimeter with lengths of 2x m and x m and the copper electrode used to clamp the calorimeter to the environment with respect to the respective surface temperatures, denoted as Q 2x and Q x ; the energy transferred by the calorimeter to the environment is Q 2x -Q x , denoted as Q loss ; the copper electrode heat transfer model to the environment is obtained by calculating the heat transferred by the copper electrode to the environment, denoted as Q x -Q loss , denoted as Q electrode ; the energy transfer model between the calorimeter and the fuel is obtained by Q fuel = Q total -Q loss -Q electrode ; In step (5), the pseudo-critical parameter measurement method comprises a function H of the fuel heat sink as a function of temperature p ; a first derivative and a second derivative of the function T boiling (P); and a fitting function T critical (P) of the fuel pseudo-critical temperature as a function of pressure; the fuel pseudo-critical temperature is determined as H p ; a first derivative and a second derivative of the function T boiling (P) and T critical (P) corresponding to the pressure value of the intersection point; In step (5), the measurement method of the pseudo-critical temperature is: gradually increasing the system pressure based on the function of the online acquired heat sink of the target substance with temperature change, and monitoring the heat sink function H p (T) when the growth inflection point appears, and the temperature is recorded as the pseudo-critical temperature T critical ; the measurement method of the pseudo-critical pressure is: gradually increasing the system pressure based on the function of the online acquired heat sink of the target substance with temperature change, and monitoring the boiling point T boiling or the phase change enthalpy ΔH vap disappears, and the pressure is recorded as the pseudo-critical pressure P critical ; In step (5), the phase diagram drawing method is to obtain the fuel gas-liquid equilibrium line through the fuel pressure-boiling point fitting curve; determine the supercritical region of the fuel by using the pseudo-critical temperature and the pseudo-critical pressure of the fuel; and draw the P-T phase diagram of the fuel.

2. The method for carbon-hydrogen fuel boiling point, near-critical parameter measurement and phase diagram plotting of claim 1, wherein, In step (1), the target substance is selected from one or a combination of at least two of alkanes, alkenes, cycloalkanes, cycloalkenes, or aromatic hydrocarbons.

3. The method of claim 1, wherein, In step (1), the target substance is delivered to the calorimeter at a flow rate of 0.1-10 g / s or 1-1000 ml / s, and the target temperature is set to 298-873 K, and the temperature rise rate is 1-5 K / min; in step (4), the system pressure is set to 0.1-12 MPa, and the step size is increased by 0.05-1 MPa.

4. The method of claim 1, wherein, In step (4), the target substance heat sink calculation formula is H p = Q fuel / m, and the function of the heat sink with temperature change is denoted as H p (T).

5. An apparatus for boiling point, pseudo-critical parameter measurement and phase diagram drawing using any of the methods of claims 1-4, the apparatus comprising: a high-pressure constant-flow pump for pumping the target substance into the calorimeter; a liquid gear flow meter for detecting the stable state of the flow; a direct-current stabilized power supply for providing stable energy to the calorimeter and monitoring the output current and voltage in real time; a calorimeter for fluid flow heat exchange platform; a back pressure valve for adjusting the system pressure; a K-type thermocouple for monitoring the fluid temperature; an infrared thermal imager for monitoring the wall surface temperature change of the calorimeter; a pressure gauge for monitoring the system pressure change; an industrial computer for recording the monitored parameters in real time, including the temperature of the target substance at the inlet and outlet positions of the calorimeter, the wall surface temperature distribution of the calorimeter, the system pressure at both ends of the calorimeter, the current and voltage applied to both ends thereof, and the resistance of the calorimeter itself; obtaining the boiling point of the target substance based on the heat transfer characteristics in the phase change process of the fluid; at the same time, obtaining the function of the heat sink of the target substance with temperature change online based on the energy transfer model between the calorimeter and the fuel; obtaining the pseudo-critical parameters of the target substance based on the pseudo-critical parameter measurement method, the pseudo-critical parameters including the pseudo-critical temperature and the pseudo-critical pressure, and drawing the P-T phase diagram thereof.

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