Method and device for hydrocarbon fuel boiling point and quasi-critical parameter measurement and phase diagram drawing

Abstract

The invention discloses a hydrocarbon fuel boiling point and quasi-critical parameter measurement and phase diagram drawing method. The method comprises the following steps: conveying a target substance to a calorimetric tube and heating the target substance to a target temperature; relevant parameters are monitored in real time; according to the parameters monitored in real time, the boiling point of the target substance is obtained based on heat transfer characteristics in the fluid phase change process; on the basis of an energy transfer model between the calorimetric tube and the fuel, a function of a target substance heat sink changing along with the temperature is obtained online; after the heat measuring pipe is cooled to the room temperature, the pressure is adjusted, and the steps continue to be executed to obtain functions of the boiling point of the target substance and the heat sink of the target substance changing along with the temperature under different pressures; based on a quasi-critical parameter measurement method, quasi-critical parameters of a target substance are obtained, and a P-T phase diagram of the target substance is drawn. The invention further discloses a device for hydrocarbon fuel boiling point and quasi-critical parameter measurement and phase diagram drawing. According to the method and the device, accurate measurement of the boiling point and the quasi-critical parameters and accurate drawing of the phase diagram can be realized.

Description

Technical Field

[0001] The invention relates to the fields of thermodynamics, calorimetry and supercritical fluid of hydrocarbon fuels, and in particular to a method and device for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams. Background Art

[0002] Active cooling technology is a commonly used cooling method in the cooling system of hypersonic aircraft. Endothermic hydrocarbon fuels with dual functions of cooling and propulsion are the main cooling media for active cooling thermal protection systems. In the cooling channel of the aircraft, hydrocarbon fuels are in a supercritical state of high temperature and pressure, and their flow heat transfer, cracking and combustion processes are significantly specific and complex. To study the flow heat transfer law, cracking mechanism and combustion mechanism of hydrocarbon fuels in essence, it is necessary to obtain its thermophysical properties under different pressures, temperatures and components. Since the thermophysical parameters of hydrocarbon fuels will change dramatically near the critical temperature, it is necessary to accurately determine their critical parameters. The fuel phase diagram derived from this further reflects the relationship between the composition of the fuel phase equilibrium system and temperature and pressure, effectively verifies the inherent consistency between thermochemical data and phase diagram data, and is of great significance to the study of hydrocarbon fuels.

[0003] At present, experimental measurement combined with model calculation is the main means to obtain the critical parameters of fluids. Common experimental measurement methods include constant volume method, variable volume method, flow method, pulse heating method, density linear diameter law method and quasi-static thermal analysis method. Eugene D et al. used 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 its critical point still depends on subjective judgment, and it must be ensured that the fluid to be measured is evenly mixed and flows during the measurement process. Yiran Wang et al. used the flow method to measure the critical temperature and critical pressure of isopropanol and isobutanol mixed with gasoline components. The results showed that isopropanol and isobutanol significantly increased the critical temperature and critical pressure of gasoline, and were verified in combination with the Redlich-Kister equation. (Yiran Wang, Tian Lan, Raza Ali. Maogang He, Measurement of the critical temperature and critical pressure of isopropanoland 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 near-critical region data is greatly affected by subjective observation, and the fitting accuracy of the subsequent fitting equation is relatively low. Zhirong Chen et al. used critical opalescence in a fused silica capillary to determine the critical temperature, and measured the critical pressure by heating the acetone aqueous solution to its critical temperature in an autoclave. In addition, they studied the PVTX relationship of acetone-water solution in combination with the 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. When a light beam is irradiated onto a fluid near the critical point, the fluid will strongly scatter the light beam. This method still relies on subjective judgment to determine the critical point, and the PVTX relationship requires a lot of fitting data, resulting in low fitting efficiency. Rao Huoyu developed a QSPR model based on quantitative structure-activity relationship for calculating the critical temperature and pressure of cycloalkanes. Among them, the multivariate linear regression (MLR) determination coefficients of the QSPR-Tc and QSPR-Pc models reached 0.9984 and 0.9979, respectively, and the standard deviations of the two models were 3.40K and 0.496bar, 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 uncertainty of the experimental values ​​of such models is closely related to the carbon number of cycloalkanes, and a smaller carbon number of 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 a multi-component mixture based on the Chueh-Prausnitz equation. The model requires the binary interaction coefficient τ to be established in advance to describe the non-ideal contribution of the binary mixture. 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. However, due to the small number of mixture types and data, this leads to lower accuracy when calculating other unknown mixtures.

[0004] In summary, existing experimental measurement methods are significantly affected by subjective observations in the near-critical region. At the same time, existing computational models face problems such as numerous fitting data requirements and low data fitting accuracy and efficiency. Summary of the invention

[0005] The present invention aims to provide a method and device for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams, so as to achieve accurate measurement of boiling point and pseudo-critical parameters and accurate drawing of phase diagrams.

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

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

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

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

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

[0011] (4) After the calorimeter tube cools down to room temperature, the pressure is adjusted, and the above steps (1) to (3) are continued to be performed to obtain the function of the boiling point of the target substance and the heat sink of the target substance changing with temperature at different pressures;

[0012] (5) Based on the pseudo-critical parameter measurement method, the pseudo-critical parameters of the target material are obtained: pseudo-critical temperature and pseudo-critical pressure, and its PT phase diagram is drawn.

[0013] In order to avoid the existing experimental measurement methods being significantly affected by subjective observations in the near-critical region, and the existing calculation models facing the problems of numerous fitting data requirements and low data fitting accuracy and efficiency, the present invention provides the above method. The technical concept of the present invention is: the present invention establishes a functional relationship between temperature-enthalpy values ​​of hydrocarbon fuels at different pressures based on the calorimetric model; the present invention establishes an accurate boiling point and pseudo-critical temperature criterion based on the development trend of fuel heat sink changes with temperature; the present invention determines the pseudo-critical pressure by fitting the intersection of the fuel pressure-pseudo-critical temperature line and the fuel pressure-boiling point curve; the present invention constructs a gas-liquid equilibrium line and a supercritical region based on the boiling point and pseudo-critical parameters, and draws a fuel PT phase diagram. The present invention verifies the inherent consistency between thermochemical data and phase diagram data, which is of great significance to the development of hydrocarbon fuels.

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

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

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

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

[0018] Furthermore, in step (3), the energy transfer model is used to calculate the temperature rise ΔT of the hydrocarbon fuel with a mass m. fuel Energy required Q fuel , covering the calorimeter tube energy input model, the calorimeter tube to the environment energy transfer model and the copper electrode to the environment energy transfer model.

[0019] The calorimeter tube energy input model is obtained by the following method: according to the voltage and current values ​​applied to the two ends of the calorimeter tube, the energy input to the calorimeter tube is calculated, which is recorded as Q total ;

[0020] The energy transfer model of the calorimeter tube to the environment is obtained by pre-calibrating the heat convection and heat radiation energy of the calorimeter tube surface with lengths of 2xm and xm and the copper electrode surface for clamping the calorimeter tube to the environment as a function of the change in their respective surface temperatures, denoted as Q 2x and Q x ; The energy transferred from the calorimeter to the environment is Q 2x -Q x , denoted as Q loss ;

[0021] The energy transfer model from the copper electrode to the environment is obtained in the following way: the heat transferred from the copper electrode to the environment is Q x -Q loss , denoted as Q electrode ;

[0022] The energy transfer model between the calorimeter tube and the fuel is obtained in the following way: Based on the principle of energy conservation, Q fuel =Q total -Q loss-Q electrode .

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

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

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

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

[0027] The pseudo-critical temperature of the fuel is determined as H p The average value of the temperature points corresponding to the respective maximum values ​​of the first-order derivative and the second-order derivative of (T);

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

[0029] Furthermore, in step (5), as another implementation method:

[0030] The method for measuring the pseudo-critical temperature is: based on the online acquired function of the heat sink of the target material changing with temperature, gradually increase the system pressure and monitor the heat sink function H p (T) The temperature corresponding to the growth inflection point, which is recorded as the pseudo-critical temperature T critical ;

[0031] The method for measuring the pseudo-critical pressure is: based on the online acquired function of the heat sink of the target material changing with the temperature, gradually increase the system pressure and monitor the boiling point T boiling or phase change enthalpy ΔH vap The corresponding pressure when it disappears is recorded as the pseudo-critical pressure P critical .

[0032] Furthermore, 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 fuel supercritical region through the fuel pseudo-critical temperature and pseudo-critical parameters; and draw the fuel PT phase diagram.

[0033] The present invention also provides a device for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams using the above method, the device comprising:

[0034] A high-pressure constant-flow pump is used to pump the target substance into the calorimetric tube; a liquid gear flowmeter is used to detect the stable state of the flow; a DC regulated power supply is used to provide stable energy to the calorimetric tube; the calorimetric tube is used as a fluid flow heat exchange platform; a back-pressure valve is used to adjust the system pressure; a K-type thermocouple is used to monitor the fluid temperature; an infrared thermal imager is used to monitor the temperature changes on the wall of the calorimetric tube; a pressure gauge is used to monitor the pressure changes in the system; and an industrial computer is used to store and process monitoring parameters.

[0035] Among them, the storage and processing of monitoring parameters used by the industrial computer specifically include: real-time recording of monitored parameters, including: the temperature of the target material at the inlet and outlet of the calorimeter tube, the temperature distribution of the calorimeter tube wall, the system pressure at both ends of the calorimeter tube, the current and voltage applied to its two ends, and the resistance of the calorimeter tube itself; obtaining the boiling point of the target material based on the heat transfer characteristics during the phase change of the fluid; at the same time, based on the energy transfer model between the calorimeter tube and the fuel, online obtaining the function of the heat sink of the target material changing with the temperature; based on the quasi-critical parameter measurement method, obtaining the quasi-critical parameters of the target material, the quasi-critical parameters include the quasi-critical temperature and the quasi-critical pressure, and drawing its PT phase diagram.

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

[0037] (1) The present invention measures the boiling point and quasi-critical parameters of hydrocarbon fuels based on flow calorimetry combined with flow heat transfer characteristics and quasi-critical parameter criteria, effectively avoiding subjective interference in the boiling point and quasi-critical parameter determination process and improving the reliability and accuracy of the boiling point and quasi-critical parameters.

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

[0039] (3) The method provided by the present invention provides data support for studying the fuel flow heat transfer mechanism and chemical thermodynamic mechanism, and provides a testing and evaluation method for the development of new fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Draw flow charts for boiling point, pseudo-critical parameter measurements and phase diagrams of hydrocarbon fuels;

[0041] Figure 2 It is a schematic diagram of the structure of the measuring device;

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

[0043] Figure 4 This is an infrared thermal image of the calorimeter tube and copper electrode;

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

[0045] Figure 6 is the variation trend of toluene temperature over time (operating conditions are 3MPa, 1g / s);

[0046] Figure 7 The variation trend of toluene heat sink with increasing temperature (operating conditions are 3MPa, 1g / s);

[0047] Figure 8 The variation trend of the first-order derivative of the toluene heat sink with the increase of temperature (operating conditions are 5MPa, 1g / s);

[0048] Fig. 9 The variation trend of the second-order conductance of the toluene heat sink with the increase of temperature (operating conditions are 5MPa, 1g / s);

[0049] Fig.10 This is the measurement diagram of the pseudo-critical pressure of toluene;

[0050] Fig.11 This is the PT phase diagram of toluene. DETAILED DESCRIPTION

[0051] The following examples can enable professionals to more fully understand the present invention, but do not limit the present invention in any way.

[0052] The flowchart of a method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams provided by the present invention is as follows: Figure 1 The structural diagram of the measuring device is shown in Figure 2 shown.

[0053] The method for measuring the boiling point and pseudo-critical parameters of hydrocarbon fuels and the method for drawing a phase diagram using the measuring device provided by the present invention include:

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

[0055] (2) A K-type thermocouple is used to monitor the fluid temperature in real time; an infrared thermal imager is used to monitor the wall temperature of the calorimeter tube in real time; a pressure gauge is used to monitor the system pressure in real time; and a DC regulated power supply is used to monitor the output current and output voltage in real time.

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

[0057] (4) After the calorimeter tube is cooled to room temperature, the pressure is adjusted by the back pressure valve, and the above steps (1) to (3) are continued to be performed to obtain the function of the boiling point of the target substance and the heat sink of the target substance changing with temperature under different pressures.

[0058] (5) Based on the pseudo-critical parameter measurement method, the industrial computer obtains the pseudo-critical parameters of the target material and draws its PT phase diagram.

[0059] Example 1

[0060] In this embodiment, taking toluene as an example, toluene is pumped into the calorimeter by a high-pressure constant current pump under the conditions of 1 g / s and 3 MPa. The DC regulated power supply outputs energy to gradually heat the toluene from 298 K to 1073 K, with a heating step of 10 K / min, to maintain a stable flow and heat exchange state of toluene.

[0061] In this embodiment, the heat transfer characteristics of the fluid phase change process are:

[0062] like Figure 3 As shown in the figure, when toluene is at 570.6K, the energy transferred by the calorimeter tube is used for its own phase change. At this time, the toluene temperature and the wall temperature at the outlet of the calorimeter tube tend to stable values ​​as the energy transfer between the calorimeter tube and the fuel continues to increase. At this time, the wall temperature is 573.7K and the toluene outlet temperature is 570.6K, which is recorded as the boiling point of toluene at 3MPa; the relative error of boiling point measurement is 2.5%.

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

[0064] Calorimeter tube energy input model: DC regulated power supply applies stable current I and voltage U at both ends of the calorimeter tube; calorimeter tube energy input Q total =UI.

[0065] like Figure 4 As shown, the calorimeter tube wall temperature T can be read from it w and the copper electrode surface temperature T electrode .

[0066] Model of energy transfer from calorimeter tube to environment: Heat up the calorimeter tube with length 2x and x without fluid, and establish the energy conservation equation, which is recorded as Q 2x and Q x ; In order to eliminate the interference of heat loss of copper electrode, the energy transfer model of the calorimeter tube with a length of x to the environment is recorded as Q loss =Q2x -Q x ; The empirical formula fitted by 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] Heat transfer model from copper electrode to environment: Heat up the calorimeter tube with length 2x and x without fluid, and establish the energy conservation equation, which is recorded as Q 2x and Q x ; The energy transfer model of the calorimeter tube with a length of x to the environment is recorded as Q loss =Q 2x -Q x ; The heat transferred from the copper electrode to the environment is recorded as Q electrode =Q x -Q loss ;like Figure 5 As shown, the empirical formula fitted by 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 equation between each model, i.e. Q fuel =Q total -Q loss -Q electrode .

[0071] Further increasing the DC power input energy, the fuel temperature continues to rise, such as Figure 6 shown.

[0072] 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, such as Figure 7Furthermore, toluene was pumped into the calorimeter by a high-pressure constant-current pump under the conditions of 1 g / s and 5 MPa, and the DC regulated power supply output energy gradually heated the toluene from 298 K to 1073 K, with a heating step of 10 K / min, to maintain a stable flow and heat transfer 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 temperature of the fuel along the process is T=H -1 (T);

[0074] In this embodiment, the first-order derivative and the second-order derivative of the toluene heat sink are calculated as a function of temperature. Figure 8 and Fig. 9 The temperature corresponding to the time when the first-order derivative value of the toluene heat sink begins to increase rapidly is recorded as T 1 The temperature corresponding to the rapid increase of the second-order derivative value of the toluene heat sink is recorded as T 2 ,

[0075] The judgment formula for the rapid growth of the first-order derivative value of the heat sink

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

[0077] The second-order derivative value of the heat sink begins to increase rapidly.

[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 quasi-critical temperature determination formula is:

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

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

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

[0083] In this embodiment, the steps of drawing the hydrocarbon fuel phase diagram are as follows: taking toluene as an example, the boiling point of toluene at different pressures, the pseudo-critical temperature and pseudo-critical pressure of toluene at different pressures are obtained respectively. Based on the definition of the gas-liquid equilibrium line and the definition of the supercritical region of the phase diagram, the industrial computer draws an accurate toluene PT phase diagram, such as Fig.11 shown.

[0084] In summary, the present invention avoids the influence of subjective measurement factors in previous quasi-critical parameter measurement methods and the disadvantages that the prediction model requires a large number of semi-empirical and empirical correlation equations, proposes a quasi-critical parameter criterion based on the relationship between temperature, heat sink and heat sink derivative, and draws an accurate fuel phase diagram based on this.

Claims

1. A method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams, characterized in that: The method comprises: (1) transporting the target substance to the calorimeter and heating it to the target temperature; (2) Real-time monitoring of the temperature of the target material at the inlet and outlet of the calorimeter tube, the temperature distribution of the calorimeter tube wall, the system pressure at both ends of the calorimeter tube, the current and voltage applied to both ends of the calorimeter tube, and the resistance of the calorimeter tube itself; (3) according to the parameters monitored in real time in step (2), the boiling point of the target substance is obtained based on the heat transfer characteristics of the fluid phase change process; at the same time, based on the energy transfer model between the calorimeter tube and the fuel, the function of the heat sink of the target substance changing with the temperature is obtained online; (4) After the calorimeter tube cools down to room temperature, the pressure is adjusted, and the above steps (1) to (3) are continued to be performed to obtain the function of the boiling point of the target substance and the heat sink of the target substance changing with temperature at different pressures; (5) Based on the pseudo-critical parameter measurement method, the pseudo-critical parameters of the target material are obtained: pseudo-critical temperature and pseudo-critical pressure, and its PT phase diagram is drawn.

2. The method for measuring boiling point, pseudo-critical parameters and phase diagram of hydrocarbon fuels according to claim 1, characterized in that: In step (1), the target substance is selected from one or a combination of at least two of alkanes, olefins, cycloalkanes, cycloolefins or aromatic hydrocarbons.

3. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: 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, the target temperature is set to 298-873 K, and the heating rate is set to 1-5 K / min; in step (4), the system pressure is set to 0.1-12 MPa, and the increase step is 0.05-1 MPa.

4. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: In step (3), the heat transfer characteristics of the fluid phase change process are as follows: the outlet temperature of the target substance and the wall temperature of the outlet end of the calorimeter tube tend to a stable value as the energy transfer between the calorimeter tube and the fuel continues to increase; when the temperature of the target substance is at the boiling point, the energy transferred by the calorimeter tube is used for its own phase change; the outlet temperature of the target substance is recorded as the boiling point T boiling .

5. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: In step (3), the energy transfer model between the calorimeter tube and the fuel is used to calculate the temperature rise ΔT of the hydrocarbon fuel with a mass m. fuel Energy required Q fuel , covering the calorimeter tube energy input model, the calorimeter tube to the environment energy transfer model and the copper electrode to the environment heat transfer model; The calorimeter tube energy input model is obtained by the following method: according to the voltage and current values ​​applied to the two ends of the calorimeter tube, the energy input to the calorimeter tube is calculated, which is recorded as Q total ; The energy transfer model of the calorimeter tube to the environment is obtained by pre-calibrating the heat convection and heat radiation energy of the calorimeter tube surface with lengths of 2xm and xm and the copper electrode surface for clamping the calorimeter tube to the environment as a function of the change in their respective surface temperatures, denoted as Q 2x and Q x ; The energy transferred from the calorimeter to the environment is Q 2x -Q x , denoted as Q loss ; The heat transfer model from the copper electrode to the environment is obtained in the following way: the heat transferred from the copper electrode to the environment is Q x -Q loss , denoted as Q electrode ; The energy transfer model between the calorimeter tube and the fuel is obtained in the following way: Based on the principle of energy conservation, Q fuel =Q total -Q loss -Q electrode .

6. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: In step (4), the target material heat sink calculation formula is H p =Q fuel / m, the function of heat sink changing with temperature is recorded as H p (T).

7. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: In step (5), the quasi-critical parameter measurement method includes the function H of the fuel heat sink varying with temperature. p The first and second derivatives of (T); the fitting function of the fuel boiling point changing with pressure T boiling (P); and the fitting function T of the fuel pseudo-critical temperature as a function of pressure critical (P); The pseudo-critical temperature of the fuel is determined to be H p The average value of the temperature points corresponding to the respective maximum values ​​of the first-order derivative and the second-order derivative of (T); The pseudo-critical pressure of the fuel is determined as the fitting function T boiling (P) and T critical (P) The pressure value corresponding to the intersection point.

8. The method for measuring boiling point, pseudo-critical parameters and phase diagram of hydrocarbon fuels according to claim 1, characterized in that: In step (5), the method for measuring the pseudo-critical temperature is: based on the function of the target material heat sink changing with temperature obtained online, gradually increase the system pressure and monitor the heat sink function H p (T) The temperature corresponding to the growth inflection point, which is recorded as the pseudo-critical temperature T critical ; The method for measuring the pseudo-critical pressure is: based on the online acquired function of the heat sink of the target material changing with the temperature, gradually increase the system pressure and monitor the boiling point T boiling or phase change enthalpy ΔH vap The corresponding pressure when it disappears is recorded as the pseudo-critical pressure P critical .

9. The method for measuring boiling point and pseudo-critical parameters of hydrocarbon fuels and drawing phase diagrams according to claim 1, characterized in that: In step (5), the phase diagram drawing method is to obtain the fuel gas-liquid equilibrium line by fitting the fuel pressure-boiling point curve; determine the fuel supercritical region by using the fuel pseudo-critical temperature and pseudo-critical pressure; Draw the fuel PT phase diagram.

10. A device for measuring boiling point and pseudo-critical parameters and drawing phase diagrams using the method according to any one of claims 1 to 9, the device comprising: A high-pressure constant-flow pump for pumping the target substance into the calorimeter tube; Liquid gear flowmeter, used to detect the steady state of flow; The DC regulated power supply is used to provide stable energy to the vector heat pipe and monitor the output current and output voltage in real time; the calorimeter tube is used for the fluid flow heat exchange platform; Back pressure valve, used to adjust system pressure; K-type thermocouple, used to monitor fluid temperature; Infrared thermal imager, used to monitor the temperature changes on the wall of the calorimeter tube; Pressure gauge, used to monitor system pressure changes; The industrial computer records the monitored parameters in real time, including: the temperature of the target material at the inlet and outlet of the calorimeter tube, the temperature distribution of the calorimeter tube wall, the system pressure at both ends of the calorimeter tube, the current and voltage applied to both ends, and the resistance of the calorimeter tube itself; the boiling point of the target material is obtained based on the heat transfer characteristics of the fluid phase change process; at the same time, the function of the heat sink of the target material changing with the temperature is obtained online based on the energy transfer model between the calorimeter tube and the fuel; based on the quasi-critical parameter measurement method, the quasi-critical parameters of the target material are obtained, and the quasi-critical parameters include the quasi-critical temperature and the quasi-critical pressure, and its PT phase diagram is drawn.

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