Compressed natural gas (CNG) dispensing methods, devices, equipment, and storage media

Abstract

This invention relates to natural gas filling technology, and discloses a method, apparatus, equipment, and computer-readable storage medium for filling compressed natural gas (CNG) using a gas dispenser. The CNG filling method includes: acquiring the current ambient temperature and the initial pressure and initial temperature inside the gas cylinder at the vehicle end; detecting the gas flow rate of the CNG being filled into the gas cylinder at the vehicle end to estimate the current pressure and temperature inside the gas cylinder at the vehicle end; if the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference, then filling the gas cylinder at the vehicle end is stopped; otherwise, filling continues. This application estimates the gas pressure and temperature inside the gas cylinder at the vehicle end during filling, and stops filling when at least one of these two data points approaches an extreme value, thereby ensuring the safety of the gas cylinder at the vehicle end and maximizing the filling volume.

Description

Technical Field

[0001] This invention relates to the field of natural gas filling technology, and in particular to a method, apparatus, equipment, and computer-readable storage medium for filling compressed natural gas. Background Technology

[0002] Currently, compressed natural gas passenger vehicles are equipped with Type III gas cylinders, which are generally composed of three layers: an inner liner, a fiber-reinforced layer, and an outer protective layer.

[0003] Natural gas refueling stations have three types of buffer cylinders at the front end of the refueling machine, each with the same pressure level. The pressure range of the high-pressure cylinder is generally 20-25 MPa, the medium-pressure cylinder is generally 18-22 MPa, and the low-pressure cylinder is generally 16-18 MPa. The refueling machine control system switches between different pressure lines according to the pressure in the vehicle's cylinder to fill the system, thereby reducing the heat generated during the filling process.

[0004] According to JJG 996 "Compressed Natural Gas Dispenser", to ensure cylinder safety, dispensing should automatically stop when the pressure in the gas cylinder of a natural gas vehicle reaches 19.5–20 MPa. However, this filling method often results in incomplete filling of the cylinder, thus reducing user satisfaction. Summary of the Invention

[0005] The purpose of this invention is to provide a method, apparatus, equipment, and computer-readable storage medium for filling compressed natural gas cylinders, which increases the amount of gas filled into the cylinders while ensuring the safety of filling the cylinders at the vehicle end.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for dispensing compressed natural gas using a refueling machine, comprising:

[0007] The system acquires the current ambient temperature, the initial pressure and initial temperature inside the vehicle-mounted gas cylinder, and detects the gas flow rate of the natural gas being filled into the vehicle-mounted gas cylinder.

[0008] Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, the current pressure and temperature inside the gas cylinder at the vehicle end are estimated and determined.

[0009] Determine whether the current pressure and the current temperature meet the conditions for stopping gas refueling; wherein, the conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference;

[0010] If so, then stop adding gas to the gas cylinder at the vehicle end;

[0011] If not, continue adding gas to the gas cylinder at the vehicle end, and use the current pressure and the current temperature as the new initial pressure and initial temperature, respectively, and repeat the step of detecting the gas flow rate of the natural gas being added to the gas cylinder at the vehicle end until the current pressure and the current temperature meet the conditions for stopping gas addition.

[0012] Optionally, the current pressure and temperature inside the vehicle-end gas cylinder are estimated and determined based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, including:

[0013] Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, and using the principle of energy conservation, the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time, is determined.

[0014] According to the heat dissipation formula Q satisfied by the gas in the gas cylinder at the vehicle end... 散 =m 当 ·C·(t 绝 -t 当 )=γ·(t 当 -t 初 ), determine the current temperature; where Q 散 t is the amount of heat dissipated by the gas in the gas cylinder at the vehicle end; 当 The current temperature; t 初 The initial temperature; t 绝 The current adiabatic temperature; m 当 γ represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas; γ represents the gas heat dissipation ratio selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, the initial pressure, and the initial temperature.

[0015] The current pressure is determined based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end.

[0016] Optionally, the process of determining the current adiabatic temperature at the current moment includes:

[0017] According to the work formula for the gas dispenser filling the gas cylinder at the vehicle end, Determine the work done by the gas dispenser on the natural gas in the gas cylinder at the vehicle end, where P is the gas pressure of the gas dispenser on the gas cylinder at the vehicle end, d is the diameter of the gas dispensing pipe of the gas dispenser, and L is the length of the gas dispensing pipe of the gas dispenser.

[0018] The initial gas mass in the vehicle-end gas cylinder is determined based on the initial pressure and the initial temperature; the current gas mass in the vehicle-end gas cylinder is determined based on the gas flow rate and the initial gas mass; and the initial internal energy of the gas in the vehicle-end gas cylinder is determined based on the initial pressure, the initial temperature, and the initial gas mass.

[0019] According to the energy conservation formula U that the gas in the gas cylinder at the vehicle end satisfies under adiabatic conditions... 初 +W=m 当 ·u 绝 Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end, wherein U 初 Let W be the initial internal energy of the gas, and W be the work done. 绝 The internal energy per unit mass of gas in the gas cylinder at the vehicle end under adiabatic conditions;

[0020] Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the gas cylinder at the vehicle end, the current adiabatic pressure of the gas at the current pressurization pressure being filled into the gas cylinder at the vehicle end is estimated.

[0021] Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions is determined.

[0022] Optionally, the current pressure is determined based on the current temperature and the relationship between the gas temperature and gas pressure in the vehicle-end gas cylinder, including:

[0023] The relationship between the current temperature and the predetermined gas temperature and pressure in the vehicle-end gas cylinder is satisfied by formula P. 当 =α*t 当 2 +β*t 当 +δ, determines the current pressure; where P 当 The current pressure is given by α, β, and δ, which are three constant coefficients determined in advance by fitting discrete experimental data formed by multiple sets of gas temperatures and corresponding gas pressures in the gas cylinders at the vehicle end.

[0024] Optionally, the process of determining the heat dissipation ratio set includes:

[0025] Under different ambient temperatures and different initial gas pressures and temperatures inside the vehicle-end gas cylinder, the natural gas is filled into the vehicle-end gas cylinder to different filling pressures and temperatures.

[0026] For each group of filling pressure and filling temperature, the heat dissipation is calculated to obtain the corresponding heat dissipation sample, and the filling temperature and the initial temperature corresponding to the heat dissipation sample are respectively used as the filling temperature sample and the initial temperature sample.

[0027] The ratio of the difference between each group of filling temperature samples and initial temperature samples to the corresponding heat dissipation samples is calculated to obtain a heat dissipation ratio set that includes the gas heat dissipation ratio corresponding to different ambient temperatures, different initial air pressures, and different filling temperatures.

[0028] A compressed natural gas (CNG) refueling device includes:

[0029] The data acquisition module is used to collect the current ambient temperature, the initial pressure and initial temperature inside the gas cylinder at the vehicle end, and to detect the gas flow rate of the natural gas being filled into the gas cylinder at the vehicle end.

[0030] The data processing module is used to estimate and determine the current pressure and current temperature inside the gas cylinder at the vehicle end based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate.

[0031] The comparison and judgment module is used to determine whether the current pressure and the current temperature meet the conditions for stopping gas refueling; wherein, the conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference; if yes, then gas refueling into the gas cylinder at the vehicle end is stopped; if no, then gas refueling into the gas cylinder at the vehicle end continues, and the current pressure and the current temperature are used as the new initial pressure and initial temperature, respectively, and the step of detecting the gas flow rate of natural gas being charged into the gas cylinder at the vehicle end is repeated until the current pressure and the current temperature meet the conditions for stopping gas refueling.

[0032] Optionally, the data processing module specifically includes:

[0033] The first calculation unit is used to determine the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time, based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, using the principle of energy conservation.

[0034] The second calculation unit is used to calculate the heat dissipation formula Q satisfied by the gas in the gas cylinder at the vehicle end. 散 =m 当 ·C·(t 绝 -t 当 )=γ·(t 当 -t 初 ), determine the current temperature; where Q 散t is the amount of heat dissipated by the gas in the gas cylinder at the vehicle end; 当 The current temperature; t 初 The initial temperature; t 绝 The current adiabatic temperature; m 当 γ represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas; γ represents the gas heat dissipation ratio selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, the initial pressure, and the initial temperature.

[0035] The third calculation unit is used to determine the current pressure based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end.

[0036] Optionally, the first calculation unit is specifically used to calculate the work done by the gas dispenser filling the gas cylinder at the vehicle end according to the formula. The work done by the gas dispenser on the natural gas in the vehicle-end gas cylinder is determined, where P is the gas pressure dispensed by the gas dispenser to the vehicle-end gas cylinder, d is the diameter of the gas dispensing pipe of the gas dispenser, and L is the length of the gas dispensing pipe of the gas dispenser; the initial gas mass in the vehicle-end gas cylinder is determined based on the initial pressure and the initial temperature; the current gas mass in the vehicle-end gas cylinder is determined based on the gas flow rate and the initial gas mass; the initial internal energy of the gas in the vehicle-end gas cylinder is determined based on the initial pressure, the initial temperature, and the initial gas mass; and the energy conservation formula U satisfies the gas in the vehicle-end gas cylinder under adiabatic conditions is applied. 初 +W=m 当 ·u 绝 Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end; wherein, U 初 Let W be the initial internal energy of the gas, and W be the work done. 绝 The internal energy per unit mass of gas in the vehicle-end gas cylinder under adiabatic conditions is given. Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the vehicle-end gas cylinder, the current adiabatic pressure of the gas at the current pressurization pressure when filled into the vehicle-end gas cylinder is estimated. Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, the current adiabatic temperature of the vehicle-end gas cylinder under adiabatic conditions is determined.

[0037] A compressed natural gas (CNG) refueling device includes:

[0038] Memory, used to store computer programs;

[0039] A processor for executing the computer program to implement the steps of the compressed natural gas refueling method as described in any of the preceding claims.

[0040] A computer-readable storage medium storing a computer program that is executed by a processor to implement the steps of the compressed natural gas refueling method as described in any of the preceding claims.

[0041] This invention provides a method, apparatus, device, and computer-readable storage medium for refueling compressed natural gas (CNG). The CNG refueling method includes: acquiring the current ambient temperature and the initial pressure and initial temperature inside the vehicle-end gas cylinder, and detecting the gas flow rate of CNG being supplied to the vehicle-end gas cylinder; estimating and determining the current pressure and current temperature inside the vehicle-end gas cylinder based on the current ambient temperature, initial pressure, initial temperature, and gas flow rate; determining whether the current pressure and current temperature meet the conditions for stopping refueling; wherein, the conditions for stopping refueling are that the difference between the current pressure and the ultimate pressure of the vehicle-end gas cylinder is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the vehicle-end gas cylinder is less than a preset temperature difference; if yes, refueling into the vehicle-end gas cylinder is stopped; if no, refueling into the vehicle-end gas cylinder continues, and the current pressure and current temperature are used as the new initial pressure and initial temperature, respectively, and the step of detecting the gas flow rate of CNG being supplied to the vehicle-end gas cylinder is repeated until the current pressure and current temperature meet the conditions for stopping refueling.

[0042] In this application, during the refueling process of compressed natural gas, the initial pressure and temperature of the gas in the vehicle-end gas cylinder are estimated by combining the initial pressure and temperature of the gas in the previous moment and the gas flow rate during the refueling process. Based on this, the estimated gas pressure and temperature are compared with the extreme pressure and extreme temperature of the vehicle-end gas cylinder. When at least one of them approaches the extreme value, the refueling of the vehicle-end gas cylinder is stopped. This maximizes the amount of gas in the vehicle-end gas cylinder while ensuring the safety of the vehicle-end gas cylinder, and to a certain extent alleviates the problem of insufficient refueling after the temperature of the vehicle-end gas cylinder cools down, thereby improving user satisfaction to a certain extent. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A schematic flowchart illustrating a method for dispensing compressed natural gas using a refueling machine, provided as an embodiment of this application;

[0045] Figure 2Auxiliary diagram for pressure drop in a pipe for adiabatic flow of compressible fluid;

[0046] Figure 3 This is a structural block diagram of a compressed natural gas refueling device provided in an embodiment of this application. Detailed Implementation

[0047] For gas cylinders in automobiles, it is generally believed that the maximum pressure they can withstand is 26MPa. However, during the process of filling the gas cylinder with natural gas, the pressure inside the cylinder cannot be directly measured. The pressure can only be roughly determined based on the filling pressure of the gas dispenser. Then, the filling of the gas cylinder is stopped when the filling pressure reaches about 20MPa.

[0048] However, for gas cylinders, the filling pressure is generally slightly higher than the pressure inside the cylinder. On the other hand, the natural gas in the gas cylinder in the vehicle will inevitably heat up during the filling process. Even if the pressure in the cylinder reaches 20MPa at this time, after filling stops, the temperature of the natural gas in the cylinder will drop due to heat exchange between the cylinder and the external environment. Based on the direct proportional relationship between gas pressure and gas temperature in the cylinder, it can be known that after the natural gas in the cylinder is completely cooled, the gas pressure in the cylinder will be much less than 20MPa, which means that the cylinder is not fully filled.

[0049] Therefore, this application provides a technical solution for adding natural gas into a vehicle's gas cylinder, which to a certain extent increases the amount of gas in the cylinder and improves the user's gas filling experience.

[0050] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] like Figure 1 As shown, Figure 1 This is a schematic flowchart illustrating a method for dispensing compressed natural gas (CNG) using a CNG dispenser, as provided in an embodiment of this application. The process of this CNG dispensing method may include:

[0052] S11: Obtain the current ambient temperature and the initial pressure and initial temperature inside the gas cylinder at the vehicle end.

[0053] S12: Detects the flow rate of natural gas being supplied to the gas cylinder at the vehicle end.

[0054] It should be noted that there are no pressure and temperature sensors inside the gas cylinder at the vehicle end, so the gas pressure and temperature inside the cylinder cannot be directly detected. However, pressure and temperature sensors are installed at the filling port on the refueling machine, which is connected to the gas cylinder via a pipe. At the initial moment of filling the gas cylinder into the vehicle, the pressure and temperature data measured by the pressure and temperature sensors on the refueling machine can be considered as the current gas pressure and temperature in the vehicle end cylinder. Therefore, at the initial moment of filling the vehicle end cylinder, the pressure and temperature data measured by the pressure and temperature sensors on the refueling machine can be directly used as the initial pressure and initial temperature, respectively.

[0055] In addition to pressure and temperature sensors, the gas dispenser is also equipped with a flow meter, which can monitor the flow rate of gas being pumped into the gas cylinder at the vehicle end through the filling pipe in real time.

[0056] S13: Based on the current ambient temperature, initial pressure, initial temperature and gas flow rate, estimate and determine the current pressure and current temperature inside the gas cylinder at the vehicle end.

[0057] It is understandable that for a vehicle-mounted gas cylinder with a fixed volume, its internal structure should satisfy the gas equation P*V=n*Z*R*T; where P is the gas pressure; V is the volume of the vehicle-mounted gas cylinder; Z is the compressibility factor inside the vehicle-mounted gas cylinder, determined by n*R and the gas temperature T inside the cylinder; n is the amount of compressed natural gas, in moles; and R is the thermodynamic constant, 8.3145 J / (K*mol). Therefore, it can be seen that there is a certain correlation between the gas pressure, gas temperature, and gas quantity inside the vehicle-mounted gas cylinder. Thus, in this embodiment, the current pressure and temperature inside the vehicle-mounted gas cylinder can be estimated based on this correlation, thereby achieving real-time estimation of the gas pressure and temperature inside the vehicle-mounted gas cylinder.

[0058] S14: Determine whether the current pressure and temperature meet the conditions for stopping gas supply; if yes, proceed to S15; otherwise, proceed to S16.

[0059] The conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than the preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than the preset temperature difference.

[0060] S15: Stop adding gas to the gas cylinder at the vehicle end;

[0061] S16: Continue adding gas to the gas cylinder at the vehicle end, and use the current pressure and current temperature as the new initial pressure and initial temperature respectively, and proceed to S12.

[0062] Based on the estimated current pressure and temperature inside the vehicle-end gas cylinder, these current pressure and temperature can be compared with the limit pressure and limit temperature, respectively. If the current pressure or temperature is close to the limit pressure or temperature, it indicates that continuing to fill the cylinder would pose a safety hazard, and filling should be stopped. Conversely, if the current pressure and temperature inside the cylinder are significantly lower than the limit pressure and temperature, it indicates that filling can continue. The estimated current pressure and temperature are used as the initial pressure and temperature for the next estimated moment, enabling iterative estimation of gas pressure and temperature inside the cylinder. This indirectly allows for real-time monitoring of gas pressure and temperature inside the cylinder. If either value reaches its corresponding limit, filling should be stopped.

[0063] Based on the above discussion, compared to the conventional method of refueling vehicle-end gas cylinders using current gas dispensers, this embodiment sets different conditions for stopping refueling. It comprehensively considers both cylinder pressure and temperature; refueling stops when either the gas pressure or temperature inside the vehicle-end gas cylinder reaches its corresponding extreme value. According to GB24160 "Compressed Natural Gas Cylinders with Steel Inner Liners for Vehicles," the temperature variation of the wound cylinder material should be within the range of -40℃ to 82℃, and the maximum permissible working pressure of the wound cylinder is 1.3 times the nominal pressure. Therefore, this embodiment considers both temperature and pressure limits inside the vehicle-end gas cylinder during the refueling process, which helps to more comprehensively ensure the safety of gas refueling at the vehicle-end cylinder. Furthermore, the extreme temperature and extreme pressure referred to in this embodiment are the maximum temperature and maximum pressure that the vehicle-end gas cylinder can withstand, respectively.

[0064] Furthermore, in this application, gas filling stops only when the gas pressure or temperature in the gas cylinder at the vehicle end reaches a limit value. Compared to the prior art where gas filling stops when the filling pressure of the gas dispenser reaches 20MPa, it is clear that the conditions for stopping gas filling set in this embodiment can ensure that more natural gas is filled into the gas cylinder at the vehicle end.

[0065] Based on this, this embodiment estimates the real-time pressure and temperature inside the gas cylinder at the vehicle end, rather than using the gas filling pressure of the gas dispenser to characterize the gas state inside the gas cylinder at the vehicle end. This improves the accuracy of determining whether to stop filling based on the estimated current pressure and temperature to a certain extent.

[0066] In summary, this application, during the refueling process of compressed natural gas, combines the initial pressure and temperature of the gas in the vehicle-end cylinder at the previous moment with the gas flow rate during the refueling process, i.e., the monitored gas flow rate, to achieve real-time estimation of the gas pressure and temperature in the vehicle-end cylinder. Based on this, the estimated gas pressure and temperature are compared with the extreme pressure and extreme temperature of the vehicle-end cylinder, respectively. When at least one of them approaches the extreme value, the refueling of the vehicle-end cylinder is stopped. This maximizes the amount of gas refueling in the vehicle-end cylinder while ensuring the safety of the cylinder, and to a certain extent alleviates the problem of insufficient refueling after the temperature inside the cylinder cools down, thereby improving user satisfaction to some extent.

[0067] Based on any of the above embodiments, in an optional embodiment of this application, the process of estimating the current pressure and current temperature of the gas cylinder at the vehicle end in step S13 may include:

[0068] S131: Based on the current ambient temperature, initial pressure, initial temperature, and gas flow rate, and using the principle of energy conservation, determine the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time.

[0069] S132: According to the heat dissipation formula Q satisfied by the gas in the gas cylinder at the vehicle end. 散 =m 当 ·C·(t 绝 -t 当 )=γ·(t 当 -t 初 ), determine the current temperature.

[0070] Among them, Q 散 The amount of heat dissipated by the gas in the gas cylinder at the vehicle end; t 当 t represents the current temperature. 初 t is the initial temperature; 绝 The current adiabatic temperature; m 当 γ represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas; γ represents the gas heat dissipation ratio selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, initial pressure, and initial temperature.

[0071] S133: Determine the current pressure based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end.

[0072] In this embodiment, during the estimation of the current pressure and temperature of the gas cylinder at the vehicle end, the current temperature is estimated first, and then the current pressure is estimated by utilizing the correlation between the gas temperature and gas pressure inside the gas cylinder.

[0073] In estimating the current temperature inside the gas cylinder at the vehicle end, the process of filling the gas cylinder with gas of Δm detected by the gas flow meter, from the initial pressure and initial temperature, to the current pressure and current temperature, can be equivalent to two stages. The first stage assumes that the gas cylinder at the vehicle end is under completely adiabatic conditions, and gas of Δm detected by the gas flow meter is filled into the gas cylinder, so that the temperature inside the gas cylinder reaches the current adiabatic temperature. The second stage is that heat exchange occurs between the gas cylinder at the current adiabatic temperature and the environment, and the gas temperature and gas pressure drop to the current temperature and current pressure, respectively.

[0074] Although the gas in the vehicle-end gas cylinder also exchanges heat with the environment during the actual gas filling process, the process of exchanging heat during gas filling is equivalent to two stages: adiabatic filling and heat exchange. This can simplify the difficulty of estimating the temperature inside the vehicle-end gas cylinder to some extent.

[0075] Based on the law of conservation of energy, the energy change within the vehicle-end gas cylinder during the adiabatic filling process mainly originates from the work done by the gas dispenser on the natural gas during filling, and the change in the total internal energy of the gas in the cylinder due to the newly added natural gas. The work done by the gas dispenser on the natural gas can be calculated based on the filling pressure, pipe cross-section, and pipe length during the filling process. However, the change in the contents of the vehicle-end gas cylinder is related to the temperature change and the change in gas mass. Therefore, this application can calculate the current adiabatic temperature based on this correlation.

[0076] In one optional embodiment of this application, the process of obtaining the current adiabatic temperature of the vehicle-end gas cylinder may include:

[0077] S1311: Based on the work formula for the gas dispenser filling the gas cylinder at the vehicle end. Determine the work done by the gas dispenser on the natural gas in the gas cylinder at the vehicle end.

[0078] Where P is the gas pressure supplied by the gas dispenser to the gas cylinder at the vehicle end, d is the diameter of the gas dispenser's gas pipeline, and L is the length of the gas dispenser's gas pipeline.

[0079] It should be noted that the gas pressure in this embodiment can be the real-time gas pressure measured by the pressure sensor installed on the gas dispenser when the gas dispenser is filling the gas cylinder at the vehicle end.

[0080] S1312: Determine the initial gas mass in the gas cylinder at the vehicle end based on the initial pressure and initial temperature; determine the current gas mass in the gas cylinder at the vehicle end based on the gas flow rate and initial gas mass; determine the initial internal energy of the gas in the gas cylinder at the vehicle end based on the initial pressure, initial temperature, and initial gas mass.

[0081] Within a fixed-volume gas cylinder at the vehicle end, based on the gas equation P*V=n*Z*R*T, it is known that the pressure, temperature, and mass of natural gas should satisfy a certain correlation. Therefore, at the initial moment when gas begins to be filled into the gas cylinder at the vehicle end, the initial gas mass in the gas cylinder can be calculated based on the initial pressure and initial temperature. During the gas filling process, the gas flow meter installed on the gas dispenser can detect the gas flow rate in real time, which makes the change in gas volume in the gas cylinder at the vehicle end known. Based on this change in gas volume and the initial gas mass at the initial moment, the current gas mass in the gas cylinder at the vehicle end can be determined.

[0082] Based on this, the internal energy of the gas in the gas cylinder at the vehicle end is a function related to the gas mass, gas temperature, and gas pressure. Therefore, the internal energy of the gas in the gas cylinder at the vehicle end before filling with gas can be calculated based on the initial pressure, initial temperature, and initial gas mass.

[0083] The calculation process for parameters such as initial gas mass and initial internal energy in the above process is a conventional thermodynamic calculation process and will not be described in detail in this application.

[0084] S1313: According to the energy conservation formula U0 of the gas in the gas cylinder at the vehicle end under adiabatic conditions... 初 +W=m 当 ·u 绝 Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end.

[0085] Among them, U 初 Let W be the initial internal energy of the gas, and W be the work done; m 当 The current gas mass; u 绝 Let be the internal energy per unit mass of gas in the gas cylinder at the vehicle end under adiabatic conditions.

[0086] S1314: Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the gas cylinder at the vehicle end, estimate the current adiabatic pressure of the gas filled into the gas cylinder at the vehicle end.

[0087] S1315: Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, determine the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions.

[0088] As mentioned earlier, the internal energy of a gas is a function of its mass, temperature, and pressure. Therefore, within a gas cylinder at the vehicle's end with a fixed volume, there is a certain correlation between the internal energy per unit mass of gas, the gas pressure, and the adiabatic temperature. Given the work done by the gas dispenser on the gas in the vehicle's end cylinder and the initial internal energy of the gas, the internal energy per unit mass of gas in the end cylinder can be calculated by combining this with the current gas mass. If the pressure under adiabatic conditions within the end cylinder is also known, the current adiabatic temperature can be determined.

[0089] The pressure value of the gas cylinder at the vehicle end under insulated conditions can be estimated based on the current pressurization pressure of the gas dispenser filling the gas cylinder at the vehicle end.

[0090] Specifically, the process of a gas dispenser filling natural gas into a vehicle-end cylinder through a filling pipeline can be considered as an adiabatic flow process of a compressible fluid. During this process, the natural gas flows from the dispenser to the vehicle-end cylinder, and there is a pressure drop in the gas pressure. (Refer to...) Figure 2 The auxiliary diagram of pressure drop in a pipe for adiabatic flow of compressible fluid is a diagram that characterizes the correspondence between different fluids under different flow velocity conditions and the ratio of inlet air pressure to outlet air pressure in the pipe.

[0091] like Figure 2 As shown, G1 / G cni It is the horizontal axis in the auxiliary diagram of pressure drop in a pipe for adiabatic flow of compressible fluid, and satisfies... G1 = W / A is a constant coefficient, where W is the gas mass flow rate collected by the gas flow meter, A is the cross-sectional area of ​​the pipe, P and T are the dispensing pressure and temperature measured by the pressure and temperature sensors on the gas dispenser, respectively, and M is the molecular weight of natural gas (which can be determined based on a comprehensive fitting of the natural gas composition). Furthermore, P / P 绝 The vertical axis of the auxiliary diagram for pressure drop in a pipe with adiabatic flow of compressible fluid is P. 绝 This represents the current adiabatic pressure of the gas cylinder at the vehicle end under adiabatic conditions.

[0092] Furthermore, the output speed of natural gas within the pipeline meets the requirements. Where D is the pipe diameter, L is the pipe length, and λ is the friction coefficient (related to the Reynolds number and the pipe), which can be taken as 0.0235 here. For different calculated N values, different curves are selected in the auxiliary graph of pipe pressure drop for adiabatic flow of compressible fluid, and the P / P ratio is read from the graph based on the calculated abscissa value. 绝 The current adiabatic pressure is determined based on the current inflation pressure. After obtaining the current adiabatic pressure, the current adiabatic temperature can be derived based on the relationship between the current adiabatic pressure and the current adiabatic temperature. This will not be described in detail in this embodiment.

[0093] Based on the above discussion, once the current adiabatic temperature is determined, the heat energy lost from the gas cylinder at the vehicle end due to heat exchange between the current adiabatic temperature and the external environment will satisfy Q. 散 =m 当 ·C·(t 绝 -t 当 ).

[0094] Based on this, for the vehicle-mounted gas cylinder, whether it is considered as filling with gas from the initial pressure and temperature to the current pressure and temperature, the amount of heat dissipated when reaching the current pressure and temperature is the same, regardless of whether it is considered as filling with gas first for insulation and then for heat dissipation, or as heat dissipation during the filling process. Therefore, in this embodiment, Q is further defined. 散 =γ·(t) 当 -t 初 In other words, during the process of filling the gas cylinder at the vehicle end with gas, the gas temperature changes from the initial temperature to the current temperature and the total heat dissipation satisfy a certain proportional relationship. This proportionality coefficient is γ, which is the gas heat dissipation ratio selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, initial pressure, and initial temperature.

[0095] The process of determining this set of heat dissipation ratios may include:

[0096] S21: Fill the gas cylinders at different ambient temperatures, initial gas pressures and initial temperatures within the cylinders at different locations with natural gas to different filling pressures and temperatures.

[0097] S22: Calculate the heat dissipation for each group of filling pressure and filling temperature to obtain the corresponding heat dissipation sample, and use the filling temperature and initial temperature corresponding to the heat dissipation sample as the filling temperature sample and initial temperature sample, respectively.

[0098] S23: Perform a ratio calculation on the difference between each group of filling temperature samples and initial temperature samples and the corresponding heat dissipation samples to obtain a heat dissipation ratio set that includes the corresponding gas heat dissipation ratios under different ambient temperatures, different initial air pressures, and different filling temperatures.

[0099] For existing CNG vehicles, the size and model of the gas cylinders at the vehicle end are relatively fixed. When determining the heat dissipation ratio set, the corresponding heat dissipation ratio set can be determined separately for each model of gas cylinder at the vehicle end.

[0100] In determining the heat dissipation ratio set corresponding to a specific model of vehicle-mounted gas cylinder, multiple sampling ambient temperatures can be set based on the actual operating temperature range of the vehicle. At each sampling ambient temperature, a certain amount of gas is filled into the vehicle-mounted gas cylinder with different initial pressures and temperatures. Since this process is to sample the pressure and temperature inside the vehicle-mounted gas cylinder, a temperature sensor can be attached to the side wall of the vehicle-mounted gas cylinder to detect the temperature inside. Given that the mass and temperature of the gas before and after filling the vehicle-mounted gas cylinder are known, the change in internal energy of the vehicle-mounted gas cylinder before and after filling can be calculated. Based on the law of conservation of energy, and based on the difference between the initial change in internal energy of the gas inside the vehicle-mounted gas cylinder and the work done by the gas dispenser on the filling gas and the heat dissipation of the vehicle-mounted gas cylinder, the heat dissipation of the vehicle-mounted gas cylinder can be calculated.

[0101] After calculating the heat dissipation, the difference between the initial temperature and the filling temperature before and after filling is calculated, and the result is compared with the heat dissipation to determine a gas heat dissipation ratio. In the same way, the gas heat dissipation ratios corresponding to the filling state of the gas cylinder at the vehicle end under various initial temperatures and initial pressures can be calculated. The various gas heat dissipation ratios can then form a heat dissipation ratio set.

[0102] Of course, in practical applications, a large number of gas heat dissipation samples obtained by solving the problem can also be used to obtain curves showing how the proportion of gas heat dissipation changes with ambient temperature, gas pressure, and gas temperature.

[0103] Furthermore, based on the above process of determining the heat dissipation ratio set, it can be seen that each gas heat dissipation ratio is related not only to the ambient temperature, but also to factors such as the initial temperature and initial pressure of the gas cylinder at the vehicle end, as well as the filling temperature and filling pressure after filling. However, when selecting a suitable gas heat dissipation ratio from the heat dissipation ratio set, the current temperature and current pressure of the gas cylinder at the vehicle end after filling are unknown. In order to select a more accurate gas heat dissipation ratio, the current ambient temperature, initial temperature, initial pressure, and the change in gas mass from the initial temperature to the current state can be used as the basis for finding a suitable gas heat dissipation ratio.

[0104] In other words, during the process of forming a set of heat dissipation ratios, each gas heat dissipation ratio can correspond to relevant parameters such as ambient temperature, initial temperature, initial pressure, and change in the mass of the filling gas. When selecting a suitable gas heat dissipation ratio, the ratio whose parameters are closest to the current time can be chosen. However, as shown in the heat dissipation formula Q above... 散 =m 当 ·C·(t 绝 -t 当 )=γ·(t 当 -t初 The calculation is performed in the engine to estimate the current temperature inside the gas cylinder at the vehicle end.

[0105] Furthermore, it is understandable that the heat dissipation ratio of each gas in the heat dissipation ratio set is a set of discrete quantities. When actually selecting a suitable gas heat dissipation ratio, there may not be any relevant parameters such as ambient temperature, initial temperature, initial pressure, and change in the mass of the filling gas that are completely consistent with the current situation. However, we can select the two or more sets of relevant parameters such as ambient temperature, initial temperature, initial pressure, and change in the mass of the filling gas that are closest to the current situation, and perform a weighted average calculation or use interpolation to obtain a gas heat dissipation ratio that meets the current conditions.

[0106] As mentioned earlier, within a fixed-volume gas cylinder at the vehicle end, there is a certain correlation between gas temperature and gas pressure. This correlation, along with the current temperature, can be used to determine the current pressure within the gas cylinder at the vehicle end.

[0107] In one optional embodiment of this application, the process of determining the current pressure based on the current temperature of the gas cylinder at the vehicle end may include:

[0108] Based on the current temperature and the predetermined relationship between the gas temperature and pressure in the gas cylinder at the vehicle end, according to formula P... 当 =α*t 当 2 +β*t 当 +δ, determines the current pressure; where P 当 The pressure is denoted as α, β, and δ, which are three constant coefficients determined by fitting discrete experimental data obtained from multiple sets of gas temperatures and corresponding gas pressures inside the gas cylinders at the vehicle end.

[0109] Inside the gas cylinder at the vehicle end, the gas equation P*V=n*Z*R*T is satisfied; where P is the gas pressure inside the gas cylinder at the vehicle end; V is the gas cylinder volume; Z is the compressibility factor, which is determined by the gas constant n*R and the gas temperature T; n is the amount of substance of compressed natural gas, in mol; R is the thermodynamic constant, which can take the value of 8.3145J / (K*mol).

[0110] Since the cylinder volumes V and R are known, n can be obtained directly based on the amount of gas filled, or it can be considered a known number. Therefore, the pressure of the compressed gas inside the cylinder can be P = f(Z, T).

[0111] The compressibility factor Z is a function of the relative pressure and relative temperature of natural gas. The relative pressure Pr is the ratio of the gas pressure P to the absolute thermodynamic critical pressure Pc of natural gas. The relative temperature Tr is the ratio of the gas temperature T to the absolute thermodynamic critical temperature Tc. Where Pc and Tc are the critical pressure and critical temperature for compressing natural gas at the absolute thermodynamic critical state; Pc can be 4.64091 MPa, and Tc can be 190.7 K. The formula for relative pressure is: The formula for the relative temperature is: In practical applications, the compressibility factor Z can be obtained through Standing-Katz lookup tables or formulas. Furthermore, through iterative formula analysis, it can be determined that the pressure inside the gas cylinder is a function of temperature, P = f(T). By measuring filling data from different gas cylinders at natural gas filling stations and fitting multiple sets of discrete experimental data using a quadratic polynomial, the polynomial formula P = α*t can be obtained. 终 2 +β*t 终 +δ;

[0112] Taking a 20MPa gas cylinder at the vehicle end as an example, a set of coefficient parameters was obtained through fitting:

[0113] α = -1.71372E-5, standard deviation is 5.78706E-7;

[0114] β = 0.11502E0, standard deviation is 2.18457E-5;

[0115] δ = 1.827761E1, with a standard deviation of 7.43924E-4.

[0116] Based on the above embodiments, this application provides a specific implementation method for real-time estimation of the current pressure and temperature of the gas cylinder at the vehicle end. However, it is understood that in practical applications, the method for estimating the current pressure and temperature inside the gas cylinder is not limited to the method provided in the above embodiments. For example, in practical applications, neural network training can be performed in advance to create a correlation model between the current pressure and temperature and the current ambient temperature, initial pressure, initial temperature, and gas flow rate of the gas cylinder at the vehicle end. When actually estimating the current pressure and temperature, the current ambient temperature, initial pressure, initial temperature, and gas flow rate can be directly input into the correlation model to directly obtain the current pressure and temperature of the gas cylinder at the vehicle end. Furthermore, this correlation model can be obtained by repeatedly filling the gas cylinder at various ambient temperatures, different initial pressures, initial temperatures, and different gas flow rates, measuring the gas temperature and gas pressure after filling, and using the ambient temperature, initial pressure, initial temperature, gas flow rate, and the corresponding refilled gas temperature and gas pressure as samples for neural network training.

[0117] Of course, in practical applications, the correlation curves between the gas pressure and gas temperature after filling the gas cylinder and the corresponding ambient temperature, initial pressure, initial temperature and gas flow rate can be directly fitted. In short, the correlation between the gas pressure and gas temperature after filling the gas cylinder at the vehicle end and the corresponding ambient temperature, initial pressure, initial temperature and gas flow rate can be determined in advance.

[0118] Similarly, the data such as the current adiabatic temperature and the proportion of gas heat dissipation can also be obtained through computer training or other methods, which will not be listed in this application.

[0119] The following describes the compressed natural gas refueling device provided in the embodiments of the present invention. The compressed natural gas refueling device described below can be referred to in correspondence with the compressed natural gas refueling method described above.

[0120] Figure 3 This is a structural block diagram of a compressed natural gas refueling device provided in an embodiment of the present invention, with reference to... Figure 3 The compressed natural gas refueling unit in the middle may include:

[0121] The data acquisition module 100 is used to acquire the current ambient temperature and the initial pressure and initial temperature inside the gas cylinder at the vehicle end, and to detect the gas flow rate of the natural gas being filled into the gas cylinder at the vehicle end.

[0122] The data processing module 200 is used to estimate and determine the current pressure and current temperature inside the gas cylinder at the vehicle end based on the current ambient temperature, the initial pressure, the initial temperature and the gas flow rate;

[0123] The comparison and judgment module 300 is used to determine whether the current pressure and the current temperature meet the conditions for stopping gas refueling; wherein, the conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference; if yes, then gas refueling into the gas cylinder at the vehicle end is stopped; if no, then gas refueling into the gas cylinder at the vehicle end continues, and the current pressure and the current temperature are used as the new initial pressure and initial temperature, respectively, and the step of detecting the gas flow rate of the natural gas being charged into the gas cylinder at the vehicle end is repeated until the current pressure and the current temperature meet the conditions for stopping gas refueling.

[0124] In one optional embodiment of this application, the data processing module 200 specifically includes:

[0125] The first calculation unit is used to determine the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time, based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, using the principle of energy conservation.

[0126] The second calculation unit is used to calculate the heat dissipation formula Q satisfied by the gas in the gas cylinder at the vehicle end. 散 =m 当 ·C·(t 绝 -t 当 )=γ·(t 当 -t 初 ), determine the current temperature; where Q 散 t is the amount of heat dissipated by the gas in the gas cylinder at the vehicle end; 当 The current temperature; t 初 The initial temperature; t 绝 The current adiabatic temperature; m 当 γ represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas; γ represents the gas heat dissipation ratio selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, the initial pressure, and the initial temperature.

[0127] The third calculation unit is used to determine the current pressure based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end.

[0128] In one optional embodiment of this application, the first calculation unit is specifically used to perform work according to the formula for filling the gas cylinder at the vehicle end by the gas dispenser. The work done by the gas dispenser on the natural gas in the vehicle-end gas cylinder is determined, where P is the gas pressure dispensed by the gas dispenser to the vehicle-end gas cylinder, d is the diameter of the gas dispensing pipe of the gas dispenser, and L is the length of the gas dispensing pipe of the gas dispenser; the initial gas mass in the vehicle-end gas cylinder is determined based on the initial pressure and the initial temperature; the current gas mass in the vehicle-end gas cylinder is determined based on the gas flow rate and the initial gas mass; the initial internal energy of the gas in the vehicle-end gas cylinder is determined based on the initial pressure, the initial temperature, and the initial gas mass; and the energy conservation formula U satisfies the gas in the vehicle-end gas cylinder under adiabatic conditions is applied. 初 +W=m 当 ·u 绝 Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end; wherein, U 初 Let W be the initial internal energy of the gas, and W be the work done. 绝The internal energy per unit mass of gas in the vehicle-end gas cylinder under adiabatic conditions is given. Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the vehicle-end gas cylinder, the current adiabatic pressure of the gas at the current pressurization pressure when filled into the vehicle-end gas cylinder is estimated. Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, the current adiabatic temperature of the vehicle-end gas cylinder under adiabatic conditions is determined.

[0129] In an optional embodiment of this application, the third calculation unit is used to calculate the current temperature and a predetermined relationship formula P between the gas temperature and gas pressure in the vehicle-end gas cylinder. 当 =α*t 当 2 +β*t 当 +δ, determines the current pressure; where P 当 The current pressure is given by α, β, and δ, which are three constant coefficients determined in advance by fitting discrete experimental data formed by multiple sets of gas temperatures and corresponding gas pressures in the gas cylinders at the vehicle end.

[0130] In an optional embodiment of this application, a set operation unit is further included, used to fill the vehicle-end gas cylinder with natural gas to different filling pressures and filling temperatures under different ambient temperatures and different initial gas pressures and initial temperatures in the vehicle-end gas cylinder; calculate the heat dissipation for each set of filling pressures and filling temperatures to obtain corresponding heat dissipation samples, and use the filling temperature and initial temperature corresponding to the heat dissipation samples as filling temperature samples and initial temperature samples, respectively; perform a ratio operation on the difference between each set of filling temperature samples and initial temperature samples and the corresponding heat dissipation samples to obtain a heat dissipation ratio set containing the gas heat dissipation ratios corresponding to different ambient temperatures, different initial gas pressures, and different filling temperatures.

[0131] The compressed natural gas (CNG) dispenser refueling device of this embodiment is used to implement the aforementioned CNG dispenser refueling method. Therefore, the specific implementation method of the CNG dispenser refueling device can be found in the embodiment section of the CNG dispenser refueling method above, and will not be repeated here.

[0132] This application also provides an embodiment of a compressed natural gas refueling device, which may include:

[0133] Memory, used to store computer programs;

[0134] A processor for executing the computer program to implement the steps of the compressed natural gas refueling method as described in any of the preceding claims.

[0135] The process of dispensing compressed natural gas using a gas dispenser, executed by the processor, may include:

[0136] The system acquires the current ambient temperature, the initial pressure and initial temperature inside the vehicle-mounted gas cylinder, and detects the gas flow rate of the natural gas being filled into the vehicle-mounted gas cylinder.

[0137] Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, the current pressure and temperature inside the gas cylinder at the vehicle end are estimated and determined.

[0138] Determine whether the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference.

[0139] If so, then stop adding gas to the gas cylinder at the vehicle end;

[0140] If not, continue adding gas to the gas cylinder at the vehicle end, and use the current pressure and the current temperature as the new initial pressure and initial temperature, respectively, and repeat the step of detecting the gas flow rate of the natural gas being added to the gas cylinder at the vehicle end until the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than the preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than the preset temperature difference.

[0141] In this embodiment, the compressed natural gas (CNG) refueling equipment can perform real-time calculations on the gas pressure and temperature inside the vehicle-end gas cylinder during the refueling process. Based on the estimated gas pressure and temperature, as well as more reasonable conditions for stopping refueling, the equipment controls the refueling process inside the vehicle-end gas cylinder. While ensuring the safety of refueling the vehicle-end gas cylinder, it increases the amount of gas in the cylinder, which is beneficial to improving the user experience.

[0142] This application also provides a computer-readable storage medium storing a computer program that is executed by a processor to implement the steps of the compressed natural gas refueling method as described in any of the preceding claims.

[0143] The computer-readable storage medium may be random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0144] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0145] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for dispensing compressed natural gas using a gas dispenser, characterized in that, include: The system acquires the current ambient temperature, the initial pressure and initial temperature inside the vehicle-mounted gas cylinder, and detects the gas flow rate of the natural gas being filled into the vehicle-mounted gas cylinder. Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, the current pressure and temperature inside the gas cylinder at the vehicle end are estimated and determined. Determine whether the current pressure and the current temperature meet the conditions for stopping gas refueling; wherein, the conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference; If so, then stop adding gas to the gas cylinder at the vehicle end; If not, continue adding gas to the gas cylinder at the vehicle end, and use the current pressure and the current temperature as the new initial pressure and initial temperature, respectively, and repeat the step of detecting the gas flow rate of the natural gas being added to the gas cylinder at the vehicle end until the current pressure and the current temperature meet the conditions for stopping gas addition. Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, the current pressure and temperature inside the vehicle-end gas cylinder are estimated and determined, including: Based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, and using the principle of energy conservation, the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time, is determined. According to the heat dissipation formula satisfied by the gas in the gas cylinder at the vehicle end. Determine the current temperature; wherein, The amount of heat dissipated by the gas in the gas cylinder at the vehicle end; The current temperature; The initial temperature; The current adiabatic temperature; C represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas. The gas heat dissipation ratio is selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, the initial pressure, and the initial temperature. The current pressure is determined based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end; The process of determining the current adiabatic temperature at the current moment includes: According to the work formula for the gas dispenser filling the gas cylinder at the vehicle end... Determine the work done by the gas dispenser on the natural gas in the vehicle-end gas cylinder, wherein, The refueling pressure of the gas dispenser to the gas cylinder at the vehicle end. The diameter of the gas dispensing pipe of the gas dispenser is [missing information]. The length of the gas filling pipe of the gas dispenser; The initial gas mass in the vehicle-end gas cylinder is determined based on the initial pressure and the initial temperature; the current gas mass in the vehicle-end gas cylinder is determined based on the gas flow rate and the initial gas mass; and the initial internal energy of the gas in the vehicle-end gas cylinder is determined based on the initial pressure, the initial temperature, and the initial gas mass. According to the energy conservation formula satisfied by the gas in the gas cylinder at the vehicle end under adiabatic conditions... Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end, wherein, The initial internal energy of the gas is... The work done; The internal energy per unit mass of gas in the gas cylinder at the vehicle end under adiabatic conditions; Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the gas cylinder at the vehicle end, the current adiabatic pressure of the gas at the current pressurization pressure being filled into the gas cylinder at the vehicle end is estimated. Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions is determined.

2. The method for dispensing compressed natural gas using a gas dispenser as described in claim 1, characterized in that, Based on the current temperature and the relationship between the gas temperature and gas pressure in the vehicle-end gas cylinder, the current pressure is determined, including: The relationship between the current temperature and the predetermined gas temperature and pressure inside the vehicle-end gas cylinder is satisfied by the following formula. Determine the current pressure; wherein, The current pressure, These are constant coefficients determined by fitting three discrete experimental data sets, which are formed by multiple sets of gas temperatures and corresponding gas pressures inside the gas cylinders at the vehicle end.

3. The method for dispensing compressed natural gas using a dispenser as described in claim 2, characterized in that, The process of determining the heat dissipation ratio set includes: Under different ambient temperatures and different initial gas pressures and temperatures inside the vehicle-end gas cylinder, the natural gas is filled into the vehicle-end gas cylinder to different filling pressures and temperatures. For each group of filling pressure and filling temperature, the heat dissipation is calculated to obtain the corresponding heat dissipation sample, and the filling temperature and the initial temperature corresponding to the heat dissipation sample are respectively used as the filling temperature sample and the initial temperature sample. The ratio of the difference between each group of filling temperature samples and initial temperature samples to the corresponding heat dissipation samples is calculated to obtain a heat dissipation ratio set that includes the gas heat dissipation ratio corresponding to different ambient temperatures, different initial air pressures, and different filling temperatures.

4. A refueling device for compressed natural gas, characterized in that, include: The data acquisition module is used to collect the current ambient temperature, the initial pressure and initial temperature inside the gas cylinder at the vehicle end, and to detect the gas flow rate of the natural gas being filled into the gas cylinder at the vehicle end. The data processing module is used to estimate and determine the current pressure and current temperature inside the gas cylinder at the vehicle end based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate. The comparison and judgment module is used to determine whether the current pressure and the current temperature meet the conditions for stopping gas refueling; wherein, the conditions for stopping gas refueling are that the difference between the current pressure and the ultimate pressure of the gas cylinder at the vehicle end is less than a preset pressure difference and / or the difference between the current temperature and the ultimate temperature of the gas cylinder at the vehicle end is less than a preset temperature difference; if yes, then gas refueling into the gas cylinder at the vehicle end is stopped; if no, then gas refueling into the gas cylinder at the vehicle end continues, and the current pressure and the current temperature are used as the new initial pressure and initial temperature, respectively, and the step of detecting the gas flow rate of the natural gas being charged into the gas cylinder at the vehicle end is repeated until the current pressure and the current temperature meet the conditions for stopping gas refueling; The data processing module specifically includes: The first calculation unit is used to determine the current adiabatic temperature of the gas cylinder at the vehicle end under adiabatic conditions, from the initial time to the current time, based on the current ambient temperature, the initial pressure, the initial temperature, and the gas flow rate, using the principle of energy conservation. The second calculation unit is used to calculate the heat dissipation formula satisfied by the gas in the gas cylinder at the vehicle end. Determine the current temperature; wherein, The amount of heat dissipated by the gas in the gas cylinder at the vehicle end; The current temperature; The initial temperature; The current adiabatic temperature; C represents the current gas mass in the gas cylinder at the vehicle end; C represents the specific heat capacity of natural gas. The gas heat dissipation ratio is selected from a pre-determined set of heat dissipation ratios based on the current ambient temperature, the initial pressure, and the initial temperature. The third calculation unit is used to determine the current pressure based on the current temperature and the relationship between the gas temperature and gas pressure in the gas cylinder at the vehicle end; The first calculation unit is specifically used to perform work according to the formula for filling the gas cylinder at the vehicle end by the gas dispenser. Determine the work done by the gas dispenser on the natural gas in the vehicle-end gas cylinder, wherein, The refueling pressure of the gas dispenser to the gas cylinder at the vehicle end. The diameter of the gas filling pipe of the gas dispenser is [missing information]. The length of the gas filling pipe of the gas dispenser is given; the initial gas mass in the vehicle-end gas cylinder is determined based on the initial pressure and the initial temperature; the current gas mass in the vehicle-end gas cylinder is determined based on the gas flow rate and the initial gas mass; the initial internal energy of the gas in the vehicle-end gas cylinder is determined based on the initial pressure, the initial temperature, and the initial gas mass; and the energy conservation formula satisfied by the gas in the vehicle-end gas cylinder under adiabatic conditions is applied. Determine the internal energy per unit mass of gas in the gas cylinder at the vehicle end; wherein, The initial internal energy of the gas is... The work done; The internal energy per unit mass of gas in the vehicle-end gas cylinder under adiabatic conditions is given. Based on the pressure drop principle of compressible fluid pipelines and the current pressurization pressure of the gas dispenser pressurizing the vehicle-end gas cylinder, the current adiabatic pressure of the gas at the current pressurization pressure when filled into the vehicle-end gas cylinder is estimated. Based on the internal energy per unit mass of gas, the current adiabatic pressure, and the correlation between the internal energy per unit mass of gas, gas pressure, and adiabatic temperature in the adiabatic gas cylinder, the current adiabatic temperature of the vehicle-end gas cylinder under adiabatic conditions is determined.

5. A compressed natural gas refueling device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the compressed natural gas refueling method as described in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement the steps of the compressed natural gas refueling method as described in any one of claims 1 to 3.

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