Hydrogenation gun heating mechanism and temperature control method for low temperature environment

Abstract

This application discloses a heating mechanism and temperature control method for hydrogen refueling guns in low-temperature environments, aiming to solve the problem of gun freezing during hydrogen refueling in low-temperature environments. It includes a pipeline heating unit, a pipeline circulation and venting unit, and a bendable gas heat exchange pipeline. Both the pipeline circulation and venting unit and the pipeline heating unit are installed inside the corresponding gun handle, and the gas heat exchange pipeline is installed inside the corresponding gun head. The pipeline heating unit includes a heating resistance wire and a spiral heating pipeline, with the heating resistance wire wound around the heating pipeline. The pipeline circulation and venting unit includes a venting pipeline and a gas inlet pipe. By setting up both the heating unit and the pipeline circulation and venting unit, gas enters the gun head through the heating pipeline to complete the heat exchange operation, thereby saving energy, improving energy utilization, and ensuring overall temperature uniformity and stability.

Description

Technical Field

[0001] This invention application relates to the field of hydrogen fuel refueling equipment technology, specifically to a hydrogen refueling gun heating mechanism and temperature control method for coping with low-temperature environments. Background Technology

[0002] With the gradual development and popularization of hydrogen energy, hydrogen fuel cell vehicles have become an important part of future new energy vehicles. However, under low temperature conditions, a sudden drop in temperature will cause water to condense and freeze. If no corresponding measures are taken, these ice blocks may block the connection between the hydrogen refueling nozzle and the vehicle interface. In addition, low temperature will make the lubricant more viscous, increasing the resistance to pulling out and making the device unable to be pulled out. Even the hydrogen refueling nozzle often encounters freezing problems during the refueling process, which may lead to the interruption of the operation of the hydrogen refueling station or even damage to the equipment, thereby affecting the user experience and the reliability of hydrogen refueling services.

[0003] Furthermore, existing heating devices typically only heat a specific part of the hydrogen refueling nozzle, failing to fully cover all areas requiring heating. This can result in some components of the nozzle malfunctioning at low temperatures, and localized heating can easily cause burns.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] In view of at least one of the above technical problems, this disclosure provides a hydrogen refueling gun heating mechanism and temperature control method for coping with low temperature environments, aiming to solve the problem of frozen guns during the hydrogen refueling process in low temperature environments.

[0006] According to one aspect of this disclosure, a pipeline heating unit, a pipeline circulation and venting unit, and a bent gas heat exchange pipeline are provided. The pipeline circulation and venting unit and the pipeline heating unit are both installed inside a corresponding gun handle. The gas heat exchange pipeline is installed inside a corresponding gun head. The gas heat exchange pipeline includes an inlet heat exchange pipeline and an outlet heat exchange pipeline. The pipeline heating unit includes a heating resistance wire and a spiral heating pipeline. The heating pipeline is connected to the inlet heat exchange pipeline, and the heating resistance wire is wound around the heating pipeline and electrically connected to an electrical control cabinet. The pipeline circulation and venting unit includes a venting pipeline and a gas inlet pipe. One end of the venting pipeline is connected to the outlet heat exchange pipeline, and the other end extends to the outside of the gun handle. One end of the gas inlet pipe is connected to the heating pipeline, and the other end extends to the outside of the gun handle. The outer surfaces of both the pipeline heating unit and the gas heat exchange pipeline are covered with thermal insulation sleeves.

[0007] In some embodiments of this disclosure, the heating conduit and the venting conduit are made of copper tubing.

[0008] In some embodiments of this disclosure, the thermal insulation sleeve includes an aluminum silicate ceramic fiber sleeve and a natural rubber sleeve, wherein the aluminum silicate ceramic fiber sleeve includes a first aluminum silicate ceramic fiber sleeve and a second aluminum silicate ceramic fiber sleeve, and the natural rubber sleeve includes a first natural rubber sleeve and a second natural rubber sleeve.

[0009] In some embodiments of this disclosure, the first aluminosilicate ceramic fiber sleeve covers the outer surface of the heating pipe and the heating resistance wire, and the first natural rubber sleeve covers the outer surface of the first aluminosilicate ceramic fiber sleeve.

[0010] In some embodiments of this disclosure, the second natural rubber sleeve covers the outer surface of the gas heat exchange pipeline, and the second aluminosilicate ceramic fiber sleeve covers the outer surface of the second natural rubber sleeve.

[0011] In some embodiments of this disclosure, an insulating sealing gasket is installed between the heating pipeline and the gas heat exchange pipeline.

[0012] In some embodiments of this disclosure, the electronic control unit is equipped with a 5V DC power supply.

[0013] In some embodiments of this disclosure, a patch-type temperature transmitter is mounted on the inner wall of the gun handle.

[0014] According to another aspect of this disclosure, a method for controlling the temperature of a hydrogen refueling gun in low-temperature environments is provided, implemented based on the aforementioned hydrogen refueling gun heating mechanism, comprising the following steps:

[0015] S1, with the heating pipe as the center, a heating resistance wire with a resistance of R is arranged on the heating pipe as the temperature control wire of the heating device. The heating power P of the heating resistance wire satisfies the following formula:

[0016] P=U 2 / R

[0017] In the formula, P is power and U is voltage;

[0018] S2, Calculate the volume V1 of nitrogen passing through the heating pipe per second, satisfying the following formula:

[0019] V1=πR1 2 v

[0020] In the formula, R1 is the radius of the heating pipe, and v is the flow velocity of nitrogen gas;

[0021] S3, Substitute V1 into M1=V1ρ1 to obtain the mass of nitrogen passing through the heating pipe per second, M1, where ρ1 is the nitrogen density.

[0022] S4, Based on the mass of nitrogen passing through per second M1, calculate the heat Q1 required per second for the resistance wire to heat from T1 to T2. Substitute M1 into the following formula:

[0023] Q1 = ΔT1M1C1

[0024] In the formula, ΔT1 is the temperature difference between T1 and T2, and C1 is the specific heat capacity of nitrogen.

[0025] S5, Calculate the contact area A of the tubing inside the natural silicone sleeve within the nozzle:

[0026] A = 2πR²L;

[0027] In the formula, R2 is the radius of the pipe inside the natural silicone sleeve, and L is the length of the pipe inside the natural silicone sleeve;

[0028] S6, Based on the contact volume A of the pipe inside the natural silicone sleeve in the nozzle, let the temperature of nitrogen reaching the nozzle be T3, and the heat exchange Q2 between T3 and the temperature T4 of the natural silicone sleeve inside the nozzle satisfies the following formula:

[0029] Q2 = ΔT2Ah;

[0030] In the formula, ΔT2 is the temperature difference between T3 and T4, and h is the surface convection heat transfer coefficient;

[0031] S7, the temperature T3 when nitrogen gas reaches the nozzle, and the heat Q3 required to heat the natural silicone sleeve inside the nozzle from temperature T4 to T5 satisfy the following formula:

[0032] Q3 = ΔT3M3C3

[0033] In the formula, ΔT3 is the temperature difference between T4 and T5, M3 is the mass of the natural rubber sleeve, and C3 is the specific heat capacity of the natural silicone sleeve.

[0034] S8, Calculate the time T required for the natural silicone sleeve in the nozzle to heat from T4 to T5:

[0035] T = Q3 / Q2.

[0036] One or more technical solutions provided in the embodiments of this application have at least one of the following technical effects or advantages:

[0037] 1. By setting up a heating unit and a pipeline circulation and venting unit, the gas enters the gun head through the heating pipeline to complete the heat exchange operation, recovering and utilizing the heat generated by the heating unit, thereby saving energy, improving energy utilization, improving heating efficiency, ensuring overall temperature uniformity and stability, and being easy to maintain and operate.

[0038] 2. An insulating sealing gasket is installed between the heating unit and the pipeline circulation and venting unit. The heating resistance wire is connected to the 5V DC power introduced from the electrical control cabinet to improve the safety of the heating device and prevent personnel accidents caused by leakage.

[0039] 3. The relevant influencing factors and parameters were effectively identified in the hydrogenation gun temperature control method, thus enabling precise temperature control and energy savings. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a hydrogen refueling gun heating mechanism for coping with low-temperature environments, according to one embodiment of this application.

[0041] Figure 2 This is a schematic diagram of the structure of a hydrogen refueling gun heating mechanism in use in response to low-temperature environments, according to one embodiment of this application.

[0042] Figure 3 This is a schematic diagram of the structure of a gas heat exchange pipeline in one embodiment of this application.

[0043] In the above figures, 1 is the pipeline heating unit; 101 is the heating resistance wire; 102 is the heating pipeline; 2 is the gas heat exchange pipeline; 201 is the inlet heat exchange pipeline; 202 is the outlet heat exchange pipeline; 3 is the pipeline circulation and venting unit; 301 is the gas inlet pipe; 302 is the venting pipeline; 4 is the gun handle; 5 is the insulating sealing gasket; and 6 is the gun head. Detailed Implementation

[0044] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "vertical," "horizontal," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first," "second," etc., used in this application are used to distinguish the described objects and do not have any sequential or technical meaning. And the terms "connection" and "linkage," unless otherwise specified, include both direct and indirect connections (linkages).

[0045] The programs involved or relied upon in the following embodiments are all conventional or simple programs in this technical field. Those skilled in the art can make conventional selections or adaptive adjustments according to specific application scenarios.

[0046] Unless otherwise specified, the mechanisms, unit modules, components, etc. involved in the following embodiments are all conventional commercially available products.

[0047] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] This example discloses a hydrogen refueling gun heating mechanism for coping with low-temperature environments, including a pipeline heating unit 1, a pipeline circulation and venting unit 3, and a bendable gas heat exchange pipeline 2.

[0050] See Figure 1 and Figure 2 The pipeline circulation and venting unit 3 and the pipeline heating unit 1 are both installed inside the corresponding gun handle 4, and the gas heat exchange pipeline 2 is installed inside the corresponding gun head 6. See [link / reference]. Figure 3 The gas heat exchange pipeline 2 includes an inlet heat exchange pipeline 201 and an outlet heat exchange pipeline 202. The inlet heat exchange pipeline 201 and the outlet heat exchange pipeline are connected in the same way. The pipeline heating unit 1 includes a heating resistance wire 101 and a spiral heating pipeline 102. The heating pipeline 102 is connected to the inlet heat exchange pipeline 201. The heating resistance wire 101 is wound around the heating pipeline 102. The heating resistance wire 101 is electrically connected to the electrical control cabinet. Specifically, the power cord is led out from the electrical control cabinet and laid along the hydrogen refueling hose. One end of the power cord is connected to the electrical control cabinet, and the other end is connected to the electrical control cabinet via an aviation plug. The addition of connecting wires and the use of aviation plugs facilitate the disassembly and installation of the heating resistance wire. Furthermore, during the overall injection molding of the gun handle, the excessive length of the wiring does not cause operational difficulties. This device uses a 5V safety power supply drawn from the internal safety pin of the hydrogen dispenser as the heating power source for the circuit. This power supply heats the heating unit 1 within the gun handle 4. A grounding wire is installed at the heating power supply to effectively prevent accidents caused by leakage. The circulating nitrogen gas is heated in the heating pipe 102, and the heated nitrogen gas flows through the gas heat exchange pipe 2 of the gun head 6, thus achieving precise heating of the gun head 6.

[0051] The pipeline circulation and venting unit 3 includes a venting pipeline 302 and a gas inlet pipe 301. One end of the venting pipeline 302 is connected to the outlet heat exchange pipeline 202, and the other end extends to the outside of the gun handle 4. Venting is performed by the venting pipeline 302. One end of the gas inlet pipe 301 is connected to the heating pipeline 102, and the other end extends to the outside of the gun handle 4. Both the heating pipeline 102 and the gas heat exchange pipeline 2 are formed by one-time extrusion. Nitrogen gas is circulated by the gun head 6 and then vented by the venting pipeline 302 inside the gun handle 4, making it simple and easy to use. Gas is introduced through the gas inlet pipe 301 and discharged through the venting pipeline 302.

[0052] Both the heating pipe 102 and the gas heat exchange pipe 2 are made of copper pipe. The pipes are heated using copper pipe. Because copper pipe has good thermal conductivity, it can efficiently transfer heat to the hydrogen gun during the heating process. In addition, copper pipe has good corrosion resistance, which enhances the service life of the heating pipe 102 and the venting pipe 302.

[0053] The outer surfaces of both the pipeline heating unit 1 and the gas heat exchange pipeline 2 are covered with thermal insulation sleeves. These sleeves consist of an aluminosilicate ceramic fiber sleeve and a natural rubber sleeve. The aluminosilicate ceramic fiber is used for insulation, while the natural rubber is used for overall injection molding. The use of natural rubber in the injection molding process provides insulation protection. Specifically, the heating pipeline 102 and the heating resistance wire 101 in the pipeline heating unit 1 are both wrapped with aluminosilicate ceramic fiber material for insulation, forming a first aluminosilicate ceramic fiber sleeve to reduce heat loss during heating. The outer surface of the first aluminosilicate ceramic fiber sleeve is cast with natural rubber material to form a first rubber sleeve. This first rubber sleeve not only provides insulation protection... The design provides protection and achieves one-piece molding, making assembly more convenient. The use of a first aluminosilicate ceramic fiber sleeve and a first natural rubber sleeve ensures a tight connection between the heating resistance wire 101 and the heating pipe 102. During the heating process, this allows for better heat transfer to the heating pipe 102, thereby heating the heating pipe 102 and reducing heat loss. The gas heat exchange pipe 2 on the nozzle 6 is injection molded with natural rubber to form a second natural rubber sleeve, which allows for better heat conduction to the nozzle. The outer surface of the second natural rubber sleeve is covered with aluminosilicate ceramic fiber insulation material to form a second aluminosilicate ceramic fiber sleeve, reducing heat loss to the outside and thus reducing energy consumption. This prevents the nozzle from freezing due to temperature changes. The use of the second aluminosilicate ceramic fiber sleeve and the second natural rubber sleeve allows the gas heat exchange pipe 2 to dissipate heat inward, concentrating the heat inward, thereby increasing the nozzle temperature.

[0054] The heating pipe 102 and the gas heat exchange pipe 2 are separate structures. An insulating sealing gasket 5 is installed between the heating pipe 102 and the gas heat exchange pipe 2. The installation of the insulating sealing gasket 5 ensures that there is no metal connection between the heating pipe 102 and the heat exchange pipe, thereby preventing personnel accidents. In addition, the insulating sealing gasket 5 has good sealing performance, making the connection more secure and maintaining good sealing performance. Compared with other connection methods, using the insulating sealing gasket 5 to connect pipes can simplify the installation process and make maintenance and replacement more convenient and quick.

[0055] A patch-type temperature transmitter is installed on the inner wall of the nozzle handle 4. This transmitter uses a 4-20mA current signal for transmission. When the temperature reaches the set temperature, the circuit automatically disconnects, thereby stopping the heating operation and ensuring temperature stability and accuracy. It also prevents overheating from damaging the hydrogen refueling nozzle. In addition, a 6mm² BVR yellow-green wire is installed on the hydrogen refueling nozzle. The BVR yellow-green wire is led out from the inlet end on the copper tube side and connected to the grounding busbar of the hydrogen refueling machine along the pipeline for electrostatic protection, ensuring the safety of the hydrogen refueling process.

[0056] When the above-mentioned hydrogen refueling gun heating mechanism is in use, the operator turns on the power and turns on the control button to start heating. The heating resistance wire 101 is supplied with 5V DC power from the electrical control cabinet to heat the heating device. Nitrogen gas is introduced through the gas inlet pipe 301. When the nitrogen gas flows through the heating pipe 102, it heats the internal air through heat exchange with the internal air. The gas enters the gas heat exchange pipe 2 in the gun head 6 through the heating pipe 102 to complete the heat exchange operation, and is discharged through the vent pipe 302, thus completing the overall heating of the hydrogen refueling gun.

[0057] Example 2

[0058] This example discloses a method for controlling the temperature of a hydrogen refueling gun in low-temperature environments. By calculating the heating heat and the heat required for nitrogen heat exchange, a suitable heating resistance wire 101 and nitrogen flow rate are selected, and pipeline design and heating heat exchange scheme design are carried out. In this embodiment, after detailed heat calculation, the nitrogen in the heating module can be heated to a maximum of 12-13℃. The nitrogen temperature is controlled within a reasonable range to prevent excessively high temperatures from damaging the circuit and device, and to keep the overall temperature within a safe range.

[0059] The following embodiment provides a detailed description of a method for controlling the temperature of a hydrogenation gun in low-temperature environments, but the present invention is not limited to the following embodiment.

[0060] (1) Calculate the heating power of heating resistance wire 101.

[0061] In this embodiment, the heating resistance wire 101 is a 3.5Ω heating resistance wire, and the heating power of the heating resistance wire 101 conforms to the following formula:

[0062] P=U 2 / R=5 2 / 3.5=7.14(J / s); (Equation 1)

[0063] Where P is power, in J / s; U is voltage, in V; and R is resistance, in Ω.

[0064] (2) Calculate the heat required by heating pipe 102

[0065] Taking heating nitrogen to 12℃ as an example, the theoretical calculation process for heating nitrogen from 0℃ to 12℃ using heating resistance wire 101 is as follows:

[0066] The mass of nitrogen passing through heating pipe 102 per second:

[0067] V1=πR1 2 v = 3.14159 × 0.4 2 ×900=452.39(cm 3 / s); (Equation 2)

[0068] M1 = V1ρ1 = 0.566 (g / s); (Equation 3)

[0069] The amount of heat required per second in heating pipe 102:

[0070] Q1 = ΔT1M1C1 = 12 × 0.566 × 1.005 = 6.825 (J / s); (Equation 4)

[0071] Where V1 is the volume of nitrogen passing through per second, in cm³. 3 R1 is the radius of the heating pipe, in cm; v is the nitrogen flow velocity, in cm / s; M1 is the mass of nitrogen passing through per second, in g; ρ1 is the nitrogen density, in g / cm³. 3 Q1 is the required heat, in J / s; ΔT1 is the heating temperature difference, in °C; C1 is the specific heat capacity of nitrogen, in J / (g·°C).

[0072] The calculation results from Equations 1 and 4 show that selecting a 3.5Ω heating resistance wire can meet the heat required to heat nitrogen gas from 0℃ to 12℃, while allowing for some heat loss.

[0073] (3) Calculate the heat exchange of the natural silicone sleeve inside the gun head.

[0074] Considering the heat loss of nitrogen in the pipeline, the temperature of nitrogen reaching nozzle 6 is approximately 10℃. The heat exchange calculation process between 10℃ nitrogen and the natural silica gel sleeve inside the nozzle at -4℃ is as follows:

[0075] A=2πR2L=2×3.14159×0.003×2.5=0.047(m 2 );

[0076] Q2= ΔT2Ah=14×0.047×10=6.597(J / s);

[0077] Where A represents the contact area of ​​the tube inside the natural silicone sleeve, in meters. 2 R2 is the radius of the pipe inside the natural silicone sleeve, in meters; L is the length of the pipe inside the natural silicone sleeve, in meters; Q2 is the heat exchange capacity, in J / s; ΔT2 is the contact temperature difference, in degrees Celsius; h is the surface convective heat transfer coefficient, in J / (m²). 2 ·s·℃).

[0078] (4) Calculate the heat required for the natural silicone sleeve inside the gun head.

[0079] In this embodiment, the calculation process for the amount of heat required to heat the natural silicone sleeve inside the -4℃ gunhead to 1℃ using 10℃ nitrogen gas is as follows:

[0080] Q3= ΔT3M3C3=5×100.379×1.5=752.84(J);

[0081] Where Q3 is the required heat in J; M3 is the mass of the natural rubber sleeve in g; ΔT3 is the temperature difference of the natural silicone sleeve in °C; and C3 is the specific heat capacity of the natural silicone sleeve in J / (g·°C).

[0082] (5) Calculate the heating time required for the natural silicone sleeve inside the gun head.

[0083] In this embodiment, the time required to heat the natural silicone sleeve inside the -4℃ gun head to 1℃ is:

[0084] T = Q3 / Q2 ≈ 114 (s); where T is the heating time in seconds.

[0085] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0086] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A hydrogen refueling gun heating mechanism for coping with low-temperature environments, comprising a pipeline heating unit, characterized in that, It also includes a pipeline circulation and venting unit and a bendable gas heat exchange pipeline. Both the pipeline circulation and venting unit and the pipeline heating unit are installed inside the corresponding gun handle. The gas heat exchange pipeline is installed inside the corresponding gun head. The gas heat exchange pipeline includes an inlet heat exchange pipeline and an outlet heat exchange pipeline. The pipeline heating unit includes a heating resistance wire and a spiral heating pipeline. The heating pipeline is connected to the inlet heat exchange pipeline, and the heating resistance wire is wound around the heating pipeline. The heating resistance wire is electrically connected to the electrical control cabinet. The pipeline circulation and venting unit includes a venting pipeline and a gas inlet pipe. One end of the venting pipeline is connected to the outlet heat exchange pipeline, and the other end extends to the outside of the gun handle. One end of the gas inlet pipe is connected to the heating pipeline, and the other end extends to the outside of the gun handle. The outer surfaces of both the pipeline heating unit and the gas heat exchange pipeline are covered with thermal insulation sleeves.

2. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 1, characterized in that, The heating pipe and the venting pipe are made of copper pipe.

3. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 1, characterized in that, The thermal insulation sleeve includes an aluminum silicate ceramic fiber sleeve and a natural rubber sleeve. The aluminum silicate ceramic fiber sleeve includes a first aluminum silicate ceramic fiber sleeve and a second aluminum silicate ceramic fiber sleeve. The natural rubber sleeve includes a first natural rubber sleeve and a second natural rubber sleeve.

4. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 3, characterized in that, The first aluminum silicate ceramic fiber sleeve covers the outer surface of the heating pipe and the heating resistance wire, and the first natural rubber sleeve covers the outer surface of the first aluminum silicate ceramic fiber sleeve.

5. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 3, characterized in that, The second natural rubber sleeve covers the outer surface of the gas heat exchange pipeline, and the second aluminum silicate ceramic fiber sleeve covers the outer surface of the second natural rubber sleeve.

6. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 1, characterized in that, An insulating sealing gasket is installed between the heating pipeline and the gas heat exchange pipeline.

7. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 1, characterized in that, The electronic control unit is equipped with a 5V DC power supply.

8. The hydrogen refueling gun heating mechanism for coping with low-temperature environments according to claim 1, characterized in that, A patch-type temperature transmitter is installed on the inner wall of the gun handle.

9. A method for controlling the temperature of a hydrogen refueling gun in low-temperature environments, characterized in that, Implemented based on the hydrogen refueling gun heating mechanism of claim 1, it includes the following steps: S1, with the heating pipe as the center, a heating resistance wire with a resistance of R is arranged on the heating pipe as the temperature control wire of the heating device. The heating power P of the heating resistance wire satisfies the following formula: P=U 2 / R In the formula, P is power and U is voltage; S2, calculate the volume V1 of nitrogen passing through the heating pipe per second, satisfying the following formula: V1=πR1 2 in In the formula, R1 is the radius of the heating pipe, and v is the flow velocity of nitrogen gas; S3, Substitute V1 into M1=V1ρ1 to obtain the mass of nitrogen passing through the heating pipe per second, M1, where ρ1 is the nitrogen density. S4, based on the mass of nitrogen passing through per second M1, calculate the heat Q1 required per second for the resistance wire to heat from T1 to T2. Substitute M1 into the following formula: Q1=ΔT1M1C1 In the formula, ΔT1 is the temperature difference between T1 and T2, and C1 is the specific heat capacity of nitrogen. S5, Calculate the contact area A of the inner tube of the natural silicone sleeve inside the gun head: A = 2πR²L; In the formula, R2 is the radius of the tube inside the natural silicone sleeve in the gun head, and L is the length of the tube inside the natural silicone sleeve. S6, based on the contact volume A of the pipe inside the natural silicone sleeve in the nozzle, let the temperature of nitrogen reaching the nozzle be T3, and the heat exchange Q2 between T3 and the temperature T4 of the natural silicone sleeve inside the nozzle satisfies the following formula: Q2=ΔT2Ah; In the formula, ΔT2 is the temperature difference between T3 and T4, and h is the surface convection heat transfer coefficient; S7, the temperature T3 when nitrogen reaches the nozzle, and the heat Q3 required to heat the natural silicone sleeve inside the nozzle from temperature T4 to T5 satisfy the following formula: Q3=ΔT3M3C3; In the formula, ΔT3 is the temperature difference between T4 and T5, M3 is the mass of the natural rubber sleeve inside the gun head, and C3 is the specific heat capacity of the natural silicone sleeve. S8, Calculate the time T required for the natural silicone sleeve in the gun head to heat from T4 to T5: T = Q3 / Q2.

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