A device and method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding.

Abstract

This application provides a device and method for steady-state measurement of the pyrolysis rate of solid fuel based on continuous fuel feeding. The measuring device includes a shell, a heating unit, a feeding unit, and a control unit. The shell has a sealed pyrolysis chamber. A solid fuel sample is placed in the sealed pyrolysis chamber. The heating unit is located in the sealed pyrolysis chamber. The feeding unit has a driving part and a transmission part. The driving part can drive the solid fuel sample to move, so that the pyrolysis surface of the solid fuel sample is always in contact with the heating surface of the heating unit. The control unit has a temperature control module and a speed control module. The temperature control module can control the output power of the heating unit. The speed control module can control the feeding rate of the driving part. This application has higher measurement accuracy: it measures the backflush rate under thermodynamic steady state, eliminating the systematic error caused by transient temperature field evolution. The steady-state feeding rate is directly equal to the backflush rate, eliminating the need to differentiate the displacement signal and avoiding the problem of noise amplification in differential operations.

Description

Technical Field

[0001] This application relates to the field of aerospace technology, and in particular to a device and method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding. Background Technology

[0002] In solid-liquid rocket engines, the thermal decomposition (pyrolysis) of the solid fuel surface controls the fuel's surface retreat process. The rate of surface retreat (i.e., the pyrolysis rate) depends primarily on the fuel's surface temperature, and the relationship between the two is typically described by an Arrhenius-type pyrolysis rate formula:

[0003] In the formula, The rate of surface retreat (mm / s); The pre-exponential factor (mm / s); The apparent activation energy is expressed in J / mol. The molar gas constant is 8.314 J / (mol·K); Let K be the thermodynamic temperature of the fuel surface. The pre-exponential factor can be obtained by fitting the above equation to measure the fuel surface retreat rate at a series of different surface temperatures. and activation energy This allows for the establishment of a pyrolysis rate model for the fuel, which can be used for internal ballistic calculations, flow field simulations, and combustion performance analysis of solid-liquid rocket engines.

[0004] Among existing methods for measuring pyrolysis rates, the most widely used is the hot rod contact heating method. This method involves placing a solid fuel charge at the bottom of a sealed, inert atmosphere chamber. A copper rod, preheated to a target temperature (800~1300 K), is dropped from above and pressed firmly against the fuel end face. The continuous descent of the copper rod ensures its close contact with the receding fuel surface. The copper rod is preheated to the target temperature in a tube furnace or high-frequency induction heating coil, and its descent timing is controlled by a vacuum adsorption-release mechanism. Thin thermocouples are pre-placed on the fuel surface to record the instantaneous surface temperature. The receding rate is obtained through high-speed camera image processing or ultrasonic thickness measurement.

[0005] However, the above method has the following drawbacks: Disadvantage 1: The copper rod falling contact heating method used results in continuous changes in the internal temperature distribution and surface temperature of the fuel throughout the entire heating process, from the start to the end of the experiment. Consequently, the pyrolysis rate also changes continuously, never reaching a strictly steady state. Researchers can only extract data within a "quasi-steady-state" timeframe for linear fitting to obtain an approximate average regression rate. This quasi-steady-state window is often very short (a few seconds), and its selection is subjective, affecting the accuracy and repeatability of the measurement results.

[0006] Disadvantage 2: Whether tracking the interface position through high-speed camera image processing or measuring the thickness of the drug cartridge using ultrasound, the raw data obtained is a signal of position (or thickness) changing over time. The retraction rate requires calculating the time derivative of this signal, but the differential operation amplifies the high-frequency noise in the signal, resulting in large fluctuations in the instantaneous retraction rate. Smoothing filtering or linear regression over a period of time is necessary to obtain usable results.

[0007] Disadvantage 3: In the traditional gravity-feed method, the copper rod continuously moves downwards during the experiment. If the copper rod is preheated by an external heating coil (such as an induction heating coil or a tube furnace), it gradually moves away from the heating area after falling, and its temperature continuously decreases. The experimental data in the literature "Measurement and Analysis of Fuel Pyrolysis Rate in Solid-Liquid Rocket Engines - Sun Dechuan" clearly demonstrates this continuous temperature decrease during the experiment. Even when using a follower heating coil, the relative position of the copper rod and the coil changes during movement, making it difficult to ensure a constant heating power.

[0008] Disadvantage 4: In the existing method, a single test corresponds to the temperature of a copper rod, obtaining a set of regression rate data. To establish a complete Arrhenius pyrolysis rate model, tests need to be conducted at 10-15 different temperatures, requiring a new solid fuel sample each time, resulting in high experimental complexity and time costs.

[0009] Therefore, there is an urgent need for a device and method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, which can, to some extent, solve the technical problems in the existing technology. Summary of the Invention

[0010] The purpose of this application is to provide a device and method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, which can transform the "passive measurement" of observing the transient regression process in traditional pyrolysis rate measurement into an "active measurement" that controls the steady-state feeding process of solid fuel samples.

[0011] This application provides a steady-state measurement device for the pyrolysis rate of solid fuel based on continuous fuel feeding, comprising: The shell has a sealed pyrolysis chamber; a solid fuel sample is disposed at a first preset position in the sealed pyrolysis chamber, and a pyrolysis surface is formed on the side of the solid fuel sample opposite to the shell. A heating unit is disposed at a second preset position in the sealed pyrolysis chamber, and the side of the heating unit opposite to the housing has a heating surface adapted to the pyrolysis surface; and A feeding unit includes a drive unit and a transmission unit connected to the drive unit. The transmission unit passes through the housing and is connected to the solid fuel sample. The drive unit, through the transmission unit, can drive the solid fuel sample to move, such that the pyrolysis surface of the solid fuel sample is always in contact with the heating surface of the heating unit. The control unit includes a temperature control module and a speed control module; the temperature control module can control the output power of the heating unit; the speed control module can control the feed rate of the drive unit.

[0012] In this embodiment, the driving unit further includes: Ball screws, and A servo motor, via a coupling, can drive the ball screw shaft to rotate, and the rotation of the ball screw shaft can drive the nut of the ball screw to move in the direction of the solid fuel sample toward the heating unit.

[0013] In the above technical solution, the transmission part further includes a feed push rod; One end of the feed push rod extends into the housing and is connected to the solid fuel sample via a fuel clamp, while the other end is connected to the nut; When the servo motor is started, the nut can drive the feed push rod to move so that the pyrolysis surface comes into contact with the heating surface.

[0014] In the above technical solution, the transmission part further includes a bellows; The bellows is connected to the outer wall of the housing at the position where the feed push rod extends into the housing, and the end of the bellows away from the housing is connected to the preset position of the feed push rod.

[0015] In the above technical solution, the speed control module further includes: The host computer can set the target contact force between the pyrolysis surface and the heating surface, and the target contact force is denoted as... ; A tension / compression sensor is disposed between the nut and the feed push rod. The sensor measures the contact force between the pyrolysis surface and the heating surface. This contact force is denoted as... The tension and compression sensors are respectively connected to the feed rate PID controller and the host computer; and A feed rate PID controller is connected to both the host computer and the servo motor; the feed rate PID controller adjusts the feed rate based on the target contact force. and measuring contact force Capable of calculating force deviation Furthermore, the feed rate PID controller can adjust the feed rate based on the force deviation. Controlling the feed rate of the servo motor So that the measured contact force Achieving the target contact force .

[0016] In the above technical solution, the heating unit further includes: A heating copper rod, one end of which is fixed to the inner wall of the housing, and the other end extends toward the interior of the sealed pyrolysis chamber and forms the heating surface; Heating coils are wound around the outer wall of the heating copper rod; and A heating power supply is connected to the heating coil, and the heating copper rod is heated to a target temperature by heating the heating coil. The target temperature is denoted as [missing information]. .

[0017] In the above technical solution, the temperature control module further includes: A temperature PID controller is connected to both the heating power supply and the host computer; and A thermocouple, with its probe inserted into the heating copper rod at a predetermined distance from the heating surface, measures and records the temperature of the heating copper rod. ; The thermocouples are connected to the temperature PID controller and the host computer, respectively. The temperature PID controller determines the target temperature based on the... and temperature detection Able to calculate temperature deviation And the temperature PID controller can adjust according to the temperature deviation. Controlling the output power of the heating power supply so that the detected temperature of the heating copper rod is... Reach the target temperature .

[0018] In the above technical solution, the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding further includes an observation unit, which includes: A quartz glass window is disposed on the side wall of the housing and corresponds at least to the contact interface formed by the contact between the pyrolysis surface and the heating surface; and A high-speed camera is positioned on the outside of the housing, corresponding to the location of the quartz glass window, and is connected to the host computer, enabling it to transmit captured images to the host computer.

[0019] In the above technical solution, the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding further includes a gas protection unit, which includes: An inert gas supply component, in communication with the housing, is capable of introducing inert gas into the housing to place the housing in an inert atmosphere; and The exhaust component, which is connected to the housing, is capable of discharging the products generated by the pyrolysis of the solid fuel sample to the outside of the housing.

[0020] This application also provides a method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, and a device for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, comprising the following steps: Installation steps: Install the heating unit and the feeding unit into the housing; Zeroing procedure: Zero the tension sensor by removing the weight of the feed push rod, fuel clamp, and solid fuel sample, as well as the elastic force of the bellows under compression, so that the reading of the tension sensor is only the contact force. Air tightness inspection procedure: Check the air tightness of the casing and place the casing in an inert atmosphere; Temperature gradient setting steps: Set the temperature gradient with Group experiment; ;correspond The target temperatures for the groups are respectively , , ......, ;correspond The feed rates of the groups are respectively , , ......, ;correspond The target contact forces of the groups are respectively , , ......, ; Temperature steady-state conditioning steps: In In the group experiment, the target temperature of the heating copper rod was controlled and adjusted by the host computer and temperature sensor as follows: , , ......, ; Speed ​​steady-state adjustment steps: In In the group experiment, the feed speed of the servo motor was adjusted by the tension / compression sensors and the host computer control. , , ......, ; Data acquisition steps: When the target temperature within any group is The feed rate is and target contact force When the feed rate fluctuates within ±5% of its mean value over a continuously preset time period, the measuring device reaches a steady state; during the steady-state time period, the feed rate is continuously collected. and the detection temperature of the heating copper rod ; Steps to establish a pyrolysis rate model: During the steady-state time period, for any set of regression rates The feed rate during this steady-state time period The time average is shown in formula (1). (1); in, and These represent the start and end times of the steady-state time period; Data correction steps: According to formula (2), the heat flow transferred from any set of heating copper rods to the solid fuel sample can be calculated. , (2); in, For latent heat of pyrolysis, For the density of fuel, The specific heat capacity of the fuel. The initial temperature of the solid fuel; at the same time, It also satisfies formula (3). (3); in, For contact thermal conductivity; combining equations (2) and (3) can solve for the solution. and obtain data groups ; Taking the natural logarithm of the regression rate, as shown in formula (4), (4), right and Perform linear regression fitting, based on the slope and intercept Find the pre-exponential factors and activation energy Thus, an Arrhenius-type pyrolysis rate model for solid fuel samples was established.

[0021] This application provides a steady-state measurement device for the pyrolysis rate of solid fuel based on continuous fuel feeding, comprising: The shell has a sealed pyrolysis chamber; a solid fuel sample is disposed at a first preset position in the sealed pyrolysis chamber, and a pyrolysis surface is formed on the side of the solid fuel sample opposite to the shell. A heating unit is disposed at a second preset position in the sealed pyrolysis chamber, and the side of the heating unit opposite to the housing has a heating surface adapted to the pyrolysis surface; and A feeding unit includes a drive unit and a transmission unit connected to the drive unit. The transmission unit passes through the housing and is connected to the solid fuel sample. The drive unit, through the transmission unit, can drive the solid fuel sample to move, such that the pyrolysis surface of the solid fuel sample is always in contact with the heating surface of the heating unit. The control unit includes a temperature control module and a speed control module; the temperature control module can control the output power of the heating unit; the speed control module can control the feed rate of the drive unit.

[0022] In summary, this application offers higher measurement accuracy: it measures the backflip rate under thermodynamic steady-state conditions, eliminating systematic errors caused by transient temperature field evolution; the steady-state feed rate is directly equal to the backflip rate, eliminating the need to differentiate the displacement signal and avoiding the problem of noise amplification in differential operations; and the measurement accuracy and repeatability are significantly better than existing transient measurement methods.

[0023] Stable heating conditions over a long period of time: The heating copper rod is fixed in place, and the heating coil can continuously and uniformly heat the copper rod. With the help of closed-loop temperature control, the temperature of the heating copper rod can be kept precisely constant for a long time, which solves the problem of continuous temperature drop caused by the movement of the copper rod in the existing technology.

[0024] Single-sample multi-temperature testing: high efficiency and small error. Multiple sets of regression rate data at different temperatures can be continuously acquired on the same solid fuel sample, significantly reducing the total test time required to obtain a complete dataset.

[0025] The device has a simple structure and no complex motion mechanisms: all motion is only low-speed linear feed, without the impact of falling copper rods or the dynamic process of vacuum adsorption and release. The mechanical structure is simple, highly reliable, and easy to operate. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1A schematic diagram of the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding provided in this application from a first-view perspective; Figure 2 A schematic diagram of the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding provided in this application from a second perspective; Figure 3 A schematic diagram of the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding provided in this application from a third-person perspective; Figure 4 A schematic diagram of the hidden shell in the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding provided in this application, viewed from a first perspective; Figure 5 A schematic diagram of the hidden shell in the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding provided in this application, viewed from a second perspective; Figure 6 A cross-sectional view of the steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding provided in this application; Figure 7 A schematic diagram of the speed control module in the steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding provided in this application; Figure 8 A schematic diagram of the temperature control module in the steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding provided in this application; Figure 9 Steady-state temperature distribution diagram provided for this application; Figure 10 The experimental parameter curves obtained from the experiment using the steady-state measurement device and method for solid fuel pyrolysis rate based on continuous fuel feeding provided in this application.

[0028] Figure reference numerals: 10-Heating copper rod; 20-Heating coil; 30-Sealed pyrolysis chamber; 40-Servo motor; 50-Feed push rod; 60-Solid fuel sample; 70-Fuel clamp; 80-Tension / compression sensor; 90-Bellwall; 100-Thermocouple; 110-Nitrogen inlet to the chamber; 120-Exhaust port; 130-Quartz glass window; 140-High-speed camera; 150-Host computer; 160 - Housing; 170 - Contact interface. Detailed Implementation

[0029] The following detailed embodiments are provided to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0030] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0031] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0032] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0033] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0034] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., swung 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0035] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0036] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0037] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0038] This application provides a steady-state measurement device for the pyrolysis rate of solid fuel based on continuous fuel feeding. This device transforms the traditional "passive measurement" of observing the transient regression process in pyrolysis rate measurement into an "active measurement" that controls the steady-state feeding process of the fuel sample. The following is in conjunction with... Figures 1-10 This application will be described in detail.

[0039] A steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding includes a housing 160, a heating unit, a feeding unit, and a control unit.

[0040] In this embodiment, the housing 160 has a sealed pyrolysis chamber; a solid fuel sample is disposed at a first preset position in the sealed pyrolysis chamber, and a pyrolysis surface is formed on the side of the solid fuel sample opposite to the housing 160. Preferably, the first preset position is the bottom of the sealed pyrolysis chamber.

[0041] The aforementioned solid fuel sample 60 is the solid fuel sample of the solid-liquid rocket engine to be tested. It is typically a cylindrical or elongated propellant grain with an outer diameter not exceeding 12 mm and a length of 30 mm-50 mm. The solid fuel sample 60 is fixed to the top of the feed pusher 50 (described below) by a fuel clamp 70. The pyrolysis surface of the solid fuel sample 60 is in contact with the heating surface of the heating copper rod 10. As the test proceeds and the feed pusher 50 pushes upward, the pyrolysis surface of the solid fuel sample 60 remains in contact with the heating copper rod 10, and the pyrolysis surface continuously recedes due to pyrolysis (fuel is consumed). In the field of solid-liquid hybrid rocket engines, the material of the solid fuel sample 60 is often hydroxyl-terminated polybutadiene (HTPB), polyethylene (PE), paraffin-based fuel, polymethyl methacrylate (PMMA), or composite fuel containing metal additives.

[0042] Specifically, the housing 160 is the main frame of the entire device, made of stainless steel, with a sealed test space inside and a cylindrical shape. The top of the housing 160 is formed by a top plate, which has mounting holes for a copper rod fixing bracket (used to fix the heating copper rod described below), lead-out holes for the control wires of the heating coil (described below) (the control wires lead out of the housing 160 through a sealed joint), and lead-out holes for the thermocouple 100 (described below).

[0043] In addition, a base plate is provided on the top of the housing 160, and a central through hole is provided on the base plate for mounting the bellows 90 (the bellows is described below) and the feed push rod 50.

[0044] In addition, flange interfaces are provided on the side wall for installing the quartz glass window 130, the nitrogen inlet 110 of the cavity, and the exhaust port 120 (the quartz glass window 130, the nitrogen inlet 110 of the cavity, and the exhaust port 120 are described below). All flange interfaces are equipped with sealing rings to ensure overall airtightness.

[0045] In this embodiment, the heating unit is disposed at a second preset position in the sealed pyrolysis chamber, and a heating surface adapted to the pyrolysis surface is formed on the side of the heating unit opposite to the housing 160. Specifically, in conjunction with Figure 4 and Figure 6 As shown, the heating unit includes a heating copper rod, a heating coil, and a heating power supply.

[0046] One end of the heating copper rod is fixed to the inner wall of the housing 160, while the other end extends towards the interior of the sealed pyrolysis chamber and forms a heating surface. Furthermore, the heating copper rod 10 is cylindrical and is mounted on the inner wall of the top plate of the sealed pyrolysis chamber 30 via a fixing bracket, remaining completely fixed throughout the test. The lower end face of the heating copper rod 10 is a flat heating surface that contacts the pyrolysis surface of the solid fuel sample 60, causing the pyrolysis surface to decompose due to heat.

[0047] The heating coil 20 is a spiral coil structure, tightly wound around the outer cylindrical surface of the heating copper rod 10, and uses a resistance heating method to achieve contact heating of the heating copper rod; since the heating coil is in contact with the heating copper rod 10 and remains fixed, the temperature of the heating copper rod is always constant.

[0048] The heating power supply is connected to the heating coil, and the heating coil is heated to the target temperature, which is denoted as [missing information]. In addition, the heating coil, controlled by a temperature PID controller, can heat the copper rod to a target temperature range of 500℃-1000℃.

[0049] More specifically, in combination Figure 4 , Figure 6 as well as Figure 7 As shown, the temperature control module includes a temperature PID controller and a thermocouple. The thermocouple probe is inserted into the heating copper rod at a preset distance (preferably 3 mm) from the heating surface to measure the temperature of the heating copper rod and record it as [temperature value missing]. .

[0050] Furthermore, thermocouple 100 is a type K armored thermocouple. Thermocouple 100 measures the temperature of the heating copper rod 10 in real time, with a measurement range covering 0℃~1300℃. The signal lead of thermocouple 100 is led out to the outside through the sealed joint on the top plate of the sealed pyrolysis chamber 30 and connected to the host computer 150 and the temperature PID controller, so that the temperature of the heating copper rod is approximately equal to the surface temperature of the solid fuel sample.

[0051] The temperature PID controller is connected to both the heating power supply and the host computer; the thermocouples are also connected to both the temperature PID controller and the host computer. The temperature PID controller adjusts the temperature based on the target temperature. and temperature detection Able to calculate temperature deviation Furthermore, the temperature PID controller can adjust according to temperature deviation. Controlling the output power of the heating power supply allows the detection temperature of the heating copper rod to be adjusted. Reach the target temperature .

[0052] This application establishes an independent temperature closed-loop control circuit using a temperature PID controller, specifically by setting the target temperature of the heating copper rod via a host computer. Thermocouple 100 measures the temperature of a copper rod in real time. The temperature PID controller calculates the temperature deviation. The system outputs a control quantity according to the PID algorithm and transmits it to the resistance heating power supply to adjust the power output to the resistance heating coil 20, thereby changing the heating power of the heating copper rod 10 and making the measured temperature of the heating copper rod approach the target temperature. Since the copper rod 10 and the heating coil 20 are always tightly fixed and wound, the spatial distribution of the heating power is constant, the stability and accuracy of the temperature control are very high, and the measured temperature of the heating copper rod can be maintained within the range of ±5℃ of the target temperature for a long time.

[0053] In this embodiment, combined with Figures 1-4 As shown, the feeding unit has a drive unit and a transmission unit connected to the drive unit. The transmission unit passes through the housing 160 and is connected to the solid fuel sample. The drive unit can drive the solid fuel sample to move through the transmission unit, so that the pyrolysis surface of the solid fuel sample is always in contact with the heating surface of the heating unit. Specifically, the drive unit includes a ball screw and a servo motor. The servo motor, mounted below and outside the sealed pyrolysis chamber 30, is the drive actuator for the continuous feeding of the solid fuel sample. The servo motor, via a coupling, drives the ball screw shaft to rotate, and this rotation drives the ball screw nut to move along the direction of the solid fuel sample toward the heating unit. Figure 1 Taking the angle shown as an example, the nut moves in a straight line in the vertical direction, causing the solid fuel sample to move upward or downward.

[0054] In addition, the servo motor has a built-in rotary encoder (1000 pulses / revolution), which can accurately measure the displacement and velocity of the solid fuel sample. The stroke of the servo motor 40 is 50 mm (covering the entire length of the solid fuel sample 60), and the feed speed range is 0.01~2 mm / s, which can cover the range of recoil rates of various solid and liquid rocket engine fuels at typical pyrolysis temperatures. The servo motor 40 is driven by the control signal output by the feed rate PID controller.

[0055] Specifically, the transmission unit includes a feed push rod; the feed push rod 50 is a stainless steel round bar, one end of the feed push rod extends into the housing 160 and is connected to the solid fuel sample through a fuel clamp, and the other end is connected to a nut; when the servo motor is started, the feed push rod can be driven to move through the nut so that the pyrolysis surface contacts the heating surface.

[0056] In addition, the transmission unit also includes a bellows; the bellows is connected to the outer wall of the housing 160 at the position where the feed push rod extends into the housing 160, and the end of the bellows away from the housing 160 is connected to a preset position of the feed push rod. The bellows here realizes a dynamic sealing function, and can move freely up and down in the vertical direction while maintaining the airtightness of the sealed pyrolysis chamber. The upper end of the feed push rod 50 is provided with a fuel clamp 70 mounting interface.

[0057] Furthermore, a bellows is installed at the central through-hole of the bottom plate of the sealed pyrolysis chamber 30 to seal the gap between the feed push rod 50 and the sealed pyrolysis chamber 30, while allowing the feed push rod 50 to move linearly along the axial direction. The upper end of the bellows 90 is welded to the bottom plate of the sealed pyrolysis chamber 30, and the lower end is welded to a sliding collar on the feed push rod 50. When the feed push rod 50 moves upward, the bellows 90 is compressed, and when it moves downward, it is stretched. The reason for choosing a bellows seal instead of an O-ring sliding seal is that the bellows is a frictionless flexible sealing element, and its deformation does not generate sliding friction. Therefore, it will not introduce unpredictable friction interference into the readings of the tension and compression sensor 80 (described below), ensuring the accuracy of force measurement (achieving feed and force measurement feedback while achieving a sealed pyrolysis test chamber). The effective stroke of the bellows 90 is not less than 50 mm, and its elastic restoring force changes approximately linearly with the compression amount, which can be removed through calibration before the test.

[0058] The aforementioned fuel clamp is used to fix the solid fuel sample 60 to the top of the feed push rod 50, keeping it vertical and coaxial with the feed push rod. The fuel clamp 70 is made of stainless steel and uses a three-jaw chuck or sleeve structure to clamp the cylindrical side of the solid fuel sample 60, preventing it from loosening or tilting, so that the solid fuel sample 60 can be pushed upward.

[0059] Specifically, the speed control module includes a host computer, tension / compression sensors, and a feed rate PID controller. The host computer can set the target contact force between the pyrolysis surface and the heating surface; this target contact force is denoted as... In practical use, the host computer includes a data acquisition card and a computer running control software. The analog input channel of the data acquisition card connects to the signals from the tension / compression sensor 80 and the thermocouple 100, while the digital input channel connects to the pulse signals from the servo motor encoder for real-time calculation of the feed rate. The host computer software can perform the following functions: display and record real-time data of force, temperature, and feed rate; implement a PID control algorithm for the feed rate (which can also be implemented by a separate PID controller hardware); implement a PID control algorithm for temperature; set the target temperature and target contact force; determine the steady state and output the steady-state retreat rate.

[0060] The tension / compression sensor is located between the nut and the feed push rod. This sensor measures the contact force between the pyrolysis surface and the heating surface. The measured contact force is denoted as... The tension and compression sensors are connected to the feed rate PID controller and the host computer, respectively.

[0061] The feed rate PID controller is connected to both the host computer and the servo motor.

[0062] Furthermore, the tension / compression sensor 80 is installed between the slide of the servo motor 40 and the lower end of the feed push rod 50. The tension / compression sensor 80 measures the axial force along the axis of the feed push rod in real time. This force is the contact force between the upper end face of the solid fuel sample 60 and the lower end face of the heating copper rod 10 (the self-weight of the feed push rod 50, fuel clamp 70, and solid fuel sample 60, as well as the elastic restoring force of the bellows 90, are zeroed before the test). The output signal of the tension / compression sensor 80 is transmitted to the host computer 150 and the feed rate PID controller. The reading of the tension / compression sensor 80 is the core feedback signal for the feed rate closed-loop control. When the contact force is too low (meaning that the pyrolysis surface is retreating too quickly and the pyrolysis surface is about to detach from the copper rod), the feed rate PID controller increases the feed rate. When the contact force is too high (meaning that the feed is too fast and the solid fuel sample 60 is being excessively pressed against the heated copper rod), the feed rate PID controller decreases the feed rate, and the system automatically converges to a steady state. At this time, the contact force is constant, the feed rate is constant and equal to the pyrolysis retreat rate.

[0063] That is, the feed rate PID controller is based on the target contact force. (Typically 2-10 N, depending on the cross-sectional area and material hardness of the solid fuel sample 60) and the contact force is measured. Capable of calculating force deviation Furthermore, the feed rate PID controller can adjust based on force deviation. Controlling the feed rate of the servo motor This makes it possible to measure contact force. Achieving target contact force .

[0064] It is worth noting that the temperature control module, which can control the output power of the heating unit, and the speed control module, which can control the feed rate of the drive unit, constitute the control unit.

[0065] In summary, combining Figure 8 As shown, if the pyrolysis retreat rate of solid fuel sample 60 is instantaneously greater than the feed rate (retreat is faster than feed), the pyrolysis surface of solid fuel sample 60 tends to move downward and separate from the heating copper rod, and the contact force is measured. Decrease and fall below the target contact force ,deviation >0, the feed rate PID controller outputs an acceleration command, the feed rate increases, and the solid fuel sample 60 is pushed upward to restore the contact force.

[0066] If the feed rate is instantaneously greater than the retraction rate (feed faster than retraction), the excess solid fuel sample 60 is pressed against the heated copper rod, and the contact force is measured. Rise above target contact force ,deviation When the value is less than 0, the PID controller outputs a deceleration command, reducing the feed rate and decreasing the contact force.

[0067] When the system converges to a steady state, the contact force is measured. Constant to target contact force feed rate Constant, and strictly satisfies under steady-state conditions = That is, the feed rate is equal to the pyrolysis retreat rate. At this time, the constant feed rate read by the encoder of the servo motor is the direct measurement value of the pyrolysis retreat rate.

[0068] It should also be noted that the two control loops are independent of each other: the controlled variable of the temperature control loop is the temperature of the heating copper rod, and the actuator is the heating power supply; the controlled variable of the feed rate control loop is the contact force, and the actuator is a servo motor. The two loops are coupled through physical processes: the temperature of the heating copper rod determines the heat flux density and the fuel surface temperature, thus determining the pyrolysis rate, and the feed rate needs to follow the changes in the pyrolysis rate. The two are decoupled and will not interfere with each other.

[0069] In this embodiment, combined with Figures 1-4 As shown, the steady-state measurement device for the solid fuel pyrolysis rate based on continuous fuel feeding also includes an observation unit, which comprises a quartz glass window and a high-speed camera. The quartz glass window is disposed on the side wall of the housing 160 and corresponds at least to the contact interface 170 formed by the contact between the pyrolysis surface and the heating surface. The high-speed camera is disposed on the outside of the housing 160 corresponding to the position of the quartz glass window and is connected to a host computer, capable of transmitting captured images to the host computer.

[0070] In this embodiment, the solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding further includes a gas protection unit, which includes an inert gas supply component and an exhaust component.

[0071] The inert gas supply component is connected to the housing 160 and can introduce inert gas into the housing 160 to maintain an inert atmosphere. Specifically, the inert gas supply component includes a nitrogen inlet 110, which is a connector located on the side wall of the sealed pyrolysis chamber 30. Nitrogen gas is introduced into the sealed pyrolysis chamber 30, maintaining an inert atmosphere and preventing oxidation of the solid fuel sample at high temperatures. Simultaneously, nitrogen flows through the area surrounding the contact between the heating copper rod 10 and the solid fuel sample 60, purging the gaseous products and soot particles generated during pyrolysis to the exhaust component for discharge, preventing soot deposition on the quartz glass window and affecting imaging. The upstream pipeline of the nitrogen inlet 110 includes a high-pressure nitrogen cylinder, a pressure reducer, and a throttle valve, providing clean nitrogen with a controllable flow rate.

[0072] The exhaust component is connected to the housing 160 and can discharge the products generated by the pyrolysis of the solid fuel sample to the outside of the housing 160. Specifically, the exhaust component includes an exhaust port 120. The exhaust port 120 is located on the side wall of the sealed pyrolysis chamber 30. Nitrogen gas entering from the nitrogen inlet 110 of the chamber carries the pyrolysis product gas and is discharged from the exhaust port 120, and is connected to the exhaust gas treatment system through a pipeline.

[0073] Combination Figure 9 As shown, the following is a detailed analysis of the steady-state temperature field: Under steady-state conditions, a coordinate system is selected that moves with the pyrolysis surface, and the following is assumed: The distance from the fuel surface to the interior of the fuel ( For pyrolysis surface, (Extending inwards). The new, unpyrolyzed fuel fraction at a rate (equal to the rate of regression) The material continuously moves from the distal end towards the pyrolysis surface. The one-dimensional steady-state energy equation is: , Thermal conductivity; Boundary conditions are (Surface temperature) (Initial fuel temperature, i.e., room temperature). Solution: In the formula The thermal diffusivity of the fuel is given. The temperature field exhibits an exponentially decaying distribution, with a characteristic penetration depth of [missing value]. For HTPB fuel ( ), at typical regression rates The thermal penetration depth is only This means that: (a) most of the fuel far from the surface is at room temperature, and the length of the solid fuel sample (typically 30-50 mm or even longer) is much greater than the thermal penetration depth, and can be considered a semi-infinite body; (b) after changing the temperature of the copper rod, the new steady-state temperature field can be obtained. The system can quickly reach a new steady state within a time frame of approximately 0.4 to 10 seconds, making it possible to continuously test multiple temperature groups on a single sample.

[0074] A steady-state measurement device for the pyrolysis rate of solid fuel based on continuous fuel feeding includes the following steps: Installation Step 100: Install the heating unit and the feeding unit onto the housing 160; specifically, extend the feeding push rod 50 from the bottom of the housing 160 through the bellows dynamic seal 90 into the sealed pyrolysis chamber 30, and connect the lower end of the feeding push rod 50 to the slide of the tension / compression sensor 80 and the servo motor 40. Mount the solid fuel sample 60 onto the fuel clamp 70 and fix it in place, then fix the fuel clamp 70 to the top of the feeding push rod 50. Confirm that the heating copper rod 10 and the heating coil 20 are installed in place and fixed together on the top plate of the sealed pyrolysis chamber 30, and insert the thermocouple 100 into the heating copper rod. Install the quartz glass window 130 and seal the sealed pyrolysis chamber 30. Connect the heating power supply line, tension sensor signal line, thermocouple signal line, motor control line, and encoder signal line to the host computer. Connect the inert gas supply component to the nitrogen inlet 110 of the chamber, and connect the exhaust port 120 to the exhaust gas treatment system.

[0075] Zeroing step 200: Zero the tension sensor by removing the weight of the feed push rod, fuel clamp, and solid fuel sample, as well as the elastic force of the bellows under compression, so that the reading of the tension sensor is only the contact force.

[0076] Air tightness check step 300: Check the air tightness of the housing 160 and ensure that the housing 160 is in an inert atmosphere. Specifically, first, seal the exhaust port 120, introduce nitrogen into the sealed pyrolysis chamber 30 and pressurize it to 0.3~0.6 MPa; then, stop the nitrogen supply and observe whether the pressure sensor reading drops significantly within 5 minutes. If there is no significant drop, the air tightness check is passed, and the exhaust port plug is removed. Finally, continuously introduce high-purity nitrogen into the sealed pyrolysis chamber 30 again and purge for 5~10 minutes to remove the air from the sealed pyrolysis chamber 30 and establish an inert nitrogen atmosphere. Afterward, maintain nitrogen at an appropriate flow rate for continuous purging.

[0077] Temperature gradient setting step 400: Set with Group experiment; ;right answer The target temperatures for the groups are respectively , , ......, ;correspond The feed rates of the groups are respectively , , ......, ;correspond The target contact forces of the groups are respectively , , ......, ; Temperature steady-state conditioning step 500: In In the group experiment, the target temperature of the heating copper rod was controlled and adjusted by the host computer and temperature sensor as follows: , , ......, Specifically, the first target temperature for the heating copper rod is set in the host computer. Taking 600k as an example, when the heating power is turned on, the temperature PID controller automatically adjusts the heating power to heat the heating copper rod 10 to [temperature value missing]. Once the temperature stabilizes and the reading of thermocouple 100 is observed, proceed to the next step.

[0078] Speed ​​steady-state adjustment step 600: In In the group experiment, the feed speed of the servo motor was adjusted by the tension / compression sensors and the host computer control. , , ......, Specifically, the target contact force is set in the host computer. Taking a contact force of 5 N as an example, the servo motor 40 is started, and the feed pusher 50 slowly pushes the solid fuel sample 60 upward. When the upper surface of the solid fuel sample 60 contacts the lower surface of the heating copper rod 10, the reading of the tension / compression sensor starts to rise from zero. The feed rate PID controller starts working and automatically adjusts the feed rate to maintain the contact force at a constant N. Nearby. It is worth noting that during the initial contact establishment phase, the heat from the heating copper rod 10 is transferred to the surface of the solid fuel sample 60, causing the surface temperature of the solid fuel sample 60 to rise rapidly and begin pyrolysis and migration. The tension / compression sensor may detect fluctuations in the contact force. After a transition process of several seconds to over ten seconds (such as...), Figure 10 As shown in the figure, the readings of the tension and compression sensors, the feed rate, and the temperature of the heated copper rod all tend to be constant, and the system enters a steady state.

[0079] Data acquisition step 700: When the target temperature within any group is The feed rate is and target contact force When the feed rate fluctuates within ±5% of its mean value over a continuously preset time period (preferably 5 seconds), the measuring device reaches a steady state; during the steady-state time period, the feed rate is continuously collected. and the detection temperature of the heating copper rod For no less than 10 seconds, a high-speed camera 140 recorded the pyrolysis process.

[0080] Data modification step 800: Modify the target temperature in the host computer. =650 K, the temperature PID controller automatically adjusts the heating power to the new... Simultaneously, the feed rate PID controller automatically adjusts the feed rate to follow the changes in the pyrolysis rate. After a brief transition, it reaches a steady state at the new temperature again, repeating data acquisition step 700 and acquiring data under the new steady state. On the same solid fuel sample, 4-6 target temperatures are set sequentially in ascending order of temperature. At each temperature, the steady state is reached and data is acquired.

[0081] End of test step 900: After completing the data acquisition for all temperature points, turn off the heating power, stop the servo motor, and continue nitrogen purging until the temperature inside the chamber drops to a safe range. Then stop data acquisition and remove the solid fuel sample 60. If a single test does not obtain a sufficient number of test points, replace the solid fuel sample 60 with a new one and repeat steps 100-800 until enough test measurement points are recorded.

[0082] Step 1000 in establishing the pyrolysis rate model: During the steady-state time period, the regression rate of any set of data... The feed rate during this steady-state time period The time average is shown in formula (1). (1); in, and The start and end times of the steady-state time period; the corresponding measured temperature. The temperature of the copper rod is taken under good contact conditions. (The average value during this steady-state period).

[0083] Data correction step 1100: In cases requiring higher accuracy, the surface temperature can be corrected using the steady-state energy conservation relationship. According to formula (2), the heat flow transferred from any set of heated copper rods to the solid fuel sample can be calculated. , (2); in, For latent heat of pyrolysis, For the density of fuel, The specific heat capacity of the fuel. The initial temperature of the solid fuel; at the same time, It also satisfies formula (3). (3); in, For contact thermal conductivity; combining equations (2) and (3) can solve for the solution. and obtain data groups ; Taking the natural logarithm of the regression rate, as shown in formula (4), (4), right and Perform linear regression fitting, based on the slope and intercept Find the pre-exponential factors and activation energy Thus, an Arrhenius-type pyrolysis rate model for solid fuel samples was established.

[0084] In summary, this application mounts the solid fuel sample on a servo motor and pushes it continuously upward from below, so that the pyrolysis surface always remains in contact with the heating surface. When the feed rate equals the pyrolysis retraction rate, the system reaches thermodynamic steady state. The steady-state feed rate is directly equal to the retraction rate, and the pyrolysis rate of the solid fuel can be directly obtained.

[0085] In addition, the contact force between the solid fuel sample and the heating copper rod is measured in real time using a tensile and compressive sensor. This force is then used as a feedback signal to input the feed rate PID controller, which automatically adjusts the feed rate to maintain a constant contact force, allowing the system to automatically converge to a steady state. This control scheme achieves the tracking of the pyrolysis retreat rate by the feed rate.

[0086] Furthermore, by taking advantage of the fact that the thermal penetration depth of fuel is much smaller than the length of the sample under steady-state conditions, the temperature setting of the heating copper rod is changed sequentially on the same solid fuel sample. After the system quickly reaches a new steady state, data is collected, enabling the acquisition of more data required for the Arrhenius pyrolysis rate model on a single solid fuel sample, thus reducing the experimental time cost.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A device for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, characterized in that, include: The shell has a sealed pyrolysis chamber; a solid fuel sample is disposed at a first preset position in the sealed pyrolysis chamber, and a pyrolysis surface is formed on the side of the solid fuel sample opposite to the shell. A heating unit is disposed in the sealed pyrolysis chamber at a second preset position, and a heating surface adapted to the pyrolysis surface is formed on the side of the heating unit away from the shell. The feeding unit has a drive unit and a transmission unit connected to the drive unit. The transmission unit passes through the housing and is connected to the solid fuel sample. The drive unit can drive the solid fuel sample to move through the transmission unit, so that the pyrolysis surface of the solid fuel sample is always in contact with the heating surface of the heating unit. as well as The control unit includes a temperature control module and a speed control module; the temperature control module can control the output power of the heating unit. The speed control module can control the feed rate of the drive unit.

2. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 1, characterized in that, The drive unit includes: Ball screws, and A servo motor, via a coupling, can drive the ball screw shaft to rotate, and the rotation of the ball screw shaft can drive the nut of the ball screw to move in the direction of the solid fuel sample toward the heating unit.

3. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 2, characterized in that, The transmission unit includes a feed push rod; One end of the feed push rod extends into the housing and is connected to the solid fuel sample via a fuel clamp, while the other end is connected to the nut; When the servo motor is started, the nut can drive the feed push rod to move so that the pyrolysis surface comes into contact with the heating surface.

4. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 3, characterized in that, The transmission unit also includes a bellows; The bellows is connected to the outer wall of the housing at the position where the feed push rod extends into the housing, and the end of the bellows away from the housing is connected to the preset position of the feed push rod.

5. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 3, characterized in that, The speed control module includes: The host computer can set the target contact force between the pyrolysis surface and the heating surface, and the target contact force is denoted as... ; A tension / compression sensor is disposed between the nut and the feed push rod. The sensor measures the contact force between the pyrolysis surface and the heating surface. This contact force is denoted as... The tension and compression sensors are respectively connected to the feed rate PID controller and the host computer; and A feed rate PID controller is connected to both the host computer and the servo motor; the feed rate PID controller adjusts the feed rate based on the target contact force. and measuring contact force Capable of calculating force deviation Furthermore, the feed rate PID controller can adjust the feed rate based on the force deviation. Controlling the feed rate of the servo motor So that the measured contact force Achieving the target contact force .

6. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 5, characterized in that, The heating unit includes: A heating copper rod, one end of which is fixed to the inner wall of the housing, and the other end extends toward the interior of the sealed pyrolysis chamber and forms the heating surface; Heating coils are wound around the outer wall of the heating copper rod; and A heating power supply is connected to the heating coil, and the heating copper rod is heated to a target temperature by heating the heating coil. The target temperature is denoted as [missing information]. .

7. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 6, characterized in that, The temperature control module includes: A temperature PID controller is connected to both the heating power supply and the host computer; and A thermocouple, with its probe inserted into the heating copper rod at a predetermined distance from the heating surface, measures and records the temperature of the heating copper rod. ; The thermocouples are connected to the temperature PID controller and the host computer, respectively. The temperature PID controller determines the target temperature based on the... and temperature detection Able to calculate temperature deviation And the temperature PID controller can adjust according to the temperature deviation. Controlling the output power of the heating power supply so that the detected temperature of the heating copper rod is... Reach the target temperature .

8. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 5, characterized in that, The solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding further includes an observation unit, which includes: A quartz glass window is disposed on the side wall of the housing and corresponds at least to the contact interface formed by the contact between the pyrolysis surface and the heating surface; and A high-speed camera is positioned on the outside of the housing, corresponding to the location of the quartz glass window, and is connected to the host computer, enabling it to transmit captured images to the host computer.

9. The steady-state measurement device for solid fuel pyrolysis rate based on continuous fuel feeding according to claim 7, characterized in that, The solid fuel pyrolysis rate steady-state measurement device based on continuous fuel feeding further includes a gas protection unit, which comprises: An inert gas supply component, in communication with the housing, is capable of introducing inert gas into the housing to place the housing in an inert atmosphere; and The exhaust component, which is connected to the housing, is capable of discharging the products generated by the pyrolysis of the solid fuel sample to the outside of the housing.

10. A method for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding, based on the device for steady-state measurement of solid fuel pyrolysis rate based on continuous fuel feeding as described in any one of claims 1-9, characterized in that, Includes the following steps: Installation steps: Install the heating unit and the feeding unit into the housing; Zeroing procedure: Zero the tension sensor by removing the weight of the feed push rod, fuel clamp, and solid fuel sample, as well as the elastic force of the bellows under compression, so that the reading of the tension sensor is only the contact force. Air tightness inspection procedure: Check the air tightness of the casing and place the casing in an inert atmosphere; Temperature gradient setting steps: Set the temperature gradient with Group experiment; ;correspond The group's goal The marked temperatures are respectively , , ......, ;correspond The feed rates of the groups are respectively , , ......, ;correspond The target contact forces of the groups are respectively , , ......, ; Temperature steady-state conditioning steps: In In the group experiment, the target temperature of the heating copper rod was controlled and adjusted by the host computer and temperature sensor as follows: , , ......, ; Speed ​​steady-state adjustment steps: In In the group experiment, the feed speed of the servo motor was adjusted by the tension / compression sensors and the host computer control. , , ......, ; Data acquisition steps: When the target temperature within any group is The feed rate is and target contact force When the feed rate fluctuates within ±5% of its mean value over a continuously preset time period, the measuring device reaches a steady state; during the steady-state time period, the feed rate is continuously collected. and the detection temperature of the heating copper rod ; Steps to establish a pyrolysis rate model: During the steady-state time period, for any set of regression rates The feed rate during this steady-state time period The time average is shown in formula (1). （1）； in, and These represent the start and end times of the steady-state time period; Data correction steps: According to formula (2), the heat flow transferred from any set of heating copper rods to the solid fuel sample can be calculated. , （2）; in, For latent heat of pyrolysis, For the density of fuel, The specific heat capacity of the fuel. The initial temperature of the solid fuel; at the same time, It also satisfies formula (3). （3）； in, For contact thermal conductivity; combining equations (2) and (3) can solve for the solution. and obtain data groups ; Taking the natural logarithm of the regression rate, as shown in formula (4), （4）， right and Perform linear regression fitting, based on the slope and intercept Find the pre-exponential factors and activation energy Thus, an Arrhenius-type pyrolysis rate model for solid fuel samples was established.

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