A method for predicting resistance to draw and ventilation of a heated cigarette based on a nonlinear network model

Abstract

The application discloses a kind of based on nonlinear network model's prediction method of heating cigarette resistance and ventilation rate, specifically includes the following steps: S1, according to heating cigarette structure, the network model of each part pressure drop or flow of cigarette is established;S2, based on the basic principle of fluid mechanics, the relationship of each part pressure drop and flow is constructed;S3, according to the equation set constructed, the expression of cigarette resistance and ventilation rate is solved;S4, the prediction value of resistance and ventilation rate is obtained by substituting cigarette parameter into expression.The prediction model provided by the application obtains the analytical expression of resistance and ventilation rate about basic structural parameters of cigarette, so that relevant field production and research and development personnel can directly calculate according to structural parameters when designing heating cigarette to accurately predict cigarette resistance and ventilation rate.

Description

Technical Field

[0001] This invention belongs to the field of heated cigarette product design, specifically involving a method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model. Background Technology

[0002] Heated cigarettes, designed with the concept of "heating without burning," are relatively low-temperature cigarettes and represent an important category of new tobacco products. They offer a similar consumption experience to traditional cigarettes, providing consumers with similar satisfaction and aroma, thus gaining widespread acceptance. Furthermore, heated cigarettes typically heat tobacco raw materials to a temperature range of 200-350℃ to produce smoke, inhibiting the high-temperature decomposition reaction of the tobacco raw materials and significantly reducing the production of harmful substances. This minimizes the harm to human health and public health, leading to a gradual increase in their market share.

[0003] Heated cigarettes generally consist of three parts: a smoke-generating section, a cooling section, and a filtering section. The empty paper tube section with ventilation holes is a commonly used cooling structure in heated cigarettes, employed by both domestic and international tobacco companies, and in various circumference and length types of heated cigarettes. The air entering through the ventilation holes mixes with the smoke generated in the smoke-generating section; the cooling effect directly affects the temperature and amount of smoke inhaled. The resistance characteristics of each functional section affect the cigarette's draw resistance, all closely related to the consumer's sensory experience. Therefore, accurate prediction of draw resistance and ventilation rate is crucial for heated cigarette design.

[0004] In their paper "A Prediction Method for Cigarette Draw Resistance and Ventilation Characteristics Based on a Linear Network Model" (Tobacco Science and Technology, 2017.12), Wang Le et al. compared cigarette draw resistance to resistance in a circuit and proposed a linear network model to predict the draw resistance and ventilation of traditional cigarettes, achieving good prediction results. However, according to the national standard GB / T23227-2018 "Determination of Air Permeability," the relationship between flow rate and pressure difference in many types of paper is non-linear, thus limiting the universality and accuracy of this method. Furthermore, while Wang Le et al.'s method uses air permeability as an experimental parameter for ventilation calculation, heated cigarettes often use online perforation, making it difficult to obtain air permeability parameters, thus rendering this method unsuitable for predicting draw resistance and ventilation.

[0005] Currently, some literature uses numerical simulation to calculate cigarette draw resistance or ventilation rate. However, numerical simulation requires strong geometric modeling, mesh generation, and model solving capabilities. It is generally carried out by professional technicians and has a high time cost, making it difficult to promote to cigarette production and R&D personnel. Summary of the Invention

[0006] To address the aforementioned technical problems in existing technologies, this invention provides a method for predicting the draw resistance and ventilation of heated cigarettes based on a nonlinear network model. According to the basic principles of fluid mechanics, the relationship between the draw resistance and ventilation of the cigarette and the structural parameters of the cigarette and ventilation holes is analyzed, which can be used to quickly and accurately calculate the draw resistance and ventilation rate of heated cigarettes.

[0007] The technical solution adopted in this invention is:

[0008] A method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model, characterized by the following steps:

[0009] S1. Establish a network model of pressure drop or flow rate of each part of the cigarette based on the structure of the heated cigarette.

[0010] S2. Based on the basic principles of fluid mechanics, construct the relationship between pressure drop and flow rate for each part;

[0011] S3. Solve for the expressions for smoke resistance and ventilation rate based on the constructed system of equations;

[0012] S4. Substitute the cigarette parameters into the expression to obtain the predicted values ​​of suction resistance and ventilation rate.

[0013] Furthermore, in step S1, the specific steps for establishing a network model of the pressure drop or flow rate of each part of the cigarette based on the heated cigarette structure are as follows:

[0014] S11. Since the smoke-generating section and each ventilation hole are connected in parallel, the air resistance through the smoke-generating section is the same as the pressure drop through each small hole. Therefore:

[0015] P1 = P 21 =P 22 =…=P 2i =…=P 2n (1)

[0016] Where n is the total number of ventilation holes, i represents the i-th ventilation hole, P1 is the pressure drop of air passing through the smoke-generating section, and P 2i Let be the local pressure drop of air passing through the i-th vent.

[0017] S12. The air passing through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from each ventilation hole. Therefore, the airflow through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from the ventilation holes.

[0018]

[0019] Where q1 is the airflow rate inside the smoke-generating section, q 2i q3 represents the airflow rate through the i-th ventilation hole, and q3 represents the airflow rate inside the filter section.

[0020] According to the national standard GB / T 22838.5-2009 "Determination of Physical Properties of Cigarettes and Filter Rods - Part 5: Cigarette Draw Resistance and Filter Rod Pressure Drop", draw resistance is the negative pressure applied to the output end to maintain a flow rate of 17.5 mL / s; therefore, the flow rate of the filtration section is constant.

[0021] q3 = const = 17.5 mL / s (3)

[0022] Furthermore, in step S2, based on the fundamental principles of fluid mechanics, the specific steps for establishing the relationship between pressure drop and gas flow rate in different parts of the cigarette are as follows:

[0023] S21. The pressure drop and gas flow rate in the smoke-generating section conform to Darcy's law:

[0024]

[0025] Where A1 is the cross-sectional area of ​​the smoke-generating section, l1 is the length of the smoke-generating section, k1 is the permeability of the smoke-generating section, and μ is the dynamic viscosity of air.

[0026] S22. Local pressure loss is directly related to the kinetic energy of the fluid. According to the expression for local pressure loss, the local pressure loss of air flowing through the ventilation hole is:

[0027]

[0028] Among them, A 0i Let C be the area of ​​the i-th ventilation hole. di Let ρ be the flow coefficient of the i-th orifice, and ρ be the density of air.

[0029] S23. The pressure drop in the filtration section is similar to that in the smoke generation section, and the pressure drop and gas flow rate also conform to Darcy's law:

[0030]

[0031] Where P3 represents the pressure drop of air passing through the filter section, A3 is the cross-sectional area of ​​the filter section, l3 is the length of the filter section, and k3 is the permeability of the filter section.

[0032] Furthermore, in step S3, the specific steps for solving the expressions for cigarette draw resistance and ventilation rate based on the constructed system of equations are as follows:

[0033] Equations (1) to (6) above constitute a closed system of equations. Solving the system of equations yields the expressions for suction resistance and ventilation rate:

[0034]

[0035] in, These are the intermediate quantities required for substitution in solving the equation.

[0036] The draw resistance of heated cigarettes is:

[0037]

[0038] Substituting equation (7) into equation (8) yields the draw resistance of heated cigarettes;

[0039] The ventilation rate of heated cigarettes is:

[0040]

[0041] Substituting equation (7) into equation (9) yields the ventilation rate of heated cigarettes;

[0042] The length and diameter of the smoke-generating section, the length and diameter of the filter section, and the diameter and number of ventilation holes are all design parameters. The absorption resistance and ventilation rate of heated cigarettes under any design parameters can be calculated by formulas (8) and (9).

[0043] Furthermore, in step S2, the permeability of the smoke-generating section and the filtration section is obtained experimentally, specifically by the following method:

[0044] The pressure drop of air passing through the smoke-generating section or filter rod was tested at different flow rates. Linear fitting was then performed on the obtained flow-pressure drop data to obtain:

[0045] P=k′Q (10)

[0046] Where P is the pressure drop of the smoke-generating section or filter rod, Q is the test flow rate, and k′ is the linear fitting coefficient.

[0047] The permeability k of the smoke-generating section or filter rod is:

[0048]

[0049] Where μ is the dynamic viscosity of air, and l and A are the length and cross-sectional area of ​​the test section, respectively. Generally, when the tobacco formula and filter filling parameters are stable, the permeability of the smoke-generating section and the filtration section can be considered constant.

[0050] Furthermore, in step S3, the flow coefficient C of the ventilation hole di This is an empirical coefficient, between 0.6 and 0.7. When the number and area of ​​ventilation holes do not change significantly, C can be considered... di As a fixed value, C can be obtained by experimentally measuring and verifying existing cigarettes. di The specific steps are as follows:

[0051] Test the suction resistance and ventilation rate of the existing cigarette. Substitute the length, diameter and permeability of the smoke-generating section of the existing cigarette, the length, diameter and permeability of the filter section, and the area and number of ventilation holes into equations (7)-(9) and adjust the flow coefficient C. diTo make the calculated suction resistance and ventilation rate in equations (8) and (9) consistent with the experimentally measured values, then C at this time... di The value is the flow coefficient value that can be used for subsequent design calculations.

[0052] Generally speaking, the size of each ventilation hole on a heated cigarette can be considered to be the same, so the equation set (1)-(6) can be simplified to:

[0053]

[0054]

[0055]

[0056] P1 = P2 (15)

[0057] q3=q1+nq2 (16)

[0058] q3 = const = 17.5 mL / s (17)

[0059] In the formula, P2 is the pressure drop of air flowing through the ventilation hole, q2 is the airflow rate in a single ventilation hole, A0 is the area of ​​a single ventilation hole, and C d It is the flow coefficient of gas flowing through the ventilation hole.

[0060] Solving the closed system of equations (12)-(17) yields:

[0061]

[0062]

[0063] in,

[0064]

[0065] The draw resistance of heated cigarettes is:

[0066]

[0067] The ventilation rate of heated cigarettes is:

[0068]

[0069] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0070] 1. The prediction model provided by this invention obtains analytical expressions for draw resistance and ventilation rate with respect to the basic structural parameters of cigarettes, thereby enabling production and R&D personnel in related fields to directly calculate and accurately predict the draw resistance and ventilation of cigarettes based on the structural parameters when designing heated cigarettes.

[0071] 2. Through the implementation of this invention, the cost of production trial or complex numerical simulation is reduced in the design stage of heated cigarettes, helping production personnel to better grasp product performance and improve R&D efficiency; it avoids the human limitations of complex numerical simulation and realizes rapid and accurate prediction of the draw resistance and ventilation rate of heated cigarettes.

[0072] 3. This invention solves the problem that the original linear model cannot be applied to heated cigarettes, and has higher prediction accuracy than the linear model.

[0073] 4. This invention provides guidance for the quality assessment and product structure design of heated cigarettes, and is particularly applicable to heated cigarettes produced by online perforation.

[0074] 5. This invention can directly predict the draw resistance and ventilation rate of heated cigarettes based on design parameters, especially the length, diameter, and area and number of ventilation holes. Compared with existing linear network models, it is more suitable for accurately predicting the draw resistance and ventilation indicators of heated cigarettes before production, thus improving the efficiency of targeted design and quality control for R&D personnel. Attached Figure Description

[0075] Figure 1 This is a schematic diagram of the heated cigarette structure of the present invention.

[0076] Figure 2 This is a network model of the suction resistance of each section of the heated cigarette in this invention.

[0077] Figure 3 The present invention describes the method steps for predicting the absorption resistance and ventilation rate of heated cigarettes based on a nonlinear network model. Detailed Implementation

[0078] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0079] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0080] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0081] refer to Figure 1 This is a schematic diagram of a heated cigarette structure, including a smoke-generating section 1, a cooling section 2, a ventilation hole 21, and a filter section 3. During inhalation, part of the external air enters the cigarette through the end of the smoke-generating section 1, and the other part enters through the ventilation hole 21, forming a parallel flow. The converged airflow then exits the cigarette through the filter section 3. The pressure drop in the cooling section 2 cavity is very small (2-3 Pa) and can be ignored.

[0082] This embodiment discloses a method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model. A network model of the pressure drop in each part of the heated cigarette is established according to its structure. Based on basic fluid mechanics principles, the relationship between pressure drop and flow rate is constructed. The expressions for draw resistance and ventilation are solved using the constructed equations. Finally, the predicted values ​​of draw resistance and ventilation are obtained by substituting the cigarette parameters into the expressions. The specific steps are as follows:

[0083] The specific steps for establishing a network model of pressure drop or flow rate in various parts of a heated cigarette based on its structure are as follows:

[0084] S11. Since the smoke-generating section and each ventilation hole are connected in parallel, the air resistance through the smoke-generating section is the same as the pressure drop through each small hole. Therefore:

[0085] P1 = P 21 =P 22 =…=P 2i =…=P 2n (1)

[0086] Where n is the total number of ventilation holes, i represents the i-th ventilation hole, P1 is the pressure drop of air passing through the smoke-generating section, and P 2i Let be the local pressure drop of air passing through the i-th vent.

[0087] S12. The air passing through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from each ventilation hole. Therefore, the airflow through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from the ventilation holes.

[0088]

[0089] Where q1 is the airflow rate inside the smoke-generating section, q 2i q3 represents the airflow rate through the i-th ventilation hole, and q3 represents the airflow rate inside the filter section.

[0090] According to the national standard GB / T 22838.5-2009 "Determination of Physical Properties of Cigarettes and Filter Rods - Part 5: Cigarette Draw Resistance and Filter Rod Pressure Drop", draw resistance is the negative pressure applied to the output end to maintain a flow rate of 17.5 mL / s; therefore, the flow rate of the filtration section is constant.

[0091] q3 = const = 17.5 mL / s (3)

[0092] Based on the fundamental principles of fluid mechanics, the specific steps for establishing the relationship between pressure drop and gas flow rate in different parts of a cigarette are as follows:

[0093] S21. The pressure drop and gas flow rate in the smoke-generating section conform to Darcy's law:

[0094]

[0095] Where A1 is the cross-sectional area of ​​the smoke-generating section, l1 is the length of the smoke-generating section, k1 is the permeability of the smoke-generating section, and μ is the dynamic viscosity of air.

[0096] S22. Local pressure loss is directly related to the kinetic energy of the fluid. According to the expression for local pressure loss, the local pressure loss of air flowing through the ventilation hole is:

[0097]

[0098] Among them, A 0i Let C be the area of ​​the i-th ventilation hole. di Let ρ be the flow coefficient of the i-th orifice, and ρ be the density of air.

[0099] S23. The pressure drop in the filtration section is similar to that in the smoke generation section, and the pressure drop and gas flow rate also conform to Darcy's law:

[0100]

[0101] Where P3 represents the pressure drop of air passing through the filter section, A3 is the cross-sectional area of ​​the filter section, l3 is the length of the filter section, and k3 is the permeability of the filter section.

[0102] The specific steps for solving the expressions for cigarette draw resistance and ventilation rate based on the constructed system of equations are as follows:

[0103] Equations (1) to (6) above constitute a closed system of equations. Solving the system of equations yields the expressions for suction resistance and ventilation rate:

[0104]

[0105] in, These are the intermediate quantities required for substitution in solving the equation.

[0106] The draw resistance of heated cigarettes is:

[0107]

[0108] Substituting equation (7) into equation (8) yields the draw resistance of heated cigarettes;

[0109] The ventilation rate of heated cigarettes is:

[0110]

[0111] Substituting equation (7) into equation (9) yields the ventilation rate of heated cigarettes;

[0112] The length and diameter of the smoke-generating section, the length and diameter of the filter section, and the diameter and number of ventilation holes are all design parameters. The absorption resistance and ventilation rate of heated cigarettes under any design parameters can be calculated by formulas (8) and (9).

[0113] The permeability of the smoke-generating section and the filtration section was obtained experimentally, specifically using the following method:

[0114] The pressure drop of air passing through the smoke-generating section or filter rod was tested at different flow rates. Linear fitting was then performed on the obtained flow-pressure drop data to obtain:

[0115] P=k′Q (10)

[0116] Where P is the pressure drop of the smoke-generating section or filter rod, Q is the test flow rate, and k′ is the linear fitting coefficient.

[0117] The permeability of the smoke-generating section or filter rod:

[0118]

[0119] Where μ is the dynamic viscosity of air, and l and A are the length and cross-sectional area of ​​the test section, respectively. Generally, when the tobacco formula and filter filling parameters are stable, the permeability of the smoke-generating section and the filtration section can be considered constant.

[0120] Flow coefficient C of ventilation hole di This is an empirical coefficient, between 0.6 and 0.7. When the number and area of ​​ventilation holes do not change significantly, C can be considered... di As a fixed value, C can be obtained by experimentally measuring and verifying existing cigarettes. di The specific steps are as follows:

[0121] Test the suction resistance and ventilation rate of the existing cigarette. Substitute the length, diameter and permeability of the smoke-generating section of the existing cigarette, the length, diameter and permeability of the filter section, and the area and number of ventilation holes into equations (7)-(9) and adjust the flow coefficient C. di To make the calculated suction resistance and ventilation rate in equations (8) and (9) consistent with the experimentally measured values, then C at this time... di The value is the flow coefficient value that can be used for subsequent design calculations.

[0122] Generally speaking, the size of each ventilation hole on a heated cigarette can be considered to be the same, so the equation set (1)-(6) can be simplified to:

[0123]

[0124]

[0125]

[0126] P1 = P2 (15)

[0127] q3=q1+nq2 (16)

[0128] q3 = const = 17.5 mL / s (17)

[0129] In the formula, P2 is the pressure drop of air flowing through the ventilation hole, q2 is the airflow rate in a single ventilation hole, A0 is the area of ​​a single ventilation hole, and C d It is the flow coefficient of gas flowing through the ventilation hole.

[0130] Solving the closed system of equations (12)-(17) yields:

[0131]

[0132]

[0133] in,

[0134]

[0135] The draw resistance of heated cigarettes is:

[0136]

[0137] The ventilation rate of heated cigarettes is:

[0138]

[0139] Specifically, in this embodiment,

[0140] First: Obtain the structural parameters of the prototype cigarette.

[0141] Heated cigarettes (YIN) produced by Zhejiang China Tobacco Industry Co., Ltd. were selected. Specifically, the cigarettes were slim, with an overall length of 84mm (42mm for the smoking section, 32mm for the cooling section, and 10mm for the filter section) and a circumference of 16.8mm. The prototype cigarette's ventilation hole structure consisted of two rows of 19 holes each. The ventilation holes were inspected using a comprehensive drilling quality platform, and the average area of ​​a single ventilation hole was found to be 1.72034 × 10⁻⁶. -8 m 2 (Equivalent diameter 0.148mm). The structural parameters of the cigarette are summarized in Table 1 below.

[0142] Table 1 Summary of Cigarette Structural Parameters

[0143]

[0144] Second: Obtain the resistance parameters of the prototype cigarette.

[0145] The smoking section of a prototype cigarette was extracted, and five smoking sections of similar weight were selected through weight screening. Five parallel experiments were conducted on a flow-pressure drop platform to obtain the flow-pressure drop curves of the smoking sections and perform linear fitting, resulting in P = k′Q. The permeability of the smoking section is then calculated. The average value of the five sets of parallel experimental data was taken, and the permeability of the smoke-generating section was obtained as k1 = 5.98802 × 10⁻⁶. -10 m 2 The same experiment and data processing were performed on the filter rods used in cigarettes, and the permeability of the filter rods was found to be k3 = 5.88235 × 10⁻⁶. -10 m 2 .

[0146] The prototype cigarette was tested on the QTM test bench, and the cigarette's suction resistance was found to be P = 623.4 Pa, and the ventilation rate was η = 60.3%. Substituting the cigarette's structural parameters l1, l3, A1, A3, A0, n and its resistance parameters k1, k3 into equations (21) and (22), the flow coefficient C was checked and adjusted. d The value of is used to make the calculated suction resistance and ventilation rate close to the experimental values, and finally the flow coefficient C of the prototype cigarette vent is obtained. d =0.65, the calculated suction resistance is 638.8 Pa, with an error of 2.5% compared to the experimental suction resistance; the calculated ventilation rate is 61.8%, with an error of 2.7% compared to the experimental ventilation rate. The prototype cigarette resistance parameters are summarized in Table 2 below.

[0147] Table 2 Summary of Prototype Cigarette Resistance Parameters

[0148]

[0149] Third: Predict the draw resistance and ventilation rate of the modified cigarette based on design parameters.

[0150] Based on the cigarette resistance parameters obtained by the above method and the design parameters of the modified cigarette, predict the suction resistance and ventilation rate of the modified cigarette.

[0151] The structural parameters of the modified cigarette remain unchanged, and the ventilation holes are still two rows of round holes, but new parameters have been designed:

[0152] Option 1 is to keep the area of ​​each ventilation hole unchanged, but change the number of holes in each row to 24;

[0153] Option two involves keeping the number of holes the same, but increasing the diameter of the ventilation holes by 0.17 mm (area of ​​2.26980 × 10). -8 m 2 ).

[0154] Substituting the new design parameters into equations (21) and (22), the draw resistance and ventilation rate of the modified cigarette were predicted, and the accuracy of the predicted data was verified through subsequent production. The calculation and test data of the draw resistance and ventilation of the modified cigarette are as follows:

[0155]

[0156]

[0157] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model, characterized in that, Specifically, the steps include the following: S1. Establish a network model of pressure drop or flow rate of each part of the cigarette based on the structure of the heated cigarette. S2. Based on the basic principles of fluid mechanics, construct the relationship between pressure drop and flow rate for each part; S3. Solve for the expressions for smoke resistance and ventilation rate based on the constructed system of equations; S4. Substitute the cigarette parameters into the expression to obtain the predicted values ​​of suction resistance and ventilation rate; In step S1, the network model for the pressure drop or flow rate of each part of the cigarette is as follows: S11. Since the smoke-generating section and each ventilation hole are connected in parallel, the air resistance through the smoke-generating section is the same as the pressure drop through each small hole. Therefore: （1） Where n is the total number of ventilation holes, and i represents the i-th ventilation hole. It is the pressure drop of air passing through the smoke-generating section. Let be the local pressure drop of air passing through the i-th ventilation hole; S12. The air passing through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from each ventilation hole. Therefore, the airflow through the filtration section is the sum of the airflow from the smoke-generating section and the airflow from the ventilation holes. = （2） in, It refers to the airflow rate inside the smoke-generating section. Let i be the airflow rate through the i-th vent. This refers to the airflow rate inside the filter section. According to the national standard GB / T 22838.5-2009 "Determination of Physical Properties of Cigarettes and Filter Rods - Part 5: Cigarette Draw Resistance and Filter Rod Pressure Drop", draw resistance is the negative pressure applied to the output end to maintain a flow rate of 17.5 mL / s; therefore, the flow rate of the filtration section is constant. （3） In step S2, based on the basic principles of fluid mechanics, the specific steps for establishing the relationship between pressure drop and gas flow rate in different parts of the cigarette are as follows: S21. The pressure drop and gas flow rate in the smoke-generating section conform to Darcy's law: （4） in, It is the cross-sectional area of ​​the smoke-generating section. It is the length of the smoke-generating section. It is the penetration rate of the smoke-generating section. It is the dynamic viscosity of air; S22. Local pressure loss is directly related to the kinetic energy of the fluid. According to the expression for local pressure loss, the local pressure loss of air flowing through the ventilation hole is: （5） in, Let i be the area of ​​the i-th ventilation hole. Let be the flow coefficient of the i-th orifice. The density of air; S23. The pressure drop in the filtration section is similar to that in the smoke generation section, and the pressure drop and gas flow rate also conform to Darcy's law: （6） in, This indicates the pressure drop of air as it passes through the filter section. It is the cross-sectional area of ​​the filter section. It is the length of the filter section. This represents the permeability of the filtration section.

2. The method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model as described in claim 1, characterized in that, In step S3, the expressions for cigarette draw resistance and ventilation rate are obtained by solving the constructed system of equations as follows: Equations (1) to (6) above constitute a closed system of equations. Solving the system of equations yields the gas flow rate within the smoke-generating section as follows: in, These are the intermediate quantities required for substitution in solving the equation. , ; The expression for the draw resistance of heated cigarettes is: Substituting equation (7) into equation (8) yields the draw resistance of heated cigarettes; The expression for the ventilation rate of heated cigarettes is: Substituting equation (7) into equation (9) yields the ventilation rate of heated cigarettes; The length and diameter of the smoke-generating section, the length and diameter of the filter section, and the diameter and number of ventilation holes are all design parameters. The suction resistance and ventilation rate of heated cigarettes under any design parameters are calculated by formulas (8) and (9).

3. The method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model as described in claim 1, characterized in that, In step S2, the permeability of the smoke-generating section and the filtration section is obtained experimentally, specifically by the following method: The pressure drop of air passing through the smoke-generating section or filter rod was tested at different flow rates. Linear fitting was then performed on the obtained flow-pressure drop data to obtain: （10） Where P is the pressure drop in the smoke-generating section or filter rod, and Q is the test flow rate. These are the linear fitting coefficients; The permeability k of the smoke-generating section or filter rod is: （11） in, Let be the dynamic viscosity of air, and l and A be the length and cross-sectional area of ​​the test section, respectively.

4. The method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model as described in claim 1, characterized in that, In step S3, the flow coefficient of the ventilation hole This is an empirical coefficient, between 0.6 and 0.7, considered appropriate when the number and area of ​​ventilation holes do not change significantly. The value is a fixed value, obtained through experimental measurement and verification of existing cigarettes. The specific steps are as follows: Test the suction resistance and ventilation rate of the existing cigarettes. Substitute the length, diameter, and permeability of the smoke-generating section, the length, diameter, and permeability of the filter section, and the area and number of ventilation holes into equations (7)-(9) to adjust the flow coefficient. To make the calculated suction resistance and ventilation rate in equations (8) and (9) consistent with the experimentally measured values, then at this time... The value is the flow coefficient value used for subsequent design calculations.

5. The method for predicting the draw resistance and ventilation rate of heated cigarettes based on a nonlinear network model as described in claim 1, characterized in that, If the size of all the ventilation holes on the cigarette is considered to be the same, then the system of equations constructed in S1 and S2 simplifies to: （12） （13） （14） （15） （16） （17） In the formula, The pressure drop of air flowing through the ventilation hole. It refers to the airflow rate within a single ventilation opening. The area of ​​a single ventilation hole. It is the flow coefficient of gas flowing through the ventilation hole; Solving the closed system of equations (12)-(17) yields: （18） （19） in, （20） The draw resistance of heated cigarettes is: （21） The ventilation rate of heated cigarettes is: （22） Substitute the cigarette design parameters into equations (21) and (22) to obtain the calculated values ​​of suction resistance and ventilation rate.

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