Hydrodynamic model for cigarette filter to filter smoke nicotine puff by puff and modeling method

Abstract

The invention discloses a hydrodynamic model for cigarette filter puff-by-puff smoke nicotine filtration and a modeling method. The modeling method comprises the following steps: 1) measuring the solid volume fraction of the cleaning filter tip by adopting a row volume method; 2) filtering the smoke puff by puff through a clean filter tip, and measuring the nicotine mass of the total smoke in each puff and the nicotine mass intercepted by the filter tip to obtain the nicotine filtering efficiency; (3) establishing a hydrodynamic model of cigarette filter puff-by-puff smoke nicotine filtration through monofilament fiber hydrodynamics according to measurement results obtained in the step (1) and the step (2); and 4) performing experimental detection and optimization on the model obtained in the step 3). According to the model, the smoke nicotine interception condition of cigarette filter puff-by-puff smoking is described based on the filter fiber solid volume fraction and the viscous resistance coefficient, the model is detected and optimized according to a puff-by-puff smoking experiment, and therefore it is guaranteed that the model has excellent accuracy and authenticity.

Description

Technical Field

[0001] This invention relates to a fluid dynamics model of a cigarette filter, specifically to a fluid dynamics model and modeling method for filtering nicotine from cigarette smoke puff by puff, belonging to the field of cigarette testing technology. Background Art

[0002] Cigarette filters are an important component of cigarettes, effectively filtering out some harmful components in the smoke. These harmful components are divided into gaseous and solid categories. The main solid component is nicotine particles, which provide the smoker with a pleasurable sensation but are also harmful to the body. Among various tobacco products, the filter's ability to retain nicotine is one of the indicators used to market health-conscious products. Because experimental research is extremely resource-intensive, some researchers have used computational fluid dynamics (CFD) to model and study the nicotine filtration of cigarette smoke during a single puff. Smoking a cigarette often requires multiple puffs, and the nicotine retained after each puff affects the next puff. However, current research on puff-by-puff filtration is limited, and experimental studies of puff-by-puff filtration are even more resource-intensive. Therefore, establishing a feasible CFD model for puff-by-puff nicotine filtration by cigarette filters is crucial for studying the impact of nicotine retention on the next puff and for guiding filter optimization. Summary of the Invention

[0003] To address the problems existing in the prior art, the first objective of this invention is to provide a hydrodynamic model for the nicotine filtration of cigarette smoke by puff. This model describes the nicotine retention of cigarette smoke by puff based on the solid volume fraction of filter fiber filaments and the viscous resistance coefficient. The model is tested and optimized based on puff-by-puff experiments to ensure that the model has excellent accuracy and realism.

[0004] The second objective of this invention is to provide a fluid dynamics modeling method for the filtration of nicotine in cigarette filters puff by puff. This modeling method is based on the synergistic effect of filter suction fluid dynamics and puff-by-puff experiments, and can predict the flow field distribution and nicotine filtration efficiency during each puff in the filter puff process. It effectively solves the problems of excessive cost and error in the experimental study of puff-by-puff in the prior art.

[0005] To achieve the above technical objectives, the present invention provides a fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff, comprising: 1) determining the solid volume fraction of the cleaned filter using the displacement volume method;

[0006] 2) Filter the smoke through the cleaned filter puff by puff, and measure the total nicotine mass of the smoke in each puff and the nicotine mass retained by the filter to obtain the nicotine filtration efficiency.

[0007] 3) Based on the measurement results obtained in steps 1) and 2), a fluid dynamic model for the filtration of nicotine in cigarette smoke by cigarette filter is established using monofilament fiber fluid dynamics.

[0008] 4) Perform experimental testing and optimization on the model obtained in step 3) to obtain the final model.

[0009] As a preferred embodiment, the process for determining the solid volume fraction of the cleaning filter is as follows:

[0010] 1) After making up the volume with deionized water in a volumetric flask, add n clean filter tips to completely submerge them in the deionized water and let stand for 5-8 minutes.

[0011] 2) After standing, remove the excess deionized water from the volumetric flask until the liquid level drops to the mark on the flask. Record the volume of water removed as V1, which is the true volume of n cleaning filters.

[0012] 4) The dummy volume of the filter tip is measured as V, and the dummy volume of n clean filter tips is denoted as V. Then, the formula for calculating the solid volume fraction of the clean filter tip is:

[0013] Formula 1:

[0014] As a preferred embodiment, the process for determining the amount of nicotine retained by the filter tip during the sequential filtration of flue gas is as follows:

[0015] 1) Randomly divide the filter tips into two groups, remove the sticky tobacco, put them into a distillation flask, and add methanol to fully leach them;

[0016] 2) After adding a strong acid solution to the distillation flask, start a first steam distillation. After discharging the first distillate, add a salt-alkali mixture for a second steam distillation. Collect the second distillate and determine its alkaloid content to obtain the product.

[0017] As a preferred embodiment, the secondary distillate is a clear solution. If the secondary distillate is turbid, it needs to be filtered and the first 55-65% of the filtrate should be discarded. The remaining filtrate is then used to determine the alkaloid content.

[0018] As a preferred embodiment, the process of establishing the hydrodynamic model of the cigarette filter for filtering nicotine in each puff is as follows: by calculating the solid volume fraction and viscous resistance coefficient of each puff of smoke filtered by the filter, the filtration efficiency model of the filter for filtering nicotine in each puff is obtained.

[0019] As a preferred embodiment, the calculation process for the solid volume fraction after each puff of flue gas is as follows: First, the filter dust loading coefficient Kd is calculated, and then the solid volume fraction α′ of the filter after that puff is completed is calculated. The calculation process is as follows:

[0020] Formula 2:

[0021] Equation 3: α′=Kd 2 α;

[0022] In Equations 2 and 3: W is the measured nicotine retention mass of the filter, α is the volume fraction of cellulose acetate, ρ is the nicotine particle density, L is the filter length, and A is the filter cross-sectional area.

[0023] As a preferred embodiment, the calculation process for the resistance coefficient of each puff of smoke filtered by the filter is as follows: First, calculate the equivalent diameter d of the fibers in the filter. f Then, the functional relationship between the pressure loss -ΔP of the single-fiber filter medium and the solid volume fraction α is calculated. Based on this functional relationship, the viscous resistance coefficient δ is obtained. The calculation process is as follows: Equation 4: d f ′=k d d f ;

[0024] Formula 5:

[0025] Formula 6:

[0026] Formula 7:

[0027] In equations 4 to 7: d f The equivalent diameter of the cellulose acetate before nicotine retention is given, μ is the fluid viscosity, L is the length of the filter medium, v is the fluid velocity, and the value of α in f(α) ranges from 0.6% to 30%.

[0028] As a preferred embodiment, the process for establishing the filtration efficiency model for nicotine filtration by the filter tip is as follows: First, the filtration efficiency η0 of the clean filter tip fibers is measured, and the filtration efficiency η of the dust-laden fibers is calculated. Then, the filtration efficiency η of nicotine filtration by the filter tip is calculated by combining the solid volume fraction and viscous resistance model. s The calculation process is as follows:

[0029] Equation 8: η=η0(1+λm);

[0030] Formula 9:

[0031] In Equations 8 and 9: λ is the single-fiber filtration efficiency increase coefficient, and m is the mass of nicotine deposited per unit volume of filter fiber.

[0032] As a preferred embodiment, the filtration efficiency model for filtering nicotine from the filter tip also includes adding a mass source term using a custom function (UDF) to describe the filtration effect of the filter tip on nicotine particles.

[0033] As a preferred option, the experimental testing and optimization process of the model is as follows: the model simulation and suction experiment are carried out using the standard suction mode, and the filter retention results obtained by the two are compared one by one. The fiber parameters in the model are adjusted until the relative error between the two converges to 3-5%.

[0034] As a preferred embodiment, the total amount of smoke per puff in the standard suction mode is 35-55 mL.

[0035] The present invention also provides a fluid dynamics model for the sequential filtration of nicotine in cigarette smoke by a cigarette filter, obtained by any of the modeling methods described above.

[0036] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are as follows:

[0037] 1) The fluid dynamics model provided by this invention describes the nicotine retention of cigarette smoke during puffing based on the solid volume fraction of filter fiber and the viscous resistance coefficient. The model is tested and optimized based on puffing experiments to ensure that the model has excellent accuracy and realism.

[0038] 2) The fluid dynamics modeling method provided by this invention is based on the synergistic effect of filter suction fluid dynamics and puff-by-puff experiments. It can predict the flow field distribution and nicotine filtration efficiency during each puff in filter suction, effectively solving the problems of cost and excessive error in experimental research on puff-by-puff in the prior art. Attached Figure Description

[0039] Figure 1 The three-dimensional model and structured mesh quality of the filter tip in Embodiment 1 of the present invention;

[0040] Figure 2 This is an axial pressure distribution cloud map obtained by simulating the computational fluid dynamics model of the filter nozzle in Embodiment 1 of the present invention at average velocity.

[0041] in, Figure 2 (a) is for 2 or 3 suctions. Figure 2 (b) involves 4 or 5 suctions. Figure 2 (c) is 6 or 7 suctions;

[0042] Figure 3 This is a graph showing the change in nicotine filtration efficiency over time obtained by simulating the computational fluid dynamics model of the filter nozzle in Embodiment 1 of the present invention under standard suction mode.

[0043] Figure 4 This is an axial pressure distribution cloud map obtained by simulating the computational fluid dynamics model of the filter nozzle in Embodiment 2 of the present invention at average velocity.

[0044] in, Figure 4(a) is for 2 or 3 suctions. Figure 4 (b) involves 4 or 5 suctions. Figure 4 (c) is 6 or 7 suctions; Figure 5 This is a graph showing the change in nicotine filtration efficiency over time during puffing, obtained by simulating the computational fluid dynamics model of the filter tip in Embodiment 2 of the present invention under standard puffing mode. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to specific embodiments. It is worth noting that the following examples are only used to explain the present invention and do not constitute a limitation of the present invention.

[0046] Example 1

[0047] The computational fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff in this embodiment includes the following steps:

[0048] 1) The solid volume fraction of the cleaned filter tip was determined using the displacement volume method;

[0049] 2) Filter the smoke through the cleaned filter puff by puff, and measure the total nicotine mass of the smoke in each puff and the nicotine mass retained by the filter to obtain the nicotine filtration efficiency.

[0050] 3) Based on the measurement results obtained in steps 1) and 2), a fluid dynamic model for the filtration of nicotine in cigarette smoke by cigarette filter is established using monofilament fiber fluid dynamics.

[0051] 4) Perform experimental testing and optimization on the model obtained in step 3) to obtain the final model.

[0052] As a preferred embodiment, the process for determining the solid volume fraction of the cleaning filter is as follows:

[0053] 1) After diluting the deionized water to 10mL in a volumetric flask, add n clean filter tips to completely submerge them in the deionized water and let stand for 5-8 minutes.

[0054] 2) After standing, remove the excess deionized water from the volumetric flask until the liquid level drops to the mark on the flask. Record the volume of water removed as V1, which is the true volume of n cleaning filters.

[0055] 4) The dummy volume of the filter tip is measured as V, and the dummy volume of n clean filter tips is denoted as V. Then, the formula for calculating the solid volume fraction of the clean filter tip is:

[0056] Formula 1:

[0057] As a preferred embodiment, the process for determining the amount of nicotine retained by the filter tip during the sequential filtration of flue gas is as follows:

[0058] 1) Randomly divide the filter tips into two groups, remove the sticky tobacco, put them into a distillation flask, add 50mL of methanol, cover and place in the dark overnight or shake on an electromagnetic shaker for 20min.

[0059] 2) After adding 7 mL of sulfuric acid solution to the distillation flask, start the first steam distillation. After discharging 150 mL of the first distillate, add a mixture of 20 g of sodium chloride and 2 g of sodium hydroxide for the second steam distillation. Collect 220-230 mL of the second distillate. Use this solution to determine the alkaloid content of the filter tip according to GB / T23226.

[0060] As a preferred embodiment, the process of establishing the hydrodynamic model of the cigarette filter for filtering nicotine in each puff is as follows: by calculating the solid volume fraction and viscous resistance coefficient of each puff of smoke filtered by the filter, the filtration efficiency model of the filter for filtering nicotine in each puff is obtained.

[0061] As a preferred embodiment, the calculation process for the solid volume fraction after each puff of flue gas is as follows: First, the filter dust loading coefficient Kd is calculated, and then the solid volume fraction α′ of the filter after that puff is completed is calculated. The calculation process is as follows:

[0062] Formula 2:

[0063] Equation 3: α′=Kd 2 α;

[0064] In Equations 2 and 3: W is the measured nicotine retention mass of the filter, α is the volume fraction of cellulose acetate, ρ is the nicotine particle density, L is the filter length, and A is the filter cross-sectional area.

[0065] As a preferred embodiment, the calculation process for the resistance coefficient of each puff of smoke filtered by the filter is as follows: First, calculate the equivalent diameter d of the fibers in the filter. f Then, the functional relationship between the pressure loss -ΔP of the single-fiber filter medium and the solid volume fraction α is calculated. Based on this functional relationship, the viscous resistance coefficient δ is obtained. The calculation process is as follows: Equation 4: d f ′=k d d f ;

[0066] Formula 5:

[0067] Formula 6:

[0068] Formula 7:

[0069] In equations 4 to 7: d fThe equivalent diameter of the cellulose acetate before nicotine retention is given, μ is the fluid viscosity, L is the length of the filter medium, v is the fluid velocity, and the value of α in f(α) ranges from 0.6% to 30%.

[0070] As a preferred embodiment, the process for establishing the filtration efficiency model for nicotine filtration by the filter tip is as follows: First, the filtration efficiency η0 of the clean filter tip fibers is measured, and the filtration efficiency η of the dust-laden fibers is calculated. Then, the filtration efficiency η of nicotine filtration by the filter tip is calculated by combining the solid volume fraction and viscous resistance model. s The calculation process is as follows:

[0071] Equation 8: η=η0(1+λm);

[0072] Formula 9:

[0073] In Equations 8 and 9: λ is the single-fiber filtration efficiency increase coefficient, and m is the mass of nicotine deposited per unit volume of filter fiber.

[0074] To verify the accuracy and authenticity of the above model, this invention also employs an experimental method to test the model, the process of which is as follows:

[0075] The suction parameters of the smoking machine are set as follows: suction capacity 55mL, suction time 2s.

[0076] A 25mm long filter rod sample was inserted into a cigarette holder containing a Cambridge filter. After the monodisperse aerosol generator produced a stable airflow, the smoking machine was started to draw smoke into the filter rod sample. Based on the experiment, the amount of nicotine in the first puff was 0.090mg, and the amount of nicotine retained by the filter was 0.044mg, resulting in a calculated nicotine filtration efficiency of 32.82%.

[0077] Take a new filter rod sample, restart the smoke machine, and take three consecutive puffs.

[0078] After the first puff, the amount of nicotine retained by the filter and the total nicotine content in the smoke were measured using the method described above for three consecutive puffs. The experiment showed that the nicotine content in the smoke from the three consecutive puffs was 0.441 mg, and the nicotine retention by the filter was 0.162 mg. Combining this with the data from the first puff, the nicotine content in the second and third puffs was calculated to be 0.351 mg, and the nicotine retention for the second and third puffs was 0.118 mg. The average efficiency of the second and third puffs was calculated to be 25.16%.

[0079] The amount of nicotine retained by the filter and the total nicotine content in the smoke were measured after five consecutive puffs using the method described above. The experiment showed that the total nicotine content in the smoke from the fourth and fifth puffs was 0.511 mg, and the amount of nicotine retained by the filter was 0.196 mg. The average nicotine filtration efficiency for the fourth and fifth puffs was calculated to be 27.72%.

[0080] The amount of nicotine retained by the filter and the total amount of nicotine in the smoke were measured using the method described above for seven consecutive puffs. Based on the experiment, the total nicotine content in the smoke from the 6th and 7th puffs was 0.512 mg, and the amount of nicotine retained by the filter was 0.21 mg. The average nicotine filtration efficiency for the 6th and 7th puffs was calculated to be 29.09%.

[0081] Because combustion is incomplete during the first puff, the amount of nicotine passing through the filter is relatively small, resulting in a higher measured filtration efficiency. Based on the theory of cumulative fiber filtration and simulation results, the filtration efficiency should gradually increase with each puff. From the second puff onwards, the amount of smoke passing through the filter is larger and more stable, and the filtration efficiency shows a clear upward trend. Therefore, the simulation verification was conducted starting with the average value of the second and third puffs.

[0082] The porosity of the coarse filter tip, measured by the displacement volume method, is 0.8987, and the equivalent diameter of the cellulose acetate is 0.0000251 μm. Based on the fiber accumulation filtration mechanism, the porosity of the coarse filter tip after the third suction inlet is calculated to be 0.89706, and the equivalent diameter of the cellulose acetate becomes 0.0000253025 μm. After the fifth suction inlet, the porosity of the coarse filter tip is calculated to be 0.894333, and the equivalent diameter of the cellulose acetate becomes 0.0000256353 μm.

[0083] Using the volume averaging method and a porous media model, a UDF was written to describe the filtration effect of the filter tip on nicotine. A computational fluid dynamics model of the filter tip filtering nicotine from cigarette smoke was established. The quality of the three-dimensional model and structured mesh of the filter tip is as follows: Figure 1 As shown.

[0084] Simulations were conducted at an average velocity of 0.38 m / s, and the pressure distribution cloud diagram of the filter nozzle axial section during sequential suction is shown below. Figure 2 As shown in the figure, the pressure drop of the filter tip during the second and third suction ports was calculated to be 784 Pa, the pressure drop during the fourth and fifth suction ports was 792.3 Pa, and the pressure drop during the sixth and seventh suction ports was 806.2 Pa. As suction proceeds port by port, the filter tip resistance increases due to the continuously increasing solid volume fraction, thus causing the pressure drop to continuously increase.

[0085] Results were obtained through simulation in standard puff mode (55 mL), showing the change in nicotine filtration efficiency per puff over time as follows: Figure 3As shown in the figure. The calculated nicotine filtration efficiency (FLFE) for the 2nd and 3rd puffs is 25.91%, for the 4th and 5th puffs it is 27.50%, and for the 6th and 7th puffs it is 30.14%. Experimentally, the FLFE for the 2nd and 3rd puffs is measured to be 25.16%, for the 4th and 5th puffs it is 27.72%, and for the 6th and 7th puffs it is 29.09%. The simulated values ​​and experimental values ​​agree well, with errors all less than 3%.

[0086] Example 2

[0087] The process in this embodiment is exactly the same as that in embodiment 1, except that the suction parameters of the smoking machine are set to a suction capacity of 35ml and a suction time of 2s.

[0088] Due to the change in aspiration volume, the real-time data during the individual aspiration experiment also changed accordingly, specifically:

[0089] A 25mm long filter rod sample was inserted into a cigarette holder containing a Cambridge filter. After the monodisperse aerosol generator produced a stable airflow, the smoking machine was started to draw smoke into the filter rod sample. The experiment showed that the amount of nicotine in the first puff was 0.056mg, and the amount of nicotine retained by the filter was 0.031mg, resulting in a calculated nicotine filtration efficiency of 35.63%.

[0090] Take a new filter rod sample, restart the smoke machine, and take three consecutive puffs.

[0091] After inhalation, the amount of nicotine retained by the filter and the total nicotine content in the smoke were measured after three consecutive puffs, following the method described above. The experiment yielded an nicotine content of 0.272 mg in the smoke from the three consecutive puffs and a filter retention of 0.118 mg. Combining this with the data from the first puff, the nicotine content in the second and third puffs was calculated to be 0.216 mg, and the nicotine retention for the second and third puffs was 0.087 mg. The average efficiency of the second and third puffs was calculated to be 28.71%.

[0092] The amount of nicotine retained by the filter and the total amount of nicotine in the smoke were measured after five consecutive puffs using the method described above. The experiment showed that the total nicotine content in the smoke from the fourth and fifth puffs was 0.333 mg, and the amount of nicotine retained by the filter was 0.142 mg. The average nicotine filtration efficiency for the fourth and fifth puffs was calculated to be 29.90%.

[0093] The amount of nicotine retained by the filter and the total nicotine content in the smoke were measured using the method described above for seven consecutive puffs. The experiment showed that the total nicotine content in the smoke from the 6th and 7th puffs was 0.342 mg, and the amount of nicotine retained by the filter was 0.163 mg. The average nicotine filtration efficiency for the 6th and 7th puffs was calculated to be 32.28%.

[0094] Because combustion is incomplete during the first puff, the amount of nicotine passing through the filter is relatively small, resulting in a higher measured filtration efficiency. Based on the theory of cumulative fiber filtration and simulation results, the filtration efficiency should gradually increase with each puff. From the second puff onwards, the amount of smoke passing through the filter is larger and more stable, and the filtration efficiency shows a clear upward trend. Therefore, the simulation verification was conducted starting with the average value of the second and third puffs.

[0095] The porosity of the coarse filter tip, measured by the displacement volume method, is 0.8987, and the equivalent diameter of the cellulose acetate is 0.0000251 μm. Based on the fiber cumulative filtration mechanism, the porosity of the coarse filter tip after the third suction inlet is calculated to be 0.89749, and the equivalent diameter of the cellulose acetate becomes 0.0000252494 μm. After the fifth suction inlet, the porosity of the coarse filter tip is calculated to be 0.895515, and the equivalent diameter of the cellulose acetate becomes 0.0000254915 μm.

[0096] Using the volume averaging method and a porous media model, and writing a UDF to describe the filtration effect of the filter on nicotine, a computational fluid dynamics model of the filter filtering nicotine in flue gas was established.

[0097] Simulations were conducted at an average velocity of 0.38 m / s, and the pressure distribution cloud diagram of the filter nozzle axial section during sequential suction is shown below. Figure 4 As shown in the figure, the pressure drop of the filter tip during the second and third suction ports was calculated to be 784.1 Pa, the pressure drop during the fourth and fifth suction ports was 790.3 Pa, and the pressure drop during the sixth and seventh suction ports was 800.3 Pa. As suction proceeds port by port, the filter tip resistance increases due to the continuously increasing solid volume fraction, thus causing the pressure drop to continuously increase.

[0098] Results were obtained through simulation in standard puff mode (35 mL), showing the change in nicotine filtration efficiency per puff over time as follows: Figure 5 As shown in the figure. The calculated nicotine filtration efficiency (FLFE) for the 2nd and 3rd puffs was 28.30%, for the 4th and 5th puffs it was 29.57%, and for the 6th and 7th puffs it was 31.64%. Experimentally, the FLFE for the 2nd and 3rd puffs was measured to be 28.71%, for the 4th and 5th puffs it was 29.90%, and for the 6th and 7th puffs it was 32.28%. The simulated values ​​and experimental values ​​agree well, with errors all less than 3%.

Claims

1. A fluid dynamics modeling method for the sequential filtration of nicotine in cigarette smoke using a cigarette filter, characterized in that, include: 1) The solid volume fraction of the cleaned filter tip was determined using the displacement volume method; 2) Filter the smoke through the cleaned filter puff by puff, and measure the total nicotine mass of the smoke in each puff and the nicotine mass retained by the filter to obtain the nicotine filtration efficiency. 3) Based on the measurement results obtained in steps 1) and 2), a fluid dynamic model for the filtration of nicotine in cigarette smoke by cigarette filter is established using monofilament fiber fluid dynamics. 4) Perform experimental testing and optimization on the model obtained in step 3) to obtain the final model.

2. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 1, characterized in that: The process for determining the solid volume fraction of the cleaning filter is as follows: 1) After making up the volume with deionized water in a volumetric flask, add n clean filter tips to completely submerge them in the deionized water and let stand for 5-8 minutes. 2) After standing, remove the excess deionized water from the volumetric flask until the liquid level drops to the mark on the flask. Record the volume of water removed as V1, which is the true volume of n cleaning filters. 4) The dummy volume of the filter tip is measured as V, and the dummy volume of n clean filter tips is denoted as V. Then, the formula for calculating the solid volume fraction of the clean filter tip is: Formula 1:

3. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 1, characterized in that: The process for determining the amount of nicotine retained by the filter tip during the sequential filtration of flue gas is as follows: 1) Randomly divide the filter tips into two groups, remove the sticky tobacco, put them into a distillation flask, and add methanol to fully leach them; 2) After adding a strong acid solution to the distillation flask, start a first steam distillation. After discharging the first distillate, add a salt-alkali mixture for a second steam distillation. Collect the second distillate and determine its alkaloid content to obtain the product.

4. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 3, characterized in that: The secondary distillate is a clear solution. If the secondary distillate is turbid, it needs to be filtered and the first 55-65% of the filtrate should be discarded. The remaining filtrate should then be used to determine the alkaloid content.

5. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 1, characterized in that: The process of establishing the fluid dynamics model for the cigarette filter to filter nicotine in each puff is as follows: by calculating the solid volume fraction and viscous resistance coefficient of each puff of smoke filtered by the filter, the filtration efficiency model for nicotine filtration by the filter is obtained.

6. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 5, characterized in that: The calculation process for the solid volume fraction of each puff of flue gas filtered by the filter is as follows: First, the filter dust loading coefficient Kd is calculated, and then the solid volume fraction α′ of the filter after each puff is completed is calculated. The calculation process is as follows: Formula 2: Equation 3: α′=Kd 2 a; In Equations 2 and 3: W is the measured nicotine retention mass of the filter, α is the volume fraction of cellulose acetate, ρ is the nicotine particle density, L is the filter length, and A is the filter cross-sectional area.

7. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 6, characterized in that: The calculation process for the resistance coefficient of each puff of smoke filtered by the filter tip is as follows: First, calculate the equivalent diameter d′ of the fibers in the filter tip. f Then, the functional relationship between the pressure loss -ΔP of the single-fiber filter medium and the solid volume fraction α is calculated. Based on this functional relationship, the viscous resistance coefficient δ is obtained. The calculation process is as follows: Equation 4: d′ f =k d d f ; Formula 5: Formula 6: Formula 7: In equations 4 to 7: d f The equivalent diameter of the cellulose acetate before nicotine retention is given, μ is the fluid viscosity, L is the length of the filter medium, v is the fluid velocity, and the value of α in f(α) ranges from 0.6% to 30%.

8. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 7, characterized in that: The process of establishing the filtration efficiency model for nicotine filtration by the filter tip is as follows: First, the filtration efficiency η0 of the clean filter tip fibers is measured, and the filtration efficiency η of the dust-laden fibers is calculated. Then, the filtration efficiency η of nicotine filtration by the filter tip is calculated by combining the solid volume fraction and viscous resistance model. s The calculation process is as follows: Equation 8: η=η0(1+λm); Formula 9: In Equations 8 and 9: λ is the single fiber filtration efficiency increase coefficient, and m is the mass of nicotine deposited per unit filter fiber volume; The filtration efficiency model for filtering nicotine from the filter tip also includes adding a mass source term using a custom function (UDF) to describe the filter tip's filtration effect on nicotine particles.

9. The fluid dynamics modeling method for filtering nicotine from cigarette smoke puff by puff according to claim 1, characterized in that: The experimental testing and optimization process of the model is as follows: the model simulation and suction experiment are carried out using the standard suction mode, and the filter retention results obtained by the two are compared one by one. The fiber parameters in the model are adjusted until the relative error between the two converges to 3-5%.

10. A fluid dynamics model for the sequential filtration of nicotine in cigarette smoke using a cigarette filter, characterized in that: Obtained by the modeling method described in any one of claims 1 to 9.

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