A direct current environmental chamber method for determining the VOC mass transfer characteristic parameters of flexible porous materials

Abstract

The application discloses a direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials. The method utilizes the closed and ventilation mode conversion of the environmental chamber, measures the VOC equilibrium concentration in the environmental chamber in the closed state and the VOC hourly concentration in the direct current ventilation state by performing adsorption in the closed stage and emission in the direct current ventilation stage on the fiber fabric sample, establishes a mathematical equation for determining the VOC mass transfer characteristic parameters of the fabric sample, and obtains the values of the VOC distribution coefficient K and the diffusion coefficient D of the fabric sample through a simple solving process. The direct current environmental chamber method can be suitable for the measurement of VOC mass transfer characteristic parameters of various flexible porous materials, and has the advantages of simple experimental process, short time consumption and high test result precision.

Description

Technical Field

[0001] The invention belongs to the technical field of indoor environmental quality detection, and in particular relates to a direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials. Background Art

[0002] Among the many factors affecting indoor air quality, volatile organic compounds (VOCs) are one of the main pollutants harmful to human health. The presence of VOCs in indoor environments can lead to "sick building syndrome," which can cause mild symptoms such as dizziness, fatigue, and chest tightness, while more severe symptoms can directly damage the liver, kidneys, brain, and nervous system.

[0003] VOCs in indoor environments are widely present in porous building materials such as furniture and artificial boards. In addition, a large number of flexible porous materials indoors will also adsorb VOC gases in the air and release them back into the air as a secondary source when the indoor VOC concentration is low. Flexible porous materials are different from building materials with hard and smooth surfaces. They have higher porosity, larger specific surface area, and higher surface roughness. Their adsorption capacity is stronger than that of hard building materials. Flexible porous materials such as carpets, curtains, and wall coverings have a very large contact area with the air and are cleaned less frequently, making them the main medium for indoor VOC storage. Some flexible porous materials such as clothing, bedding, and sofas are in close contact with the human body. VOCs adsorbed in these fabrics will penetrate into the human body through the respiratory tract and skin, further increasing the risk to human health. Accurately measuring the VOC mass transfer characteristics of flexible porous materials is of great significance for predicting indoor air quality and formulating appropriate prevention and control strategies.

[0004] Current experimental methods for determining VOC mass transfer parameters primarily target rigid porous materials, such as building materials, which initially emit high concentrations and exhibit source properties. However, flexible porous materials often act as sinks indoors, making existing VOC mass transfer parameter testing methods for rigid building materials difficult to directly apply. Designing appropriate testing protocols tailored to the characteristics of porous flexible materials to obtain the most accurate VOC mass transfer parameters remains a common concern for researchers in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a direct current environmental chamber method for measuring the VOC mass transfer characteristic parameters of flexible porous materials, so as to efficiently and accurately measure the VOC mass transfer characteristic parameters of fiber fabrics of different materials: distribution coefficient K and diffusion coefficient D.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials comprises the following steps:

[0008] Step 1: Place the fiber fabric sample 3 to be tested in a clean and closed environmental chamber 2 with constant temperature and humidity, turn on the circulation fan 9 in the chamber, and let it stand for a sufficient time to allow the temperature and humidity in the chamber to reach a stable state;

[0009] Step 2: Place the prepared VOC standard solution in a headspace bottle, use a medical syringe to pierce the headspace bottle stopper to extract a certain amount of headspace gas, and then quickly inject it into the environmental chamber 2. The VOC gas concentration in the chamber at this time is measured to be C equ,1 ;

[0010] Step 3: Keep the environmental chamber 2 sealed and the temperature and humidity constant, and measure the VOC concentration decline curve until the VOC concentration reaches equilibrium. At this time, the VOC gas equilibrium concentration in the chamber is C equ,2 ;

[0011] Step 4: Remove the fiber fabric sample 3 from the chamber and store it in a sealed container away from light. Use distilled water to clean the environmental chamber 2 until the background VOC concentration is lower than the detection limit.

[0012] Step 5: Switch the environmental chamber 2 to the DC ventilation mode. The temperature and humidity parameters are the same as those in Steps 1, 2, and 3. Take out the fiber fabric sample 3 to be tested and place it back into the environmental chamber 2. Close the door and measure and record the VOC concentration C of the gas at different times in the chamber. a,exp (t i );

[0013] Step 6: According to the law of conservation of mass, the fabric VOC distribution coefficient K and the initial VOC emitting concentration C0 are obtained and substituted into the complete analytical solution C of the VOC concentration in the environmental chamber under DC ventilation mode. a,cal (t i ), and combined with the measured value C a,exp (t i ) Perform nonlinear fitting on the analytical solution to obtain the fabric VOC diffusion coefficient D.

[0014] In one embodiment, the wall of the environmental chamber 2 is made of a material that has no adsorption to VOCs, the circulating fan 9 is arranged at the top of the chamber, the wind speed is controlled below 0.3m / s, and a VOC gas inlet 1 is also provided on the top of the chamber. The air temperature in the chamber ranges from 10 to 40°C with an accuracy of ±0.5°C, and the relative humidity ranges from 30% to 90% with an accuracy of ±5%.

[0015] In one embodiment, the concentration of the VOC standard solution is 1 mg / mL to 100 mg / mL, the volume of the headspace bottle is 10 to 20 mL, and the volume of the extracted headspace gas is 0.5 mL to 2 mL.

[0016] In one embodiment, the fiber fabric sample 3 to be tested is pretreated before testing to ensure that no free VOC remains, and the volume ratio of the air volume in the chamber to the fiber fabric sample 3 to be tested is 100-1000.

[0017] In one embodiment, in the ventilation mode of the environmental chamber 2, the ventilation frequency is 0.5 to 2 times / h, and the flow rate is constant during ventilation.

[0018] In one embodiment, the VOC concentration is detected by an online gas analyzer 4, and the single sampling volume does not exceed 30cm 3 The sampling frequency in ventilation state shall not be less than 0.5h each time.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The method for determining the VOC mass transfer characteristic parameters of flexible porous materials of the present invention is universal and applicable to a wide range of objects.

[0021] (2) The present invention has a short testing time, and the test of the fabric sample can be completed by only adjusting the temperature, humidity and ventilation status of the environmental chamber, which saves the preparatory time and material consumption.

[0022] (3) The test results of the present invention are reliable. The nonlinear fitting based on the weight factor ensures the fitting effect of the experimental data at each stage, thereby improving the accuracy of the experimental results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the test system in which the fabric sample to be tested is placed in the environmental chamber.

[0024] Figure 2 Schematic diagram of the environmental chamber system for injecting VOC gas into the fabric sample to be tested.

[0025] Figure 3 Schematic diagram of the VOC emission test system for the fabric sample to be tested in the DC ventilation mode of the environmental chamber.

[0026] Figure 4 This is a comparative analysis chart of the measured and predicted VOC concentrations emitted by the flexible porous material in the example.

[0027] The numbers in the figure represent: 1-VOC gas inlet, 2-environmental chamber, 3-fiber fabric sample to be tested, 4-online gas analyzer, 5-wireless temperature and humidity recorder, 6-computer, 7-thermocouple temperature sensor, 8-thermocouple temperature recorder, 9-circulation fan, 10-air inlet, 11-rotor flowmeter, 12-clean air generator, 13-exhaust port, 14-valve. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0029] The present invention provides a direct current environmental chamber method for measuring the VOC mass transfer characteristic parameters of flexible porous materials. This method is primarily applicable to environmental chambers with controllable ventilation rates and can efficiently and accurately measure the VOC mass transfer characteristic parameters of flexible porous materials. This method utilizes the sealed and ventilation mode conversions of the environmental chamber to perform adsorption in the sealed phase and emission in the direct current ventilation phase on fiber fabric samples, thereby measuring the VOC equilibrium concentration within the environmental chamber under the sealed state and the VOC hourly concentration under the direct current ventilation state. A mathematical equation for determining the VOC mass transfer characteristic parameters of the fabric samples was established, and through a simple solution process, the values ​​of the VOC distribution coefficient K and diffusion coefficient D of the fabric samples were obtained. The direct current environmental chamber method described in the present invention is suitable for measuring the VOC mass transfer characteristic parameters of various flexible porous materials. The experimental process is simple, time-saving, and the test results are highly accurate.

[0030] like Figure 1 、 Figure 2 and Figure 3 As shown, the method of the present invention mainly comprises the following steps:

[0031] Step 1: Prepare a VOC solution of standard concentration, place it in a headspace bottle, seal it and keep it away from light. m The fiber fabric sample 3 to be tested is placed in a clean environment chamber 2 with constant temperature and humidity. At this time, the environment chamber is not ventilated and is in a closed state. The circulation fan 9 in the chamber is turned on and the chamber is left to stand for a sufficient time so that the temperature and humidity in the chamber reach a stable state.

[0032] Reference again Figure 1 The environmental chamber 2 used in the present invention has an air inlet 10 on its top and an exhaust port 13 with a valve 14 on its bottom. The air inlet 10 is connected to a clean air generator 12, and a rotor flowmeter 11 is provided on the connecting pipeline. Ventilation can be achieved through the air inlet 10 and the exhaust port 13. A VOC gas inlet 1 is provided at the top of the environmental chamber 2 for the experiment of the present invention. In addition, a circulating fan 9 is provided at the top of the chamber, and its main function is to accelerate the uniformity of the internal gas. At the same time, in order to achieve measurement, the present invention also provides measuring elements, mainly including: an online gas analyzer 4, a wireless temperature and humidity recorder 5, a thermocouple temperature sensor 7 and a thermocouple temperature recorder 8. At the same time, in order to facilitate calculation, the outputs of the above-mentioned measuring elements are all connected to a computer 6. The wireless measurement sensor 5 measures the air temperature and humidity in the chamber, and the thermocouple temperature sensor 7 and the thermocouple temperature recorder 8 record the wall temperature inside the environmental chamber.

[0033] In this embodiment of the present invention, the walls of environmental chamber 2 are constructed of a material that is non-adsorbent to VOCs, such as stainless steel, to minimize any impact on experimental results. The wind speed of circulating fan 9 should be kept to a minimum, typically below 0.3 m / s. During the experiment, the air temperature within the chamber was maintained within a range of 10-40°C with an accuracy of ±0.5°C, and the relative humidity was maintained within a range of 30%-90% with an accuracy of ±5%.

[0034] The fiber fabric sample 3 to be tested is the experimental material of the present invention, and is pretreated before testing to ensure that no free VOC remains.

[0035] Step 2: Place the prepared VOC standard solution in a headspace bottle, pierce the headspace bottle stopper with a medical syringe to extract a certain amount of headspace gas, and then quickly inject it into the environmental chamber 2. Figure 2 As shown, the VOC gas concentration in the cabin is measured to be C equ,1 , mg / m 3 .

[0036] In this embodiment, the concentration of the VOC standard solution is 1 mg / mL to 100 mg / mL, the volume of the headspace bottle is 10 to 20 mL, the volume of the extracted headspace gas is 0.5 mL to 2 mL, and the volume V (m 3 )The value is generally 10L~1000L.

[0037] The volume ratio of the air volume in the cabin to the volume of the fiber fabric sample 3 to be tested is 100-1000.

[0038] The VOC concentration of the present invention is detected by an online gas analyzer 4, and the single sampling volume does not exceed 30cm 3 The sampling frequency in ventilation state shall not be less than 0.5h each time.

[0039] Step 3: Keep the environmental chamber 2 sealed and the temperature and humidity constant, and measure the VOC concentration decline curve until the VOC concentration reaches equilibrium. At this time, the VOC gas equilibrium concentration in the chamber is C equ,2 , mg / m 3 The volume of the fiber fabric sample 3 to be tested is V m , m 3 The fabric VOC distribution coefficient is K, and the initial VOC emission concentration after the fabric adsorbs VOC gas to reach equilibrium is C0, mg / m 3 , which represents the VOC equilibrium concentration inside the fiber fabric sample 3 after the VOC gas is adsorbed and stabilized. The following equation is established based on the law of conservation of mass:

[0040] C equ.1 V=C equ.2 V+C0V m =C equ.2V+KC equ.2 V m (1)

[0041] The initial VOC emitting concentration C0 and the fabric VOC distribution coefficient K of the fiber fabric sample 3 to be tested can be obtained by formula (1).

[0042] Step 4: Take out the fiber fabric sample 3 to be tested in step 3 from the environmental chamber 2 and store it in a sealed state away from light. Use distilled water to clean the environmental chamber 2 until the background VOC concentration is lower than the detection limit.

[0043] Step 5: Switch the environmental chamber 2 to DC ventilation mode. The temperature and humidity parameters are the same as those in steps 1, 2, and 3. Figure 3 Take out the fiber fabric sample 3 from the sealed bag and put it back into the environmental chamber 2. Close the door and measure and record the VOC concentration C of the gas at different times in the environmental chamber. a,exp (t i ), mg / m 3 .

[0044] In the embodiment of the present invention, in the ventilation mode of the environmental chamber 2, the ventilation frequency is set to 0.5 to 2 times / h, and the flow rate is constant during ventilation, which meets the control method of the general environmental chamber with controllable ventilation frequency.

[0045] Step 6: Use formula (1) to calculate the fabric VOC distribution coefficient K and the initial VOC emitting concentration C0, and substitute them into the complete analytical solution C of the VOC concentration in the environmental chamber under DC ventilation mode. a,cal (t i ), mg / m 3 . And combined with the measured value C a,exp (t i ) Perform nonlinear fitting on the analytical solution to obtain the fabric VOC diffusion coefficient D, m 2 / s.

[0046] Complete analytical solution of VOC concentration in environmental chamber under DC ventilation mode a,cal (t i )as follows:

[0047]

[0048] α=QL 2 / VD (5)

[0049] Bi m =h m L / D (6)

[0050] Fo m =-DL -2 t (7)

[0051] Where C in is the VOC concentration at the air inlet, mg / m 3 ; β is the solid-gas ratio, and its calculation formula is β=V m / V;q n is the positive root of formula 3, n is a natural number starting from 1; G n It is an intermediate variable in the equation and has no specific physical meaning; L is half the thickness of the fiber fabric sample 3 to be tested, m; Bi m is the Biot number of the fiber fabric sample 3 to be tested; Q is the ventilation volume, m 3 / s;Fo m is the mass transfer Fourier number; h m is the convective mass transfer coefficient, m / s; t i is the time for the fabric sample to emit gas in DC ventilation mode, and i is the number of gas sampling times.

[0052] Substituting C0 and K into formula (2), the diffusion coefficient D is nonlinearly fitted using the improved relative least squares method. The calculation formula η of the concentration curve fitting error is as follows:

[0053]

[0054] Where, J Di is the normalized relative sensitivity coefficient of the VOC concentration of the i-th sampling to D; w Di is the weight factor of the concentration data of the i-th sampling; η is the error; M is the total number of sampling times in the DC ventilation mode; ε is the variation range of D.

[0055] By adjusting the value of the diffusion coefficient D, compared with the theoretical value C a,cal (t i ) and the measured value C a,exp (t i ), when the η value is the minimum, the diffusion coefficient D of the fiber fabric sample 3 to be tested can be determined.

[0056] In a more specific embodiment of the present invention, the environmental chamber 2 has an air volume of 30 L. The temperature and humidity within the chamber are controlled by a control panel within a temperature range of 10-40°C and a relative humidity range of 30%-90%, with a temperature accuracy of ±0.5°C and a relative humidity accuracy of ±5%. The chamber gas is sampled and analyzed using an online gas analyzer 4. This test was conducted only in the sealed mode of the environmental chamber. In this closed state, both the air inlet 10 and the exhaust 13 were closed. The interior walls of the environmental chamber 2 were constructed of stainless steel, which is inert and non-adsorbent to VOCs. The hatch was sealed with non-adsorbent sealing strips. A circulating fan 9 maintained an air velocity of 0.1 to 0.3 m / s within the chamber, ensuring a uniform distribution of VOC concentrations. The fabric sample 3 to be tested was placed in the center of the environmental chamber using a stainless steel wire harness, with the air flow parallel to the surface of the fabric sample 3. During the experiment, the temperature of the environmental chamber 2 was set at 23°C, and the relative humidity was controlled at 50±5%.

[0057] VOC gas composition and concentration analysis in this embodiment: When measuring single or mixed VOC gases, the mixed gas in the chamber is sampled using an online gas analyzer 4. All sampled data is stored, processed, and analyzed by a computer 6. In this experiment, the online gas analyzer sampling frequency was set at 15 minutes.

[0058] This example measured the formaldehyde emission characteristics of fabrics. The fabric sample 3 used for testing had dimensions of 405 mm × 205 mm × 0.6 mm (length × width × thickness) and a solid-to-gas ratio β of 1 / 602. The formaldehyde concentration was calibrated to 100 mg / mL using distilled water and placed in a sealed headspace vial, protected from light.

[0059] See also Figure 1 When the experiment begins, set the temperature and humidity of the environmental chamber 2 and record the temperature and humidity working condition as working condition 1. Place the fiber fabric sample 3 to be tested in the environmental chamber 2, close the door, close the air inlet 10 and the exhaust valve 14, and turn on the circulation fan 9 in the chamber. At this time, the experimental supplies in the environmental chamber are placed as follows. Figure 1 .

[0060] like Figure 2 As shown in the figure, 1 mL of headspace VOC gas was injected into the environmental chamber using a medical syringe. The VOC gas concentration in the chamber was measured using an online gas analyzer 4 and was found to be 3.037 mg / m3, which is C equ,1 The VOC concentration in the chamber was then monitored hourly, with a gas sampling frequency of 15 minutes per time and a gas sampling volume of 10 cm 3 When the average formaldehyde concentration changes by no more than 1% within one hour, it is considered that the gaseous formaldehyde concentration in the cabin has reached equilibrium, and the value at this time is 1.205 mg / m 3, which is C equ,2 Open the door, take out the fiber fabric sample 3 from the environmental chamber 2 and store it in a sealed place away from light, discharge the VOC gas in the chamber, and wipe the inner wall of the environmental chamber 2 with distilled water to return the environmental chamber 2 to a clean state.

[0061] like Figure 3 As shown, the environmental chamber 2 is switched to DC ventilation mode, the air inlet 10 and the exhaust valve 14 are opened, the ventilation frequency is 1 time / h, and the temperature and humidity parameters are the same as the above steps. The fabric sample is taken out of the sealed bag and placed in the environmental chamber. The door is closed and the VOC concentration of the gas at different times in the environmental chamber is measured and recorded. a,exp (t i ), the gas sampling frequency is 15min / time, and the single gas sampling volume is 10cm 3 .

[0062] The initial emitting concentration C0 and the distribution coefficient K of the fiber fabric sample 3 to be tested can be obtained by formula (1). The C0 value is 1004 mg / m3 and the K value is 1016. In order to obtain the corresponding diffusion coefficient D value, the initial emitting concentration C0 and the distribution coefficient K values ​​obtained above are substituted into the complete analytical solution C of the VOC concentration in the DC environmental chamber. a,cal (t i ), that is, formula (2). According to formula (8), the diffusion coefficient D value is fitted using the improved relative least squares method. When the concentration curve fitting error η is the minimum, the diffusion coefficient D of the fiber fabric sample 3 to be tested can be determined, and its value is 5.0×10 -12 m 2 / s.

[0063] Substitute the mass transfer characteristic parameters determined above into the complete analytical solution C a,cal (t i ) and compared with the experimental test value C a,exp (t i ) for comparison, the results are as follows Figure 4 The relative error between the predicted and experimental values ​​of the gas-phase VOC concentration in the cabin is less than 12% over the entire emission period, indicating a high prediction accuracy.

[0064] The DC environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials proposed in the present invention has a simple principle, short test time, a wide range of applicable objects, and high precision of the obtained parameter measurement results, which is suitable for engineering promotion and application.

Claims

1. A direct current environmental chamber method for determining VOC mass transfer characteristic parameters of flexible porous materials, characterized in that: The steps include: Step 1: placing the fiber fabric sample (3) to be tested in a clean and closed environmental chamber (2) with constant temperature and humidity, turning on the circulating fan (9) in the chamber, and allowing the chamber to stand for a sufficient time to allow the temperature and humidity in the chamber to reach a stable state, wherein the wall surface of the environmental chamber (2) is made of a material that has no adsorption to VOCs, and the fiber fabric sample (3) to be tested is pretreated before testing to ensure that no free VOCs remain; Step 2: Place the prepared VOC standard solution in a headspace bottle, use a medical syringe to pierce the headspace bottle stopper to extract a certain amount of headspace gas, and then quickly inject it into the environmental chamber (2). The VOC gas concentration in the chamber at this time is measured to be C equ,1 ; Step 3: Keep the environmental chamber (2) airtight and the temperature and humidity constant, and measure the VOC concentration drop curve until the VOC concentration reaches equilibrium. At this time, the VOC gas equilibrium concentration in the chamber is C equ,2 ; Step 4: Take out the fiber fabric sample (3) from the chamber and store it in a sealed container away from light. Use distilled water to clean the environmental chamber (2) until the background VOC concentration is lower than the detection limit. Step 5: Switch the environmental chamber (2) to the DC ventilation mode, and the temperature and humidity parameters are the same as those in Steps 1, 2, and 3; take out the fiber fabric sample (3) to be tested and place it in the environmental chamber (2) again, close the door, and measure and record the VOC concentration C of the gas at different times in the chamber. a,exp (t i ); Step 6: According to the law of conservation of mass, establish the equation as follows: C equ.1 V=C equ.2 V+C0V m =C equ.2 V+KC equ.2 V m (1) The fabric VOC distribution coefficient K and the initial VOC emitting concentration C0 are obtained by the above formula, and the complete analytical solution C of the VOC concentration in the environmental chamber under DC ventilation mode is substituted into it. a,cal (t i ), and combined with the measured value C a,exp (t i ) performs nonlinear fitting on the analytical solution to obtain the fabric VOC diffusion coefficient D, where V is the volume of the environmental chamber (2), V m is the volume of the fiber fabric sample (3) to be tested; The complete analytical solution of VOC concentration in the environmental chamber under DC ventilation mode is C a,cal (t i ) is calculated as follows: α=QL 2 / VD (5) Ball m h m L / D (6) Fo m =-DL -2 t (7) Where C in is the VOC concentration at the air inlet; β is the solid-gas ratio, and its calculation formula is β=V m / V;q n is the positive root of formula (3), n is a natural number starting from 1; G n It is an intermediate variable in the equation and has no specific physical meaning; L is half the thickness of the fiber fabric sample (3) to be tested; Bi m is the Biot number of the fiber fabric sample to be tested; Q is the ventilation volume; Fo m is the mass transfer Fourier number; h m is the convective mass transfer coefficient; t i is the time for the fabric sample to emit gas in DC ventilation mode, and i is the number of gas sampling times.

2. The direct current environmental chamber method for determining VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: The circulating fan (9) is arranged on the top of the cabin, and the wind speed is controlled below 0.3m / s. A VOC gas inlet (1) is also provided on the cabin top. The air temperature in the cabin ranges from 10 to 40°C with an accuracy of ±0.5°C, and the relative humidity ranges from 30% to 90% with an accuracy of ±5%.

3. The direct current environmental chamber method for determining VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: The concentration of the VOC standard solution is 1 mg / mL to 100 mg / mL, the volume of the headspace bottle is 10 to 20 mL, and the volume of the extracted headspace gas is 0.5 mL to 2 mL.

4. The direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: The volume ratio of the air volume in the cabin to the volume of the fiber fabric sample (3) to be tested is 100 to 1000.

5. The direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: In the ventilation mode of the environmental chamber (2), the ventilation air exchange frequency is 0.5 to 2 times / h, and the flow rate is constant during the ventilation period.

6. The direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: The VOC concentration is detected by an online gas analyzer (4), and the single sampling volume does not exceed 30cm 3 The sampling frequency in ventilation state shall not be less than 0.5h each time.

7. The direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials according to claim 1, characterized in that: Substituting C0 and K into formula (2), the diffusion coefficient D is nonlinearly fitted using the improved relative least squares method. The calculation formula η of the concentration curve fitting error is as follows: Where, J Di is the normalized relative sensitivity coefficient of the VOC concentration of the i-th sampling to D; w Di is the weight factor of the concentration data of the i-th sampling; η is the error; M is the total number of sampling times in the DC ventilation mode; ε is the variation range of D.

8. The direct current environmental chamber method for measuring VOC mass transfer characteristic parameters of flexible porous materials according to claim 7, characterized in that: By adjusting the value of the diffusion coefficient D, compared with the theoretical value C a,cal (t i ) and the measured value C a,exp (t i ), when the η value is the minimum, the diffusion coefficient D of the fiber fabric sample (3) to be tested can be determined.

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