Non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials

Abstract

The present invention provides a non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials, calculates the initial VOC emission concentration of the material in each temperature segment, and sets the potential of the initial VOC emission concentration of the material in each temperature segment; constructs a geometric simulation model for material VOC emission through finite element analysis; obtains the hourly VOC emission concentration of the material in each temperature segment, the hourly VOC emission concentration of the material, and the hourly VOC emission concentration of the air at each grid node, and by adjusting the temperature conditions, obtains the control target value of the VOC emission concentration in the material, and obtains the hourly concentration value of the air VOC emitted into the surrounding air by the material VOC under changing temperature conditions after a certain period of time. For the non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials described in the present invention, the reliability of the simulation results is relatively high, and further, the reliability of the control target value of the VOC concentration in the material set based on the simulation results and its supporting storage temperature control scheme is relatively high.

Description

Technical Field

[0001] The present invention belongs to the field of organic matter analysis, and particularly relates to a non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials. Background Technique

[0002] Automotive interiors such as seats, instrument panels, carpets, roofs, and seals are generally made of petrochemical products such as plastics, leathers, and adhesives, and contain a certain amount of volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, xylene, styrene, formaldehyde, acetaldehyde, and acrolein, which will continue to emit during the consumer's use of the vehicle. By reducing the concentration of VOCs in the interior before loading, the air quality inside the vehicle can be effectively improved, and the health of the driver and passengers can be guaranteed.

[0003] The VOCs contained in automotive interior materials will emit into the surrounding air under the drive of the concentration gradient, and this process is greatly affected by the ambient temperature and is relatively complex. On the one hand, the higher the ambient temperature, the greater the diffusion coefficients of VOCs in the material and in the air, and the smaller the partition coefficient at the material-air interface, making it easier for VOCs to diffuse from the material interior into the air, thus reducing the concentration of VOCs in the material more quickly; on the other hand, the higher the ambient temperature, the greater the molecular kinetic energy of the VOCs in the material, resulting in an increase rather than a decrease in the available emission concentration of the VOCs in the material. In view of the complex emission situation of VOCs under the above non-isothermal conditions, there is currently no simulation calculation method that conforms to the gas emission mechanism, which seriously affects the setting of the VOC concentration target in interior materials and the formulation of the storage temperature control plan for interior materials. Summary of the Invention

[0004] In view of this, the present invention aims to propose a non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials to solve the problems that it is difficult to set the VOC concentration target in interior materials and it is difficult to formulate the storage temperature control plan for interior materials.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] A non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials, the specific method is as follows:

[0007] S1. Set the hourly temperature C(t) during the VOC emission process of the material, determine the simulation temperature range, divide the temperature segments, calculate the initial available emission concentration of the material VOC in each temperature segment, and set the potential of the initial available emission concentration of the material VOC in each temperature segment;

[0008] S2. Calculate the diffusion coefficient Dm(C(t)) of the material VOC and the partition coefficient K(C(t)) of the material VOC at each hourly temperature within the simulation temperature range;

[0009] S3. Calculate the simulated temperature range and the VOC diffusion coefficient Da(C(t)) of the air at each hourly temperature;

[0010] S4. Calculate the initial VOC emission concentration Cm(C(t0)) of the material at the temperature C(t0) at the initial moment of the VOC simulation of the material;

[0011] S5. Construct a geometric simulation model for the VOC emission of the material through finite element analysis, set the material mesh, the mesh at the material-air interface, and the air mesh. According to Cm(C(t0)), Dm(C(t0)), K(C(t0)), Da(C(t0)), and combining Fick's second diffusion law and Henry's law, perform mesh division on each type of mesh and set the mesh node parameters. Set the total duration t_total of the simulated emission and the time step t_step of the simulation calculation;

[0012] S6. Through simulation calculation, obtain the VOC emission concentration Cm of the material and the VOC emission concentration Ca of the air at each mesh node after one time step of emission;

[0013] S7. According to the temperature C(t - t_step) after one time step of emission and the initial emission concentration potential of each temperature segment less than or equal to this temperature C(t - t_step), distribute the VOC emission concentration Cm of the material at each mesh node according to the relative ratio of the initial emission concentration potential Cm0p_Temp of each temperature segment, and assign it to the initial emission concentration Cm0v_Temp of each temperature segment less than or equal to C(t - t_step);

[0014] S8. According to the initial emission concentration Cm0v_Temp of each temperature segment obtained in step S7 after one time step of emission, calculate the temperature C(t) at the beginning of the next time step, calculate the sum of the initial emission concentrations of each temperature segment less than or equal to this temperature C(t), and update the sum result to the VOC emission concentration Cm of the material at each mesh node;

[0015] S9. Judge whether the current simulation duration t is less than the total simulation duration t_total. If so, after updating the mesh nodes Dm(C(t)), K(C(t)), Da(C(t)) of the geometric simulation model for the VOC emission of the material, repeat steps S6 - S8; if not, the simulation calculation ends, and output the hourly VOC emission concentration Cm0v_Temp(t) of each temperature segment, the hourly VOC emission concentration Cm(t) of the material, and the hourly VOC emission concentration Ca(t) of the air at each mesh node, and calculate the average value of the hourly emission concentrations of each mesh node in the material mesh and the average value of the hourly emission concentrations of each mesh node in the air mesh.

[0016] Further, in step S1, determine the simulation temperature range, divide it into temperature segments, calculate the initial VOC emission concentration of the material in each temperature segment, and set the potential of the initial VOC emission concentration of the material in each temperature segment. The specific method is as follows:

[0017] S11. Conduct the VOC emission test of the material to obtain the VOC emission parameters of the material under the constant temperature conditions of 25°C and 65°C, including the initial emission concentration Cm0_25mg / m under the condition of 25°C 3 and the initial emission concentration Cm0_65mg / m under the condition of 65°C 3 , the diffusion coefficient Dm_25m under the condition of 25°C 2 / s, the diffusion coefficient Dm_65m under the condition of 65°C 2 / s, the partition coefficient K_25 under the condition of 25°C, and the partition coefficient K_65 under the condition of 65°C;

[0018] S12. Perform the parameter fitting of the temperature effect equation. According to the VOC emission parameters of the material under the constant temperature conditions of 25°C and 65°C, obtain Cm0_a and Cm0_b for calculating the initial VOC emission concentration of the material at any temperature, Dm_a and Dm_b for the VOC diffusion coefficient in the material, and K_a and K_b for the VOC partition coefficient at the material-air interface;

[0019] Where:

[0020] Cm0_b = -2518.1×(log(Cm0_65 / Cm0_25) + 0.5×0.1259)

[0021] Cm0_a = Cm0_25 / (298.15^(-0.5)×exp(Cm0_b / 298.15))

[0022] Dm_b = -2518.1×(log(Dm_65 / Dm_25) - 1.25×0.1259)

[0023] Dm_a = Dm_25 / (298.15^(1.25)×exp(Dm_b / 298.15))

[0024] K_b = -2518.1×(log(K_65 / K_25) - 0.5×0.1259)

[0025] K_a = K_25 / (298.15^(0.5)×exp(K_b / 298.15));

[0026] S13. Set the simulation temperature range as (25 - 65) °C, and divide the temperature range. The specific method is to divide each 1 °C within the range of (25 - 65) °C into a temperature segment, Temp = 25, 26, …, 65;

[0027] S14. According to the initial VOC emission concentration parameters of the material, calculate the initial VOC emission concentration of the material in each temperature segment, and set the potential of the initial VOC emission concentration of the material in each temperature segment.

[0028] Furthermore, in step S14, according to the initial VOC emission concentration parameters of the material, calculate the initial VOC emission concentration of the material in each temperature segment. The specific calculation method is:

[0029] According to Cm0_a and Cm0_b, calculate the initial VOC emission concentration Cm0v_25mg / m in each temperature segment within the range of (25 - 65) °C 3 , Cm0v_26mg / m 3 , Cm0v_27mg / m 3 , ……, Cm0v_65mg / m 3 ; Cm0v_25 = Cm0_a × (25 + 273.15)^-0.5 × exp(Cm0_b / (25 + 273.15)); Cm0v_Temp’ = Cm0_a × (Temp + 273.15)^-0.5 × exp(Cm0_b / (Temp + 273.15)) - Cm0_a × (Temp - 1 + 273.15)^-0.5 × exp(Cm0_b / (Temp - 1 + 273.15)), Temp’ = 26, 27, …, 65;

[0030] Set the potential of the initial VOC emission concentration of the material in each temperature segment. The specific method is:

[0031] Set the potential of the initial VOC emission concentration Cm0p_25mg / m of the material in each temperature segment within the range of (25 - 65) °C 3 , Cm0p_26mg / m 3 , Cm0p_27mg / m 3 , ……, Cm0p_65mg / m 3 , where:

[0032] Cm0p_Temp = Cm0v_Temp, Temp = 25, 26, …, 65.

[0033] Furthermore, in step S2, calculate the diffusion coefficient Dm(C(t)) of the material VOC and the partition coefficient K(C(t)) of the material VOC at each hourly temperature within the simulation temperature range. The specific calculation formulas are:

[0034] Dm(C(t)) = Dm_a×(C(t) + 273.15)^1.25×exp(Dm_b / (C(t) + 273.15))

[0035] K(C(t)) = K_a×(C(t) + 273.15)^0.5×exp(K_b / (C(t) + 273.15));

[0036] In step S3, calculate the diffusion coefficient Da(C(t)) of VOC in the air at each hourly temperature. The specific method is to consult the literature to obtain the diffusion coefficient Da_25 of the material VOC in the air at 25°C.

[0037] Da(C(t)) = Da_25×((C(t) + 273.15) / 298.15)^1.81.

[0038] Furthermore, in step S4, calculate the initial volatile concentration Cm(C(t0)) of the material VOC at the temperature C(t0) at the initial moment of the material VOC simulation emission. The specific calculation formula:

[0039] Cm(C(t0)) = Cm0_a×(C(t0) + 273.15)^-0.5×exp(Cm0_b / (C(t0) + 273.15)).

[0040] Furthermore, in step S5, construct a geometric simulation model of the material VOC emission through finite element analysis. Set the material grid, the grid at the material-air interface, and the air grid. According to Cm(C(t0)), Dm(C(t0)), K(C(t0)), Da(C(t0)), and combined with Fick's second law of diffusion and Henry's law, perform mesh division on each type of grid and set the grid node parameters. Set the total duration t_total s of the simulation emission and the time step t_step s of the simulation calculation. The specific method:

[0041] S51. Construct a geometric model of the material VOC emission in the finite element analysis software. Set the material grid, the grid at the material-air interface, and the air grid, and perform mesh division on each type of grid.

[0042] S52. Set relevant parameters at each grid node, including: set the initial volatile concentration Cm(C(t0)) and diffusion coefficient Dm(C(t0)) at the initial moment t0 of the simulation emission at the material grid node; set the distribution coefficient K(C(t0)) at the grid node at the material-air interface; set the initial concentration Ca = 0 and diffusion coefficient Da(C(t0)) at the air grid node.

[0043] S53. Set the total duration \(t_{total}\) s of the simulated emission and the time step \(t_{step}\) s of the simulation calculation;

[0044] S54. Apply Fick's second law of diffusion to the material and air grid nodes, and apply Henry's law to the grid nodes at the material-air interface.

[0045] Furthermore, in step S7, according to the temperature \(C(t - t_{step})\) after one time step of emission and the initial potential emission concentration of each temperature segment less than or equal to this temperature \(C(t - t_{step})\), distribute the material VOC emission concentration \(C_m\) at each grid node according to the relative ratio of the initial potential emission concentration \(C_{m0p\_Temp}\) of each temperature segment, and assign it to the initial emission concentration \(C_{m0v\_Temp}\) of each temperature segment with a temperature less than or equal to \(C(t - t_{step})\). The specific formula is:

[0046]

[0047] \(C_{m0v\_Temp}' = if(C(t - t_{step}) <= Temp' - 1, C_{m0v\_Temp}',

[0048]

[0049] Temp' = 26, 27, …, 65, Temp = Temp':65;

[0050] The meaning of Temp = Temp':65 is that Temp takes values in sequence from Temp' to 65 with a step of 1;

[0051] In step S8, according to the initial emission concentration \(C_{m0v\_Temp}\) of each temperature segment obtained in step S7 after one time step of emission, calculate the temperature \(C(t)\) at the start of the next time step, calculate the sum of the initial emission concentrations of each temperature segment less than or equal to this temperature \(C(t)\), and update the sum result to the material VOC emission concentration \(C_m\) at each grid node. The specific formula is,

[0052]

[0053] Furthermore, in step S9, calculate the hourly average concentration of each grid node in the material grid and the hourly average emission concentration of each grid node in the air grid. The specific method is as follows:

[0054] S91. Calculate the hourly concentration average value of each grid node in the material grid based on the hourly VOC emission concentration Cm0v_Temp(t) of the material in each temperature segment and the hourly VOC emission concentration Cm(t) of the material, to obtain the hourly VOC emission concentration of the material under the hourly changing temperature condition C(t) and the hourly VOC emission concentration of each temperature segment within the simulation temperature range. By adjusting the temperature condition, obtain the control target value of the VOC emission concentration of the material;

[0055] S92. Calculate the hourly emission concentration average value of each grid node in the air grid based on the hourly VOC emission concentration Ca(t) of the air, to obtain the hourly VOC concentration value of the air in which the material VOC is emitted into the surrounding air after a certain period of time under the changing temperature condition.

[0056] Furthermore, in step S91, to calculate the hourly concentration average value of each grid node in the material grid and obtain the hourly VOC emission concentration average value of the material under the hourly changing temperature condition C(t) and the hourly VOC emission concentration average value of each temperature segment within the simulation temperature range, the specific method is as follows:

[0057] Let the number of material grid nodes be x, and the names of each grid node be n1, n2, ……, nx;

[0058] Calculate the average value of the hourly concentration of each grid node of the material. Set Cm_avg(t) as the hourly VOC emission concentration average value of the material under the hourly changing temperature condition C(t). The specific formula is:

[0059]

[0060] Set Cm0v_25_avg(t), Cm0v_26_avg(t), ……, Cm0v_65_avg(t) to represent the hourly VOC emission concentration average values of each temperature segment within the range of (25 - 65)°C in sequence. The specific calculation formula is,

[0061]

[0062] Temp = 25, 26, …, 65, t = 0:t_step:t_total,

[0063] The meaning of t = 0:t_step:t_total is that the time variable t takes values in sequence from 0 to t_total with t_step as the step size.

[0064] Furthermore, in step S92, to calculate the hourly emission concentration average value of each grid node in the air grid and obtain the hourly VOC concentration value of the air in which the material VOC is emitted into the surrounding air after a certain period of time under the changing temperature condition, the specific method is as follows:

[0065] Let the number of air grid nodes be y, and the grid nodes be a1, a2, ……, ay respectively;

[0066] Set the average concentration Ca_avg(t) of volatile organic compounds (VOCs) at each air grid node over time. The specific calculation formula is,

[0067]

[0068] Ca_j(t) is the VOC concentration value of the air read at the j-th grid node of the air grid at time t, and j represents one of the grid nodes a1, a2, ……, ay.

[0069] Compared with the prior art, the non-isothermal emission simulation calculation method for volatile organic compounds in the automotive interior materials of the present invention has the following beneficial effects:

[0070] (1) The non-isothermal emission simulation calculation method for volatile organic compounds in the automotive interior materials of the present invention adopts the finite element analysis simulation calculation method, which conforms to the emission mechanism of VOC gases in solid materials. Therefore, the reliability of the simulation results is relatively high, and further, the reliability of the control target value of the VOC concentration in the interior materials set based on the simulation results and its supporting storage temperature control scheme is relatively high.

[0071] (2) In the non-isothermal emission simulation calculation method for volatile organic compounds in the automotive interior materials of the present invention, since VOCs in solid materials are generally considered to have two existence states. One state is the volatile state of the air-phase VOC existing in the micropores inside the solid; the other state is the non-volatile state of the adsorbed-phase VOC adsorbed and combined on the solid. The non-volatile state can be converted into the volatile state, but an adsorption energy barrier needs to be overcome. By increasing the molecular kinetic energy of the adsorbed-phase VOC by raising the temperature, this energy barrier can be overcome. This application calculates the initial volatile concentration of the material VOC in each temperature segment, and takes the initial volatile concentration of the material VOC in each temperature segment as the VOC container, reflecting the mutual conversion of these two states under non-isothermal emission conditions;

[0072] (3) In the non-isothermal emission simulation calculation method of volatile organic compounds in the automotive interior materials of the present invention, since the adsorption energy barrier involved in the mutual conversion between non-emissible VOCs and emissive VOCs is a characteristic constant related to the properties of solid materials and VOCs, and does not change with the change of VOC concentration, this constant-type energy barrier will directly affect the distribution ratio when emissive VOCs are distributed into VOC containers at each temperature segment. In this application, according to the temperature C(t - t_step) at the start of the simulation time step and the initial emissive concentration potential of each temperature segment less than or equal to this temperature C(t - t_step), the concentration Cm at each grid node of the material is distributed according to the relative ratio of each initial emissive concentration potential, and the absolute magnitude of the initial emissive concentration of each temperature segment less than or equal to C(t - t_step) is correspondingly assigned. By using the initial emissive concentration potential of each temperature segment as the determining factor for the distribution ratio, the accuracy of the simulation results is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0074] Figure 1 It is a schematic diagram of the non-isothermal emission simulation calculation method of volatile organic compounds in the automotive interior materials according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0075] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0076] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0077] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0078] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0079] 1) Conduct material VOC emission tests to obtain the key VOC emission parameters of the material under the constant temperature conditions of 25°C and 65°C, including the initial releasable concentration Cm0_25 mg / m 3 under the condition of 25°C, the initial releasable concentration Cm0_65 mg / m 3 under the condition of 65°C, the diffusion coefficient Dm_25 m 2 / s under the condition of 25°C, the diffusion coefficient Dm_65 m 2 / s under the condition of 65°C, the partition coefficient K_25 under the condition of 25°C, and the partition coefficient K_65 under the condition of 65°C.

[0080] 2) Perform parameter fitting of the temperature effect equation to obtain Cm0_a and Cm0_b for calculating the initial releasable concentration of VOC in the material at any temperature, obtain Dm_a and Dm_b for calculating the diffusion coefficient of VOC in the material at any temperature, and obtain K_a and K_b for calculating the VOC partition coefficient at the material-air interface. Among them:

[0081] Cm0_b = -2518.1×(log(Cm0_65 / Cm0_25) + 0.5×0.1259) (Equation 1)

[0082] Cm0_a = Cm0_25 / (298.15^(-0.5)×exp(Cm0_b / 298.15)) (Equation 2)

[0083] Dm_b = -2518.1×(log(Dm_65 / Dm_25) - 1.25×0.1259) (Equation 3)

[0084] Dm_a = Dm_25 / (298.15^(1.25)×exp(Dm_b / 298.15)) (Equation 4)

[0085] K_b = -2518.1×(log(K_65 / K_25) - 0.5×0.1259) (Equation 5)

[0086] $K_a = K_{25} / (298.15^{0.5}×exp(K_b / 298.15))$ (Equation 6)

[0087] 3) Calculate the initial emission concentration $Cm0v_{25}mg / m$ for each temperature segment in the range of (25 - 65)°C based on $Cm0_a$ and $Cm0_b$. 3 $Cm0v_{26}mg / m$ 3 $Cm0v_{27}mg / m$ 3 $Cm0v_{65}mg / m$ 3 etc. The suffix symbol "v" is the first letter of "variable". The values of these parameters will change and update with the emission of the material VOC, reflecting the absolute magnitude of the initial emission concentration of the material VOC in different temperature segments. Among them:

[0088] $Cm0v_{25}=Cm0_a×(25 + 273.15)^{-0.5}×exp(Cm0_b / (25 + 273.15))$ (Equation 7)

[0089]

[0090] 4) Set the potential of the initial emission concentration of the material VOC $Cm0p_{25}mg / m$ for each temperature segment in the range of (25 - 65)°C 3 $Cm0p_{26}mg / m$ 3 $Cm0p_{27}mg / m$ 3 $Cm0p_{65}mg / m$ 3 etc. The suffix symbol "p" is the first letter of "potential". The values of these parameters are constants and do not change and update with the emission of the material VOC, reflecting the relative magnitude of the initial emission concentration of the material VOC in different temperature segments. Among them:

[0091]

[0092] 5) Set the hourly temperature $C(t)°C$ during the emission process of the material VOC.

[0093] 6) Based on the temperature $C(t0)$ at the initial moment $t0$ of the simulated emission of the material VOC, calculate the initial emission concentration $Cm(C(t0))mg / m$ of the simulated emission 3 .

[0094] $Cm(C(t0)) = Cm0_a×(C(t0)+273.15)^{-0.5}×exp(Cm0_b / (C(t0)+273.15))$ (Equation 10)

[0095] 7) Calculate the key emission parameters of VOCs in the material at each hourly temperature within the range of (25 - 65)°C, including the diffusion coefficient Dm(C(t)) m 2 / s and the partition coefficient K(C(t)). Wherein:

[0096] Dm(C(t)) = Dm_a × (C(t) + 273.15)^1.25 × exp(Dm_b / (C(t) + 273.15)) (Equation 11)

[0097] K(C(t)) = K_a × (C(t) + 273.15)^0.5 × exp(K_b / (C(t) + 273.15)) (Equation 12)

[0098] 8) Obtain the diffusion coefficient Da_25 m 2 / s of VOCs in air at 25°C through literature retrieval, and calculate the diffusion coefficient Da(C(t)) m 2 / s of VOCs in air at each hourly temperature.

[0099] Da(C(t)) = Da_25 × ((C(t) + 273.15) / 298.15)^1.81 (Equation 13)

[0100] 9) Construct a geometric model of VOC emission in the material in the finite element analysis software and perform mesh division. Set relevant parameters at each mesh node, including: 1) Set the initial emission concentration Cm(C(t0)) mg / m 3 and the diffusion coefficient Dm(C(t0)) m 2 / s at the material mesh node at the initial simulation emission time t0; 2) Set the partition coefficient K(C(t0)) at the mesh node at the material-air interface; 3) Set the initial concentration Ca = 0 mg / m 3 and the diffusion coefficient Da(C(t0)) m 2 / s at the air mesh node.

[0101] 10) Set the total duration t_total s of the simulation emission and the time step t_step s of the simulation calculation.

[0102] 11) Apply Fick's second law of diffusion at the material and air mesh nodes, and apply Henry's law at the mesh nodes at the material-air interface

[0103] 12) Calculate the concentrations Cm mg / m 3 and Ca mg / m 3 at each mesh node after one time step of emission.

[0104] 13) After the simulation, the temperature C(t - t_step) after one time step and the initial VOC emission concentration potential Cm0p_25mg / m of each temperature segment less than or equal to this temperature C(t - t_step) 3 、Cm0p_26mg / m 3 etc. The concentration Cm at each grid node of the material is distributed according to the relative ratio of the initial VOC emission concentration potential of each temperature segment of the material, and is assigned to the initial emission concentration Cm0v_25mg / m of each temperature segment where the temperature is less than or equal to the temperature C(t - t_step) 3 、Cm0v_26mg / m 3 etc.

[0105] Among them:

[0106]

[0107]

[0108] The meaning of Temp = 25:65 after the If conditional statement is that Temp takes values in sequence from 25 to 65 with a step of 1 until the subsequent value taking stops after the if conditional statement is judged to be true.

[0109] 14) According to the initial emission concentration Cm0v_Temp of each temperature segment obtained in step S7 after one time step of emission, calculate the temperature C(t) at the beginning of the next time step, calculate the sum of the initial emission concentrations of each temperature segment less than or equal to this temperature C(t), and update the sum result to the VOC emission concentration Cm mg / m of the material at each grid node 3 ,

[0110]

[0111] 15) Determine whether the current simulation duration t is less than the total simulation duration t_total. If so, update the diffusion coefficient at the material grid node to Dm(C(t)) m 2 / s, update the distribution coefficient at the grid node at the material - air boundary to K(C(t)), update the diffusion coefficient at the air grid node to Da(C(t)) m 2 / s, and then execute 12 - 14 in sequence; if not, the simulation calculation ends, and the hourly concentrations Cm(t) mg / m 3 、Ca(t) mg / m 3 、Cm0v_25(t) mg / m 3 、Cm0v_26(t) mg / m 3 、……、Cm0v_65(t) mg / m 3 are output.

[0112] 16) Denote the number of material grid nodes as x, and the grid nodes are n1, n2, ……, nx respectively. Calculate the average hourly concentration Cm_avg(t) mg / m of each material grid node 3 , Cm0v_25_avg(t) mg / m 3 , Cm0v_26_avg(t) mg / m 3 , ……, Cm0v_65_avg(t) mg / m 3 , which are the hourly emission concentrations of the material VOC under the hourly changing temperature condition C(t) and the hourly emission concentrations of each temperature segment within the range of (25 - 65)°C. By changing the hourly changing temperature condition C(t), that is, changing the storage temperature control plan of the interior material, the hourly emission concentrations of the material and the hourly emission concentrations of each temperature segment within the range of (25 - 65)°C can be simulated and calculated. Based on these temperature - emission concentration data, the control target value of the VOC concentration in the interior material and its supporting storage temperature control plan can be accurately set. Among them:

[0113]

[0114]

[0115] The meaning of formula (17) is that the time variable t takes values in sequence from 0 to t_total with a step of t_step, and after adding the emission concentrations Cm_h(t) mg / m of each grid node at the same moment 3 and then dividing by the number of material grid nodes x.

[0116] 17) Denote the number of air grid nodes as y, and the grid nodes are a1, a2, ……, ay respectively. Calculate the average hourly concentration Ca_avg(t) mg / m of each air grid node 3 , which is the hourly concentration of air VOC caused by the emission of the material VOC into the surrounding air under the changing temperature condition C(t) over a certain period of time.

[0117]

[0118] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials, characterized in that: The specific method is as follows: S1. Set the hourly temperature C(t) during the VOC emission process of the material, determine the simulation temperature range, divide the temperature segments, calculate the initial VOC emission concentration of the material in each temperature segment, and set the potential of the initial VOC emission concentration of the material in each temperature segment; S2. Calculate the diffusion coefficient Dm(C(t)) of the material VOC and the partition coefficient K(C(t)) of the material VOC at each hourly temperature within the simulation temperature range; S3. Calculate the diffusion coefficient Da(C(t)) of the VOC in the air at each hourly temperature within the simulation temperature range; S4. Calculate the initial VOC emission concentration Cm(C(t0)) of the material at the temperature C(t0) at the initial moment of the material VOC simulation emission; S5. Construct a geometric simulation model for the material VOC emission through finite element analysis, set the material grid, the grid at the material-air interface, and the air grid. According to Cm(C(t0)), Dm(C(t0)), K(C(t0)), Da(C(t0)), and combined with Fick's second diffusion law and Henry's law, perform grid division on each type of grid and set the grid node parameters. Set the total duration t_total of the simulation emission and the time step t_step of the simulation calculation; S6. Through simulation calculation, obtain the VOC emission concentration Cm of the material and the VOC emission concentration Ca of the air at each grid node after one time step; S7. According to the temperature C(t - t_step) after one time step and the potential of the initial emission concentration of each temperature segment less than or equal to this temperature C(t - t_step), distribute the VOC emission concentration Cm of the material at each grid node according to the relative ratio of the potential Cm0p_Temp of the initial emission concentration of each temperature segment, and assign it to the initial emission concentration Cm0v_Temp of each temperature segment less than or equal to C(t - t_step); S8. According to the initial emission concentration Cm0v_Temp of each temperature segment obtained in step S7 after one time step, calculate the temperature C(t) at the start of the next time step, calculate the sum of the initial emission concentrations of each temperature segment less than or equal to this temperature C(t), and update the sum result to the VOC emission concentration Cm of the material at each grid node; S9. Judge whether the current simulation duration t is less than the total simulation duration t_total. If so, after updating the grid nodes Dm(C(t)), K(C(t)), Da(C(t)) of the geometric simulation model of the material VOC emission, repeat steps S6 - S8; if not, the simulation calculation ends, output the hourly VOC emission concentration Cm0v_Temp(t) of each temperature segment of the material, the hourly VOC emission concentration Cm(t) of the material, and the hourly VOC emission concentration Ca(t) of the air at each grid node, and calculate the average value of the hourly emission concentration of each grid node in the material grid and the average value of the hourly emission concentration of each grid node in the air grid.

2. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 1, characterized in that: In step S1, determine the simulation temperature range, divide it into temperature segments, calculate the initial VOC emission concentration of the material in each temperature segment, and set the potential of the initial VOC emission concentration of the material in each temperature segment. The specific method is as follows: S11. Conduct material VOC emission tests to obtain material VOC emission parameters under constant temperature conditions of 25°C and 65°C, including the initial emission concentration Cm0_25mg / m 3 at 25°C, the initial emission concentration Cm0_65mg / m 3 at 65°C, the diffusion coefficient Dm_25m 2 / s at 25°C, the diffusion coefficient Dm_65m 2 / s at 65°C, the partition coefficient K_25 at 25°C, and the partition coefficient K_65 at 65°C; S12. Perform parameter fitting of the temperature effect equation. Obtain Cm0_a and Cm0_b for calculating the initial VOC emission concentration of the material at any temperature, Dm_a and Dm_b for the VOC diffusion coefficient in the material, and K_a and K_b for the VOC partition coefficient at the material-air interface based on the VOC emission parameters of the material under the constant temperature conditions of 25°C and 65°C; Where: Cm0_b = -2518.1×(log(Cm0_65 / Cm0_25)+0.5×0.1259) Cm0_a = Cm0_25 / (298.15^(-0.5)×exp(Cm0_b / 298.15)) Dm_b = -2518.1×(log(Dm_65 / Dm_25)-1.25×0.1259) Dm_a = Dm_25 / (298.15^(1.25)×exp(Dm_b / 298.15)) K_b = -2518.1×(log(K_65 / K_25)-0.5×0.1259) K_a = K_25 / (298.15^(0.5)×exp(K_b / 298.15)); S13. Set the simulation temperature range as (25 - 65)°C and divide it into temperature segments. The specific method is to divide each 1°C within the range of (25 - 65)°C into a temperature segment, Temp = 25, 26,..., 65; S14. Calculate the initial VOC emission concentration of the material in each temperature segment according to the initial VOC emission concentration parameters of the material, and set the potential of the initial VOC emission concentration of the material in each temperature segment.

3. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 2, characterized in that: In step S14, calculate the initial VOC emission concentration of the material in each temperature segment according to the initial VOC emission concentration parameters of the material. The specific calculation method: According to Cm0_a and Cm0_b, the initial emission concentration Cm0v_25mg / m at each temperature segment within the range of (25 to 65)°C is calculated 3 , Cm0v_26mg / m 3 , Cm0v_27mg / m 3 , ……, Cm0v_65mg / m 3 ; Cm0v_25 = Cm0_a × (25 + 273.15)^-0.5 × exp(Cm0_b / (25 + 273.15)); Cm0v_Temp’ = Cm0_a × (Temp + 273.15)^-0.5 × exp(Cm0_b / (Temp + 273.15)) - Cm0_a × (Temp - 1 + 273.15)^-0.5 × exp(Cm0_b / (Temp - 1 + 273.15)), Temp’ = 26, 27, …, 65; Set the potential of the initial VOC emission concentration of the material in each temperature segment. The specific method: Set the initial VOC emission concentration potential Cm0p_25mg / m at each temperature segment within the range of (25 - 65)°C 3 ,Cm0p_26mg / m 3 ,Cm0p_27mg / m 3 ,……,Cm0p_65mg / m 3 ,where: Cm0p_Temp = Cm0v_Temp, Temp = 25, 26,..., 65.

4. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 3, characterized in that: In step S2, calculate the VOC diffusion coefficient Dm(C(t)) of the material and the VOC partition coefficient K(C(t)) of the material at each hourly temperature within the simulation temperature range. The specific calculation formulas: Dm(C(t)) = Dm_a×(C(t)+273.15)^1.25×exp(Dm_b / (C(t)+273.15)) K(C(t)) = K_a×(C(t)+273.15)^0.5×exp(K_b / (C(t)+273.15)); In step S3, calculate the VOC diffusion coefficient Da(C(t)) in the air at each hourly temperature. The specific method is to obtain the diffusion coefficient Da_25 of the material VOC in the air at 25°C by referring to the literature. Da(C(t)) = Da_25×((C(t) + 273.15) / 298.15)^1.81。 5. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 4, characterized in that: In step S4, calculate the initial VOC emission concentration Cm(C(t0)) of the material at the initial temperature C(t0) of the material VOC simulation emission. The specific calculation formula is: Cm(C(t0)) = Cm0_a×(C(t0) + 273.15)^-0.5×exp(Cm0_b / (C(t0) + 273.15)).

6. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 5, characterized in that: In step S5, construct a geometric simulation model for the VOC emission of the material through finite element analysis. Set the material grid, the grid at the material-air interface, and the air grid. According to Cm(C(t0)), Dm(C(t0)), K(C(t0)), Da(C(t0)), and combined with Fick's second law of diffusion and Henry's law, perform mesh division on each type of grid and set the grid node parameters. Set the total duration t_total s of the simulation emission and the time step t_step s of the simulation calculation. The specific method is: S51. Construct a geometric model for the VOC emission of the material in the finite element analysis software. Set the material grid, the grid at the material-air interface, and the air grid, and perform mesh division on each type of grid. S52. Set the relevant parameters at each grid node, including: set the initial VOC emission concentration Cm(C(t0)) and diffusion coefficient Dm(C(t0)) at the initial time t0 of the simulation emission at the material grid node; set the distribution coefficient K(C(t0)) at the grid node at the material-air interface; set the initial concentration Ca = 0 and diffusion coefficient Da(C(t0)) at the air grid node. S53. Set the total duration t_total s of the simulation emission and the time step t_step s of the simulation calculation. S54. Apply Fick's second law of diffusion at the material and air grid nodes, and apply Henry's law at the grid node at the material-air interface.

7. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 4, characterized in that: In step S7, according to the temperature C(t - t_step) after a time step of emission and the initial VOC emission concentration potential of each temperature segment less than or equal to this temperature C(t - t_step), distribute the VOC emission concentration Cm of the material at each grid node according to the relative ratio of the initial VOC emission concentration potential Cm0p_Temp of each temperature segment, and assign it to the initial VOC emission concentration Cm0v_Temp of each temperature segment less than or equal to C(t - t_step). The specific formula is: Cm0v_Temp’ = if(C(t - t_step) <= Temp’ - 1, Cm0v_Temp’, Temp’ = 26, 27, …, 65, Temp = Temp’:65; The meaning of Temp = Temp’:65 is that Temp takes values from Temp’ to 65 in steps of 1 in sequence. In step S8, based on the initial volatile concentration Cm0v_Temp of each temperature segment after a time step obtained in step S7, calculate the temperature C(t) at the start of the next time step, calculate the sum of the initial volatile concentrations of each temperature segment less than or equal to this temperature C(t), and update the sum result to the material VOC volatile concentration Cm on each grid node. The specific formula is as follows:

8. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 7, characterized in that: In step S9, calculate the hourly concentration average value of each grid node in the material grid and the hourly volatile concentration average value of each grid node in the air grid. The specific method is as follows: S91. Based on the hourly volatile concentration Cm0v_Temp(t) of the material VOC in each temperature segment and the hourly volatile concentration Cm(t) of the material VOC, calculate the hourly concentration average value of each grid node in the material grid, obtain the hourly volatile concentration of the material VOC under the hourly changing temperature condition C(t) and the hourly volatile concentration of each temperature segment within the simulation temperature range, and obtain the control target value of the material VOC volatile concentration by adjusting the temperature condition; S92. Based on the hourly volatile concentration Ca(t) of the air VOC, calculate the hourly volatile concentration average value of each grid node in the air grid, and obtain the hourly concentration value of the air VOC that the material VOC emits into the surrounding air after a certain time under the changing temperature condition.

9. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 8, characterized in that: In step S91, calculate the hourly concentration average value of each grid node in the material grid, and obtain the hourly volatile concentration average value of the material VOC under the hourly changing temperature condition C(t) and the hourly volatile concentration average value of each temperature segment within the simulation temperature range. The specific method is as follows: Denote the number of material grid nodes as x, and name each grid node as n1, n2,..., nx respectively; Calculate the average value of the hourly concentration on each grid node of the material. Set Cm_avg(t) as the hourly volatile concentration average value of the material VOC under the hourly changing temperature condition C(t). The specific formula is: Set Cm0v_25_avg(t), Cm0v_26_avg(t),..., Cm0v_65_avg(t) to represent the hourly volatile concentration average values of each temperature segment within the range of (25 - 65)°C in sequence. The specific calculation formula is as follows: Temp = 25, 26,..., 65, t = 0:t_step:t_total, The meaning of t = 0:t_step:t_total is that the time variable t takes values in sequence from 0 to t_total with a step size of t_step.

10. The non-isothermal emission simulation calculation method for volatile organic compounds in automotive interior materials according to claim 8, characterized in that: In step S92, calculate the hourly volatile concentration average value of each grid node in the air grid, and obtain the hourly concentration value of the air VOC that the material VOC emits into the surrounding air after a certain time under the changing temperature condition. The specific method is as follows: Denote the number of air grid nodes as y, and each grid node is a1, a2,..., ay respectively; Set the average value Ca_avg(t) of the hourly concentration on each grid node of the air. The specific calculation formula is as follows: Ca_j(t) is the air VOC concentration value read at the j grid node of the air grid at time t, and j represents one of the grid nodes a1, a2,..., ay.

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