A method and system for quantitatively detecting CO2 in a ventilation dead zone of an industrial park
By using a multi-point spatial monitoring array and a dual exponential decay model, the problem of quantitatively assessing the volume and exchange rate of ventilation dead zones in industrial parks was solved, enabling accurate detection and risk assessment of ventilation dead zones and providing effective ventilation strategies to reduce pollutant retention.
Patent Information
- Application Number
- CN202610500589.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-16
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies struggle to accurately and quantitatively assess the volume of ventilation dead zones and the rate of pollutant exchange in the complex environments of industrial parks. Fluid dynamics simulations rely on idealized settings, and single-point sensors cannot provide key physical parameters.
By employing a multi-point spatial monitoring array and a dual exponential decay model, multiple gas concentration sensors record the concentration decrease sequence, and the volume and exchange efficiency of the ventilation dead zone are calculated by inversion. Combined with a set of mass conservation differential equations, quantitative detection of the ventilation dead zone is achieved.
It enables precise quantitative assessment of the volume and exchange efficiency of ventilation dead zones, improves the accuracy and confidence of detection, and provides ventilation strategies to reduce the risk of pollutant retention and ensure safety.
Smart Images
Figure CN122449062A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of data processing technology, and in particular to a method and system for quantitative detection of CO2 in the ventilation dead zone of an industrial park. Background Technology
[0002] China has clearly stated its goal of peaking carbon dioxide emissions before 2030 and striving to achieve carbon neutrality before 2060. Industrial parks, as areas of high energy consumption and carbon emissions, are the main battleground for achieving carbon neutrality. The dense distribution of enterprises and buildings within these parks creates a highly complex urban underlying surface structure. In the complex environment of industrial parks, airflow is easily obstructed by buildings or obstacles, leading to flow separation and the formation of vortex zones or stagnation zones on the leeward side—the so-called "ventilation dead zones." These dead zones cause long-term accumulation of gases such as CO2, making it difficult to exchange with external airflow.
[0003] Studies on flow fields and pollutant diffusion in such complex environments primarily rely on computational fluid dynamics simulations or single-point sensor monitoring. However, computational fluid dynamics simulations involve enormous computational demands and are highly dependent on idealized boundary conditions (such as constant wind speed and regular geometry). When faced with real-world complex turbulent environments, they often fail to fully reproduce the actual physical processes and lack empirical data to support their accuracy. Single-point sensors can only qualitatively determine whether a location is a dead zone based on concentration levels, but cannot quantitatively provide key physical parameters such as the size of the dead zone and the rate of exchange between the dead zone and the main airflow. Summary of the Invention
[0004] In view of this, the present invention proposes a quantitative detection method for CO2 in the ventilation dead zone of an industrial park, in order to solve the technical problems mentioned in the background art, such as the huge amount of computation required for fluid dynamics simulation and its extreme dependence on the idealized setting of boundary conditions, which often makes it difficult to fully reproduce the real physical process when facing the complex turbulent environment; and the inability of single-point sensors to quantitatively provide key physical parameters such as the size of the dead zone and the speed of exchange between the dead zone and the main airflow.
[0005] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a method for quantitative detection of CO2 in dead ventilation zones of industrial parks, comprising: Physical environment construction and parameter initialization: A transparent sealed experimental chamber was set up. The obstacle model components were fixed to the bottom plate of the experimental chamber according to a preset array. A fan with variable frequency speed control function was installed on the side wall of the experimental chamber. The net free volume V of the experimental chamber was measured. total And set a constant external mechanical ventilation flow rate Q; Close the vents, inject a fixed amount of CO2 gas into the experimental chamber, then stop the injection and wait for the concentration in the experimental chamber to stabilize and reach the initial equilibrium state. The fan is turned on to perform constant flow displacement, and multiple gas concentration sensors in the space monitoring array are used to simultaneously record the concentration decrease sequence C at N different measuring points. i (t); The instantaneous spatial average concentration curve within the experimental chamber is obtained by performing arithmetic or weighted averaging on multiple data collected from various gas concentration sensors. ; The calculated average concentration curve The fit is a double exponential decay function C(t), where C(t) is a function based on the fast decay eigenvalue λ1, the slow decay eigenvalue λ2, and the fitting coefficients A and B. Based on the eigenvalue properties of the mass conservation differential equations, using Q and V total The inversion calculations using λ1 and λ2 determine the mainstream volume V1, the dead zone volume V2, and the exchange flow rate Q between the dead zone and the mainstream zone. e ; Output the dead zone volume ratio v and the exchange efficiency index q to evaluate the ventilation efficiency and pollutant retention risk under this experimental chamber layout.
[0006] In some alternative implementations, preferably, the calculated average concentration curve is... The fit is a double exponential decay function C(t), including: Let the concentrations in the mainstream region and the dead region be θ1(t) and θ2(t), respectively; For the mainstream region, the inflow of fresh air is Q, the outflow concentration is θ1, and the exchange flow rate with the dead zone is Q. e via Q, Q e Calculate dθ1 / dt using θ1, θ2, and V1; For dead zones, there is no direct inflow or outflow; they only exchange with mainstream zones via Q. e Calculate dθ2 / dt using θ1 and θ2; By simultaneously solving the calculated dθ1 / dt and dθ2 / dt, the general solution is obtained. ; Through θ1(t), θ2(t), V1, V2 and V total Calculate the spatial average concentration , will general solution Substitute spatial average concentration We obtain functions of λ1, λ2, A, and B; according to By introducing the constant term C0, we obtain the double exponential decay function C(t).
[0007] In some optional implementations, preferably, the output dead zone volume ratio v and the exchange efficiency index q are used to evaluate the ventilation efficiency and pollutant retention risk under the experimental chamber layout, including: Quantitatively assess the current pollutant retention level in the park's building layout, provide risk warnings, and ventilation strategies.
[0008] In some optional implementations, preferably, the step of stopping the injection of a quantitative amount of CO2 gas into the experimental chamber and waiting for the concentration in the experimental chamber to stabilize and reach an initial equilibrium state includes: the reading deviation of the gas concentration sensors at each monitoring point being within a preset range.
[0009] In some alternative implementations, preferably, the utilization of Q and V... total The inversion calculations using λ1 and λ2 determine the mainstream volume V1, the dead zone volume V2, and the exchange flow rate Q between the dead zone and the mainstream zone. e ,include: Through Q, V total Calculate the mainstream volume V1 using λ1 and λ2; Through V total Calculate the ventilation dead zone volume V2 based on the mainstream zone volume V1; Calculate the exchange flow Q between the dead zone and the mainstream zone using V1, V2, λ1, λ2, and Q. e .
[0010] In some optional implementations, preferably, the output dead zone volume ratio v and the exchange efficiency index q include: the ventilation dead zone volume V2 and the net free volume V of the experimental chamber. total Calculate the dead zone volume percentage v, and the exchange flow Q between the dead zone and the mainstream zone. e The exchange efficiency index q is calculated based on the external mechanical ventilation flow rate Q.
[0011] Secondly, this invention provides a quantitative detection system for CO2 in the ventilation dead zone of an industrial park, comprising a physical simulation subsystem, a multi-point spatial monitoring array subsystem, and a parameter inversion calculation module, wherein: The physical simulation subsystem is used to construct the flow field environment to be tested, including a transparent sealed experimental chamber, a model of building obstacles set on the bottom plate of the experimental chamber, and a fan unit installed on the side wall of the experimental chamber with variable frequency speed control function. The fan unit is used to provide a constant external ventilation flow rate Q. The multi-point spatial monitoring array subsystem includes multi-point gas concentration sensors arranged at different heights and horizontal positions inside the experimental chamber. The sensor positions cover the windward side, leeward side, and top recirculation area of the building obstacle model. It is used to synchronously collect the gas concentration at each characteristic point during the gas dissipation process and obtain data on the concentration change over time. The parameter inversion calculation module is connected to the multi-point gas concentration sensor monitoring array subsystem and is used to analyze data. By calculating the spatial average concentration and executing the dual-zone model algorithm, it quantifies the dead zone volume ratio v and the exchange efficiency index q.
[0012] In some alternative implementations, preferably, the multi-point spatial monitoring array subsystem includes at least a plurality of first sensors arranged on the leeward side of the upper level of the building obstacle model, a plurality of second sensors arranged in the street canyon area, and a plurality of third sensors arranged in the return flow area at the top of the experimental chamber.
[0013] In some alternative implementations, preferably, the fan unit is calibrated to output an accurate external ventilation flow rate value Q, and this value is input as a known constant into the parameter inversion calculation module.
[0014] In some alternative embodiments, preferably, the transparent sealed experimental chamber is made of one or more chemically inert materials selected from polymethyl methacrylate, polycarbonate, or tempered glass; the obstacle model assembly has a hollow structure and all surface seams are sealed.
[0015] The present invention provides a method and system for quantitative detection of CO2 in dead ventilation zones of industrial parks, which has the following advantages over the prior art: (1) The average concentration decay data of the real space in the experimental chamber is obtained by multiple gas concentration sensors in the space monitoring array. Combined with the analytical algorithm of the dual-zone physical model, the accurate quantitative inversion of the dead zone volume ratio v and the exchange efficiency index q in the confined space is realized. For the first time, the "invisible" dead zone volume and exchange flow rate are inferred from the macro concentration data, and the evaluation of the ventilation dead zone is upgraded from "qualitative description" to "quantitative calculation". The use of multi-point space array monitoring combined with the average concentration algorithm avoids the problem that single-point monitoring is easily affected by local flow field fluctuations, and ensures that the data input to the dual-zone model is representative, thereby improving the confidence of the inversion results. (2) For the mainstream area, the inflow of fresh air is Q, the outflow concentration is θ1, and the exchange flow rate with the dead zone is Q. e Calculate dθ1 / dt; for dead zones, there is no direct inflow or outflow, only exchange with the main flow zone, calculate dθ2 / dt; combine the calculated dθ1 / dt and dθ2 / dt to obtain the general solution. ; through θ1(t), θ2(t), V1, V2 and V total Calculate the spatial average concentration , will general solution Substitute spatial average concentration We obtain functions of λ1, λ2, A, and B; according to With the introduced constant term C0, we obtain the double exponential decay function C(t); after fitting it to the double exponential decay function, we obtain λ1 and λ2, which can provide the parameter basis for subsequent parameter inversion calculations. (3) By outputting the dead zone volume ratio v and the exchange efficiency index q, evaluate the ventilation efficiency and pollutant retention risk under the experimental box layout, quantitatively assess the pollutant retention degree of the current building layout in the park, provide risk warning and ventilation strategy, for example, suggest long-term monitoring of pollutant concentration that is harmful to human health in the dead zone with the greatest pollutant retention risk, provide pollutant risk warning, and install ventilation equipment as soon as possible in high-risk situations to reduce the pollutant concentration in the area and ensure safety. (4) The step of injecting a quantitative amount of CO2 gas into the experimental chamber and then stopping the injection and waiting for the concentration in the experimental chamber to stabilize and reach the initial equilibrium state includes: the reading deviation of the gas concentration sensor at each monitoring point is within the preset range, thereby determining that the concentration in the experimental chamber has reached the initial equilibrium state, which facilitates subsequent ventilation and measurement, provides a stable and reliable environmental basis for subsequent calculations, and improves the accuracy of measurement. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic flowchart of the CO2 quantitative detection method for the ventilation dead zone in an industrial park according to the present invention. Figure 2 This is a schematic diagram of the physical simulation subsystem of the present invention. Figure 2 (a) is a schematic diagram of a blank test chamber. Figure 2 (b) is a schematic diagram of the building obstacle model. Figure 2 (c) is a schematic diagram of the fan; Figure 3 This is a schematic diagram showing the numerical distribution of CO2 concentration detected by sensors S1-S4 of the present invention; Figure 4 This is a schematic diagram of the numerical distribution of CO2 concentration detected by sensors S5-S8 of the present invention; Figure 5 This is a schematic diagram of the numerical distribution of CO2 concentration detected by the sensors S9-S12 of the present invention; Figure 6 This is a schematic diagram of the average concentration decay curves in each region of the present invention; Figure 7This is a schematic diagram of the average concentration decay curve during the ventilation process and the fitting curves of its single and double exponential decay functions according to the present invention. Figure 8 A flowchart illustrating the quantitative detection method for CO2 in the ventilation dead zone of an industrial park.
[0018] Figure labeling: 100 - Physical simulation subsystem, 200 - Multi-point spatial monitoring array subsystem, 300 - Parameter inversion calculation module. Detailed Implementation
[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0020] A first aspect of the present invention, referring to Figure 1 and Figure 2 As shown, a quantitative CO2 detection system for ventilation dead zones in industrial parks is proposed, comprising a physical simulation subsystem 100, a multi-point spatial monitoring array subsystem 200, and a parameter inversion calculation module 300, wherein: The physical simulation subsystem 100 is used to construct the flow field environment to be tested, including a transparent sealed experimental chamber, a model of building obstacles set on the bottom plate of the experimental chamber, and a fan unit with variable frequency speed control function installed on the side wall of the experimental chamber. The fan unit is used to provide a constant external ventilation flow rate Q. The obstacle model assembly adopts a hollow structure, and all surface seams are sealed. The experimental chamber is made of one or more chemically inert materials selected from polymethyl methacrylate, polycarbonate, or tempered glass. In the following embodiments, polymethyl methacrylate is used as an example. Experimental chamber construction: A cubic experimental chamber was constructed using 5mm thick transparent PMMA (polymethyl methacrylate) sheets, with internal net dimensions of [missing information]. The side wall seams of the enclosure are double-sealed with conductive rubber strips and sealing tape to ensure airtightness. Considering the ease of disassembly and assembly of the device, the entire device was not fully sealed in this experiment. Instead, the seams between surfaces were sealed with tape to ensure effective airtightness. Building obstacle model layout: Several hollow building models are fixed on the base plate of the box according to the preset industrial park planning map. This embodiment includes 3 ordinary factory building models (numbered A, B, and C, with dimensions of...). ) and 1 high-rise building model (No. D, size The total volume of all models was calculated to be... Then the net free volume of the experimental chamber ;
[0021] Fluid environment setup: An air inlet is installed on one side of the experimental chamber, and a variable frequency speed-controlled fan is installed to provide a constant external ventilation flow. An exhaust vent is provided on the opposite side; the fan unit is calibrated to output an accurate external ventilation flow rate value Q, and this value is input as a known constant into the parameter inversion calculation module 300; The multi-point spatial monitoring array subsystem 200 includes multiple gas concentration sensors arranged at different heights and horizontal positions within the experimental chamber. The sensor positions cover the windward side, leeward side, and top recirculation zone of the building obstacle model, used to synchronously collect gas concentration data at various characteristic points during the gas dispersion process, obtaining data on concentration changes over time; to obtain data representative of the dual-zone model... In this embodiment, the single-point monitoring scheme is abandoned, and a system containing 12 data points is constructed. Spatial array of concentration sensors: Sensors S1-S4: Placed on the leeward side of high-rise building D (simulating a typical dead zone). Sensors S5-S8: Located in the street canyon area (simulated mixed area) between factory buildings A and B; Sensors S9-S12: Located in the top reflux zone of the experimental chamber (simulating the upper mainstream zone); Each sensor is connected to the host computer via a data acquisition card, and the sampling frequency is set to 0.2Hz; The parameter inversion calculation module 300 is connected to the multi-point gas concentration sensor monitoring array subsystem and is used to analyze data. By calculating the spatial average concentration and executing the dual-zone model algorithm, it quantifies the dead zone volume ratio v and the exchange efficiency index q.
[0022] Based on the same concept, a second aspect of the present invention is described, with reference to... Figures 3-8 As shown, a method for quantitative detection of CO2 in the ventilation dead zone of an industrial park is proposed, including: Step S1: Constructing the physical environment and initializing parameters: Set up a transparent sealed experimental chamber. Fix the obstacle model components to the bottom plate of the experimental chamber according to a preset array. Install a fan with variable frequency speed control function on the side wall of the experimental chamber. Measure the net free volume V of the experimental chamber. total And set a constant external mechanical ventilation flow rate Q; In step S1, the net free volume V of the experimental chamber is measured. total =0.12m 3 Turn on the fan, adjust the inverter frequency, calibrate the average air velocity at the air inlet using an anemometer, and calculate the external mechanical ventilation flow rate Q = 0.015 m³ / h. 3 / s; Step S2: Close the vent, inject a fixed amount of CO2 gas into the experimental chamber, stop the injection, and wait for the concentration in the experimental chamber to stabilize and reach the initial equilibrium state. In step S2, injection is poured into the box through the pre-drilled hole. The gas is stirred for 30 seconds using a built-in micro fan. If the readings of the gas concentration sensors at each monitoring point are within the preset range, it is determined that the initial equilibrium state has been reached. Step S3: Turn on the fan to perform constant flow displacement, and use multiple gas concentration sensors in the space monitoring array to simultaneously record the concentration decrease sequence C at N different measuring points. i (t); In step S3, the main fan is turned on for ventilation and heat exchange. The host computer synchronously records the concentration decrease curves over time (C1(t), C2(t), C3(t), ..., C...) of 12 sensors during the gas dispersion process. 12 (t); Step S4: Perform arithmetic or weighted average processing on the multi-channel data collected by multiple gas concentration sensors to obtain the instantaneous spatial average concentration curve within the experimental chamber. ; In step S4, the data processing unit performs arithmetic averaging on the three signals to obtain the instantaneous spatial average concentration curve. : (1); In equation (1), C S1-S4 (t) is the average of C1(t), C2(t), C3(t), and C4(t), C S5-S8 (t) is the average of C5(t), C6(t), C7(t), and C8(t), C S9-S12 (t) represents C9(t), C 10 (t), C 11 (t) and C 12 The average value of (t); Step S5: Calculate the average concentration curve The fit is a double exponential decay function C(t), where C(t) is a function based on the fast decay eigenvalue λ1, the slow decay eigenvalue λ2, and the fitting coefficients A and B. Step S5 specifically includes: selecting The effective data segment from the initial time to when it approaches the background concentration. Let the concentrations in the mainstream region and the dead region be θ1(t) and θ2(t), respectively; From the mass-conserved coupled ODE system (ordinary differential equation system): For the mainstream region, the inflow of fresh air is Q, the outflow concentration is θ1, and the exchange flow rate with the dead zone is Q. e via Q, Q eCalculate dθ1 / dt using θ1, θ2, and V1; the calculation formula is as follows: (2); In equation (2), V1 is the volume of the main flow zone, Q is the external mechanical ventilation flow rate, and Q e θ1 represents the exchange flow between the dead zone and the mainstream zone, and θ2 represents the concentrations in the mainstream zone and the dead zone, respectively. For dead zones, there is no direct inflow or outflow; they only exchange with mainstream zones via Q. e Calculate dθ2 / dt using θ1 and θ2; the formula is as follows: (3); In equation (3), V2 is the volume of the ventilation dead zone; The following formula is obtained by rearranging the coupled ODE system: (4); In equation (4), ; By simultaneously solving the calculated dθ1 / dt and dθ2 / dt, the general solution is obtained. ; (5); In equation (5), , ; Through θ1(t), θ2(t), V1, V2 and V total Calculate the spatial average concentration , will general solution Substitute spatial average concentration The function obtained is related to λ1, λ2, A, and B; spatial average concentration. The calculation formula is as follows: (6); General solution Substituting into equation (6), we obtain the following formula: (7); In equation (7), , ; according to Including the introduced constant term C0, the double exponential decay function C(t) is calculated. The formula for calculating the double exponential decay function C(t) is as follows:
[0023] (8); In equation (8), C0 is the lowest average concentration level that can be achieved under the current wind strength Q; Using the nonlinear least squares method, the custom fitting function of formula (8) is selected for fitting, and the average concentration curve is obtained. The fit is a double exponential decay function, yielding two key eigenvalues λ1 and λ2, and a constant term C0: λ1 = 0.24378 (s). -1 ), λ2=0.00765 (s -1 C0 = 438.42 ppm. The goodness of fit of the two-zone model was also obtained. It is significantly better than single-exponential fitting. This verifies the applicability of the two-zone model.
[0024] Step S6: Based on the eigenvalue properties of the mass conservation differential equation system, using Q and V... total The inversion calculations using λ1 and λ2 determine the mainstream volume V1, the dead zone volume V2, and the exchange flow rate Q between the dead zone and the mainstream zone. e ; Step S6 specifically includes: via Q, V total Calculate the mainstream volume V1 using λ1 and λ2; based on the eigenvalue relationship: (9); (10); The formula for calculating the mainstream volume V1 can be obtained from equations (9) and (10) as follows: (11); Substituting the values into equation (11), we get V1 = 0.0634m 3 ; Through V total Calculate the ventilation dead zone volume V2 based on the mainstream zone volume V1; the calculation formula is as follows: (12); Substituting the values into equation (12), we obtain V2 = 0.0566m. 3 ; Calculate the exchange flow Q between the dead zone and the mainstream zone using V1, V2, λ1, λ2, and Q. e Q e The calculation formula is as follows:
[0025] (13); Substituting the values into equation (13), we can calculate Q. e =4.46×10 -4 m 3 / s.
[0026] Step S7: Output the dead zone volume ratio v and the exchange efficiency index q to evaluate the ventilation efficiency and pollutant retention risk under this experimental chamber layout. In Step S7, the dead zone volume ratio v and the exchange efficiency index q include: the volume of the ventilated dead zone V2 and the net free volume V of the experimental chamber. total Calculate the dead zone volume percentage v, and the exchange flow Q between the dead zone and the mainstream zone. e The exchange efficiency index q is calculated based on the external mechanical ventilation flow rate Q; the formula for calculating the dead zone volume ratio v is as follows:
[0027] (14); Substituting the values into equation (14), the dead zone volume ratio v = 47.2% is calculated; this indicates that under the current obstacle layout, about half of the space is in a state of poor ventilation. The formula for calculating the exchange efficiency index q is as follows: (15); Substituting the values into equation (15), we obtain the exchange efficiency index q = 2.97%, which explains why λ2 is much smaller than λ1, meaning that pollutants in the dead zone are extremely difficult to be discharged, verifying the physical cause of the final concentration value tending to remain unchanged. Step S7 also includes: quantitatively assessing the current pollutant retention level of the building layout in the park, providing risk warnings and ventilation strategies, such as recommending long-term monitoring of pollutant concentrations that are harmful to human health in dead zones with the greatest risk of pollutant retention, providing pollutant risk warnings, and installing ventilation equipment as soon as possible in high-risk situations to reduce pollutant concentrations in the area and ensure safety.
[0028] The method and system for quantitative detection of CO2 in the ventilation dead zone of an industrial park proposed in this invention have the following advantages: (1) High degree of quantification: For the first time, it has realized the reverse inference of the "invisible" dead zone volume and exchange flow rate through macro concentration data, and improved the evaluation of ventilation dead zone from "qualitative description" to "quantitative calculation"; (2) Good measurement accuracy: The use of multi-point spatial array monitoring combined with the average concentration algorithm avoids the problem that single-point monitoring is easily affected by local flow field fluctuations, ensuring that the data input to the dual-zone model is representative, thereby improving the confidence of the inversion results; (3) The algorithm has clear physical meaning: The double exponential model derived from the average approximation of the Navier-Stokes equation can accurately separate the two physical processes of "rapid scouring in the mainstream area" and "slow release in the dead zone", providing a direct theoretical basis for optimizing the building layout of industrial parks.
[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for quantitative detection of CO2 in dead ventilation zones of industrial parks, characterized in that, include: Physical environment construction and parameter initialization: A transparent sealed experimental chamber was set up. The obstacle model components were fixed to the bottom plate of the experimental chamber according to a preset array. A fan with variable frequency speed control function was installed on the side wall of the experimental chamber. The net free volume V of the experimental chamber was measured. total And set a constant external mechanical ventilation flow rate Q; Close the vents, inject a fixed amount of CO2 gas into the experimental chamber, then stop the injection and wait for the concentration in the experimental chamber to stabilize and reach the initial equilibrium state. The fan is turned on to perform constant flow displacement, and multiple gas concentration sensors in the space monitoring array are used to simultaneously record the concentration decrease sequence C at N different measuring points. i (t); The instantaneous spatial average concentration curve within the experimental chamber is obtained by performing arithmetic or weighted averaging on multiple data collected from various gas concentration sensors. ; The calculated average concentration curve The fit is a double exponential decay function C(t), where C(t) is a function based on the fast decay eigenvalue λ1, the slow decay eigenvalue λ2, and the fitting coefficients A and B. Based on the eigenvalue properties of the mass conservation differential equations, using Q and V total The inversion calculations using λ1 and λ2 determine the mainstream volume V1, the dead zone volume V2, and the exchange flow rate Q between the dead zone and the mainstream zone. e ; Output the dead zone volume ratio v and the exchange efficiency index q to evaluate the ventilation efficiency and pollutant retention risk under this experimental chamber layout.
2. The method for quantitative detection of CO2 in the dead ventilation zone of an industrial park as described in claim 1, characterized in that, The calculated average concentration curve The fit is a double exponential decay function C(t), including: Let the concentrations in the mainstream region and the dead region be θ1(t) and θ2(t), respectively; For the mainstream region, the inflow of fresh air is Q, the outflow concentration is θ1, and the exchange flow rate with the dead zone is Q. e via Q, Q e Calculate dθ1 / dt using θ1, θ2, and V1; For dead zones, there is no direct inflow or outflow; they only exchange with mainstream zones via Q. e Calculate dθ2 / dt using θ1 and θ2; By simultaneously solving the calculated dθ1 / dt and dθ2 / dt, the general solution is obtained. ; Through θ1(t), θ2(t), V1, V2 and V total Calculate the spatial average concentration , will general solution Substitute spatial average concentration We obtain functions of λ1, λ2, A, and B; according to With the introduced constant term C0, the double exponential decay function C(t) is calculated.
3. The method for quantitative detection of CO2 in the dead ventilation zone of an industrial park as described in claim 1, characterized in that, The output dead zone volume ratio v and the exchange efficiency index q are used to evaluate the ventilation efficiency and pollutant retention risk under this experimental chamber layout, including: Quantitatively assess the current pollutant retention level in the park's building layout, provide risk warnings, and ventilation strategies.
4. The method for quantitative detection of CO2 in the dead ventilation zone of an industrial park as described in claim 1, characterized in that, The step of injecting a quantitative amount of CO2 gas into the experimental chamber, stopping the injection, and waiting for the concentration in the experimental chamber to stabilize and reach an initial equilibrium state includes: the reading deviation of the gas concentration sensors at each monitoring point being within a preset range.
5. The method for quantitative detection of CO2 in the dead ventilation zone of an industrial park as described in claim 1, characterized in that, The use of Q, V total The inversion calculations using λ1 and λ2 determine the mainstream volume V1, the dead zone volume V2, and the exchange flow rate Q between the dead zone and the mainstream zone. e ,include: Through Q, V total Calculate the mainstream volume V1 using λ1 and λ2; Through V total Calculate the ventilation dead zone volume V2 based on the mainstream zone volume V1; Calculate the exchange flow Q between the dead zone and the mainstream zone using V1, V2, λ1, λ2, and Q. e .
6. The method for quantitative detection of CO2 in the dead ventilation zone of an industrial park as described in claim 1, characterized in that, The output dead zone volume ratio v and the exchange efficiency index q include: the volume of the ventilation dead zone V2 and the net free volume V of the experimental chamber. total Calculate the dead zone volume percentage v, and the exchange flow Q between the dead zone and the mainstream zone. e The exchange efficiency index q is calculated based on the external mechanical ventilation flow rate Q.
7. A quantitative detection system for CO2 in the ventilation dead zone of an industrial park, characterized in that, It includes a physical simulation subsystem, a multi-point spatial monitoring array subsystem, and a parameter inversion calculation module, wherein: The physical simulation subsystem is used to construct the flow field environment to be tested, including a transparent sealed experimental chamber, a model of building obstacles set on the bottom plate of the experimental chamber, and a fan unit installed on the side wall of the experimental chamber with variable frequency speed control function. The fan unit is used to provide a constant external ventilation flow rate Q. The multi-point spatial monitoring array subsystem includes multi-point gas concentration sensors arranged at different heights and horizontal positions inside the experimental chamber. The sensor positions cover the windward side, leeward side, and top recirculation area of the building obstacle model. It is used to synchronously collect the gas concentration at each characteristic point during the gas dissipation process and obtain data on the concentration change over time. The parameter inversion calculation module is connected to the multi-point gas concentration sensor monitoring array subsystem and is used to analyze data. By calculating the spatial average concentration and executing the dual-zone model algorithm, it quantifies the dead zone volume ratio v and the exchange efficiency index q.
8. The CO2 quantitative detection system for dead ventilation zones in industrial parks as described in claim 7, characterized in that, The multi-point spatial monitoring array subsystem includes at least a number of first sensors arranged on the leeward side of the upper floor of the building obstacle model, a number of second sensors arranged in the street canyon area, and a number of third sensors arranged in the return flow area at the top of the experimental chamber.
9. The CO2 quantitative detection system for dead ventilation zones in industrial parks as described in claim 7, characterized in that, The fan unit, after flow rate calibration, can output an accurate external ventilation flow rate value Q, and this value is input as a known constant into the parameter inversion calculation module.
10. The CO2 quantitative detection system for dead ventilation zones in industrial parks as described in claim 7, characterized in that, The transparent sealed experimental chamber is made of one or more chemically inert materials selected from polymethyl methacrylate, polycarbonate, or tempered glass; the obstacle model assembly has a hollow structure and all surface seams are sealed.