A method for determining cabin ventilation rate based on online equipment and sulfur hexafluoride release.

Abstract

This invention belongs to the field of in-vehicle environment testing technology, specifically relating to a method for determining the air exchange rate of a vehicle cabin based on online equipment and sulfur hexafluoride (SF6) release. This invention uses SF6 as a tracer gas. By constructing a physical model of the SF6 release process within the vehicle cabin, and combining this with the high-precision online gas monitoring device INNOVA to monitor real-time changes in SF6 concentration inside and outside the vehicle, nonlinear fitting of the data enables accurate determination of the air exchange rate in both occupied and unoccupied vehicle cabins. This invention features a simple operation process and accurate measurement results, avoiding the potential harm to human health caused by traditional CO2 tracer gas measurement methods. Furthermore, the use of online equipment improves the convenience and safety of the measurement, providing a more accurate and intuitive technical means for evaluating vehicle cabin ventilation performance. It is applicable to the measurement of air exchange rates in different types of vehicles and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of in-vehicle environment testing technology, and specifically relates to a method for measuring the cabin ventilation rate based on online equipment and sulfur hexafluoride release. Background Technology

[0002] In modern vehicle design and air quality control, the measurement of cabin air exchange rate is of great significance. Air exchange rate is a crucial parameter for measuring the air circulation capacity within a vehicle cabin, directly impacting passenger comfort and health. Therefore, cabin air quality has become a focus of public attention, and how to accurately and conveniently measure cabin air exchange rate has become an important research topic for both academia and industry.

[0003] Currently, common methods for measuring ventilation rate mainly rely on tracer gas methods, with carbon dioxide (CO2) being the most frequently used tracer gas. The principle is to release a certain amount of CO2 into the vehicle cabin and monitor changes in its concentration to calculate the ventilation rate. However, this method has a significant limitation: excessively high CO2 concentrations can have adverse effects on human health, making it unsuitable for measurement when people are in the vehicle cabin.

[0004] In contrast, sulfur hexafluoride (SF6) is harmless to humans at concentrations below 1000 ppm, making it an ideal tracer gas. Furthermore, in practical applications, using online gas monitoring equipment (such as the INNOVA acoustic-optical multi-component gas analyzer) to measure gas concentration further improves the efficiency and convenience of ventilation rate determination. INNOVA online equipment can monitor changes in gas concentration in real time and transmit the data to a display screen, making the monitoring process more convenient and intuitive.

[0005] In summary, the method for measuring the actual cabin ventilation rate based on online equipment and SF6 release is not only applicable to the measurement of ventilation rate in unmanned cabins, but also enables safe and accurate measurements when passengers are present. This invention overcomes the limitations of traditional methods and improves the accuracy and reliability of measurements, providing strong technical support for cabin air quality monitoring and passenger health protection. Summary of the Invention

[0006] A method for determining the cabin ventilation rate based on online equipment and sulfur hexafluoride release, comprising the following steps:

[0007] (1) Sulfur hexafluoride (SF6) was used as the tracer gas. The SF6 cylinder was connected to a flow controller and placed inside the vehicle compartment as the release source. Before the experiment, a physical model of the SF6 release process inside the vehicle compartment and an analytical solution for the SF6 release process were established:

[0008] C a (0) = C1(2)

[0009]

[0010] In this model: V represents the actual vehicle cabin volume, m 3 C a The concentration of SF6 inside the vehicle cabin, mg / m³ 3 Q1 represents the air exchange rate between the vehicle cabin and the environment, in meters (m). 3 / h;C in The concentration of SF6 outside the vehicle cabin, mg / m³ 3 E is the release rate of SF6 gas from the cylinder, mg / h; C in formula (2) a (0) represents the SF6 concentration in the cabin at the initial moment. In formula (3), Q1 / V represents the ventilation rate N, h -1 ;

[0011] (2) Place two high-precision online gas monitoring devices, namely INNOVA acoustic and optical multi-component gas analyzers, inside and outside the vehicle cabin respectively, and manually set the recording time of the two online devices to be the same.

[0012] (3) Simultaneously turn on the INNOVA online devices inside and outside the vehicle cabin, and monitor the changes in SF6 concentration in the environment inside and outside the vehicle in real time on the display. During the experiment, keep the doors and windows closed.

[0013] (4) Set the vehicle cabin to be manned. When the personnel in the vehicle cabin open the SF6 gas cylinder, according to the SF6 safety concentration standard, preset the release rate of the flow controller to ensure that the concentration in the vehicle cabin is always kept within a safe range during the gas release process.

[0014] (5) Observe the readings on the INNOVA displays inside and outside the vehicle. Stop the experiment after about 1 hour, close the SF6 cylinder, and export the SF6 concentration data from the two INNOVA online devices.

[0015] (6) The SF6 concentration C inside the cabin was obtained from the exported data. a (t), taking the average value of the SF6 concentration data outside the vehicle cabin as C. in Take the initial SF6 concentration value at the start of the experiment as C1, take the preset value in step (4) as the SF6 cylinder release rate E, and substitute the above parameters into formula (3).

[0016] (7) Using a genetic algorithm combined with formula (3), C a (t)-C in The experimental data that change over time are nonlinearly fitted to determine Q1, and then the Q1 / V of the actual manned vehicle cabin, i.e., the ventilation rate N, is obtained.

[0017] This invention is still applicable to the measurement of ventilation rate in unmanned vehicle cabins. SF6 gas cylinders can be connected to wireless remote-controlled electric valve switches. After the experiment begins, the experimenter remotely opens the SF6 gas cylinders from outside the cabin, and the remaining steps are the same as described above.

[0018] Features and effects of the present invention:

[0019] This invention belongs to the field of in-vehicle environment testing technology, specifically relating to a method for determining the air exchange rate of a vehicle cabin based on online equipment and sulfur hexafluoride (SF6) release. This invention uses SF6 as a tracer gas. By constructing a physical model of the SF6 release process within the vehicle cabin, and combining this with the high-precision online gas monitoring device INNOVA to monitor real-time changes in SF6 concentration inside and outside the vehicle, nonlinear fitting of the data enables accurate determination of the air exchange rate in both occupied and unoccupied vehicle cabins. This invention features a simple operation process and accurate measurement results, avoiding the potential harm to human health caused by traditional CO2 tracer gas measurement methods. Furthermore, the use of online equipment improves the convenience and safety of the measurement, providing a more accurate and intuitive technical means for evaluating vehicle cabin ventilation performance. It is applicable to the measurement of air exchange rates in different types of vehicles and has broad application prospects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the experimental system of the present invention;

[0021] Figure 2 This is a schematic diagram of the nonlinear fitting results used by the present invention to determine the actual cabin air exchange rate. Detailed Implementation

[0022] The present invention proposes a method for determining the cabin ventilation rate based on online equipment and sulfur hexafluoride release, which is described in detail below with reference to the accompanying drawings and embodiments:

[0023] The experimental system diagram of the present invention is as follows: Figure 1 As shown, actual environment 1 refers to the vehicle cabin environment, with the INNOVA online gas concentration monitoring device 3 placed both inside and outside the vehicle cabin. When personnel are present in the vehicle cabin, personnel 2 inside the cabin activate the SF6 cylinder 4 located inside the vehicle, simultaneously activating the INNOVA online device 3 both inside and outside the vehicle. After 1 hour, the experiment is stopped, the SF6 cylinder 4 is shut off, and the data from both online devices 3 are exported. The cabin ventilation rate Q1 is obtained through nonlinear fitting of the data, and thus the actual ventilation rate N of the manned vehicle cabin is obtained. When personnel are absent from the vehicle cabin, personnel 2 remotely activates the SF6 cylinder 4 inside the vehicle from outside, with the remaining steps identical to those under manned conditions.

[0024] The method for determining the cabin ventilation rate based on online equipment and sulfur hexafluoride release in this embodiment includes the following steps:

[0025] (1) Sulfur hexafluoride (SF6) was used as the tracer gas. The SF6 cylinder was connected to a flow controller and placed inside the vehicle compartment as the release source. Before the experiment, a physical model of the SF6 release process inside the vehicle compartment and an analytical solution for the SF6 release process were established:

[0026] C a (0) = C1(2)

[0027]

[0028] In this model: V represents the actual vehicle cabin volume, m 3 C a The concentration of SF6 inside the vehicle cabin, mg / m³ 3 Q1 represents the air exchange rate between the vehicle cabin and the environment, in meters (m). 3 / h;C in The concentration of SF6 outside the vehicle cabin, mg / m³ 3 E is the release rate of SF6 gas from the cylinder, mg / h; C in formula (2) a (0) represents the SF6 concentration in the cabin at the initial moment. In formula (3), Q1 / V represents the ventilation rate N, h -1 ;

[0029] (2) Place two high-precision online gas monitoring devices, namely INNOVA acoustic and optical multi-component gas analyzers, inside and outside the vehicle cabin respectively, and manually set the recording time of the two online devices to be the same.

[0030] (3) Simultaneously turn on the INNOVA online devices inside and outside the vehicle cabin, and monitor the changes in SF6 concentration in the environment inside and outside the vehicle in real time on the display. During the experiment, keep the doors and windows closed.

[0031] (4) Set the vehicle cabin to be manned. When the personnel in the vehicle cabin open the SF6 gas cylinder, according to the SF6 safety concentration standard, the release rate of the flow controller is preset to E = 1000 mg / h to ensure that the concentration in the vehicle cabin is always kept within the safe range during the gas release process.

[0032] (5) Observe the readings on the INNOVA displays inside and outside the vehicle. Stop the experiment after about 1 hour, close the SF6 cylinder, and export the SF6 concentration data from the two INNOVA online devices.

[0033] (6) The SF6 concentration C inside the cabin was obtained from the exported data. a (t), taking the average of the SF6 concentration data outside the vehicle compartment, 1.5 mg / m³. 3 As C in The initial SF6 concentration at the start of the experiment was 1.5 mg / m³. 3As C1, taking the preset value from step (4), the SF6 cylinder release rate E = 1000 mg / h and the vehicle compartment volume V = 3.7 m³ are obtained. 3 Substitute the above parameters into formula (3);

[0034] (7) Using a genetic algorithm combined with formula (3), C a (t)-C in Nonlinear fitting was performed on the experimental data that varied over time, yielding Q1 = 0.662m. 3 / h, thus obtaining Q1 / V = 0.179h for the actual manned cabin. -1 That is, the ventilation rate N = 0.179 h⁻¹ -1 .

Claims

1. A method for determining the cabin ventilation rate based on online equipment and sulfur hexafluoride release, comprising the following steps: (1) Sulfur hexafluoride (SF6) was used as the tracer gas. The SF6 cylinder was connected to a flow controller and placed inside the vehicle compartment as the release source. Before the experiment, a physical model of the SF6 release process inside the vehicle compartment and an analytical solution for the SF6 release process were established: C a (0)=C1 (2) In this model: V represents the actual vehicle cabin volume, m 3 C a The concentration of SF6 inside the vehicle cabin, mg / m³ 3 Q1 represents the air exchange rate between the vehicle cabin and the environment, in meters (m). 3 / h;C in The concentration of SF6 outside the vehicle cabin, mg / m³ 3 E is the release rate of SF6 gas from the cylinder, mg / h; C in formula (2) a (0) represents the SF6 concentration in the cabin at the initial moment. In formula (3), Q1 / V represents the ventilation rate N, h -1 ; (2) Place two high-precision online gas monitoring devices, namely INNOVA acoustic and optical multi-component gas analyzers, inside and outside the vehicle cabin respectively, and manually set the recording time of the two online devices to be the same. (3) Simultaneously turn on the INNOVA online devices inside and outside the vehicle cabin, and monitor the changes in SF6 concentration in the environment inside and outside the vehicle in real time on the display. During the experiment, keep the doors and windows closed. (4) Set the vehicle cabin to be manned. When the personnel in the vehicle cabin open the SF6 gas cylinder, according to the SF6 safety concentration standard, preset the release rate of the flow controller to ensure that the concentration in the vehicle cabin is always kept within a safe range during the gas release process. (5) Observe the readings on the INNOVA displays inside and outside the vehicle. Stop the experiment after about 1 hour, close the SF6 cylinder, and export the SF6 concentration data from the two INNOVA online devices. (6) The SF6 concentration C inside the cabin was obtained from the exported data. a (t), taking the average value of the SF6 concentration data outside the vehicle cabin as C. in Take the initial SF6 concentration value at the start of the experiment as C1, take the preset value in step (4) as the SF6 cylinder release rate E, and substitute the above parameters into formula (3). (7) Using a genetic algorithm combined with formula (3), C a (t)-C in The experimental data that change over time are nonlinearly fitted to determine Q1, and then the Q1 / V of the actual manned vehicle cabin, i.e., the air exchange rate N, is obtained. The method is still applicable to the determination of ventilation rate in unmanned vehicle cabins. SF6 gas cylinders can be connected to wireless remote-controlled electric valve switches. After the experiment starts, the experimenters remotely open the SF6 gas cylinders from outside the cabin. The remaining steps are the same as described above.

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