CN108106887A - Motor-vehicle tail-gas particulate matter and volatile organic contaminant divided working status sampling system - Google Patents

Abstract

In order to solve the technical problem that the existing time-segmented off-line sampling method cannot reflect the emission characteristics of the vehicle under various working conditions, the present invention provides a vehicle exhaust particulate matter and volatile organic pollutant component that can be used for actual road vehicle testing. Working condition sampling system. The invention sets a plurality of parallel sampling channels, and utilizes a sampling controller for different working conditions to control the opening and closing of the sampling channels according to the transient vehicle speed/exhaust gas flow, thereby realizing synchronous sampling of volatile organic compounds, particulate matter and semi-volatile organic compounds in different working conditions , the sampling results can well reflect the emission characteristics of vehicles under different working conditions. The invention has a wide application range, and can flexibly set the number of corresponding acquisition channels and the vehicle speed/flow range of each channel to meet different test requirements.

Description

Sampling system for motor vehicle exhaust particulate matter and volatile organic pollutants under different working conditions

technical field

The invention belongs to the technical field of environmental monitoring instruments, and relates to a sampling system for motor vehicle tail gas particles and volatile organic pollutants in different working conditions.

Background technique

With the increase of the number of motor vehicles in recent years, motor vehicle emissions have gradually become the main source of air pollution. The pollutants emitted by motor vehicles contain a large amount of solid and gaseous organic compounds (such as polycyclic aromatic hydrocarbons, etc.), which seriously endanger human health. In order to better control motor vehicle emissions, a lot of testing and research work needs to be carried out. Traditionally, motor vehicles (or engines) have been primarily simulated on laboratory benches. The current emission standards only require laboratory bench tests to carry out time-segmented off-line sampling of motor vehicle exhaust particulate matter (PM), but there is no measurement requirement for volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). In addition, although the laboratory bench test is easy to control the test conditions and the repeatability of the test results is good, but due to the complex and changeable actual road conditions of motor vehicles, there may be a significant increase in emissions during actual use, so the laboratory bench Rack testing cannot reflect the true level of vehicle emissions on actual roads.

Therefore, the actual road vehicle test has gradually become one of the mainstream methods of motor vehicle emission testing. There have been a large number of researches on the vehicle-mounted method to measure the emission characteristics of gaseous pollutants on the actual road in the world. However, the sampling and measurement of organic matter in different phases such as PM, SVOCs, and VOCs is still a difficult point in the research on vehicle emissions testing, because the existing off-line sampling methods in different time periods cannot accurately reflect the emission characteristics of vehicles under various operating conditions. .

Contents of the invention

In order to solve the technical problem that the existing time-segmented off-line sampling method cannot reflect the emission characteristics of the vehicle under various working conditions, the present invention provides a vehicle exhaust particulate matter and volatile organic pollutant component that can be used for actual road vehicle testing. Working condition sampling system.

Technical solution of the present invention is:

Motor vehicle exhaust particulate matter and volatile organic pollutants sampling system by working condition, including a control host; its special feature is that it also includes an off-line sampler for VOCs by working condition, PM and SVOCs by working condition, all connected to the control host Offline sampler;

The VOCs off-line sampler for different working conditions includes a first sampling controller for different working conditions and a plurality of VOCs sampling channels set in parallel;

The sampling controller according to the first working condition is used to obtain the instantaneous vehicle speed/exhaust gas flow, and control the opening and closing of the VOCs sampling channel according to the obtained information;

The inlet end of each VOCs sampling channel is connected with the tail gas dilution system at the front end of the sampling system through the sampling controller of the first sub-working condition, and the outlet end of each VOCs sampling channel is connected with a VOCs vacuum sampling tank; Each is also provided with a flow control valve connected to the control host;

The off-line sampler for PM and SVOCs in different working conditions includes a particle pre-classifier, a second sampling controller in different working conditions, and a plurality of PM and SVOCs sampling channels set in parallel;

The second sampling controller according to working conditions is used to obtain the instantaneous vehicle speed/exhaust gas flow, and control the opening and closing of the PM and SVOCs sampling channels according to the obtained information;

The inlet port of each PM and SVOCs sampling channel is communicated with the outlet port of the particulate matter pre-classifier through the second sub-condition sampling controller, and the inlet port of the particulate matter pre-classifier is communicated with the tail gas dilution system at the front end of the sampling system, all A vacuum pump is provided at the outlet of the PM and SVOCs sampling channels, or the outlets of all the PM and SVOCs sampling channels converge in the same pipeline, and a vacuum pump is provided on the pipeline; the vacuum pump is connected to the control host;

Each PM and SVOCs sampling channel is also provided with a PM and SVOCs sampling unit and a flow controller connected to the control host, and is located between the particulate matter pre-classifier and the vacuum pump;

Both the first sampling controller for working conditions and the second sampling controller for working conditions are connected to the control host.

Further, each PM and SVOCs sampling channel is also provided with a pressure sensor connected to the control host.

Further, all PM and SVOCs sampling units are arranged in a temperature control box; the temperature control box is connected with the control host.

Further, the sampling pipeline of the VOCs sampling channel adopts a polytetrafluoroethylene tube.

Further, the sampling pipelines of the PM and SVOCs sampling channels adopt carbon fiber tubes.

Further, the particle size of the particle pre-classifier is 2.5 μm.

Further, there are three VOCs sampling channels, corresponding to the three vehicle speed segments of low speed, medium speed, and high speed, respectively, or respectively corresponding to the three exhaust gas flow segments of low, medium, and high speeds; there are three sampling channels for PM and SVOCs, respectively corresponding to low speed , medium speed, and high speed, or correspond to low, medium, and high exhaust gas flow sections respectively.

Further, the PM and SVOCs sampling unit includes a filter holder equipped with a particle sampling filter membrane and a SVOCs filter cartridge equipped with PUF arranged in sequence along the airflow direction.

Further, the control host has a human-computer interaction function.

The present invention has following beneficial effects:

The invention realizes the synchronous sampling of volatile organic compounds (VOCs), particulate matter (PM) and semi-volatile organic compounds (SVOCs) in motor vehicle exhaust, and the sampling results can well reflect the emissions of vehicles under different working conditions feature.

The invention has a wide application range, and can flexibly set the number of corresponding acquisition channels and the vehicle speed/flow range of each channel to meet different test requirements.

Description of drawings

Fig. 1 is a schematic diagram of an embodiment of the present invention.

Explanation of reference signs:

1-VOCs off-line sampler for different working conditions, 11-VOCs vacuum sampling tank, 12-flow control valve, 13-sampling pipeline, 14-sampling controller for the first working condition;

2-PM and SVOCs off-line sampler in different working conditions, 21-vacuum air pump, 22-flow controller, 23-sampling pipeline, 24-pressure sensor, 25-PM and SVOCs sampling unit, 251-membrane bracket, 252 -SVOCs filter cartridge, 26-temperature control box, 27-sampling controller for the second working condition, 28-particle pre-classifier;

3-auxiliary equipment, 4-control host.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

Referring to Fig. 1, the sampling system of motor vehicle exhaust particulate matter and volatile organic pollutants in this embodiment includes a control host 4, and a VOCs off-line sampler 1 connected to the control host 4, a PM and SVOCs offline sampler 2;

The off-line VOCs sampler 1 according to working conditions includes a first working condition sampling controller 14 connected to the control host 4 and three VOCs sampling channels arranged in parallel; the three VOCs sampling channels correspond to three vehicle speeds of low speed, medium speed and high speed respectively section, or respectively corresponding to low, medium, and high exhaust gas flow sections; in other embodiments, there may also be more than three VOCs sampling channels, and the corresponding vehicle speed section/exhaust flow section can be subdivided according to actual sampling requirements; PTFE tube can withstand positive pressure of 1.6Mpa, negative pressure of 77Kpa, high temperature resistance, low temperature resistance (can be used normally within -60℃～+260℃), has excellent chemical stability, reliable and excellent corrosion resistance (For most chemicals and solvents, it shows inertness, strong acid and alkali resistance, water and various organic solvents), so the material of the sampling pipeline 13 of the VOCs sampling channel in this embodiment is polytetrafluoroethylene;

The first working condition sampling controller 14 is used to obtain the instantaneous vehicle speed/exhaust gas flow from the auxiliary equipment 3, and control the opening and closing of the three VOCs sampling channels according to the obtained information; the inlet port of each VOCs sampling channel passes through the first The sampling controller of a working condition is communicated with the outlet port of the tail gas dilution system located at the front end of the sampling system, and the outlet port of each VOCs sampling channel is connected with a VOCs vacuum sampling tank 11; the tank environment of the VOCs vacuum sampling tank 11 is relative to the environment The air pressure is negative pressure, which can provide sampling power; each VOCs sampling channel is also provided with a flow control valve 12 connected to the control host 4 for adjusting the sampling flow; each flow control valve 12 is equipped with a pressure gauge , the pressure gauge is communicated with the sampling pipeline 13 of the VOCs sampling channel; when the VOCs vacuum sampling tank 11 is opened, the airtightness of the VOCs sampling channel sampling pipeline can be checked by changing the pressure indication number;

Auxiliary equipment 3 can be satellite navigation positioning system, can provide real-time vehicle speed for the sampling controller 14 of the first sub-working condition; It can also be an automobile ECU data reading device, can provide real-time vehicle speed/ Exhaust gas flow; it can also be an existing portable vehicle test system on the market, which can provide real-time vehicle speed/exhaust gas flow for the sampling controller 14 of the first sub-working condition;

During work, the tail gas diluted by the tail gas dilution system (not a part of the present invention, which is an existing instrument, because the concentration of motor vehicle tail gas pollutants is higher, so it needs to be diluted in equal proportions before sampling), is off-line from the VOCs in different working conditions The air inlet of the sampler enters three VOCs sampling channels, and the VOCs in the exhaust gas are collected by the corresponding VOCs vacuum sampling tank 11, realizing simultaneous collection of three vehicle speed/exhaust gas flow sections.

The PM and SVOCs off-line sampler 2 of sub-working conditions includes a particulate matter pre-classifier 28, a sampling controller 27 connected to the second sub-working mode of the control host 4, and three PM and SVOCs sampling channels set in parallel; in the present embodiment, the particulate matter The split particle size of the pre-classifier 28 is 2.5 μm, which can make at least 99% (mass concentration) of particles with a particle size of 1 μm enter and pass through its outlet; the three PM and SVOCs sampling channels correspond to three low-speed, medium-speed and high-speed respectively. Vehicle speed section, or corresponding to low, medium and high exhaust gas flow sections respectively. In other embodiments, there can also be more than three PM and SVOCs sampling channels, and the corresponding vehicle speed sections/exhaust gas flow sections can be subdivided according to actual sampling requirements; due to the high strength, corrosion resistance, fatigue resistance and creep resistance of carbon fiber tube Variable, has the advantages of electrical conductivity (antistatic adsorption), small thermal expansion coefficient, energy absorption and shock resistance, the material of the sampling pipeline 23 of the PM and SVOCs sampling channels in this embodiment is selected from carbon fiber tubes; wherein, the conductivity of the carbon fiber tubes can prevent particulate matter Electrostatic adsorption occurs during transport in the sampling line;

The second sub-working condition sampling controller 27 is used to obtain the instantaneous vehicle speed/exhaust gas flow from the auxiliary equipment 3, and control the opening and closing of the PM and SVOCs sampling channels according to the obtained information; the inlet ports of each PM and SVOCs sampling channels are The sampling controller of the second working condition is communicated with the outlet end of the particulate matter pre-classifier 28, and the inlet end of the particulate matter pre-classifier 28 is communicated with the outlet end of the tail gas dilution system located at the front end of the present invention, and all PM and SVOCs sampling channel outlets converge In the same pipeline, the pipeline is provided with a vacuum pump 21 connected to the control host 4, and the vacuum pump 21 is used to provide sampling power; each PM and SVOCs sampling channel is also provided with a PM and SVOCs sampling unit 25 and connected with the control host 4 connected flow controllers 22 for adjusting the size of the sampling flow, the PM and SVOCs sampling unit 25 and the flow controller 22 are located between the particle pre-classifier 28 and the vacuum pump 21; the second sub-mode sampling controller 27 and control The host 4 is connected;

Auxiliary equipment 3 can be satellite navigation positioning system, can provide real-time vehicle speed for the sampling controller 27 of the second working condition; It can also be an automobile ECU data reading device, can provide real-time vehicle speed/ Exhaust gas flow; it can also be an existing portable vehicle test system on the market, which can provide real-time vehicle speed/exhaust flow for the second sub-working condition sampling controller 27; the first sub-working condition sampling controller 14 and the second sub-working condition sampling The controller 27 can also share a set of auxiliary equipment 3 .

The PM and SVOCs sampling unit 25 includes a filter holder 251 equipped with a particle sampling filter membrane and a SVOCs filter cartridge 252 equipped with a PUF arranged in sequence along the airflow direction;

Considering that gas and solid phase SVOCs will change the phase distribution of SVOCs as the temperature changes (for example, gas phase SVOCs transforms into solid phase SOVCs), therefore, this embodiment will divide the three sampling channels of PM and SVOCs off-line samplers under working conditions The PM and SVOCs sampling units 25 are all arranged in the temperature control box 26 connected to the control host 4, and the temperature in the SVOCs collection unit is kept constant within a certain range by the temperature control box 26, so as to prevent the SVOCs from increasing with the temperature after sampling. changes to change the phase distribution of SVOCs. In addition, the influence of different sampling temperatures on the sampling results of SVOCs can also be studied by changing the temperature in the temperature control box 26 .

In order to realize the leak detection function of the sampling system and prevent the loss of sample gas, the present embodiment is also provided with a pressure sensor 24 connected to the control host 4 on each PM and SVOCs sampling channel; before sampling, the sampling pipeline gas can be checked first. Tightness.

When working, the vacuum air pump 21 draws the tail gas at a constant flow rate, and the tail gas enters the three PM and SVOCs sampling channels from the air inlet of the PM and SVOCs off-line sampler 2 under different working conditions, and the PM in the tail gas smaller than 2.5 μm is passed by the particle pre-classifier 28 It is separated from the exhaust gas and trapped on a particle sampling filter membrane of known quality, while SVOCs are collected by the SVOCs filter cartridge 252 equipped with PUF, thereby realizing simultaneous sampling of PM particles and SVOCs in three vehicle speed/exhaust gas flow sections.

In addition, the control host 4 of this embodiment has a touch display screen, and is loaded with sampling control software, and has a human-computer interaction function, and can input sampling instructions through the touch display screen on it, such as sampling timing, delayed sampling, timing sampling, query Sampling data, etc.; the sampling sequence, trigger parameters, etc. can also be set through the control host to realize sampling control by working conditions.

Claims (9)

1. motor-vehicle tail-gas particulate matter and volatile organic contaminant divided working status sampling system, including control host (4)；Its feature It is：Further include it is equal with it is described control host (4) be connected the offline sampling instruments of divided working status VOCs (1), divided working status PM and SVOCs from Line sampling instrument (2)；

The offline sampling instruments of divided working status VOCs (1) include the first divided working status sampling controller (14) and multiple parallel arrangement of VOCs sampling channels；

The first divided working status sampling controller (14) is for obtaining transient state speed/exhaust flow, according to acquired information control Make the keying of the VOCs sampling channels；

The arrival end of each VOCs sampling channels passes through the first divided working status sampling controller (14) and the tail of sampling system front end Gas dilution system connects, and the port of export of each VOCs sampling channels is respectively connected with VOCs vacuum sample can (11)；Each VOCs is adopted The flow control valve (12) being connected with the control host (4) is both provided on sample passage；

The offline sampling instruments of divided working status PM and SVOCs (2) include the pre- clasfficiator of particulate matter (28), the second divided working status controlling of sampling Device (27) and multiple parallel arrangement of PM and SVOCs sampling channels；

The second divided working status sampling controller (27) is for obtaining transient state speed/exhaust flow, according to acquired information control Make the keying of the PM and SVOCs sampling channels；

The arrival end of each PM and SVOCs sampling channels is pre- by the second divided working status sampling controller (27) and the particulate matter The port of export connection of clasfficiator (28), the arrival end of the pre- clasfficiator of particulate matter (28) and the tail gas dilution system of sampling system front end Connection, all PM and SVOCs sampling channels exits are both provided with vacuum air pump (21) or all PM and SVOCs samplings are logical Road outlet converges at same pipeline, and vacuum air pump (21) is provided on the pipeline；The vacuum air pump (21) and the control Host (4) is connected；

PM and SVOCs sampling units (25) are additionally provided on each PM and SVOCs sampling channels and control host (4) with described Connected flow controller (22), and between the pre- clasfficiator of the particulate matter (28) and vacuum air pump (21)；

The first divided working status sampling controller (14) and the second divided working status sampling controller (27) control host (4) with described It is connected.

2. motor-vehicle tail-gas particulate matter according to claim 1 and volatile organic contaminant divided working status sampling system, It is characterized in that：The pressure sensor being connected with the control host (4) is additionally provided on each PM and SVOCs sampling channels (24)。

3. motor-vehicle tail-gas particulate matter according to claim 2 and volatile organic contaminant divided working status sampling system, It is characterized in that：All PM and SVOCs sampling units (25) are all disposed in temperature control box (26)；The temperature control box (26) and the control Host (4) processed is connected.

4. motor-vehicle tail-gas particulate matter according to claim 3 and volatile organic contaminant divided working status sampling system, It is characterized in that：The sample lines (13) of the VOCs sampling channels use polyfluortetraethylene pipe.

5. motor-vehicle tail-gas particulate matter according to claim 4 and volatile organic contaminant divided working status sampling system, It is characterized in that：The sample lines (23) of the PM and SVOCs sampling channels use carbon fiber pipe.

6. motor-vehicle tail-gas particulate matter according to claim 5 and volatile organic contaminant divided working status sampling system, It is characterized in that：The cut diameter of the pre- clasfficiator of particulate matter (28) is 2.5 μm.

7. according to any motor-vehicle tail-gas particulate matters of claim 1-6 and volatile organic contaminant divided working status sampling system System, it is characterised in that：There are three the VOCs sampling channels, corresponds to low speed, at a high speed middling speed, three speed sections, Huo Zhefen respectively Basic, normal, high three exhaust flow sections are not corresponded to；

There are three PM the and SVOCs sampling channels, corresponds to three low speed, middling speed, high speed speed sections respectively or corresponds to respectively Basic, normal, high three exhaust flow sections.

8. according to any motor-vehicle tail-gas particulate matters of claim 1-6 and volatile organic contaminant divided working status sampling system System, it is characterised in that：PM the and SVOCs sampling units (25) include particle sampling is housed along what airflow direction was set gradually The filter membrane bracket (251) of filter membrane and the SVOCs filter core cylinders (252) equipped with PUF.

9. motor-vehicle tail-gas particulate matter according to claim 1 and volatile organic contaminant divided working status sampling system, It is characterized in that：The control host (4) has human-computer interaction function.