JP5489324B2 - Particle counting system - Google Patents

Description

  The present invention relates to a particle number measurement system for measuring the number of solid particles such as PM contained in engine exhaust gas, and more particularly to a diluter used in the particle number measurement system.

  As a method for measuring particulate matter (PM), which is one of exhaust substances from the engine, a filter mass method is known in which PM is collected using a filter and the PM mass is measured. By the way, the amount of PM emission is very small, and the filter weight method has become severe in terms of accuracy. Under such circumstances, a method developed as an alternative to the filter weight method is a method for measuring the number of PM in exhaust gas. As a specific system configuration, for example, a dilution unit for diluting the exhaust gas of the engine with air or the like is provided in the front stage of the particle number measuring device, and a part of the diluted exhaust gas is led to the particle number measuring device. In addition, there is known one that counts the number of particles contained therein (see Patent Document 1).

  Conventionally, in such a system, as shown in Patent Document 2, a dilution unit is provided with a diluter (mixing unit) provided at a connection point between a main flow path through which exhaust gas flows and a dilution gas flow path through which dilution gas flows or in the vicinity thereof. ), A flow rate measuring mechanism for measuring the mass flow rate of the exhaust gas introduced into the diluter, a dilution gas flow control unit for controlling the mass flow rate of the dilution gas introduced into the diluter, and the exhaust gas An exhaust gas flow rate control unit that varies the mass flow rate of the exhaust gas. The flow rate of the exhaust gas flowing into the dilution unit is measured by the flow rate measuring mechanism and controlled by the exhaust gas flow rate control unit to realize a desired dilution ratio.

  The mixer is provided with a pipe having a predetermined length so that the exhaust gas and the dilution gas mixed at the connection point are sufficiently mixed from the connection point between the main flow path and the dilution gas flow path. It is composed by. As the piping constituting the diluter, a straight pipe or a spiral pipe is used.

  However, in order to uniformly mix the exhaust gas and the dilution gas using such a diluter, there is a problem that a sufficient pipe length is required and the particle number measuring system becomes large.

  Further, in the conventional particle number measuring system, the flow path direction is changed by curving the pipe constituting the main flow path, but the exhaust gas containing solid particles flows in the pipe. In the pipe bending portion, particle loss occurs. As a result, there is a problem that it is difficult to accurately measure solid particles contained in the exhaust gas. Here, it is possible to suppress the particle loss by determining the bending radius of the piping based on the flow velocity range of the exhaust gas flowing in the piping, but it is difficult to reduce the volume occupied by the piping, and the system size is It must be large.

  Furthermore, in the particle number measuring system, an evaporator for vaporizing volatile particles contained in the exhaust gas is provided, and a diluter is provided between the evaporator and the particle number measuring device. In this configuration, the pipe constituting the diluter has a straight tube shape or a spiral shape as described above, and when the diluter, the evaporator, and the particle number measuring device are connected, the pipe becomes complicated, and the entire system There is also a problem that it becomes a complicated structure.

JP 2006-194726 A JP 2008-164446 A

  Therefore, the present invention was made to solve the above problems all at once, enabling the flow direction of the pipe to be changed while making the structure of the pipe constituting the main flow path compact in the particle number measurement system, Further, it is a main intended problem to prevent a complicated structure as a whole system and to make it possible to sufficiently mix exhaust gas and dilution gas.

That is, the particle number measurement system according to the present invention includes a main flow path having one end connected to an exhaust gas introduction port for introducing engine exhaust gas, and one end connected to the dilution gas introduction port for introducing dilution gas. Is connected to the main flow path, is provided in the main flow path, is an evaporator that vaporizes volatile particles in the exhaust gas, is provided downstream of the evaporator, the evaporator A downstream diluter that dilutes the exhaust gas by mixing the exhaust gas that has passed through, a particle number measuring device that measures the number of solid particles in the exhaust gas diluted by the downstream diluter, and wherein the diluted exhaust gas, the provided from the downstream side diluter configured to flow without being heated to the particle counting device, the downstream diluter is, toward the other end from one end A body having an inner space in the shape of a rotating body that has a diameter, and an introduction pipe that is provided along or perpendicular to the central axis of the internal space and introduces exhaust gas and dilution gas into the internal space; A discharge pipe having a straight pipe shape that is provided perpendicular to the introduction pipe and that discharges the exhaust gas diluted by the swirling flow generated in the internal space to the outside of the internal space, and the body includes A central axis of the internal space is provided so as to be substantially horizontal, the introduction pipe is connected to the evaporator, and the outlet pipe is connected to the particle number measuring device.

  In such a case, the downstream diluter has an introduction pipe and a lead-out pipe orthogonal to each other, and the lead-out pipe leads the exhaust gas diluted by the swirling flow in the internal space of the body. Since the exhaust gas and dilution gas can be mixed thoroughly and the flow direction can be changed by the side diluter, the volume occupied by the pipe due to the bending radius based on the flow velocity can be eliminated as in the past, and it is compact. The flow path direction can be converted to In particular, in the downstream diluter, since the central axis of the internal space is provided so as to be substantially horizontal, the particles from the downstream diluter to the particle number measuring device are in a straight pipe shape, and the particles in the pipe The diluted exhaust gas can be sent to the particle number measuring device without causing accumulation or the like. Moreover, it is possible to prevent the system as a whole from being complicated due to the structure in which the downstream diluter is not installed on the lower side in the vertical direction of the particle number measuring apparatus having a large capacity and weight. Furthermore, the downstream side diluter and its downstream are considered to be at room temperature without having a structure for heating the exhaust gas and the piping, so the temperature falls and particles may adhere to the piping, but the piping can be shortened, It is possible to prevent particles from adhering to the pipe. In addition, by making the exhaust gas and the dilution gas into the swirl flow in the internal space, the flow path in which the exhaust gas and the dilution gas are mixed can be made longer, and further, the swirl flow leads from the other end to the one end. Since the exhaust gas and the dilution gas that have flowed back are led out to the outside from the outlet, the exhaust gas and the dilution gas can be sufficiently mixed without lengthening the piping.

  In order to suppress the particle loss in the pipes by forming the inlet and outlet pipes of the downstream side diluter into straight pipes, the inlet pipe connecting part in the evaporator and the outlet pipe in the particle number measuring device are used. It is desirable that the connecting portion is arranged orthogonally.

  In order to more compactly configure the particle number measuring system as a whole, an upstream side diluter is provided on the upstream side of the evaporator, and dilutes the exhaust gas by mixing it with the exhaust gas introduced inside. The upstream diluter has a rotating body-shaped internal space whose diameter decreases from one end to the other end, and is orthogonal to or along the central axis of the internal space. An introduction pipe that introduces exhaust gas and dilution gas into the internal space, and an exhaust pipe that is provided orthogonal to the introduction pipe and diluted by a swirling flow generated in the internal space. A lead-out pipe that leads out, and the upstream diluter is heated and the downstream diluter is cooled, and a heater is attached to the outer wall of the body in the upstream diluter It is desirable to mount plane is formed.

  In addition, in the upstream diluter that is the previous stage, the exhaust gas may contain foreign substances other than the measurement target substance or solid particles larger than a predetermined particle diameter, and in order to suitably remove the foreign substances and large particles In the upstream diluter, the inner space has a rotating body shape whose diameter gradually decreases as it goes vertically downward, and it is desirable that a dust collecting portion is provided below the inner space. At this time, the upstream diluter is preferably provided with a function of removing foreign matters and solid particles larger than the size of the measurement target substance.

  According to the present invention configured as described above, it is possible to change the direction of the flow path of the pipe while making the configuration of the pipe constituting the main flow path compact in the particle number measurement system, and to make the entire system a complicated structure. This can prevent the exhaust gas and the dilution gas from being sufficiently mixed.

1 is an overall configuration diagram of a particle number measurement system according to an embodiment of the present invention. It is an information transmission figure which shows the flow of the information in the embodiment. It is a perspective view of the 1st diluter of the embodiment. It is a perspective view of the 2nd diluter of the embodiment. It is a longitudinal cross-sectional view along the central axis of the interior space of the diluter of the embodiment. It is a longitudinal cross-sectional view along the central axis of the inlet tube of the diluter of the embodiment. It is a cross-sectional view along the central axis of the introduction pipe of the diluter of the same embodiment. It is a perspective view which shows typically arrangement | positioning of the 1st diluter of the same embodiment, a 2nd diluter, an evaporator, and a particle number measuring device.

  Hereinafter, an embodiment of a particle number measurement system according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the particle number measuring system 100 according to the present embodiment guides engine exhaust gas from an exhaust gas introduction port PT1 to a main flow path ML provided therein, and performs dilution, vaporization, and the like. Thereafter, PM, which is a solid particle in the exhaust gas, is measured by the particle number measuring device 2 provided in the main channel ML.

  The exhaust gas introduction port PT1 is connected to an exhaust line from an engine (not shown). The exhaust gas introduction port PT1 is diluted with, for example, a direct exhaust gas from the engine or a full-flow dilution tunnel or a diversion dilution tunnel. The exhaust gas is guided. In the following description, the exhaust gas is used to include the diluted exhaust gas as described above.

  Part of the exhaust gas introduced into the interior from the exhaust gas introduction port PT1 via the opening / closing valve V1 is exhausted from the first bypass passage BL1, and the remainder is a plurality of stages provided in series (2 in this embodiment). Stage) diluters PND1 and PND2, and are diluted by air as a dilution gas.

  Note that air is supplied from the dilution gas introduction port PT2 to the various locations of the main flow path ML or the second bypass flow path BL2 via the regulator REG and the plurality of dilution gas flow paths DL1 to DL3.

  The first bypass flow path BL1 merges with the main flow path ML downstream of the particle number measuring apparatus 2 described later, and maintains a constant flow rate through the opening / closing valve V2 and the bypass flow path BL1, etc. Constant flow device CFO1 is provided in this order.

  Furthermore, the main channel ML and the bypass channel BL1 are arranged downstream of the junction of the main channel ML and the bypass channel (including the first bypass channel BL1 and other bypass channels BL2 and BL3 described later). A suction pump P is connected for introducing exhaust gas under a negative pressure of BL3. A buffer chamber VC for smoothing fluctuations in the suction force of the suction pump P is provided in the vicinity of the upstream side of the suction pump P.

  The first diluter (upstream diluter) PND1 is provided at or near the downstream of the connection point between the main flow path ML and the dilution gas flow path DL, and heats the exhaust gas introduced into the first diluter PND1. In addition, the exhaust gas is diluted.

  The exhaust gas that is the gas to be diluted introduced into the first diluter PND1 is measured by the flow rate measuring mechanism 3 provided upstream of the first diluter PND1, more specifically, upstream of the connection point. ing.

  The flow rate measuring mechanism 3 adjusts the temperature of the fluid, the orifice part 31 that becomes a fluid resistance, the pressure sensor 32 that measures the differential pressure of the orifice part 31, the pressure sensor 33 that measures the absolute pressure on the upstream side, and the fluid temperature. The temperature controller 34 is provided, and based on the pressure information on the upstream and downstream of the orifice portion 31 and the temperature information from the temperature controller 34, the information processing device 4 (see FIG. 2 in particular) provided separately performs the first dilution. The mass flow rate of the exhaust gas introduced into the container PND1 can be calculated. The information processing apparatus 4 includes a CPU, a memory, an input unit, a display, and the like, and is a general-purpose or dedicated so-called computer in which the CPU and peripheral devices operate in cooperation according to a predetermined program stored in the memory.

  Further, the mass flow rate of the dilution gas introduced into the first diluter PND1 is controlled by the dilution gas flow rate control unit MFC1 provided on the dilution gas flow path DL1. When the dilution gas flow rate control unit MFC1 is provided with the target flow rate data from the information processing device 4, the actual flow rate measured by a flow sensor (not shown) provided therein is the value of the target flow rate data (hereinafter referred to as target flow rate data). The flow rate is controlled locally by adjusting an internal valve (not shown) so that the flow rate is also referred to. This target flow rate is calculated from the dilution ratio by the information processing device 4.

  Further, an evaporator EU for vaporizing volatile particles is provided downstream of the first diluter PND1. Further, a second bypass channel BL2 that branches from between the first diluter PND1 and the evaporator EU and joins the main channel ML downstream of the particle number measuring device 2 is provided. A dilution gas flow path DL2 provided with a dilution gas flow rate control unit MFC2 is connected to the bypass flow path BL2. Further, the bypass flow path BL2 is provided with a constant flow rate device CFO2 such as a critical orifice for keeping the flow rate flowing through the open / close valve V3 and the bypass flow path BL2 in this order. With such a configuration, the dilution gas flow rate control unit MFC2 is controlled by the information processing device 4, whereby the dilution gas flowing into the bypass flow path BL2 is adjusted, and as a result, the main flow path ML changes to the bypass flow path BL2. Adjust the mass flow rate of the incoming exhaust gas.

  The second diluter (downstream diluter) PND2 is provided at or near the connection point between the main flow path ML and the dilution gas flow path DL3, and cools the exhaust gas introduced into the second diluter PND2. In addition, the exhaust gas is diluted.

  The dilution gas introduced into the second diluter PND2 has its mass flow rate controlled by a dilution gas flow rate control unit MFC3 provided in the dilution gas flow path DL3. The dilution gas flow rate control unit MFC3, like the dilution gas flow rate control unit MFC1, receives the target flow rate data from the information processing device 4, and is measured by a flow sensor (not shown) provided therein. However, the flow rate is controlled locally by adjusting an internal valve (not shown) so that the value of the target flow rate data (hereinafter also referred to as a target flow rate) is obtained. This target flow rate is calculated from the dilution ratio by the information processing device 4.

  In such a configuration, the pipe from the first diluter PND1 and the vicinity thereof to the second diluter PND2 is heated to, for example, 150 degrees or more by a temperature controller having a heating unit such as a heater (not shown). This prevents PM from adhering or agglomerating on the inner wall of the pipe, thereby suppressing counting errors.

  Further, downstream of the second diluter PND2, a particle number measuring device 2 for measuring the number of solid particles in the exhaust gas diluted by the first diluter PND1 and the second diluter PND2 is provided via an open / close valve V5. It has been. Further, a third bypass flow path BL3 that branches from the second diluter PND2 and the particle number measuring device 2, specifically, from the upstream side of the open / close valve V5 and merges with the main flow path ML downstream of the particle number measuring device 2. Is provided. The bypass channel BL3 is provided with a constant flow device CFO3 such as a critical orifice and an on-off valve V4 in this order, which keep the flow rate flowing through the bypass channel BL3 constant. An open air passage AL having an open / close valve V6 and a filter in this order is formed between the open / close valve V5 and the particle number measuring device 2, and the open / close valve V5 is closed when the suction pump P is stopped. When opened, the open / close valve V6 is opened to open the particle number measuring device 2 to the atmosphere.

  The particle number measuring apparatus 2 mixes organic gas such as alcohol or butanol in a supersaturated state and adheres to the PM in the exhaust gas, thereby growing the PM to a large diameter, and discharging the grown PM from the slit. The particles that come out are counted with a laser beam. Since this particle number measuring device 2 is configured to discharge the grown PM from the slit, the slit has a function as a constant flow device, and the particle measuring device 2 has an exhaust gas at a constant flow rate. Will flow.

  With such a configuration, part of the exhaust gas diluted by the two-stage diluters PND1 and PND2 is guided to the particle number measuring device 2, and the number of solid particles contained in the exhaust gas is counted. Then, the count data measured by the particle number measuring device 2 is output to the information processing device 4 and appropriately processed.

  Therefore, the first diluter PND1 and the second diluter PND2 of the present embodiment include a body 5 having an internal space S into which exhaust gas and dilution gas are introduced, as shown in FIGS. 5 is provided with an introduction pipe 6 for introducing exhaust gas and dilution gas into the internal space S, and a lead-out pipe 7 for leading out exhaust gas diluted from the internal space S. 3 shows the first diluter PND1, FIG. 4 shows the second diluter PND2, and the configurations of the first diluter PND1 and the second diluter PND2 are the same except for the outlet pipe 7.

  As shown in FIG. 5, the body 5 has a rotating body-shaped internal space S having a tapered portion that gradually decreases in diameter from one end to the other end. Specifically, the internal space S includes a cylindrical space portion S1 and a conical space portion S2. The other end portion of the internal space S is provided with a dust collection portion 8 for collecting dust contained in the exhaust gas introduced into the internal space S so as to communicate with the internal space S. .

  Further, on the outer wall of the body 5, there is formed a mounting plane 5A for mounting a heater for heating the exhaust gas introduced into the internal space S when used in the first diluter PND1.

  The introduction pipe 6 dilutes the exhaust gas and the dilution gas into the internal space S so that the exhaust gas and the dilution gas flow downward (on the other end side) along the inner peripheral wall of the body 5. It introduces from the cylindrical part. Specifically, as shown in FIG. 6, the introduction pipe 6 is orthogonal to the central axis C of the internal space S in the cylindrical space S <b> 1 above the tapered portion (conical space S <b> 2) in the internal space S. Further, as shown in FIG. 7, the inflow direction of the exhaust gas and the dilution gas is provided at a position that is tangential to the cylindrical wall 501 that is the inner peripheral wall of the body 5. The exhaust gas and the dilution gas that flowed in from the introduction pipe 6 change from a linear flow to a vortex flow in the cylindrical space portion S1, descend while rotating along the cylindrical wall 501 (toward the other end), and enter the conical space portion S2. When it reaches, it further descends (toward the other end) while increasing the rotation speed, reverses the direction near the lower end of the conical space S2, rises while rotating the center, and is discharged through the outlet pipe 7. .

  As shown in FIG. 5, the lead-out pipe 7 is provided along the central axis C of the internal space S at least in the internal space S, and the lead-out port 7 a is in the internal space S (specifically, a cylindrical space). The exhaust gas diluted by the swirling flow generated in the internal space S is led out of the internal space S. That is, the outlet pipe 7 and the inlet pipe 6 in the internal space S are provided to be orthogonal to each other. Thereby, it is set as the structure which changes the flow path direction of the piping which comprises the main flow path ML in the diluters PND1 and PND2. Furthermore, the outlet 7 a of the outlet pipe 7 is positioned below the opening of the inlet pipe 6 so that the exhaust gas and dilution gas do not flow directly from the inlet pipe 6 to the outlet pipe 7.

  In the present embodiment, the outlet pipe 7 of the first diluter PND1 is a curved pipe that curves outside the internal space S as shown in FIG. 3, and the outlet pipe 7 of the second diluter PND2 is the same as that shown in FIG. As shown in FIG. 3, the straight pipe is straight outside the internal space S.

  In the diluters PND1 and PND2 configured as described above, the first diluter PND1 is provided so that the inner space S gradually decreases in diameter as it goes vertically downward. That is, the first diluter PND1 is arranged so that the central axis C of the internal space S is substantially vertical. Thereby, the dust contained in the exhaust gas introduced into the first diluter PND1 is centrifuged and accommodated in the dust collecting unit 8. The first diluter PND1 has a function of removing particles larger than the particle size of the solid particles contained in the exhaust gas (for example, larger than 2.5 μm). On the other hand, the second diluter PND2 is arranged so that the central axis C of the internal space S is substantially horizontal. That is, the second diluter PND2 of this embodiment does not have a dust collection function.

  Next, an arrangement relationship among the first diluter PND1 and the second diluter PND2, the evaporator EU, and the particle number measuring device 2 will be described with reference to FIG. The first diluter PND1 is provided above the evaporator EU so that the central axis C of the internal space S is substantially vertical, and the outlet pipe 7 of the first diluter PND1 is curved in a U shape. Yes. The lead-out pipe 7 is connected to one end of an evaporator EU provided below. The introduction pipe 6 of the second diluter PND2 is connected to the introduction pipe connection part (exhaust gas outlet) EU1 of the evaporator EU. The second diluter PND2 is provided such that the central axis C of the internal space S is substantially horizontal. The outlet pipe 7 of the second diluter PND2 has a straight pipe shape, and the particle number measuring device 2 Connected to the outlet pipe connecting portion (exhaust gas inlet) 21. At this time, the inlet pipe connecting part EU1 of the evaporator EU and the outlet pipe connecting part 21 of the particle number measuring device 2 are provided on the base body 9 so as to be orthogonal to each other in a substantially horizontal plane. The PNDs 2 are provided on the lateral sides of the evaporator EU so as to face the inlet pipe connecting part EU1 of the evaporator EU and the outlet pipe connecting part 21 of the particle number measuring device 2. More specifically, the cylindrical space portion side of the second diluter PND2 is provided so as to face the outlet tube connecting portion of the particle number measuring device 2.

<Effect of this embodiment>
According to the particle number measuring system 100 according to the present embodiment configured as described above, the introduction pipe 6 that introduces the exhaust gas and the dilution gas so that the diluters PND1 and PND2 form a swirling flow along the inner peripheral wall of the body 5. And the outlet pipe 7 provided along the central axis C of the internal space S, the exhaust gas and the dilution gas are sufficiently mixed by the diluters PND1 and PND2 and the flow direction is changed. Therefore, the volume occupied by the pipe due to the bending radius based on the flow velocity can be eliminated as in the prior art, and the flow path direction can be converted in a compact manner. In particular, in the second diluter PND2, since the central axis C of the internal space S (cylindrical space portion S1 and conical space portion S2) is provided so as to be substantially horizontal, the pipe to the particle number measuring device 2 is a straight pipe. The diluted exhaust gas can be sent to the particle number measuring device 2 without forming particles (PM) pools in the pipe. Moreover, it is possible to prevent the system as a whole from having a complicated structure by the structure in which the second diluter PND2 is not installed on the lower side in the vertical direction of the particle number measuring apparatus 2 having a large capacity and weight. Furthermore, since the second diluter PND2 and its downstream do not have a structure for heating the exhaust gas and the piping, it is conceivable that particles adhere to the piping. However, since the piping can be shortened, particles (PM) are connected to the piping. Can be prevented from adhering to. Further, by making the exhaust gas and the dilution gas into a swirl flow along the inner peripheral wall of the body 5, it is possible to take a long flow path in which the exhaust gas and the dilution gas are mixed. Since the exhaust gas and the dilution gas that have flowed back toward the outside are led out to the outside from the outlet 7a, the exhaust gas and the dilution gas can be sufficiently mixed without lengthening the piping.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the first diluter has a dust collecting function and no dust remover is provided upstream of the first diluter, but the first diluter has no dust collecting function. A dust remover may be provided upstream of the first diluter. At this time, it is not necessary to provide the first diluter so that the internal space S is arranged along the vertical direction.

  Moreover, in the said embodiment, although the 1st diluter and the 2nd diluter are set as the same structure, it is good also as a different structure. In this case, it is good also as a structure which provides a dust collecting part in a 1st diluter, and does not provide a dust collecting part in a 2nd diluter.

  Further, the diluter of the above embodiment has one introduction pipe for introducing both the exhaust gas and the dilution gas into the internal space, but the exhaust pipe for introducing the exhaust gas into the internal space and You may have the introduction pipe | tube for dilution gas which introduce | transduces dilution gas into internal space.

  In addition, the outlet pipe of the first diluter of the above embodiment is a curved pipe, and the outlet pipe of the second diluter is a straight pipe, but these outlet pipes are connected downstream of the diluter. It can be appropriately changed depending on the arrangement of the parts.

  In addition, the diluter of the above embodiment is configured such that the introduction pipe is provided perpendicular to the central axis of the internal space and the outlet pipe is provided along the central axis of the internal space. It may be provided along the central axis of the internal space, and the outlet pipe may be provided orthogonal to the central axis of the internal space. In this case, in order to generate a swirling flow in the internal space, it is desirable to provide a stirring blade in the internal space.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

100 ... Particle number measurement system PT1 ... Exhaust gas introduction port PT2 ... Dilution gas introduction port ML ... Main flow path DL ... Dilution gas flow path 2 ... Particle number measurement device 21・ Estimating pipe connection part EU of the particle number measuring device... Evaporator EU1... Evaporator introduction pipe connection part PND1.
PND2 ... Second diluter (downstream diluter)
DESCRIPTION OF SYMBOLS 5 ... Body S ... Internal space C ... Center axis 5A of internal space ... Mounting plane 6 ... Introducing pipe 7a ... Deriving port 7 ... Deriving pipe

Claims (3)

A main flow path having one end connected to an exhaust gas introduction port for introducing exhaust gas of the engine;
A dilution gas flow path having one end connected to a dilution gas introduction port for introducing a dilution gas and the other end connected to the main flow path;
An evaporator provided in the main flow path for vaporizing volatile particles in the exhaust gas;
A downstream diluter that is provided downstream of the evaporator and dilutes the exhaust gas by mixing the diluent gas with the exhaust gas that has passed through the evaporator;
A particle number measuring device for measuring the number of solid particles in the exhaust gas diluted by the downstream diluter,
The diluted exhaust gas is configured to flow without being heated from the downstream diluter to the particle number measuring device,
A body having a rotating body-shaped internal space whose diameter is reduced as the downstream side diluter goes from one end to the other;
An introduction pipe which is provided along or perpendicular to the central axis of the internal space and introduces exhaust gas and dilution gas into the internal space;
A discharge pipe that is orthogonal to the introduction pipe and has a straight pipe shape for discharging the exhaust gas diluted by the swirling flow generated in the internal space to the outside of the internal space;
A particle number measurement system in which the body is provided so that a central axis of the inner space thereof is substantially horizontal, the introduction pipe is connected to the evaporator, and the lead-out pipe is connected to the particle number measurement device .   The particle number measurement system according to claim 1, wherein an introduction pipe connection part in the evaporator and a lead-out pipe connection part in the particle number measurement apparatus are arranged orthogonally. An upstream diluter provided on the upstream side of the evaporator and diluting the exhaust gas by mixing the exhaust gas introduced into the exhaust gas;
The upstream diluter is provided with a body having a rotating body-shaped internal space whose diameter decreases from one end to the other end, and is provided along or perpendicular to the central axis of the internal space, An introduction pipe that introduces exhaust gas and dilution gas into the internal space, and a lead-out pipe that is provided orthogonal to the introduction pipe and that extracts exhaust gas diluted by a swirling flow generated in the internal space to the outside of the internal space And having
The upstream diluter is heated and the downstream diluter is cooled;
The particle number measuring system according to claim 1 or 2, wherein in the upstream diluter, a mounting plane on which a heater is mounted is formed on the outer wall of the body.