Chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows

Abstract

Chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, which comprises a body (1) with separate inlet and outlet openings (2, 3), which comprises a frustoconical inlet area (1.1); a cylindrical laminarisation area (1.2); and a sampling area (1.3) with a first cylindrical part (6.1) and a second frustoconical part (6.2) and comprising two or more sampling sections with two or more intakes (8); wherein the sampling sections are separated by a distance greater than or equal to the minimum separation for obtaining zero disturbance in the downstream sampling section, and each intake (8) comprises an access hole (9) for insertion of a probe (10) with a sampling nozzle (10.1) capable of penetrating a certain length into the chamber to bridge the flow boundary layer.

Description

CHAMBER FOR CONTINUOUS AND SIMULTANEOUS SUBSAMPLING OF AEROSOLS FROM STATIONARY OR TRANSIENT CONFINED FLOWS Technical field of the invention

[0001] The present invention relates to the technical field of the environment and air pollution, specifically to the study and characterization of the immissions and emissions of aerosol particles, and more specifically to the field of systems and devices that allow the sampling of particles before their physical-chemical characterization can be carried out. Background of the Invention

[0002] Currently, the methodology for in situ characterization of aerosol particles is carried out, in general terms, by applying particle sampling and measurement systems, based on the coupled arrangement of vapors, equipment and measuring or collection instruments whose simultaneous use allows obtaining an integral characterization of the aerosol, which involves all the physicochemical properties that can determine its behavior and environmental effects.

[0003] The process typically used involves dividing the main confined flow sample (sampling line) using a series of flow dividers (splitters and manifolds). These are connected to the main sampling line to obtain the secondary samples, understood as fractions or subsamples of the main sample, required to supply the connected measuring equipment. Dividing the sample with these flow dividers does not alter the characteristics of the gaseous phase, but it can negatively affect the particulate phase of the aerosol, changing its original characteristics, especially when the operating flow rates of the measuring equipment vary significantly.

[0004] To alleviate this situation, sampling or subsampling chambers are usually used, which have one entrance and one or more exits.

[0005] Continuous sampling chambers, whether they have a single sampling point or multiple points, may require suction systems downstream of these points. In these cases, the inlet flow rate does not correspond to the sum of the flows. subsampled, but is higher than these, with the excess flow being evacuated by the general extraction system.

[0006] The problem with these chambers is that when there are multiple outlets, there is no ability to effectively control the influence of one outlet on another. This is crucial to avoid altering the characteristics of the aerosol sampled through each outlet, as the flows of each individual subsample often cause interactions and disturbances among themselves, and even with the main flow passing through the chamber, affecting the quality and representativeness of the aerosol sampling.

[0007] Examples of the state of the art can be cited in reference documents CN 110186723, CN204214685 and CN 109632398.

[0008] Document CN 110186723 defines a device for introducing samples of fine particles from ambient air at high altitudes, collected in flight by aircraft. This device distributes the sample between vapors and physical / chemical particle analysis instruments via conductive silicone tubing, for particles smaller than 2.5 µm. It features a bent stainless steel sampling piece with an air inlet nozzle on one side. The inlet dimension is smaller than the outlet dimension, thus reducing the gas flow rate.

[0009] A plurality of outlets is arranged at the rear of the cutting head, with said outlets connected to different fine particle analysis instruments via conductive silicone tubing.

[0010] In this case, a precise flow adjustment is necessary for each instrument using a flow meter.

[0011] Furthermore, in this device the sample is distributed to the equipment through perpendicular connections and by adjusting the flow rate before measurement with instruments, which implies a lot of particle loss due to impaction at the 90° angles formed by the perpendicular connections and particles that remain inside the flow meter.

[0012] Reference document CN204214685 relates to a system for sampling dust particles suspended by road traffic, comprising a sampling tube, a mixing tube, a first vacuum pump, a cutting head, a support of membrane, a rotameter, a butterfly valve, a second vacuum pump, and a plurality of sampling tubes.

[0013] It is geared towards sampling particulate matter generated by vehicles traveling on the road, the dust that is raised being normally fine particles (PIVk.s) and coarse particles (PM10).

[0014] One end of the mixing tube is connected to the sample inlet tube, and the other end is connected to an air suction port of the first vacuum pump. The mixing tube has multiple openings, and the multiple sampling tubes are inserted from the openings into the mixing tube to establish communication with it.

[0015] Each sampling tube contains a cutting head, a film holder, a rotameter, vacuum pumps, a membrane, a cutting device to remove particles above a certain diameter, and a butterfly valve, arranged sequentially along the gas flow direction within the sampling tube. It may also include a flow meter and a controller in each sampling tube. The problem is that all these components introduce significant losses of particulate matter.

[0016] Furthermore, it is not suitable for direct emissions and immissions produced by an internal combustion engine, and even less so by an aircraft turbine.

[0017] Document CN 109632398 describes an atmospheric sampling system with a PM2.5 constant velocity sampling head assembled in multiple flow stages. The head comprises a plurality of main pipes, which can be detachably connected to adjacent main pipes. Each main pipe section is provided with a branch port used for external connection to a monitoring instrument.

[0018] In this case, the probe guide tubes are perpendicular to the sampling chamber, which produces many particle losses due to impaction, and the outlet flow rates depend on the specifications of the sampling heads, being at constant flow.

[0019] This system performs constant speed coaxial sampling which, as indicated, can minimize the loss of aerosol samples in said sampling; however, there may be losses of particles of significant values.

[0020] It is a suitable system for instruments with different flow rates, but it is not recommended for cases where the equipment has different degrees of suction or vacuum pressure to capture the sample.

[0021] Therefore, there are two types of aerosol sample division systems, each with its advantages and disadvantages, but neither prototype prevents sample losses or transformations. Therefore, a device is needed that incorporates the characteristics of both systems and allows the continuous and simultaneous division of the aerosol particle sample into subsamples and their redirection to different sampling and measurement equipment, avoiding changes in the original sample due to flow disturbances and deposition at the sampling points during the sample division process, towards the different measuring instruments.

[0022] Furthermore, this device must allow the sampling of aerosols with very small particle sizes, including ultrafine particles. Therefore, losses due to diffusion and / or agglomeration for submicron particle sizes must be avoided, as well as the influence of each sampling point on subsequent downstream points. Description of the invention

[0023] The chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, presented here, is indicated for measuring vapor subsamples from a continuous initial sample in sample transfer lines that feed different aerosol measuring equipment with different operating conditions (flow rate and pressure).

[0024] This chamber allows for the simultaneous collection of several subsamples from an original sample and their transmission to different collection and measurement devices. The original sample comes from both channeled (ducts, chimneys, etc.) and non-channeled (ambient air) flows, and the subsamples are fractions of the original.

[0025] This chamber comprises a body having an inlet opening at one end, an outlet opening at the opposite end, and an intermediate space with the appropriate geometry to allow aerosol flow and suitable sample subdivisions.

[0026] This body also includes an entrance zone from the entrance opening to a first section, which has a truncated conical inner section with an increasing diameter that facilitates homogeneous distribution towards said first section.

[0027] It also features a laminar flow zone, extending from the first section to a second section. This laminar flow zone has a cylindrical inner section whose length is greater than or equal to the minimum length necessary to allow a fully developed laminar flow profile in that zone.

[0028] Next, it comprises a subsampling zone from the second section to the outlet opening. This subsampling zone has a first part with a cylindrical inner section from the second section to a third section, and a second part with a truncated conical inner section of decreasing diameter from said third section to the outlet opening.

[0029] The subsampling zone has two or more subsampling sections, which in turn comprise two or more intakes located equidistantly around the axis, where the intakes of the same subsampling section have the same outlet flow rate.

[0030] Furthermore, the sampling points in one subsampling section are staggered with respect to an upstream subsampling section. Additionally, the subsampling sections are separated by a distance greater than or equal to the minimum separation that would produce zero disturbance in the downstream subsampling section.

[0031] Each intake comprises an access hole capable of allowing the passage of a probe that has a sampling nozzle capable of penetrating a certain length inside the chamber such that it allows overcoming the boundary layer of the flow.

[0032] This access hole has an angle of inclination with respect to the camera axis.

[0033] The chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows proposed here represents a significant improvement over the state of the art.

[0034] This is achieved by designing a continuous and simultaneous aerosol subsampling chamber based on joining pieces of different cross-sections—truncated cones and cylinders—which form an interior section where, although the average flow velocity varies, the velocity profile is maintained. This allows for quasi-isokinetic sampling at different speeds. This design makes it feasible to use different aerosol measurement devices operating at different flow rates with this chamber.

[0035] The dimensions of the chamber and the location of the subsampling sections are suitable for achieving fully developed laminar flow conditions prior to sampling.

[0036] Furthermore, the different subsampling sections are defined according to the operating flow rates of the measuring instruments to be used, which allows minimizing the length of the chamber.

[0037] These subsampling sections are located at a sufficient distance to avoid disturbances at downstream sampling points, and the effect between adjacent sampling points is virtually zero.

[0038] Furthermore, the designed configuration of the subsampling ports avoids sampling at the boundary layer, and the angle of inclination relative to the chamber axis of these probes allows for sampling close to isoaxial sampling. With the appropriate configuration of the probes used in the sampling, it is achieved in a quasi-isokinetic manner. The profile of the probes inserted into the chamber, when in the correct position, minimizes disturbances to the flow downstream towards the chamber outlet.

[0039] This chamber is versatile and can have different configurations depending on the measuring equipment that is intended to be connected to it, and it is very effective because it manages to integrate the functions of a classic aerosol sampling chamber and flow dividers or splitters.

[0040] The chamber is versatile and designed to be positioned ideally at some point along the sampling line, after the sampling probe and before the sample measurement equipment. It is designed to divide the continuously incoming main aerosol flow sample into different secondary subsamples (fractions of the main sample), doing so simultaneously and continuously through probes with an appropriate geometry. The subsamples maintain the same physicochemical characteristics as the original sample at all times, making them fully representative of it. Brief description of the drawings

[0041] In order to aid a better understanding of the characteristics of the invention, according to a preferred embodiment thereof, a series of drawings are provided as an integral part of this description, where, for illustrative and non-limiting purposes, the following has been represented:

[0042] Figure 1 shows a perspective view of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0043] Figure 2 shows a cross-sectional view of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0044] Figure 3 shows the exploded view of a sampling chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0045] Figure 4 shows a cross-sectional view of the first piece of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0046] Figure 5 shows a cross-sectional view of the second part of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0047] Figure 6 shows a cross-sectional view of the third part of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0048] Figures 7.1 and 7.2 show cross-sectional views along perpendicular cutting planes of the fourth part of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for a preferred embodiment of the invention.

[0049] Figure 8 shows a diagram of the test bench used for the analysis of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, in a first configuration.

[0050] Figure 9 shows a diagram of the test bench used for the analysis of the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, in a second configuration. Detailed description of a preferred embodiment of the invention

[0051] In view of the figures provided, it can be observed how, in a preferred embodiment of the invention, the chamber for continuous and simultaneous subsampling of aerosols from stationary or transient confined flows, for measuring several subsamples from a continuous initial sample in sample transfer lines that feed different measuring equipment, proposed herein, comprises a body (1) having an inlet opening (2) at one end, an outlet opening (3) at an opposite end, and an intermediate space suitable for allowing the flow of the aerosol between both, as well as the subdivisions of the sample.

[0052] As shown in Figure 2, this body (1) comprises an inlet zone (1.1), a lamination zone (1.2) and a sampling zone (1.3).

[0053] The inlet zone (1.1) is the one that extends from the inlet opening (2) to a first section (4), and has a truncated conical inner section with increasing diameter for the distribution of the flow towards said first section (4).

[0054] The laminar zone (1.2) has a cylindrical inner section and extends from the first section (4) to a second section (5). The length of this zone is greater than or equal to the minimum length necessary to allow a fully developed laminar flow profile as it passes through it.

[0055] Finally, the subsampling zone (1.3) extends from the second section (5) to the outlet opening (3). This subsampling zone (1.3) is subdivided into a first part (6.1) with a cylindrical inner section, comprising from the second section (5) to a third section (7), and a second part (6.2) with a truncated conical inner section of decreasing diameter from said third section (7) to the outlet opening (3).

[0056] This subsampling zone (1.3), as shown in Figures 1 and 2, comprises two or more subsampling sections with two or more taps (8) located equidistantly around the axis, where the taps (8) of the same section have the same outlet flow rate.

[0057] As can be seen in Figure 1, the taps (8) of a subsampling section are arranged in a staggered pattern with respect to an upstream subsampling section, and the subsampling sections are separated by a distance greater than or equal to the minimum separation likely to produce zero disturbance in the downstream subsampling section.

[0058] Likewise, as shown in Figure 3, each intake (8) comprises an access hole (9) of a probe (10) that has a sampling nozzle (10.1) capable of penetrating the interior of the chamber to a certain length, allowing it to pass through the boundary layer of the flow. This access hole (9) has an angle of inclination α with respect to the axis of the chamber.

[0059] In this preferred embodiment of the invention, the body (1) is formed by four consecutively arranged and aligned pieces, which have ends that can be assembled. All these pieces are formed from a round core of the selected material, which in this embodiment is austenitic stainless steel with a 2R finish on the inside of the pieces, thus avoiding joints or welds between parts.

[0060] It is essential to ensure quality manufacturing and proper joining of these four pieces to prevent deposits, internal turbulence, and leaks that could affect their operation.

[0061] A first piece (11) corresponds to the entry zone (1.1) of the body (1), a second piece (12) corresponds to the assembly formed by the lamination zone (1.2) and the first part (6.1) of the subsampling zone (1.3), i.e., the zones with a cylindrical inner section and, a third and a fourth piece (13, 14) correspond respectively to an initial and final portion (15.1 , 15.2) of the second part (6.2) of the subsampling zone (1.3).

[0062] Likewise, in this preferred embodiment of the invention, the camera comprises a first subsampling section (16) in the second part (12), at the height of the first part (6.1) of the subsampling zone (1.3). This first subsampling section (16) has four ports (8) arranged symmetrically with respect to the camera axis.

[0063] A second subsampling section (17) is located in the third piece (13), and has two symmetrical shots (8) with respect to the camera axis, which are staggered, or more specifically in this case, interspersed with the position of the shots (8) of the first subsampling section (16).

[0064] Finally, a third and a fourth subsampling section (18, 19) are located in the fourth piece (14), and both have a pair of shots (8) respectively. The shots (8) of each pair are positioned symmetrically with respect to the camera axis and, between themselves and with respect to those of the second subsampling section (17), they are staggered.

[0065] In this design, the speed increases along the length of the chamber, and the equipment that works at lower flow rates is connected in the first subsampling section (16), closer to the inlet opening (2) to the chamber, while the equipment with higher flow rates is connected in the second, third and fourth subsampling sections (17, 18, 19).

[0066] In this preferred embodiment of the invention, as shown in Figures 4 to 7.2, the four pieces comprise assembly means by means of flanges (25) and a tongue and groove at their fixing ends. They also have a recess (27) at these fixing ends for the placement of a sealing gasket.

[0067] It is very important that the parts are hermetically sealed together and that there are no steps or changes in cross-section on the internal surface, thus eliminating any potential flow disturbances. Furthermore, the four-part flanged design facilitates chamber cleaning, as the four parts can be disassembled, allowing for thorough and easy cleaning, preferably using ultrasound.

[0068] As can be seen in Figures 4 to 6, in this preferred embodiment of the invention, each outlet (8) comprises a guide conduit (20) fixed to the access hole (9) by means of fastening, which in this case is by welding. This guide conduit (20) is capable of allowing the probe (10) to enter through its interior. It also comprises a sealing connector (21) fixed to the free end of the guide conduit (20).

[0069] For its part, the diameter of the sampling nozzle (10.1) of the probe (10) is calculated based on the flow velocity in the corresponding subsampling section and the flow rate out to the equipment connected to it.

[0070] As shown in Figures 5 and 6, since the first subsampling section (16) is located in the second piece (12), with a cylindrical inner section, and the remaining subsampling sections are in the third and fourth pieces (13, 14), with a truncated conical inner section, both the length of the probe (10) and the angle of inclination of this with respect to the inner wall of the chamber will be different between the sampling points (8) of the first subsampling section (16), as represented in Figure 5, and the points (8) of the remaining pieces, shown in Figure 6.

[0071] The angle α formed by the probe (10) or the access holes (9) with the camera axis is the same in all samples (8), regardless of the subsampling section. As already seen, due to the large number of samples (8) to be defined and a limited camera length, isoaxial sampling is not feasible, but in this case, the smallest possible angle α is considered to approximate the subsampling to isoaxial conditions.

[0072] In this preferred embodiment, the chamber comprises one or more sealing plugs (not shown in the Figures) for one or more ports (8). Thus, the probes (10) that are not used in a subsampling operation, are preferably closed by means of these plugs which are placed in the sealing connector (21) of the tap, when The probe is not installed, or the outer end of the probe is closed (10), if it is already installed.

[0073] As shown in Figures 4, 7.1 and 7.2, this camera comprises an input connector (22) and an output connector (23) fixed to the input opening (2) and the output opening (3) respectively.

[0074] In this preferred embodiment of the invention, the angle of inclination a, of the access holes (9) with respect to the axis of the camera is between 25 and 35°.

[0075] Likewise, in this case, the angle y of the truncated conical section of the third and fourth pieces (13, 14) is between 5 and 15°.

[0076] Furthermore, in this preferred embodiment, the angle p of the truncated conical section of the first piece (11) is between 10 and 25°.

[0077] In this preferred embodiment of the invention, a dual process of theoretical and experimental validation has been carried out. The experiments involved continuous and simultaneous subsampling of aerosol flows, typical of channeled emissions from any exhaust into the atmosphere, whether from mobile or stationary sources.

[0078] To determine the versatility of the camera, two identical cameras were implemented in the experimental validation, designed and manufactured following the concepts described above for the preferred embodiment of the invention and with the following specific characteristics:

[0079] The first chamber has implemented a calibration bench with the configuration of a series of equipment called "Configuration 1" and the second chamber has implemented another calibration bench with the configuration of another series of equipment called "Configuration 2", the objective of both being to achieve a distribution of the primary sample from aerosol flows to each series of measuring equipment simultaneously.

[0080] In both cases, a configuration of equipment is proposed whose working flow rates / pressures differ from each other, connected to different outlets of the chamber through the sampling probe with the appropriate geometry.

[0081] In this preferred embodiment of the invention, the first part has a truncated conical section angle of p=18°. The length of this part is 102 mm and the inlet opening (2) has a DN25 vacuum inlet connector (22) with a length of 20.1 mm. This inlet connector (22) is welded around the inlet opening (2), which has a female recess (24) for fitting the inlet connector (22).

[0082] As shown in Figure 4, the opposite end of this first piece (11), which corresponds to the first section (4) of the body (1), comprises a flange (25) with six through holes (26) of internal diameter 0, which in this case has a value of 11 mm. It also features the recess (27) for a sealing gasket and a projection (28) for making a tongue-and-groove joint with the second piece (12) of the body (1).

[0083] In this preferred embodiment, as can be seen in Figure 5, the second piece (12) has a flange (25) at both ends. The flange (25) located at the end corresponding to the first section (4) of the body (1), suitable for connecting with the flange (25) of the first piece (11), also has six holes (26) of the same diameter as those of the flange (25) of the first piece (11), as well as a female recess (24).

[0084] Furthermore, the flange (25) at the opposite end is machined with four M10 metric holes (26) for threading screws for joining it to the third piece (13) and also features a recess (27) for a sealing gasket and a male projection (28) for its tongue-and-groove connection with the third piece (13).

[0085] The length of this second part (12), in this preferred embodiment, is 207 mm. This second part (12) has four access holes (9) with four guide channels (20) welded into each of them. These guide channels (20) have an angle α = 30° with the axis of the camera and an angle of inclination θ = 30° of the access hole (9) or of the probe (10) with respect to the inner wall of the camera.

[0086] As shown in Figure 6, in this preferred embodiment of the invention, the third piece (13) also has flanges (25) for joining it to the second and fourth pieces (12, 14) respectively. The flange (25) for joining it to the second piece (12) has four through holes (26) of 11 mm diameter and comprises four recesses (27.1) that correspond to the access holes (9) of the second piece (12), so as not to interfere with the placement of the four guide channels (20). In addition, it has a female recess (24) for tongue and groove connection with the second piece (12).

[0087] The flange (25) for joining with the fourth piece (14) has six through holes (26) of 11mm diameter in this case, a recess (27) for the sealing gasket and a male protrusion (28) for the tongue and groove joint between the two.

[0088] It also comprises an interior angle of the truncated conical section y=8° and a length of 172mm. In this case, it has two guide channels (20) in two respective access holes (9), and these guide channels (20) form an angle a=30° with the axis of the camera and the access hole (9) or the probe (10) form an angle of inclination o=34° with respect to the inner wall of the camera.

[0089] Finally, the fourth piece (14) has the same interior angle, y=8°, as the truncated conical section, a length of 167.5 mm, and four guide channels (20) in four access holes (9), two of which are located in the third subsampling section (18) and the other two in the fourth subsampling section (19). The distance between the access holes of both the third and fourth subsampling sections (18, 19) is 61 mm in this case.

[0090] The guide channels (20) of this fourth piece (14) also form an angle a=30° with the axis of the chamber and an angle of inclination o=34° of the access hole (9) or of the probe (10) with the inner wall of the chamber.

[0091] Furthermore, this fourth piece (14) comprises an outlet connector (23), DN25, with a length of 20.21 mm, and at the end where it joins the third piece (13) it has the corresponding flange (25) with six holes (26).

[0092] First, a theoretical validation of the sampling chamber was performed through a computational fluid dynamics (CFD) simulation. This consisted of three stages: a pre-processing stage where the fluid domains were defined and the meshing was performed; a processing stage that consisted of the discretization and solution of the equations involved in the fluid; and finally a post-processing stage for the treatment of the data obtained.

[0093] The internal volume geometry design was done using AutoCAD software and the meshing was done using ICEM CFD software included in ANSYS.

[0094] For the fluid dynamics calculation, the ANSYS FLUENT software was used, employing the k-epsilon turbulence model, widely used in engineering calculations. This is a semi-empirical model based on two separate transport equations, one for turbulent kinetic energy (k) and another for turbulent kinetic energy dissipation (e), whose solution allows for the independent determination of turbulent velocity and length scales.

[0095] Although several models exist, in this case the standard realizable ke model was used, which satisfies certain mathematical restrictions on Reynolds stresses, consistent with the physics of turbulent and incompressible flows.

[0096] The simulation of the chamber for "Configuration 1" of aerosol flow measurement allows the following verifications to be performed:

[0097] It is verified that the velocity, for an inlet flow rate of 30 l / min, increases along the chamber, from 0.25 m / s in the first sampling section (16), to 2.5 m / s in the fourth sampling section (19), achieving a fully developed laminar flow prior to subsampling.

[0098] It is verified that with the chosen configuration, disturbances in the sampling points (8) along the chamber are negligible, maintaining laminar flow. It is also verified that if the subsampling flows are greater than 0.1 l / min, reverse flows that would impede the proper development of the subsampling are completely avoided.

[0099] It is verified that at each subsampling point, internal flow velocities in the chamber and subsampling velocities very close to each other are achieved.

[0100] It is verified that inserting the probes at a certain distance from the bulk of the fluid allows avoiding the boundary layer, even in the first sections where subsampling is more difficult.

[0101] It is verified that the insertion of the sampling probes to avoid the boundary layer generates a stagnation point downstream, however, the distance considered between the intakes (8) is adequate to avoid any influence between them.

[0102] The simulation of the chamber with the “Configuration 2” aerosol flow measurement allowed the following verifications to be performed:

[0103] It is verified that the velocity, for an inlet flow rate of 30 l / min, increases along the chamber, from 0.25 m / s in the first sampling section (16), to 1.3 m / s in the fourth sampling section (19), achieving a fully developed laminar flow prior to subsampling.

[0104] It is verified that there are no disturbances at the subsampling points along the chamber, maintaining the laminar regime.

[0105] It is verified that at each subsampling point, internal flow velocities in the chamber and subsampling velocities very close to each other are achieved.

[0106] It is verified that inserting probes at a distance from the bulk of the fluid allows avoiding the boundary layer, especially in the first subsampling sections.

[0107] It is verified that the insertion of the sampling probes to avoid the boundary layer generates a stagnation point downstream; however, the sufficient distance considered between the intakes prevents any influence between them, and therefore the stagnation point.

[0108] Two calibration benches were designed for the experimental validation of the cameras. The objective with both cameras was:

[0109] Obtain different subsamples from primary aerosol flows and characterize them using different measuring equipment, with different working flow rates / pressures, all connected simultaneously to the different outlets of the subsampling chambers.

[0110] Compare the particle concentration at each sampling point in the chamber where subsampling is performed with the concentration at the chamber inlet. Optimal performance would imply a particle concentration at each sampling point equal to that at the inlet.

[0111] All tests were performed using ambient air as the inlet aerosol, maintaining a constant concentration in each test. The equipment used to measure the numerical particle concentration was a TSI CPC model 3775.

[0112] In the case of “Configuration 1” for aerosol flow measurement, the chamber validation was performed by introducing an aerosol flow rate of 30 l / min through the inlet.

[0113] This configuration has four subsampling points called OPC (31), OFFLINE (32), DMS500 (33) and PAM (34), which correspond to the name of the four connected measuring devices, located in different sampling sections of the chamber (2, 3 and 4), which work at different operating flow rates, as shown in Figure 8.

[0114] Depending on the required flow rate at each inlet (8), the isolation valve at the chamber outlet is adjusted. This valve is located on a line connecting the chamber to a suction pump (35), ensuring a constant inlet flow rate of 30 L / min. All inlets (8) are connected to a small, conventional subsampling chamber (36), used for this validation. A subsample is drawn from the chamber and sent to the numerical particle concentration (NPC) measuring device (37) for particle concentration measurement. Each inlet (8) has an isolation valve (38) connected to it, so that when one inlet is operating, the others remain closed. This allows for a direct comparison of the particle concentration in the inlet aerosol with the concentration measured at each inlet (8) at each subsampling point.

[0115] Once the simulation was performed, the deviation of each subsampling sample (8) was observed, calculated as the numerical concentration of particles in that sample compared to the numerical concentration measured at the inlet. In no case did the average value of this deviation exceed 10%. In some specific measurements, such as the OPC sample (31), due to the variability of the sample aerosol, the maximum values ​​reached 20%, while in the remaining samples (8) they showed values ​​below 20%.

[0116] In the case of “Configuration 2” for aerosol flow measurement, the chamber validation is performed by introducing an aerosol flow rate of 30 l / min of aerosol through the inlet.

[0117] This configuration also has four subsampling ports (8). One of them is connected to an axial dilution system (41), DAD (30), while the rest do not have any dilution, and are called LICOR (39), ELPI+ (40) and Lll (29), which again corresponds to the designation of the corresponding measuring equipment.

[0118] They are also located in different subsampling sections of the chamber (2, 3 and 4), and operate at different flow rates, as shown in Figure 9.

[0119] As in the previous case, depending on the flow rate that must come out of each outlet (8), the isolation valve is adjusted at the outlet located in the line that connects it to a suction pump (35), so that an inlet flow rate of 30 l / min is always maintained.

[0120] All the inlets (8) are connected to a small, conventional sampling chamber (36) from which the CPC (37) measures the particle concentration. Each inlet has an isolation valve (38) connected to it, so that when one inlet is operating, the other inlets (8) remain closed. In this way, the particle concentration in the incoming aerosol is directly compared with the concentration measured at each inlet (8).

[0121] Measuring the numerical concentration of the diluted sample (8) allows calculating the experimental dilution factor based on the parameters used in the DAD (30). The parameters measured in the DAD axial diluter are: Aerosol flow rate = 0.100 l / min. Outlet flow rate = 1,034 l / min Pressure = 3,450 bar.

[0122] With these values, a theoretical dilution factor of 10:1 is expected in this sample.

[0123] The data obtained from the undiluted samples (8) show a mean deviation value of less than 10%. The data obtained from the DAD sample (30) indicate a dilution factor, determined based on the numerical concentration of particles, of 10.2:1.

Claims

CLAIMS 1- Chamber for continuous and simultaneous sub-sampling of aerosols from stationary or transient confined flows, for measuring various sub-samples from a continuous initial sample in sample transfer lines that feed different aerosol measuring equipment with different flow and pressure conditions, characterized in that it comprises a body (1) that has an inlet opening (2) at one end, an outlet opening (3) at an opposite end and an intermediate space suitable for allowing the flow of the aerosol between both and the subdivisions of the sample, where said body (1) comprises - an inlet area (1.1), from the inlet opening (2) to a first section (4), which has a truncated conical inner section with increasing diameter for distribution towards said first section (4); - a laminating zone (1.2), from the first section (4) to a second section (5), with a cylindrical inner section and a length greater than or equal to the minimum length capable of allowing a laminar flow profile, and; - a sub-sampling zone (1.3) from the second section (5) to the outlet opening (3), which has a first part (6.1) with a cylindrical inner section from the second section (5) to a third section (7) and a second part (6.2) with a truncated conical inner section with a decreasing diameter from said third section (7) to the outlet opening (3) and comprising two or more sub-sampling sections with two or more inlets (8) located equidistantly around the axis, where the inlets (8) of the same section have the same outlet flow rate and the inlets (8) of a sub-sampling section are arranged in a staggered manner with respect to a sub-sampling section located upstream; where the sub-sampling sections are separated by a distance greater than or equal to the minimum separation likely to produce zero disturbance in the downstream sub-sampling section, and where each inlet (8) comprises an access orifice (9) with an angle of inclination a with respect to the axis of the chamber for insertion of a probe (10) having a sampling nozzle (10.1) capable of penetrating a determined length inside the chamber such that it allows crossing the boundary layer of the flow. 2- Camera according to claim 1, where the body (1) is formed by four pieces placed consecutively and aligned that have ends that can be assembled, where a first piece (11) corresponds to the entrance area (1.1) of the body (1), a second piece (12) corresponds to the set formed by the laminarization zone (1.2) and the first part (6.1) of the subsampling zone (1.3) and, a third and a fourth piece (13, 14) correspond respectively to an initial and final portion (15.1, 15.2) of the second part (6.2) of the subsampling zone (1.3). 3- Chamber according to claim 2, comprising - a first sub-sampling section (16) in the second part (12), at the height of the first part (6.1) of the sub-sampling zone (1.3), where this first sub-sampling section (16) has four sockets (8) arranged symmetrically with respect to the axis of the camera; - a second subsampling section (17) located in the third part (13), which has two sockets (8) symmetrical with respect to the axis of the camera; - a third and a fourth sub-sampling section (18, 19) located in the fourth part (14), where both have a pair of sockets (8) respectively and where the sockets (8) of each pair are located symmetrically with respect to the axis of the chamber; and where the sockets (8) of each sub-sample section are arranged in a staggered manner with respect to the sockets of a consecutive sample section. 4- Chamber according to any of claims 2 and 3, where the four pieces comprise assembly means by means of flanges (25) and a tongue and groove at their fixing ends and have a recess (27) at said fixing ends, for a sealing joint. 5- Chamber according to any of the preceding claims, wherein each inlet (8) comprises a guide conduit (20) fixed to the access orifice (9) by means of fixing means, capable of allowing the entry of the probe (10) and a hermetic closure connector (21) fixed to the free end of the guide conduit (20), where the diameter of the sampling nozzle (10.1) of the probe (10) is calculated as a function of the flow velocity in the corresponding sub-sampling section and the output flow rate towards the equipment connected to it. 6- Camera according to any of the preceding claims, wherein the angle of inclination a of the access holes (9) with respect to the axis of the camera is between 25 and 35°. 7- Chamber according to any of the previous claims, wherein the angle and interior of the truncated conical section of the third and fourth piece (13, 14) is between 5 and 15°. 8- Chamber according to any of the previous claims, wherein the interior angle of the truncated conical section of the first piece (11) is between 10 and 25°. 9- Chamber according to any of the preceding claims, comprising one or more closing plugs for one or more inlets (8). 10- Camera according to any of the preceding claims, comprising an input connector (22) and an output connector (23) fixed to the input opening (2) and the output opening (3) respectively.

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