Particle concentration analysis system and method

Abstract

A particle concentration analysis system is disclosed for testing the particle concentration of a fluid sample, such as the concentration of engine emission particles present in the exhaust gas of an engine. The particle concentration analysis system includes a saturation chamber, a condenser, and a condensing particle counter having a laser optical particle counter. The analysis system further includes a working fluid tank, a working fluid pump, and a sampling probe. The system provides a robust analysis system that allows a user to test vehicle emissions without requiring advanced training on the device, as the device is protected from misuse. A position-sensitive sensor is used to prevent damage to the system if it is tipped over or placed in a position that could produce false results. Additional features include a differential pressure sensor, a sealed and replaceable tamper-proof working fluid tank, a solvent recovery system, a cheat-proof device, and a fluid purity sensor.

Description

Technology Field

[0001] The present invention relates particularly to a particle concentration analysis system associated with a condensation particle counter. Background Technology

[0002] As more and more vehicles fill highways and streets around the world and environmental pollutants continue to emit pollutants, standards for engine emissions and air quality are becoming increasingly important to the planet. Testing vehicle engine exhaust emissions is a global concern to ensure that engines do not excessively pollute the Earth. Current measurement systems are typically large, expensive, and time-consuming. Furthermore, to ensure that engines comply with regulations throughout their entire service life, vehicle emissions must be checked on a large scale and periodically for all pollutants. Another problem with vehicle emissions testing is the possibility that test facilities, technicians, or customers could "cheate" the test by allowing ambient air to penetrate the system, thereby causing a false pass.

[0003] One type of emission analyzer is the hybrid Condensation Particle Counter (CPC) for measuring particle number concentrations in the size range of 10 to 200 nm (nanometers). Such particle counters are used to determine particle concentrations in engine emissions to monitor environmental air quality, as well as for other applications where particle concentration is a concern. The CPC must be periodically refilled with a working fluid (e.g., butanol or isopropyl alcohol). Refilling is typically achieved using a gravity feed system or a syringe from an external tank. means of solving the problem

[0004] The following concerns low-cost and low-complexity products developed for air quality testing and analysis, such as measuring the particle number (PN) concentration in exhaust pipes, particularly in relation to Periodic Technical Inspection (PTI). Condensed particle counters (CPCs) are commonly used to count particles in sample fluids during air quality testing and analysis. Typically, a skilled operator must monitor the CPC, for example, to monitor the working fluid and ensure that the working fluid is not only always fully charged but also sufficiently pure and free from contamination. Applying low-cost emission testing technology to the Periodic Technical Inspection (PTI) of vehicles requires not only low-cost, repeatable, and accurate measuring devices but also automated systems and measurement checks to verify that the devices are functioning properly and being used correctly.

[0005] In one aspect of the present invention, a particle concentration analysis system comprising a condensation particle counter is provided for analyzing the particle concentration of a vehicle emission sample. The analysis involves inserting a sampling probe into a vehicle under test and recording the number concentration of particulate matter in the vehicle emissions over a prescribed test sequence (e.g., idle engine operation). The vehicle is considered to have passed or failed this emission test if the recorded level is higher than the applicable standard.

[0006] In one embodiment, a fully integrated particle concentration analysis system according to the present invention uses a CPC combined with a sampling probe and an ambient air conditioning system to analyze particle concentrations in vehicle emission samples. The analysis system may be configured to determine whether the vehicle engine passes or fails during a PTI particle number (PN) test with the engine in an idle state. The analyzer measures the maximum allowable particle number at 250,000 cm⁻¹ -3It can be further configured to determine whether the vehicle engine passes or fails during a PTI particle number test in which the vehicle is tested over three 1-minute samples after less than "snap acceleration".

[0007] In one aspect of the present invention, an on-board diagnostics (OBD) system is integrated with an analysis system configured to determine whether the vehicle is "warmed up" and ready for a PTI PN test. During the test, second-by-second data of both OBD parameters (RPM, coolant temperature, and mass airflow velocity) and PN concentration are recorded to facilitate further data evaluation as well as the PTI PN pass or fail result.

[0008] The mixed-type CPC operates in a state where the aerosol flow (sample flow) is kept separate from the saturated air source and mixed before being transported through a condenser. The full-flow CPC operates in a state where particle-filled (sample) air passes through a heated wick surrounded by a working fluid to be saturated. In both the full-flow and mixed-type CPCs, supersaturated vapor condenses onto sample particles and grows into droplets of approximately 5–10 µm. These droplets are then focused through a nozzle, passed through a laser beam, and counted by a light-scattering particle counter, such as a pulse detection electronic device. The mixed-type CPC offers advantageous properties compared to the full-flow CPC, including the absence of performance degradation associated with the saturator or wick, because the wick is not contaminated with sample particles that would lower the supersaturation level over time.

[0009] Since the saturator can be mechanically separated from the condenser and the measuring optical system, robustness is improved, including significantly lower sensitivity to optical system contamination from the working fluid caused by vibration, orientation, etc.

[0010] The analysis system includes an electronic controller having a dedicated microprocessor for controlling the CPC. In addition, the analysis system may be equipped with a low-cost family of microcomputers for data storage, a wireless communication (WiFi) system, Bluetooth communication for a self-diagnostic device adapter, an HTML-based graphical user interface, and additional systems that allow the system to operate independently for various applications. Optionally, the CPC of the analysis system includes a three-way solenoid valve that periodically drains fluid from the CPC condenser.

[0011] In one embodiment, the analysis system comprises a HEPA filter for filtering dilution and saturator flow, an external working fluid tank, a microprocessor-controlled pump, and system d 50 It includes additional components to increase functionality and efficiency, including a diffusion screen, sampling hose, and sampling probe to increase to 23 nm. Optionally, the analysis system ranges particle number concentrations in cubic centimeters (# / cm²). 3 It includes a second diluent to expand to 6,000,000 particles per 1000 millimeters. However, concentrations exceeding 250,000 # / cm³ provide a reliable indication of defective diesel and gasoline particle filters. An evaporator tube for removing semi-volatile particles may also be included in the analysis system.

[0012] The particle analyzer can be calibrated to meet the performance criteria of ISO 27891:2015. However, due to the inherent linearity and performance predictability of CPC technology, a much reduced calibration range can be used with little to no adverse effects, providing corresponding significant cost savings. The particle analyzer can also be configured to meet or exceed the Swiss PTI performance criteria of the Swiss Federal Ordinance on Air Pollution Control (OAPC) 814.318.142.1. SR 814.318.142.1 is currently the only established PTI PN program. The CPC of the analysis system is t of less than 3 seconds 10 -t 90 It can be configured to operate as a response.

[0013] As reflected in the ISO 27891 calibration methodology and the annual interval between calibrations, the operational degradation factor for a well-designed CPC is essentially zero. In contrast, diffusion-based PN measurement systems or diffusion chargers (DCs) are typically susceptible to degradation during normal operation from various sources, such as contamination of traps and corona sources. In the typical size range of interest for effluent particle concentration analysis, CPCs have no particle size dependency, whereas DCs have a significant size dependency and can yield irregular results when particles are pre-charged (e.g., in Selective Catalytic Reduction (SCR) after treatment systems).

[0014] Sample capillaries may be included to measure fluid flow in various components of an analysis system, which reduces or eliminates the need for individual flow calibrations. Fluid or gas flow rates determined by pressure measurements across confining sections often require individual calibration. However, the very strict engineering and surface tolerances of low-cost subcutaneous injection needles (i.e., capillaries) provide strict control over flow rate measurements based on pressure drop without calibration. Hybrid CPCs are typically configured to measure at least three or four of the total four flows in real time (e.g., extraction flow, sample flow, drainage flow, and / or saturator flow). Each flow measurement requires a relatively expensive pressure sensor or pressure transducer. Hybrid CPCs typically measure sample flow by subtracting the saturator and drainage flows from the total exhaust gas. Such an approach requires highly accurate flow calibrations for the total exhaust, saturator, and drainage flows to reduce errors in the determined sample flow. Since sample capillaries are included in the analysis system to measure and / or calculate sample flow, they reduce or eliminate potential sources of error and decrease the complexity and cost of the analyzer. Using a 3-way solenoid valve to drain the CPC can further reduce or eliminate complexity and costs by eliminating the need to measure the drain flow.

[0015] Instead of including a pressure transducer at each point for measurement, the differential pressure between two pressure sources can be measured by using a single pressure transducer or pressure sensor to determine the differential pressure by circulating each pressure source and then calculating the pressure of the system. The first pressure (P1) and the second pressure (P2) can be determined by measuring the pressure response (P) through the periodic circulation of the source to P1 or P2. The pressure response P = P1 + P2; thus, during normal operation, P1 = P-P2, and with the P1 source turned off, P2 = P. A single differential pressure transducer instead of two independent transducers reduces the complexity of the resources required for pressure response measurement because the electronics required to turn off the pressure source are simpler and cost only a fraction of the cost of each complex pressure transducer. The interval between isolating one pressure source and measuring both can be determined and set based on the stability of the pressure signal.

[0016] The efficiency of the CPC is determined by the achieved supersaturation level, which depends on the temperature difference between the saturator and the condenser. In practice, since not all particles in the ambient air experience or reach the same level of supersaturation, the efficiency of the optical particle counter decreases progressively at lower levels of supersaturation. Lower levels of supersaturation produce smaller particle sizes that are relatively less likely to be detected by the optical counter. The acceptable lower cutoff size for particles to be analyzed by the optical counter is generally defined as the particle size at which 50% (d50) of the present particles are calculated. Typically, the lower cutoff particle size is a diameter of approximately 15 nm. Since a d50 particle size of 15 nm is smaller than the "Automotive - PMP" standard, which requires measuring particles larger than 23 nm, a higher d50 is required when analyzing engine exhaust gases. Diffusion screens can increase the d50 to an acceptable size.

[0017] Engines emit a significant amount of carbon dioxide (for example, an estimated exhaust gas concentration of 16 volume% from a gasoline engine operating under stoichiometric combustion conditions). If the sampling probe is not fully or correctly inserted into the vehicle's exhaust pipe, the measured carbon dioxide mixes with ambient air and is lower than expected. As a result, engine exhaust particulates may be diluted by clean ambient air, allowing a "dirty vehicle" to pass through that fails to pass a properly performed exhaust gas analysis. The carbon dioxide sensor included in the analysis system provides an anti-cheat device that prevents the user from intentionally failing to sufficiently insert the sampling probe into the vehicle's exhaust pipe to allow the vehicle to "pass."

[0018] In one aspect of the present invention, the CPC may be configured to automatically adjust the reported count of particle concentration present in the laser measurement zone. This adjustment is referred to as the "coincidence correction factor." High particle concentrations can interfere with testing and reduce the accuracy of the analysis system. The higher the particle concentration in the sample flow, the higher the probability that more than one grown sample particle droplet is present in the laser measurement zone, and the optical system may only "count" one of the more than one particle in the measurement zone. As a result, a missed count occurs. For example, high particle concentrations per cubic centimeter (#cm) of fluid volume -3 It can exist at a particle concentration of 30,000 particles per ) . When automatic correction is applied, CPC is R 2 Up to 30,000 #cm with linearity of 0.99 and a maximum simultaneous correction factor of less than 15% -3 It enables the measurement of. CPC has the maximum particle concentration at which particles can be accurately counted in the flow, and this maximum value is referred to as the upper concentration in single-count mode (undiluted). For example, CPC is 30,000 #cm in single-count mode. -3It can have a higher concentration, which can be increased by using a diffusion screen or diluent included in the analysis system.

[0019] Accordingly, the particle concentration analysis system of the present invention provides a robust analysis system comprising a condensing particle counter for performing particle concentration analysis of a sample fluid, such as an engine exhaust gas PTI particle number test. The particle concentration analysis system can be configured for use in test facilities and for use in off-site tests, such as field test engines. The analysis system can be used in various environments, including vehicle engine exhaust gas analysis, power plant exhaust gas analysis, ambient air quality analysis, and other environments. The analysis system includes a sealed working fluid tank and a safety position switch to prevent damage, misuse, and contamination during test procedures and during transport of the analysis system. The analysis system includes pressure sensors and flow sensors to measure, verify, and calibrate the analysis system to ensure that tests performed by the analysis system meet predetermined quality requirements. A solvent recovery system may be included to reduce overall fluid consumption by recovering working fluid from the tested fluid flow to reduce the working fluid consumption rate and to increase the number of tests that can be performed without recharging the working fluid in the analysis system. The analysis system includes an automatic working fluid refill system that monitors and refills the working fluid consumed during testing to reduce handling and contamination that may be introduced by manual refilling of the working fluid. Additional features include an evaporator tube that evaporates volatile particles before releasing them into the ambient environment, an ejector diluter that dilutes the concentration of particles in the sample flow to increase the efficiency of the optical particle counter, a diffusion screen that selectively removes very small particles before they enter the condensation particle counter, and a precision capillary for simple and inexpensive flow verification.

[0020] These and other objects, advantages, objectives, and features of the present invention will become more apparent from a review of the following specification together with the drawings. Brief explanation of the drawing

[0021] FIG. 1 is a diagram of a particle concentration analysis system according to the present invention; FIG. 2 is a flowchart of a particle concentration analysis system according to the present invention; FIG. 3 is a rear elevation view of a particle concentration analysis system according to the present invention; FIG. 4 is a front elevation view of a particle concentration analysis system according to the present invention; FIG. 5 is a cross-sectional view of a capillary flow monitor for monitoring system flow in a particle concentration analysis system; FIG. 6 is a cross-sectional view of a three-way solenoid for drainage of a particle concentration analysis system; FIG. 6a is a detailed view of the 3-way solenoid valve of FIG. 6 in the "normally open" configuration; FIG. 6b is a detailed view of the 3-way solenoid valve of FIG. 6 in the "normally closed" configuration; FIG. 7 is a cross-sectional view of a cooled solvent recovery system for the recovery of working fluid in a particle concentration analysis system; FIG. 8 is a flowchart illustrating the calibration of a particle concentration analysis system; FIG. 9 is a perspective view of a particle concentration analysis system according to the present invention prepared for testing vehicle emissions; FIG. 10 is an exploded perspective view of a particle concentration analysis system according to the present invention; FIG. 11 is a cross-sectional view of a particle concentration analysis system according to the present invention; FIG. 11a is another cross-sectional view of the particle concentration analysis system of FIG. 11, illustrating the components and contents of the saturator of the particle concentration analysis system. Specific details for implementing the invention

[0022] Now, referring to the drawings and the exemplary embodiments illustrated in the drawings, a system (10) for analyzing particle concentration in a fluid is provided, comprising a condensation particle counter (CPC) (12), to analyze a sample fluid or aerosol to determine particle concentration or particle number in a sample (Fig. 1). The analysis system (10) may be configured to analyze various forms of fluid or aerosol samples, including, for example, engine exhaust gas, ambient atmosphere, power generation exhaust gas, etc., for periodic technical inspections (PTI). The analysis system (10) is configured to operate with a working fluid, such as isopropyl alcohol (IPA), to supersaturate the ambient air flow. The saturated ambient air flow is mixed with the sample air, and then the mixture of ambient air and sample air passes through a condenser, where the supersaturated ambient air condenses onto the particles of the sample air flow to grow the particles of the sample air flow, making the particles visible to an optical particle counter. The analysis system (10) includes a working fluid filling or refilling system (16) for monitoring the working fluid in the analysis system (10) and automatically filling or refilling it. The working fluid filling system (16) includes a pump (18) for filling and maintaining a sufficiently full level of working fluid in the analysis system (10). A working fluid tank (20) is included in the particle analysis system (10) to provide a source of working fluid to the analysis system (10). The analysis system (10) may be configured for use in a test facility where a trained operator can monitor and maintain the system (10). Optionally, the analysis system (10) may be suitable for portable use as a freestanding, portable, and robust particle analysis system (10a), such as for field testing of farm equipment (see FIG. 4 and FIG. 9).

[0023] The CPC (12) is configured to operate with a working fluid, such as isopropyl alcohol (IPA), to supersaturate the ambient air flow. In the exemplary embodiment of FIG. 1, the CPC (12) is a mixed CPC, so that the ambient air flow is supersaturated with the working fluid in a saturator block or fluid saturation chamber (22) independently of the sample fluid (e.g., engine exhaust gas). After supersaturation is achieved, the saturated ambient air is mixed with a sample flow of fluid, air, or aerosol between the saturator block (22) and the condenser (24). The saturated ambient air flow and the sample air flow may be mixed in a mixing chamber (25) upstream of the condenser (24), in the condenser (24), or at a mixing connection (27) of the saturated flow and the sample flow. Next, a mixture of ambient air flow and sample air flow passes through a condenser (24), where supersaturated ambient air condenses onto particles of sample air flow to grow sample air particles, which are then visible to an optical particle counter (14). When saturated ambient air condenses onto sample air particles, the sample air particles grow into larger droplets, such as droplets with a size of 5-10 micrometers (μm). A fluid or air filter (23), such as a HEPA filter, may be included in the analysis system (10) upstream of the saturator (22) to filter out unwanted particles from the ambient air, and such unwanted particles may interfere with the analysis results.

[0024] The grown particles are concentrated at or pass through a nozzle (28) having a wide end and a narrower end near the laser beam (30) at or near the inlet side (14a) of the optical particle counter (14). The nozzle (28) directs the flow of grown particles into a substantially uniform flow through the laser beam (30) and the optical field of the optical counter (14). The optical counter (14) counts the grown particles as they flow by the laser (30) by utilizing light scattering characteristics, for example using a pulse detection electronic device, to determine the number of sample air particles present in the sample fluid flow. After passing through the laser (30) and the optical particle counter (14), the analyzed fluid flow is discharged from the exhaust side (14b) of the optical counter (14).

[0025] In the exemplary embodiments of FIGS. 1 and 2, the particle analysis system (10) includes an automatic working fluid refill system (16) for automatically monitoring and refilling the working fluid in the saturator (22) when it is depleted during saturation of the HEPA-filtered ambient air flow. The fluid refill system (16) includes a working fluid pump (18) and a working fluid tank (20). The pump (18) draws the working fluid from the working fluid tank (20) and pumps it into the reservoir portion (26) of the saturator block (22). As illustrated in FIG. 1, the pump (18) is a peristaltic pump. A reservoir fluid level sensor (32) is placed in the reservoir (26) to monitor the level of the working fluid in the saturator (22). The fluid level sensor (32) electronically communicates with the pump (18) to maintain a sufficient level of working fluid in the saturator (22) to ensure proper operation of the analysis system (10). The automatic charging system (16) reduces fluid handling by technicians and reduces contamination of the working fluid.

[0026] The analysis system (10) may include an electronic controller (34) that communicates with the pump (18) and the fluid level sensor (32) and controls the pump (18) based on information received from the fluid level sensor (32). The controller (34) includes software configured to control the analysis system (10). The embedded computer may be provided with a software controller (34) that facilitates web-based wireless communication, a graphical user interface, or the integration of a third-party device (e.g., a Bluetooth-enabled diagnostic device, or a USB-based GPS module) with the analysis system (10) to control or monitor the system (10). The electronic controller includes a switch (35) for selectively operating different pumps in the analysis system (10).

[0027] The working fluid tank (20) requires periodic refilling and / or replacement during normal use of the CPC (12) and analysis system (10). Since the working fluid may be hygroscopic and flammable, safe handling of the working fluid is important. The working fluid tank (20) may be sealed, for example, with a self-sealing cap (e.g., a diaphragm) so that it does not leak even if tipped over and the hygroscopic working fluid inside the tank (20) is not exposed to water vapor, which could contaminate the working fluid. When the sealed tank (20) is removed, the self-sealing cap (not shown) contains the fluid inside the tank (20) to mitigate contamination and safety issues. Optionally, as described in more detail below, the working fluid tank (20) may include a molecular sieve for removing water from the working fluid.

[0028] The working fluid tank (20) and the working fluid pump (18) are fluidly connected to the CPC (12). The fluid tank (20) and the fluid pump (18) may be located away from the CPC (12). The tank (20) and the pump (18) may be disconnected from the CPC (12) to be replaced or recharged. Optionally, the working fluid pump (18) may be connected to the saturator block (22) and the working fluid tank (20) may be separated from the working fluid pump (18) so that the tank (20) may be disconnected from the pump (18) to be replaced or recharged. In another embodiment, the housing (36) accommodates and supports the CPC (12) and the fluid filling system (16) to provide a self-supporting analysis system (10a) (Figs. 4 and 9). The working fluid tank (20) of the system (10a) may be removed from the system to be recharged or replaced. Optionally, the working fluid tank (20) of the system (10a) can be refilled from an external tank so that removal from the housing (36) is unnecessary.

[0029] In one embodiment, the working fluid used in the analysis system (10) is isopropyl alcohol (IPA) with a purity of over 99%. Other fluids, such as n-butanol, may be used as the working fluid. The working fluid must be maintained at a high purity (e.g., over 99%). Impurities in the working fluid (e.g., water) can alter the vapor pressure / temperature relationship and cause inaccurate readings from the analysis system (10). The amount and purity of the IPA vapor generated in the saturator (22) are important for stable and accurate measurements. Since isopropyl alcohol, n-butanol, and other working fluids are hygroscopic, they may absorb water over time, which reduces the analytical efficiency of the analysis system (10). A water-absorbing material (not shown) may be supplied to the working fluid tank (20) to prevent or remove contamination or deterioration of the working fluid. The water-absorbing material in the working fluid tank (20) may be a 3A molecular sieve in the tank (20) to remove any water contamination from the surrounding air before entering the saturator (22) and thereby extend the working life of the fluid.

[0030] Under normal operation of the analysis system (10), the working fluid consumption rate may be 1-2 ml per hour. As illustrated, the saturator block reservoir (26) has a capacity of 10 ml of liquid working fluid. Due to the low consumption rate of the working fluid, the analysis system (10) can operate for a long period without the need to refill or replace the working fluid tank (20). A working fluid consumption rate of 1-2 ml per hour results in approximately 5 to 10 hours of continuous operation. For example, in the case of a 5-minute PTI test, approximately 60-120 PTI tests can be performed without refilling the saturator block reservoir (26). The working fluid tank (20) extends the operating period of the analyzer to several months, and the capacity of the working fluid tank (20) can be selected to accommodate shorter or longer test periods.

[0031] In one embodiment, the analysis system (10) includes at least one diffusion screen (not shown) upstream of the CPC (12) to improve the quality of the test results. The diffusion screen upstream of the CPC (12) is included to increase the response of the analysis system (10) to the currently established "automotive-PMP" standard of 23 nm. The number of diffusion screens required can be selected to meet different d50 cutoff points.

[0032] The CPC (12) can be configured to automatically adjust the reported count of particle concentration present in the laser measurement zone (30a). The adjustment ("simultaneous correction factor") enables the optical counter (14) to accurately count particles even when the particle concentration of the sample fluid is high. Without additional dilution means and using the simultaneous correction factor, the CPC (12) can 30,000 #cm -3 By correcting and verifying the analysis up to this point, the upper concentration can be displayed in a single count mode (undiluted) for the analysis system (10).

[0033] In the exemplary embodiment of FIG. 2, the analysis system is up to approximately 600,000 #cm -3 It includes an ejector diluent (40) that facilitates single particle counting at a concentration. A dilution air pump (42) is included upstream of the ejector diluent (40) to provide a dilution air flow to the ejector diluent (40) through the diluent input (40a). The ejector diluent (40) can be configured to dilute the sample flow of fluid at a nominal dilution ratio of 20:1. The ejector diluent (40) can be adjusted to change the dilution ratio. The ejector diluent (40) can also overcome humidity issues associated with testing vehicles and engines (e.g., gasoline engines) that emit high concentrations of water vapor by mixing the sample flow with ambient filtered dilution air. Optionally, about 600,000 #cm -3To test the particle concentration of the above, an additional ejector diluent (not shown) may be installed in the analysis system (10). For example, an additional dilution ejector diluent having a dilution ratio of 10:1 may increase the upper concentration limit of the analysis system (10) to 6,000,000 #cm -3 It can be extended. A filter (41), such as a HEPA filter, can be combined with the ejector diluent (40) to filter ambient air before it enters the ejector diluent (40).

[0034] The critical flow and pressure of the ejector diluent (40) and additional ejector diluents are monitored and controlled by the controller (34). Optionally, the ejector diluent (40) is coupled to an external part of the CPC (12) and provides cooling to the CPC (12) block through heat transfer from the CPC (12) block to the ejector diluent (40). In one embodiment, the ejector diluent (40) is integrated with the CPC, so that the mechanical pneumatic circuit (not shown) of the diluent (40) is completely constrained and thus does not require unique verification for particle loss.

[0035] The analysis system (10) may include an evaporator tube (not shown) for removing semi-volatile particles from the sample flow before the sample flow is mixed with the saturated flow and enters the condenser (24). The evaporator operates at approximately 300°C and enables a semi-volatile particle removal efficiency of over 95%, such as a tetracontan removal efficiency of over 95%. The analysis system (10) may be operated with an evaporator in an active or disabled configuration to facilitate, for example, the investigation of the possibility of reporting false vehicle PTI failures caused by intermittent emission of semi-volatile nanoparticles by a vehicle or engine during testing. When the analysis system (10) is configured to have additional ejector diluents and evaporator tubes, the analysis system (10) meets the Swiss PTI performance standards of the Swiss Federal Ordinance on Air Pollution Control (OAPC) 814.318.142.1.

[0036] An exhaust or extraction pump (44) is included in the analysis system (10) to draw the fluid away from the CPC (12) after the fluid is analyzed by the optical sensor (14). The extraction pump (44) is connected to the drain port (45) of the condenser (24) so ​​as to drain the CPC (12) as needed. The extraction pump communicates electronically with the electronic controller (34) and can be operated to turn on and off to exhaust the CPC (12), replenish fluid flow in the analysis system (10), drain the analysis system (10), or measure pressure values ​​in various components of the analysis system (10).

[0037] The analysis system (10) includes at least one differential pressure sensor or pressure transducer to determine each individual pressure by measuring two independent pressures and periodically controlling the pressure source (e.g., by turning on or off a pump). The analysis system (10) of the exemplary embodiment of FIG. 2 includes a differential pressure sensor (46) having two pressure measuring ports (46a and 46b). Two independent pressures, P1 and P2, can be determined by measuring the pressure response (P) through the periodic circulation of the source to P1 or P2. Pressure response P = P1 + P2, thus P1 = P-P2 during normal operation and P2 = P when the P1 source is turned off. The differential pressure sensor (46) reduces the complexity of resources required for pressure response measurement because the electronic device (34) required to turn off the dilution pump (42) or exhaust pump (44) is simpler and costs only a fraction of the cost of a more complex pressure transducer. The interval between isolating one pressure source and measuring both can be determined and set by the stability of the pressure signal.

[0038] Referring to FIG. 2, the pressure sensor (46) measures the negative pressure caused by the exhaust pump (44) and the positive pressure caused by the dilution air pump (42). The pumps (42, 44) are controlled using the pump controller electronic device (34). Under normal operation, the pressure sensor (46) reports the total differential pressure between the two sources, the dilution pump (42) and the exhaust pump (44). When the dilution air pump (42) is periodically turned off by the controller (34), the reported pressure is only the pressure caused by the exhaust pump (44). This difference can be used to determine or calculate the dilution air pump pressure under normal operation.

[0039] In the exemplary embodiment of FIG. 5, a flow measuring device or differential pressure sensor (48) having a precision capillary (50) for flow measurement is included to reduce or eliminate the need for individual flow correction in various flow paths of the analysis system (10). Individual flow correction may be required when the gas flow rate is determined by pressure measurement across a limiting part, such as an extraction orifice (52). A precision-manufactured capillary (50), such as a subcutaneous injection needle, is manufactured with strict engineering and surface tolerances and provides strict control tolerances for flow measurement by pressure drop without the need for correction. The flow rate (54) determined by the capillary is shown in FIG. 5 along with the corresponding differential pressure drop.

[0040] The sample flow (e.g., engine exhaust gas) to be analyzed by the analysis system (10) is directly measured by a sample differential pressure sensor (56) comprising a sample flow precision capillary (58). By directly calculating the sample flow using the sample capillary (58) of the sample sensor (56), potential sources of error can be reduced and the complexity and cost of the analysis system (10) can be reduced.

[0041] As illustrated in FIGS. 2 and 6, a three-way solenoid valve (60) is included to regulate fluid flow in the analysis system (10) and may be configured, for example, to drain the CPC (12) of the analysis system (10) from the drain port (45) of the condenser (24). The three-way valve (60) eliminates the need for real-time measurement of the drain flow. The three-way solenoid valve (60) can be optionally operated to periodically drain fluid from the condenser (24) (Fig. 6). The three-way solenoid (60) is controlled by a controller (34) to periodically switch the flow path from a "normally open" position (60a) to a "normally closed" position (60b) (see FIGS. 6a and 6b). The three-way solenoid valve (60) includes a drain port (45) of the CPC (12), an extraction orifice (52), and fluid connections to an extraction pump (44).

[0042] The extraction and drainage flow from the CPC (12) contains working fluid in both gaseous and liquid phases. In the exemplary embodiment of FIG. 7, the analysis system (10) includes a solvent or working fluid recovery system (64) to recover working fluid in both gaseous and liquid phases from the extraction and drainage flow. The recovery system (64) is coupled with the working fluid tank (20) to return the recovered working fluid to the working fluid tank (20) for reuse in the analysis system (10). An exhaust pump (44) pumps the extraction and drainage flow to the recovery inlet port (66) of the solvent recovery system (64). The recovery system (64) includes a vent (68) configured to exhaust vapor or gas from the recovery system (64) and also from the working fluid tank (20). The recovery system (64) reduces the concentration of vapor released through the vent (68) to recover a portion of the working fluid and reduce the overall working fluid consumption rate. As illustrated in FIG. 7, the solvent recovery system (64) includes a cooled heat exchanger (70), such as a Peltier device, to condense the working fluid vapor within the solvent recovery system (64), and the condensed working fluid is directed to return by gravity to the working fluid tank (20).

[0043] The analysis system (10) illustrated in FIG. 7 includes an operating fluid tank level sensor (72) for monitoring the level of the operating fluid in the operating fluid tank (20) and an operating fluid tank refill port (74) for refilling the operating fluid tank (20). The tank sensor (72) transmits the level of the operating fluid in the tank (20) to a controller (34), and the controller can then refill the operating fluid tank (20) by controlling the operating fluid pump (18) to draw fluid from an external fluid tank (not shown) into the operating fluid tank (20). Optionally, the controller (34) may provide a signal or warning to an operator that the operating fluid tank (20) needs to be refilled. A drain port (76) included in the analysis system (10) allows a user to drain the operating fluid tank (20), for example, for cleaning or transporting the system (10).

[0044] As illustrated in the exemplary embodiments of FIGS. 3 and 4, the analysis system (10 and 10a) includes selectable calibration ports (78, 80) to facilitate manual or automatic calibration of various components of the analysis system (10) without internal instrument access or disassembly or dismantling of the analysis system (10). The selectable port (78) is configured for calibration of the CPC (12), and the selectable port (80) is configured for the combined calibration of the CPC (12) and the ejector diluent (40). Calibration of the analysis system (10) is performed by introducing an aerosol or fluid having a known reference particle number and size. The selectable ports (78, 80) may be connected to a calibration system (82) configured to determine the calibration status of the analysis system (10) and to calibrate an incorrectly calibrated analysis system (10) ( FIG. 8).

[0045] The calibration system (82) includes a calibration manifold (84), a controllable data management analysis software system (86), a reference particle generator or source (88), and a reference particle counting device (90). The data management system (86) communicates electronically with the reference particle generator (88) and the reference particle counting device (90). The calibration manifold (84) is coupled to any one selectable port (78, 80) of one or more analysis systems (10). Each analysis system (10) coupled to the calibration system (82) communicates electronically with the data management system (86). The calibration system (82) is controlled by the data management system (86) to calibrate or verify the analysis system (10). The reference particle generator (88) generates a calibration fluid flow having a uniform number of particles and particle size. The reference particle counter (90) analyzes the calibration fluid flow to determine the uniform number of particles and particle size generated by the particle generator (88). The calibration system (82) and calibration manifold (84) may be configured to calibrate or verify multiple devices or systems (10) in parallel using one reference particle generator (88) and one reference particle counting device (90).

[0046] The analysis system (10) includes a gas sensor system (92) for flow correction or verification. The gas sensor system (92) can provide flow, measurement, correction, and verification by determining the number of particles in a reference flow of a reference gas having a known particle density of parts per million. The gas sensor system (92) includes a gas sensor (94) to facilitate checking the system flow. The gas sensor (94) has a parts per million (ppm) measurement range such as 0 to 10,000 ppm. In an exemplary embodiment, carbon dioxide of a known concentration is introduced into the analysis system (10) as a reference gas through a reference gas inlet or input port (96). Particles of the reference gas are mixed or diluted with diluted air from an ejector diluent (40) and then further diluted or mixed with saturated air from a CPC saturator (22). The concentration of the reference gas can be measured in the exhaust gas of the ejector diluent (40) or the CPC exhaust gas (52), and the measured concentration can be calculated using a reference gas of a known concentration to verify the dilution ratio and flow of the analysis system (10). For example, when a reference carbon dioxide gas having a known concentration of 10,000 ppm, reporting a dilution ratio of 20:1 as measured, calculated, and reported by the system electronic device module (34), is introduced into the system through the input (96) and passes through the ejector diluent (40), the concentration in the exhaust gas of the ejector diluent (40) should be 500 ppm (10,000 ppm ÷ 20). At the exhaust gas outlet of the CPC (52), the concentration of carbon dioxide will be further reduced by the ratio of the CPC sample flow rate (54) to the saturator flow rate when entering the CPC saturator (22). If the concentration measured by the CO2 sensor (94) is within a predetermined margin (e.g., < 5%) of the expected carbon dioxide concentration in the ejector diluter (40) exhaust gas or CPC exhaust gas (52), the flow and analysis system (10) is verified.

[0047] A carbon dioxide sensor (94) may be configured to check whether a sampling probe (98) inserted into the engine (e.g., the vehicle's exhaust pipe) is correctly inserted (see FIG. 9). The sampling probe (98) is connected to an analysis system (10) via a sampling line or hose (99) at a sample line vacuum input port (112) and collects or receives a sample fluid (e.g., engine exhaust gas) from a source such as an exhaust pipe. Since the sampling probe (98) is detachable from the analysis system (10), the analysis system (10) can receive the sample fluid directly through the sample input port (112). The engine emits a significant amount of carbon dioxide (e.g., 16 volume% from a gasoline engine operating under stoichiometric combustion conditions). If the sampling probe (98) is not fully or correctly inserted into the vehicle's exhaust pipe, the measured carbon dioxide is mixed with ambient air and is lower than expected. As a result, engine exhaust particulates may be diluted with clean ambient air, allowing a "dirty vehicle" to pass through that does not pass through a properly performed exhaust gas analysis. The carbon dioxide sensor (94) provides a cheat-prevention device that prevents the user from intentionally failing to insert the sampling probe (98) sufficiently into the vehicle exhaust pipe to "pass" the vehicle. The concentration of carbon dioxide measured by the carbon dioxide sensor (94) is compared with the expected gas concentration (e.g., 16%) to verify whether the sampling probe (98) is properly inserted into the exhaust pipe and does not receive a diluted exhaust gas sample.

[0048] The optical particle counter (14) of the CPC (12) includes an optical chamber (114) having a lens (not shown) and a laser diode light source (30a). Because the analysis system (10) uses a working fluid to grow particles before they are counted in the particle counter (14), the working fluid may move or be transported unintentionally into the optical chamber (114), potentially contaminating the optical system. The tipping or misalignment of the analysis system (10) may cause the working fluid to be pumped or transported into the optical chamber (114) while the analysis system (10) is turned on. The analysis system (10) includes a safety or tipping protection unit (116). The safety unit (116) includes a 3-axis capacitive micro-machined accelerometer (e.g., NMA8451 from NXP Semiconductors) (not shown). The safety unit (116) communicates with the electronic controller (34), and the output from the accelerometer is transmitted to the controller (34) to convert or calculate the device inclination angle. If the calculated angle is greater than a predetermined safety angle or a designed orientation, the controller (34) triggers a "protection mode" and turns off the pumps (18, 42 and 44). The safety operating angle can be up to 40 degrees from the vertical axis in any direction. The protection mode prevents damage to the analysis system (10) and potentially costly repairs.

[0049] The condition or purity of the working fluid is important for the proper operation of the analysis system (10). Contamination or improper filling can degrade or render the working fluid in the analysis system (10) unusable, for example, by filling the working fluid tank (20) with the wrong fluid. In such a situation, the level sensor, the reservoir fluid level sensor (32), or the working fluid tank liquid level sensor (72) may still report that the analysis system (10) is ready for operation. Operating the analysis system (10) with contaminated or wrong working fluid can cause damage to various components of the analysis system (10). Options for monitoring and controlling the condition of the working fluid, as well as other options being considered, include measuring the concentration of the working fluid in the extraction flow using a gas purity sensor (48) placed close to the extraction orifice (52), providing a sealed tamper-proof working fluid tank (20), or providing a sealed tamper-proof bottle for an external refill container used to refill the working fluid tank (20).

[0050] The saturator (22) of the CPC (12) includes a saturating material or wick (118) that fills the internal voids of the saturator (22). The wick (118) absorbs working fluid from the working fluid reservoir (26), so that ambient air flowing through the saturator (22) passes through the wick (118) and the absorbed working fluid is available to saturate the ambient air of the saturator (22). The wick (118) provides increased efficiency during the saturation process to provide a higher level of supersaturation to the ambient air.

[0051] Changes and modifications to the specifically described embodiments may be made without departing from the principles of the invention, which are intended to be limited only by the scope of the appended claims as interpreted in accordance with the principles of patent law, including the doctrine of equivalents.

[0052] An embodiment of the present invention for which an exclusive property or privilege is claimed is limited as follows:

Claims

Claim 1 A particle concentration analysis system configured to count the particle concentration of a sample fluid, comprising: a working fluid tank configured to receive a working fluid; a sample fluid input configured to receive a sample fluid to be analyzed; a fluid saturation chamber configured to saturate ambient air flow with a working fluid; a condenser configured to condense the working fluid-saturated ambient air flow from the fluid saturation chamber onto the sample fluid; and a condensation particle counter comprising an optical particle counter configured to count sample particles present in the sample fluid; a fluid level sensor disposed inside the fluid saturation chamber; and a working fluid pump configured to transfer the working fluid from the working fluid tank to the fluid saturation chamber. and an electronic control unit that counts sample particles present in the sample fluid in response to the optical particle counter; the electronic control unit controls the working fluid pump in response to the fluid level sensor to automatically fill the fluid saturation chamber with the working fluid in response to information from the fluid level sensor regarding the working fluid level in the fluid saturation chamber; an exhaust pump located downstream of the condensing particle counter configured to draw fluid from the condensing particle counter; the exhaust pump communicates electronically with the electronic control unit; an ejector diluent located upstream of the condensing particle counter; the ejector diluent is coupled to or integrated with the condensing particle counter; and a dilution pump located upstream of the ejector diluent and configured to pump a dilution air flow to the ejector diluent; the dilution air flow is separated from the ambient air flow, and the ejector diluent is configured to dilute the concentration of sample particles in the fluid sample to a predetermined dilution ratio before the sample fluid enters the condensing particle counter by introducing the dilution air flow into the sample fluid, and the ejector diluent and the dilution pump communicate electronically with the electronic control unit. Communicating particle concentration analysis system. Claim 2 A particle concentration analysis system according to claim 1, wherein the working fluid tank, the working fluid pump, the sample fluid input, the condensed particle counter, and the electronic control unit are interconnected as an assembly and configured to count particles of the sample fluid. Claim 3 A particle concentration analysis system according to claim 1, further comprising a safety unit communicating with the electronic control unit, wherein the electronic control unit is configured to automatically turn off the working fluid pump, the exhaust pump, and the dilution pump of the analysis system when the analysis system is not within a predetermined position, and the safety unit comprises a 3-axis accelerometer that outputs a signal to the electronic control unit. Claim 4 A particle concentration analysis system according to claim 1, further comprising a sampling probe for insertion into a vehicle exhaust pipe and a sampling line having one end coupled to the sampling probe and the opposite end removablely coupled to the sample fluid input upstream of the condenser, wherein the sampling line is fluidly communicating with the sample fluid input and the sampling probe. Claim 5 delete Claim 6 delete Claim 7 A particle concentration analysis system according to claim 1, further comprising a differential pressure sensor disposed along the flow path of the analysis system and configured to determine the differential pressure of the analysis system. Claim 8 A particle concentration analysis system according to claim 7, wherein the differential pressure sensor is configured to measure a first pressure at a first pressure measuring port disposed in the system and to measure a second pressure at a second pressure measuring port disposed in the system. Claim 9 A particle concentration analysis system according to claim 8, wherein the electronic control unit further responds to the exhaust pump and the dilution pump to measure a first pressure by selectively turning off the dilution pump and instructing the differential pressure sensor to measure the first pressure while the dilution pump is turned off, or to measure a second pressure by selectively turning off the exhaust pump and instructing the differential pressure sensor to measure the second pressure while the exhaust pump is turned off, and the electronic control unit is configured to calculate the differential pressure between the first pressure and the second pressure. Claim 10 A particle concentration analysis system according to claim 1, wherein the working fluid tank is self-supporting and removable from the condensation particle counter, and the working fluid tank is sealed so as not to flow or leak when moved, inverted, or switched. Claim 11 In paragraph 10, the particle concentration analysis system, wherein the working fluid tank further comprises a water-absorbing material to prevent contamination or deterioration of the working fluid. Claim 12 A particle concentration analysis system according to claim 11, wherein the water-absorbing material is a molecular sieve configured to be placed in the working fluid tank to remove contaminants from the working fluid. Claim 13 In paragraph 11, the particle concentration analysis system, wherein the water-absorbing material is a hygroscopic material configured to remove water contaminants from a working fluid. Claim 14 A particle concentration analysis system according to claim 1, further comprising an evaporator tube configured to remove semi-volatile particles from the analysis system. Claim 15 A particle concentration analysis system according to claim 1, further comprising a gas sensor disposed downstream of the working fluid tank and configured to measure the purity of the working fluid transferred from the working fluid tank to the fluid saturation chamber. Claim 16 A particle concentration analysis system according to claim 1, further comprising a solvent recovery system configured to recover a working fluid from the exhaust flow of a sample fluid discharged from the condensing particle counter after passing through the optical particle counter, wherein the solvent recovery system returns the recovered working fluid to the working fluid tank for reuse in the particle concentration analysis system. Claim 17 In claim 16, the solvent recovery system is a particle concentration analysis system comprising a cooling device. Claim 18 A particle concentration analysis system according to claim 4, further comprising a cheat prevention device, wherein the cheat prevention device comprises a carbon dioxide concentration sensor configured to measure the concentration of carbon dioxide present in the sample fluid, and wherein the cheat prevention device is configured to compare the measured carbon dioxide concentration with an expected carbon dioxide concentration and evaluate whether to insert a sampling probe into a vehicle exhaust pipe based on the compared concentration. Claim 19 A particle concentration analysis system according to claim 1, wherein the working fluid pump is a peristaltic pump configured to automatically fill the working fluid tank with the working fluid. Claim 20 A particle concentration analysis system according to claim 1, further comprising a gas concentration sensor located downstream of the sample fluid input and configured to measure the gas concentration of the particle concentration analysis system. Claim 21 A particle concentration analysis system according to claim 20, wherein the electronic control unit is further configured to determine whether the particle concentration analysis system is calibrated by comparing the gas concentration measured by the gas concentration sensor with a known gas concentration of a reference gas introduced upstream of the gas concentration sensor, and the electronic control unit is configured to calculate and determine whether the measured gas concentration is within a specific range of the known gas concentration. Claim 22 In claim 21, the above gas concentration sensor is a particle concentration analysis system including a carbon dioxide concentration sensor. Claim 23 A particle concentration analysis system according to claim 1, further comprising a liquid level sensor disposed within the fluid saturation chamber, wherein the liquid level sensor is configured to indicate the working fluid level within the fluid saturation chamber. Claim 24 A particle concentration analysis system according to claim 1, further comprising a fluid tank level sensor disposed within the working fluid tank, wherein the fluid tank level sensor is configured to indicate the working fluid level within the working fluid tank. Claim 25 A particle concentration analysis system according to claim 1, wherein the electronic control unit further comprises a low-cost wireless communication system configured to wirelessly communicate with the electronic control unit to control the particle concentration analysis system. Claim 26 A particle concentration analysis system according to claim 1, wherein the electronic control unit further includes a low-cost graphical user interface. Claim 27 A particle concentration analysis system according to claim 1, wherein the electronic control unit comprises a plurality of electronically controlled pump switches. Claim 28 A particle concentration analysis system according to claim 27, wherein the plurality of electronically controlled pump switches comprises an exhaust pump switch and an operating fluid pump switch, wherein the exhaust pump switch is configured to electronically control power to the exhaust pump and the operating fluid pump switch is configured to electronically control power to the operating fluid pump. Claim 29 A particle concentration analysis system configured to count the particle concentration of a sample fluid, comprising: a working fluid tank configured to receive a working fluid; a sample fluid inlet configured to receive a sample fluid to be analyzed; a fluid saturation chamber configured to saturate ambient air flow with the working fluid; a condenser configured to condense the working fluid-saturated ambient air flow from the fluid saturation chamber onto the sample fluid; and a condensation particle counter comprising an optical particle counter configured to count sample particles present in the sample fluid; a fluid level sensor disposed inside the fluid saturation chamber; a working fluid pump configured to transfer the working fluid from the working fluid tank to the fluid saturation chamber; and an exhaust pump located downstream of the condensation particle counter and configured to draw fluid from the condensation particle counter—the exhaust pump electronically communicates with an electronic control unit—; An ejector diluent located upstream of the condensation particle counter—the ejector diluent being coupled to or integrated with the condensation particle counter—and a dilution pump located upstream of the ejector diluent and configured to pump a dilution air flow to the ejector diluent—the dilution air flow being separated from the ambient air flow, and the ejector diluent being configured to dilute the concentration of sample particles in the fluid sample to a predetermined dilution ratio before the sample fluid enters the condensation particle counter by introducing the dilution air flow into the sample fluid, and the ejector diluent and the dilution pump communicating electronically with the electronic control unit—; a differential pressure sensor positioned along the flow path of the analysis system and configured to determine the differential pressure of the analysis system; a safety unit communicating with the electronic control unit—the electronic control unit being configured to automatically turn off the working fluid pump, the exhaust pump, and the dilution pump of the analysis system when the analysis system is not within a predetermined position, and the safety unit including a 3-axis accelerometer that outputs a signal to the electronic control unit—;A particle concentration analysis system comprising, wherein the electronic control unit determines a differential pressure between the exhaust pump and the dilution pump in response to the exhaust pump, the dilution pump, and the differential pressure sensor, and the electronic control unit further responds to selectively turn off the dilution pump and instruct the differential pressure sensor to measure the exhaust pump pressure while the dilution pump is turned off and the exhaust pump is operating, and selectively turn off the exhaust pump and instruct the differential pressure sensor to measure the dilution pump pressure while the exhaust pump is turned off and the dilution pump is operating, and the electronic control unit is configured to calculate a differential pressure between the exhaust pump pressure and the dilution pump pressure based on the pressure measured by the differential pressure sensor. Claim 30 delete Claim 31 delete Claim 32 delete Claim 33 delete Claim 34 delete Claim 35 A method for analyzing the particle concentration of a fluid sample, comprising: a directing step of directing a sample of the sample fluid to a particle concentration analysis system, wherein the analysis system comprises a working fluid tank, a working fluid pump, a fluid saturator block, a saturator fluid level sensor disposed within the fluid saturator block, a mixing chamber, a condenser, a particle counter, and an electronic control unit; a step of controlling the working fluid pump with the electronic control unit and pumping the working fluid from the working fluid tank to the fluid saturator block in response to information from the fluid level sensor regarding the fluid level within the fluid saturator block; a step of heating the working fluid in the fluid saturator block; a step of directing ambient air flow to the fluid saturator block; a step of saturating the ambient air flow with the heated working fluid to generate a saturated fluid flow; a step of transporting the saturated fluid to a mixing chamber; a step of mixing the saturated fluid with the sample fluid in the mixing chamber to generate a mixture of the sample fluid and the saturated fluid; a step of transporting the mixture to a condenser downstream of the mixing chamber; a step of condensing the saturated fluid onto the sample particles of the sample fluid to grow the sample particles; and an optically A step of transporting through a particle counter; a step of counting the grown sample particles with the optical particle counter; a step of receiving information from the optical particle counter in an electronic control unit that electronically communicates with the optical particle counter; a step of determining the concentration of sample particles in a sample fluid using the electronic control unit; a step of exhausting the sample particles counted from the optical particle counter through an exhaust pump located downstream of the condensation particle counter and configured to draw fluid from the condensation particle counter, wherein the exhaust pump electronically communicates with the electronic control unit;A method comprising: a step of pumping a dilution air flow to an ejector dilutor through a dilution pump located upstream of the ejector dilutor, wherein the dilution air flow is separated from the ambient air flow, and the ejector dilutor is located upstream of the condensation particle counter and is coupled to or integrated with the condensation particle counter; and a dilution step comprising introducing the dilution air flow into the sample fluid to dilute the concentration of sample particles in the fluid sample by a predetermined dilution ratio before the sample fluid enters the condensation particle counter, wherein the ejector dilutor and the dilution pump communicate electronically with an electronic control unit. Claim 36 A method according to claim 35, further comprising the step of diluting a sample fluid in an ejector diluent and transporting the diluted sample to the mixing chamber by a dilution pump. Claim 37 A method according to claim 36, further comprising the steps of: alternately turning off the dilution pump and the exhaust pump using the electronic control unit - wherein the electronic control unit comprises a plurality of pump switches -, measuring the pressure between the dilution pump and the exhaust pump using a differential pressure sensor that communicates electronically with the electronic control unit while alternately turning off the dilution pump and the exhaust pump, and calculating the differential pressure between the dilution pump and the exhaust pump using the electronic control unit. Claim 38 A method according to claim 35, further comprising the steps of: monitoring the fluid level of the fluid saturator block using a saturator fluid level sensor; monitoring the fluid level of the working fluid tank using a fluid tank level sensor; transmitting information of the measured fluid level to the electronic control unit; and automatically refilling the working fluid in the fluid saturator block based on information received by the electronic controller from the saturator fluid level sensor and the fluid tank level sensor. Claim 39 The method of claim 35 further comprises the step of turning off the working fluid pump, the exhaust pump, and the dilution pump of the particle concentration analysis system by the electronic control unit communicating with a safety unit when the particle concentration analysis system is not in an ideal operating position, wherein the safety unit includes a 3-axis accelerometer, and the electronic control unit is configured to turn off the working fluid pump, the exhaust pump, and the dilution pump when the 3-axis accelerometer detects that the particle concentration analysis system is not within a predetermined position. Claim 40 A method according to claim 35, further comprising the steps of recovering a working fluid from a discharged counted aerosol using a solvent recovery system and returning the recovered working fluid to a working fluid tank so that it is recirculated and reused in the particle concentration analysis system. Claim 41 A method according to claim 35, further comprising the steps of measuring the concentration of carbon dioxide present in a sample fluid using a gas concentration sensor that electronically communicates with the electronic control unit, and evaluating whether to insert a sampling probe into a vehicle exhaust pipe using the electronic control unit by comparing the gas concentration measured from the gas concentration sensor with an expected exhaust gas concentration. Claim 42 A method according to claim 35, further comprising the steps of: introducing a reference fluid flow into the particle concentration analysis system at a reference gas inlet port upstream of the condenser—the reference fluid having a known particle concentration—; measuring the particle concentration in the particle concentration analysis system with a gas sensor positioned downstream of the condenser—the gas sensor communicating electronically with the electronic control unit—receiving the particle concentration measured from the gas sensor in the electronic control unit; comparing the measured particle concentration with an expected particle concentration based on the known particle concentration of the reference fluid using the electronic control unit; and determining whether the flow value of the particle concentration analysis system is within a required calibration margin based on the comparison of the measured particle concentration and the expected particle concentration. Claim 43 A method according to claim 35, further comprising the step of measuring the purity of a working fluid from a working fluid tank using a gas purity sensor - said gas purity sensor electronically communicates with said electronic control unit - and the step of verifying whether said working fluid meets a required purity using said electronic control unit. Claim 44 delete Claim 45 delete Claim 46 delete Claim 47 delete

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