APPARATUS AND METHOD FOR SAMPLING AN EXHAUST GAS

[0001] This invention relates to a sampling apparatus for sampling an exhaust gas, and to a method of sampling an exhaust gas, for example a combustion engine exhaust gas of a vehicle.

BACKGROUND

[0002] When a combustion engine is operated various inorganic and organic pollutants are generated, including carbon dioxide, carbon monoxide, nitrogen oxides, nitrous oxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons, sulfur dioxide, and ammonia. These pollutants are emitted from the tailpipe, and regulations in many jurisdictions stipulate limits on some of these pollutants and so vehicle manufacturers and regulators must measure the amounts of the pollutants being emitted by specific combustion engines.

[0003] Similar requirements exist for other forms of combustion exhaust, for example gas boilers, power generators, and the like.

[0004] Traditionally, to measure combustion engine emissions under simulated driving conditions in the laboratory, a Constant Volume Sampling (CVS) dilution tunnel is used. The CVS dilution tunnel captures the complete raw exhaust and dilutes it with a large quantity of clean ambient air such that the total volume flowrate though the tunnel is held constant. This process simulates the conditions under which the combustion engine releases exhaust into the atmosphere and facilitates the analytical measurement under both real-time and integrated sampling techniques. These CVS systems are both large and expensive.

[0005] Mini-dilution tunnels based on partial exhaust sampling have been developed, such as described in US. Pat. No. US 2007/0068236A1. These systems work by sampling part of the engine exhaust gas flow, keeping a constant split ratio (the ratio of exhaust flow to sampled flow). Holding this split ratio constant allows for mass-based emission calculations to be calculated with non-real-time instrumentation.

[0006] To quantify the split ratio, both the exhaust flow rate and the sample flow rate must be either measured and/or calculated. For example, the exhaust flow rate can be determined by commercially available Exhaust Flow Meters (EFM), or by sensor-based measurements (for example fuel flow and intake air flow).

[0007] When an engine operates under transient conditions the exhaust flow rate changes dynamically and so partial flow proportional sampling systems require fast and accurate control of the various flows to maintain a constant real-time split ratio. Laws, standards, and regulations exist for such systems (for example ISO 16183) and typically contain metrics for response rates, accuracy, and linearity of the ratio of the sampled flow to exhaust flow (split ratio). Typically, high speed (<100ms) and accurate response rate control of the various controls is required and has typically resulted in sophisticated, expensive, and large enclosures.

[0008] The diluted pollutants are measured using a combination of real-time and post test analysis though the use of integrated samples. For example, inert bags may be filled during various phases of the laboratory simulated driving sequence for post-test analysis. For integrated gaseous samples, the diluted exhaust is often sampled into inert bags (for example, Tedlar and Kynar) for analysis and are typically sized in the region of 75 x 120 cm. Operating bags under real-driving conditions is problematic due to size and transport of the bags to and from the analysis laboratory.

[0009] The analytical techniques employed to measure the gaseous pollutants typically include optical (non-disperse and Fourier-transform) spectroscopy, but other solutions based on for example photo-acoustic spectroscopy are also used. Real-time Fourier transform infrared spectroscopy is generally the preferred solution for VOC speciation, but these devices are typically expensive and not suitable for real-driving emissions measurements.

[0010] For real-driving emissions measurements, Portable Emission Measurement Systems (PEMS) are the standard regulatory equipment, and they include real-time exhaust flow measurements in addition to the main criteria pollutants (C02, CO, NOX, THC and particulates). These devices are commercially available from a number of companies including Sensors Inc, Horiba and AVL.

[0011] For integrated sampling, sorbent tubes have been used since the 1970’s to collect various pollutants for post-collection quantitative and qualitative analysis. These tubes are typically small and contain one-or more adsorbent materials for the collection of a wide variety of compounds. They can be operated in either a passive (diffusion) or active (pumped) manner. For active sampling, the maximum flow rate is governed by the breakthrough or retention of the specific pollutant and is typically around 200 ml/min. These tubes are small, inexpensive and can be stored and shipped in both a clean and used condition.

[0012] For sorbent tubes being processed as thermal desorption tubes, the sample tube is initially leak tested then heated in a flow of carrier gas (typically helium) to desorb the collected analytes. The desorption temperature needs to be high enough (typically 200-300 degrees Celsius) to extract all the analytes, but not so high as to generate artefacts from thermal degradation of the sorbent. The desorption volume should be as small as possible but sufficient enough to extract all the analytes from the sorbent. The desorbed analytes are concentrated on a low mass focusing trap (FT), usually maintained at sub-ambient temperature and often referred to as the ‘cold’ trap. If dilution is required, an inlet split allows some of the desorbed sample to be vented to waste or, in some systems, into a clean sorbent tube for subsequent reanalysis. At the end of the desorption period the FT is rapidly heated, and the collected analytes are flushed into the gas chromatography (GC) system via an outlet split where, if required, a second dilution may be made.

[0013] Thermal desorption offers several benefits over Solvent Desorption (SD). In particular, during thermal desorption analysis around 2% of the desorbed analytes reach the GC detector compared with less than 0.1% for a 1 ml injection of a sample desorbed into 1 ml of solvent. Consequently, thermal desorption offers much greater sensitivity than solvent desorption. In addition, Chromatograms obtained using thermal desorption contain no solvent peak, the presence of which can mask the presence of some analytes and hinder the use of MS-based detection. Also, modern thermal desorption equipment sample tubes can be analysed with minimal sample handling thereby reducing labour costs and improving precision.

[0014] Gas chromatography (GC) is the preferred separation technique for smaller volatile and semi-volatile organic molecules such as hydrocarbons, alcohols, and aromatics, as well as pesticides, steroids, fatty acids, and hormones, making this analytical technique common in many application areas and industry segments, particularly for food safety and environmental testing. When combined with the detection power of mass spectrometry (MS), Gas Chromatography Mass Spectrometry (GC-MS) can be used to separate complex mixtures, quantify analytes, identify unknown peaks, and determine trace levels of contamination.

[0015] GC-MS can be used to study liquid, gaseous or solid samples. Analysis begins with the gas chromatograph, where the sample is effectively vaporized into the gas phase and separated into its various components using a capillary column coated with a stationary (liquid or solid) phase. The compounds are propelled by an inert carrier gas such as helium, hydrogen, or nitrogen. As components of the mixture are separated, each compound elutes from the column at a different time based on its boiling point and polarity. The time of elution is referred to as a compound's retention time. GC has the capacity to resolve complex mixtures or sample extracts containing hundreds of compounds. GC columns represent the stationary phase and separation tool of a gas chromatography analysis. The stationary phase ensures that different compounds are adequately separated and eluted from the column at different times. Different types of columns with different stationary phases can be used for different applications, such as determining volatile organic compounds (VOCs) or dioxins. They can be designed to separate polar or non-polar compounds or process samples at different speeds. It is important that columns do not release stationary phase compounds, thus providing minimal background signal in the resulting chromatogram, sometimes referred to as being “low bleed”. Inertness of GC column material is also a critical factor to considering in order to prevent unwanted chemical interactions with the sample.

[0016] Once the components leave the GC column, they are ionized and fragmented by the mass spectrometer using electron or chemical ionization sources. Ionized molecules and fragments are then accelerated through the instrument’s mass analyser, which is usually a quadrupole, time of flight or ion trap. It is here that ions are separated based on their different mass-to-charge (m/z) ratios. GC-MS data acquisition can be performed in either full scan mode, to cover either a wide range of m/z ratios, or selected ion monitoring (SIM) mode, to gather data for specific masses of interest.

[0017] The final steps of the process involve ion detection and analysis, with fragmented ions appearing as a function of their m/z ratios. Peak areas, meanwhile, are proportional to the quantity of the corresponding compound. When a complex sample is separated by GC-MS, it will produce many different peaks in the gas chromatogram and each peak generates a unique mass spectrum used for compound identification. Using extensive commercially available libraries of mass spectra, compounds and target analytes can be identified and quantified.

[0018] High-performance liquid chromatography (HPLC) is a type of liquid chromatography used to separate and quantify compounds that have been dissolved in solution. HPLC is used to determine the amount of a specific compound in a solution.

In HPLC and liquid chromatography, where the sample solution is in contact with a second solid or liquid phase, the different solutes in the sample solution will interact with the stationary phase as described. The differences in interaction with the column can help separate different sample components from each other. The type and composition of the mobile phase affects the separation of the components. Different solvents are used for different types of HPLC. For normal-phase HPLC, the solvent is usually nonpolar, and, in reverse-phase HPLC, the solvent is normally a mixture of water and a polar organic solvent. The purity of solvents and inorganic salts used to make the mobile phase is paramount.

[0019] HPLC has various components which includes mobile phase, a pump, injector, column, detector and integrator or acquisition and display system. The heart of the system is the column where separation occurs. Since the stationary phase may be composed of micron-sized porous particles, a high-pressure pump is required to move the mobile phase through the column. The chromatographic process begins by injecting the solute into the injector at the end of the column. Separation of components occurs as the analytes and mobile phase are pumped through the column. The most widely used packing materials for HPLC (column) separations are silica-based. The most popular material is octadecyl-silica (ODS-silica), which contains C18 coating, but materials with C1, C2, C4, C6, C8 and C22 coatings are also available. Miscellaneous chemical moieties bound to silica, as well as polymeric packing, are designed for purification of specific compounds. Other types of column packing materials include zirconia, polymer-based and monolithic columns. Eventually, each component elutes from the column as a peak on the data display. Detection of the eluting components is important, and the method used for detection is dependent upon the detector used.

The response of the detector to each component is displayed on a chart recorder or computer screen and is known as a chromatogram. To collect, store and analyse the chromatographic data, integrators and other data-processing equipment are frequently used. The detector is used to sense the presence of a compound passing through and to provide an electronic signal to a data-acquisition device. The main types of detectors used in HPLC are refractive index (Rl), ultraviolet (UV-Vis) and fluorescence, but there are also diode array, electrochemical and conductivity detectors.

[0020] HPLC can also be hyphenated with other techniques which will improve the ability to separate and identify multiple entities within a mixture. These techniques include liquid chromatography-mass spectrometry (LC-MS), liquid chromatography- mass spectrometry-mass spectrometry (LC-MSMS), liquid chromatography-infrared spectroscopy (LC-IR) and liquid chromatography-nuclear magnetic resonance (LCNMR). These techniques usually involve chromatographic separation followed by peak identification with a traditional detector such as UV, combined with further identification of the compound with the MS, IR or NMR.

[0021] The determined mass-based measurements of the various analytics collected on the sorbent tubes described above can be used to determine the combustion engine emission rates emitting from the tailpipe by calculation using the sampling split-ratio. [0022] Although many methods have been developed and validated by occupational and safety organizations as well as regulatory bodies, applying these generic principles to automotive tail-pipe sampling that requires proportional sampling to determine mass- emission rates is generally laboratory-based complicated, difficult, and expensive.

BRIEF SUMMARY OF THE DISCLOSURE

[0023] An aspect of the present invention provides a method of sampling an exhaust gas, for example a combustion engine exhaust gas, the method comprising: separating a sample flow from an exhaust gas flow, and based on a variable parameter: directing the sample flow into a first integrated sampler, or directing the sample flow into a second integrated sampler.

[0024] The method may further comprise directing the sample flow into a third integrated sampler, a fourth integrated sampler, a fifth integrated sampler and so on, based on the variable parameter.

[0025] By directing the sample flow into the different integrated samplers based on the variable parameter, different integrated samples can be obtained based on the variable parameter. For example, as the variable parameter changes the method may obtain different integrated samples, allowing the obtained samples to be analysed to determine a property of the exhaust gas corresponding to the variable parameter. For example, as explained in more detail below, if the variable parameter were an engine operating temperature, then different integrated samples could be obtained for different engine operating temperatures and the different integrated samples could be analysed to determine pollutant levels in the exhaust gas at the different engine operating temperatures.

[0026] In examples, the variable parameter may comprise an operator input. For example, the operator input may be provided by an operator interface such as a control panel, switch or computing device. The operator input allows an operator to choose when to change from the first integrated sampler to the second integrated sampler.

[0027] In examples, the variable parameter may comprise time. For example, the sample flow may be directed into the first integrated sampler during a first time period, and the sample flow can be directed into the second integrated sampler during a second time period. Accordingly, different integrated samples can be obtained at different times. [0028] In examples, the method may further comprise detecting the variable parameter by one or more sensors. In examples, the method may additionally or alternatively comprise receiving the variable parameter, for example from an external control system such as a control system of the combustion equipment that generates the exhaust flow. In some examples, the method may comprise receiving information relating to the variable parameter and determining the variable parameter from the received information.

[0029] In examples, the variable parameter may comprise a variable parameter of the sample flow. For example, the variable parameter may comprise a temperature of the sample flow, a pressure of the sample flow, a flow rate (volumetric or mass) of the sample flow, and/or an integrated volume of the sample flow. The variable parameter of the sample flow may be detected by one or more sensors.

[0030] In examples, the method may comprise directing the sample flow into the first integrated sampler until the integrated volume of the sample flow passed into the first integrated sampler reaches a threshold. After the threshold has been met the sample flow is not directed into the first integrated sampler. The threshold may be based on a saturation of the first integrated sampler. Such an integrated volume threshold may be used in combination with any of the other example variable parameters to prevent saturation of the integrated sampler.

[0031] In examples, the variable parameter may comprise a variable parameter of the exhaust gas flow. For example, the variable parameter may be a temperature of the exhaust gas flow, a pressure of the exhaust gas flow, a flow rate (volumetric or mass) of the exhaust gas flow, and/or an integrated volume of the exhaust gas flow. The variable parameter of the exhaust gas flow may be detected by one or more sensors, or the variable parameter of the exhaust gas flow may be communicated from an external control system, or the variable parameter of the exhaust gas flow may be determined based on detected or received information (e.g., exhaust flow rate may be calculated from the inlet fuel flow rate and inlet air flow rate of an engine).

[0032] In examples, the exhaust gas is generated by a combustion engine, and the variable parameter may comprise an engine dynamics parameter. For example, the engine dynamics parameter may comprise an engine torque, an engine operating temperature, and/or an engine speed. The engine dynamics parameter may be detected by one or more sensors, or the engine dynamics parameter may be communicated from an external control system, for example a control system of the combustion engine. [0033] In examples, the exhaust gas flow is generated by a combustion engine comprising an aftertreatment system, and the variable parameter may comprise an aftertreatment system variable parameter. For example, the aftertreatment system variable parameter may comprise an operating temperature, and/or an exhaust gas flow rate (volumetric or mass) through the aftertreatment system. The variable parameter of the aftertreatment system may be detected by one or more sensors, or the variable parameter of the aftertreatment system may be communicated from an external control system, for example a control system of the combustion engine or aftertreatment system.

[0034] In examples, the sampling method may be performed in-situ at the location of the combustion apparatus generating the exhaust gas flow.

[0035] In examples, the exhaust gas may be a combustion engine exhaust gas of a vehicle. In such examples, the method of sampling the exhaust gas flow may be performed on the vehicle, and in particular on the vehicle during on-road driving. The method can be performed by a sampling apparatus that is mounted on the vehicle, with a sampling probe positioned in the vehicle exhaust pipe to separate the sample flow from the exhaust gas flow. Accordingly, the sample flow can be representative of real- life, on-road driving, with the associated unpredictability and varying conditions.

[0036] In such examples, the variable parameter may comprise a vehicle dynamics parameter. In examples, the vehicle dynamics parameter may comprise a vehicle velocity, a vehicle acceleration, and/or a vehicle location. The vehicle dynamics parameter may be detected by one or more sensors, or the vehicle dynamics parameter may be communicated from an external control system, for example a control system of the vehicle (e.g., Onboard Diagnostics (OBD) system). The sensors may include a velocity sensor and/or an accelerometer, or a location sensor (e.g.,

GPS) that can be used to determine location, velocity and acceleration. The location sensor may determine the longitude and latitude of the vehicle.

[0037] In examples, the variable parameter may be a location within one or more geofencing areas. For example, the sample flow may be directed into the first integrated sampler when the location of the vehicle is within a first geofencing area, and the sample flow may be directed into the second integrated sampler when the location of the vehicle is within a second geofencing area. Accordingly, different integrated samples can be obtained based on the area in which the vehicle is operating. In examples, the first geofencing area may be an urban area and the second geofencing area may be a rural area, or the different geofencing areas may be distinguished by the type or size of road. Further geofencing areas may additionally be provided. The geofencing areas may be defined by mapping references, and the location of the vehicle can be compared to the geofencing areas to determine if the vehicle is within a geofencing area, or not, and which geofencing area.

[0038] In examples, the variable parameter may comprise a combination of the various example variable parameters described above. For example, any of the example variable parameters described above may be combined with time and/or a user input and/or an integrated volume passing through the first and/or second integrated sampler.

[0039] In examples, the integrated samplers are configured to retain one or more constituents of the sample flow, in particular the exhaust gas flow. The one or more constituents may comprise a gaseous and/or particulate constituent. In examples, the one or more constituents may comprise one or more pollutants. In various examples, the one or more constituents may comprise various inorganic and organic pollutants, for example one or more of: carbon dioxide, carbon monoxide, nitrogen oxides, nitrous oxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons, sulfur dioxide, and/or ammonia.

[0040] In examples, the first and second integrated samplers each comprise a sorbent tube. For example, the first and second integrated samplers each comprise a thermal desorption tube. The sample flow is passed through the sorbent tubes and each sorbent tube is configured to retain at least one constituent of the sample flow. The sample flow (without the retained constituents) is output from the sorbent tubes. The output from the sorbent tubes can be exhausted to atmosphere.

[0041] In examples, each of the first and second integrated samplers comprises a plurality of sorbent tubes, and the method may comprise passing the sample flow through the plurality of sorbent tubes. At least some of the plurality of sorbent tubes may be configured to retain different constituents of the sample flow.

[0042] In examples, the method may further comprise passing the sample flow through a first sorbent tube of the first or second integrated samplers at a first flow rate, and passing the sample flow through a second sorbent tube of the first or second integrated samplers at a second flow rate different to the first flow rate. Different flow rates may be provided for retention of different constituents. The flow rate may be a volumetric flow rate or a mass flow rate. [0043] In other examples, the or each integrated sampler may comprise one or more of a canister, a bag, or a can. The or each integrated sampler may contain a solid or liquid sorbent, which may be a single or multicomponent material.

[0044] In examples, the method may further comprise restricting the flow rate of the sample flow such that the flow rate of the sample flow at the first or second integrated sampler is directly proportional to the flow rate of the exhaust gas flow. In particular, the method may comprise linearizing the flow rate of the sample flow to the flow rate of the exhaust gas flow. The flow rate may be a volumetric flow rate or a mass flow rate. Accordingly, a split ratio (sample flow as a proportion of the exhaust gas flow) can be held substantially constant despite variations in the exhaust gas flow. In examples, the split ratio is held at a value of between about 1% and 5%, for example about 2%.

[0045] In examples, the method may further comprise diluting the sample flow before the sample flow reaches the first or second integrated sampler. The sample flow may be diluted by air, for example filtered air, or an inert gas such as nitrogen. The sample flow is diluted downstream of the flow restriction described above. The sample flow may be diluted to provide a substantially constant flow rate of diluted sample flow entering the first or second integrated sampler. Accordingly, the proportion of dilution gas to sample flow varies as the exhaust gas flow rate varies.

[0046] In examples, the method may further comprise measuring a flow rate of the exhaust gas flow. The measured flow rate may be a volumetric flow rate or a mass flow rate. The measured flow rate of the exhaust gas flow may be recorded or logged and used to determine the mass flow rate of the one or more constituents of the sample flow retained in the integrated samplers. In particular, as the split ratio (sample flow rate : exhaust gas flow rate) is substantially constant, the measured flow rate of the exhaust gas flow may be used to determine the flow rate of one or more pollutants in the exhaust gas flow based on a quantity of that pollutant in the first and/or second integrated sampler.

[0047] In examples, the method may further comprise measuring a flow rate of the sample flow. The measured flow rate may be a volumetric flow rate or a mass flow rate. In particular, the method may comprise measuring the flow rate of the sample flow passing through the first and/or second integrated sampler. The method may comprise operating a pump to draw a substantially constant flow rate of diluted sample flow through the first and/or second integrated sampler. The pump may be operated based on the measured flow rate of the sample flow. [0048] In examples, the method comprises recording the flow rate of the exhaust gas flow and the flow rate of the sample flow passing through the first and/or second integrated sampler over time. The recorded flow rate may be a volumetric flow rate or a mass flow rate.

[0049] In examples, the method may further comprise detecting one or more real-time characteristics of the sample flow. In particular, the sample flow may be directed through a sensing enclosure comprising one or more sensors configured to detect a real-time characteristic of the sample flow. The sample flow may be directed through the sensing enclosure and not through an integrated sampler, for example the sample flow may bypass the first and second integrated samplers and pass through the sensing enclosure.

[0050] In examples, the method may further comprise testing the sample collected in first integrated sampler and/or the second integrated sampler. For example, the testing may comprise Gas Chromatography (GC) or Gas Chromatography Mass Spectrometry (GC-MS). As explained above, by measuring the amount of the constituent retained in the integrated sampler, and using the measured exhaust gas flow rate, a (mass or volumetric) flow rate can be determined for the constituent in the exhaust gas flow.

[0051] The present invention also provides a sampling apparatus for sampling an exhaust gas, for example a vehicle exhaust gas, the sampling apparatus comprising: a sampling line adapted to receive a sample flow from an exhaust gas flow, a first integrated sampler and a second integrated sampler, and a flow directing unit configured to direct the sample flow from the sample line into the first integrated sampler or into the second integrated sampler based on a variable parameter.

[0052] In examples, the sampling apparatus may further comprise a controller configured to determine or receive information relating to the variable parameter. For example, the controller may receive information relating to the variable parameter from one or more sensors, or from an external control system such as an Onboard Diagnostics (OBD) system of a vehicle. The controller may receive the variable parameter from an external control system or from a sensor. The controller may additionally be configured to control the flow directing unit to direct the sample flow into the first integrated sampler or into the second integrated sampler based on the variable parameter. [0053] In examples, the sampling apparatus may further comprise one or more sensors arranged to detect the variable parameter, the sensor being in communication with the controller. For example, depending on the variable parameter, the one or more sensors may be a temperature sensor, a pressure sensor, a flow rate sensor, a location sensor (e.g., GPS), or the like.

[0054] In various examples, as described above, the variable parameter may comprise one or more of: an operator input, time, a variable parameter of the sample flow, or a variable parameter of the exhaust gas flow.

[0055] In examples, the exhaust gas is generated by a combustion engine, and the variable parameter may comprise an engine dynamics parameter. The engine dynamics parameter may comprise one or more of an engine torque, an engine operating temperature, or an engine operating speed.

[0056] In examples, the exhaust gas flow is generated by a combustion engine comprising an aftertreatment system, and the variable parameter may comprise an aftertreatment system variable parameter.

[0057] In examples, the sampling apparatus may be portable and can be installed on a combustion apparatus in-situ for sampling an exhaust gas flow of the combustion apparatus.

[0058] In examples, the exhaust gas may be a combustion engine exhaust gas of a vehicle. In such examples, the sampling apparatus may be mounted to the vehicle, and the sampling line can be arranged to separate the sample flow from the exhaust gas flow in the exhaust pipe. In particular, the sampling line may include a sampling probe that can be mounted within an exhaust pipe of the vehicle. The sampling apparatus can be mounted to the vehicle such that the vehicle can be driven in on-road conditions. Accordingly, the sample flow can be representative of real-life, on-road driving, with the associated unpredictability and varying conditions.

[0059] In such examples, the variable parameter may comprise a vehicle dynamics parameter, such as one or more of a vehicle velocity, a vehicle acceleration, or a vehicle location.

[0060] The sampling apparatus may include one or more sensors to detect the vehicle dynamics parameter, or the vehicle dynamics parameter may be received by a controller of the sampling apparatus from an external control system, for example a control system of the vehicle (e.g., Onboard Diagnostics (OBD) system). The sensors may include a velocity sensor and/or an accelerometer, or a location sensor (e.g.,

GPS) that can be used to determine location, velocity and acceleration.

[0061] In examples, a controller of the sampling apparatus may be configured to compare the location of the vehicle to one or more geofencing areas. In examples, the flow directing unit may direct the sample flow into the first integrated sampler when the location of the vehicle is within a first geofencing area, and the flow directing unit may direct the sample flow into the second integrated sampler when the location of the vehicle is within a second geofencing area. Accordingly, different integrated samples can be obtained based on the area in which the vehicle is operating. In examples, the first geofencing area may be an urban area and the second geofencing area may be a rural area, or the different geofencing areas may be distinguished by the type or size of road. Further geofencing areas may additionally be provided. The geofencing areas may be defined by mapping references, and the location of the vehicle can be compared to the geofencing areas to determine if the vehicle is within a geofencing area, or not, and which geofencing area.

[0062] In examples, the first and second integrated samplers are configured to retain one or more constituents of the sample flow. The one or more constituents may comprise a gaseous and/or particulate constituent. In examples, the one or more constituents may comprise one or more pollutants. In various examples, the one or more constituents may comprise various inorganic and organic pollutants, for example one or more of: carbon dioxide, carbon monoxide, nitrogen oxides, nitrous oxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons, sulfur dioxide, and/or ammonia.

[0063] In examples, each of the first and second integrated samplers may comprise at least one sorbent tube. For example, each sorbent tube may be a thermal desorption tube. The sorbent tubes may be configured to retain at least one constituent of the sample flow as the sample flow passes through the sorbent tube.

[0064] In examples, each of the first and second integrated samplers may comprise a plurality of sorbent tubes.

[0065] In examples, during use the sample flow passes through the sorbent tubes of the first and second integrated samplers. The sampling apparatus may comprise an exhaust outlet for exhausting the sample flow downstream of the first and second integrated samplers. The sample flow may pass through the sorbent tube of the first integrated sampler at a first flow rate, and pass through the sorbent tube of the second integrated sampler at a second flow rate different to the first flow rate. Different flow rates may be provided for retention of different constituents.

[0066] In other examples, the or each integrated sampler may comprise one or more of a canister, a bag, or a can. The or each integrated sampler may contain a solid or liquid sorbent, which may be a single or multicomponent material.

[0067] In examples, the flow directing unit may comprise one or more valves operable to control flow of the sample flow to the first integrated sampler and the second integrated sampler. The valves may be solenoid valves controlled by the controller to open and close flow paths through the first and/or second integrated samplers. The flow directing unit may further comprise one or more pumps, for example a suction pump, arranged to direct the sample flow into the first integrated sampler and/or the second integrated sampler.

[0068] In examples, the sampling apparatus may further comprise a flow restrictor arranged to restrict the flow of the sample flow upstream of the first integrated sampler and the second integrated sampler. The flow restrictor may be a mechanical flow restrictor, in particular an orifice such as a critical flow orifice. In other examples, the flow restrictor may comprise one or more capillaries. In other examples, the flow restrictor may be a needle valve. The flow restrictor may define a fixed restricted flow passage through which the sample flow passes. The flow restrictor, in particular the fixed restricted flow passage, may be configured to restrict the flow rate of the sample flow such that the flow rate of the sample flow is directly proportional to the flow rate of the exhaust gas flow. The flow rate may be a volumetric flow rate or a mass flow rate. That is, the flow restrictor may be configured to linearize the sample flow rate to the exhaust gas flow rate. Accordingly, the split ratio (sample flow rate : exhaust gas flow rate) remains substantially constant. The flow restrictor may be configured to provide a split ratio of between about 1% and about 5%, for example about 2%.

[0069] In examples, the sampling apparatus may further comprise a dilution chamber disposed downstream of the flow restrictor and upstream of the first integrated sampler and the second integrated sampler. The dilution chamber may comprise a dilution fluid inlet for diluting the sample flow in the dilution chamber. The dilution fluid inlet may comprise an overflow such that dilution fluid is drawn into the dilution chamber as required, based on pressure. The dilution fluid may be air, for example filtered air, or an inert gas such a nitrogen.

[0070] The sampling apparatus may comprise a pump arranged to direct the diluted sample flow into the first and/or second integrated sampler. The pump may be operable to maintain a substantially constant flow rate (mass or volumetric) of the diluted sample flow passing into the first and/or second integrated sampler. The pump may be operated based on a sample flow rate measured by a sample flow rate sensor.

[0071] In examples, the controller may be configured to receive information relating to the flow rate of the exhaust gas flow. The flow rate of the exhaust gas flow may be a volumetric flow rate or a mass flow rate. In examples, the sampling apparatus may further comprise a flow meter arranged to measure a flow rate of the exhaust gas flow, and the flow meter may communicate with the controller. In other examples, the controller may receive information relating to the flow rate of the exhaust gas flow from an external control system, for example an Onboard Diagnostics (OBD) system of a vehicle.

[0072] In examples, the sampling apparatus, in particular the controller, may comprise a memory configured to store the measured flow rate of the exhaust gas flow. The measured flow rate of the exhaust gas flow may be recorded or logged and used to determine the mass flow rate of the one or more constituents of the sample flow collected in the integrated samplers. In particular, as the split ratio (sample flow rate : exhaust gas flow rate) is substantially constant, the measured flow rate of the exhaust gas flow may be used to determine the flow rate of one or more pollutants in the exhaust gas flow based on a quantity of that pollutant in the first and/or second integrated sampler.

[0073] In examples, the sampling apparatus may further comprise a flow meter arranged to measure a flow rate of the sample flow through the sampling apparatus, in particular through the or each integrated sampler. The flow rate of sample flow may be a volumetric flow rate or a mass flow rate. The measured flow rate of the sample flow through the sampling apparatus can be logged to determine an integrated volume or mass of sample flow passing through the integrated samplers. The integrated volume may be used to determine the flow rate (mass or volumetric) of one or more pollutants in the exhaust gas flow based on a quantity of that pollutant in the first and/or second integrated sampler.

[0074] In examples, the sampling apparatus may further comprise a bypass between the sample line and an exhaust outlet that bypasses the first and second integrated samplers. In examples, one or more gas sensors may be arranged in the bypass. In examples, the bypass includes a sensing enclosure and the one or more gas sensors may be arranged in the sensing enclosure. The one or more gas sensors may be configured to detect real-time characteristics of the sample flow passing through the bypass.

[0075] A further aspect of the invention provides a sampling apparatus for sampling an exhaust gas, the sampling apparatus comprising: a sampling line adapted to receive a sample flow from an exhaust gas flow, a flow restrictor arranged to restrict a flow rate of the sample flow from the sampling line, and an integrated sampler arranged to capture one or more constituents of the restricted sample flow, wherein the flow restrictor comprises at least one fixed flow passage configured to restrict the flow rate of the sample flow, and wherein the at least one flow passage is configured based on at least one dimension of the sampling line such that the restricted flow rate of the sample flow is directly proportional to a flow rate of the exhaust gas flow.

[0076] The flow restrictor with a fixed flow passage provides for linearizing the flow rate of the sample flow to the flow rate of the exhaust gas flow, and so maintains a constant spit ratio between the sample flow and the exhaust gas flow. For example, the flow restrictor may be configured to provide a flow rate of the sample flow of between about 1 % and about 5% of the flow rate of the exhaust gas flow, for example about 2%.

[0077] A flow restrictor having a fixed flow passage will operate (i.e. , react to changes in flow rate / pressure of the exhaust gas flow) at speeds approaching the speed of sound. Accordingly, the flow restrictor having a fixed flow passage provides a reactive and reliable device for linearizing the flow rate of the sample flow to the flow rate of the exhaust gas flow.

[0078] In examples, the flow restrictor may be a mechanical flow restrictor, in particular an orifice such as a critical flow orifice. In other examples, the flow restrictor may comprise one or more capillaries. In other examples, the flow restrictor may be a needle valve.

[0079] In examples, the integrated sampler may be configured to retain one or more constituents of the sample flow. The one or more constituents may comprise a gaseous and/or particulate constituent. In examples, the one or more constituents may comprise one or more pollutants. In various examples, the one or more constituents may comprise various inorganic and organic pollutants, for example one or more of: carbon dioxide, carbon monoxide, nitrogen oxides, nitrous oxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons, sulfur dioxide, and/or ammonia.

[0080] For example, as described above, the integrated sampler may comprise a sorbent tube, a canister, a bag, or a can.

[0081] In examples, the sampling apparatus may further comprise a dilution chamber disposed downstream of the flow restrictor and upstream of the first integrated sampler and the second integrated sampler. The dilution chamber may comprise a dilution fluid inlet for diluting the sample flow in the dilution chamber. The dilution fluid inlet may comprise an overflow such that dilution fluid is drawn into the dilution chamber as required, based on pressure. The dilution fluid may be air, for example filtered air, or an inert gas such a nitrogen.

[0082] The sampling apparatus may comprise a pump arranged to direct the diluted sample flow into the first and/or second integrated sampler. The pump may be operable to maintain a substantially constant flow rate of the diluted sample flow passing into the first and/or second integrated sampler. The pump may be operated based on a sample flow rate measured by a sample flow rate sensor. The measured flow rate may be a volumetric flow rate or a mass flow rate.

[0083] In examples, the sampling apparatus may comprise a controller as described above. The sampling apparatus may have a first integrated sampler and a second integrated sampler, and a controller of the sampling apparatus may be configured to direct the sample flow into the first integrated sampler or the second integrated sampler based on a variable parameter. The variable parameter may be as described above.

[0084] A further aspect of the invention provides a method of sampling an exhaust gas, for example a combustion engine exhaust gas, the method comprising: separating a sample flow from an exhaust gas flow, passing the sample flow through a flow restrictor having a fixed flow passage such that the restricted flow rate of the sample flow is directly proportional to a flow rate of the exhaust gas flow, and passing the diluted sample flow into an integrated sampler.

[0085] By restricting the flow rate of the sample flow such that it is directly proportional to the flow rate of the exhaust gas flow, the method linearizes the flow rate of the sample flow to the flow rate of the exhaust gas flow. Accordingly, a substantially fixed split ratio (sample flow rate : exhaust gas flow rate) is maintained. The split ratio may be between about 1% and about 5%, for example about 2%. The flow restrictor therefore provides a constant split ratio despite transient exhaust gas flow, making the sampling apparatus particularly suited for sampling an exhaust gas flow of a vehicle during on-road driving conditions.

[0086] In particular, the exhaust gas may be a combustion engine exhaust gas of a vehicle. In such examples, the method of sampling the exhaust gas flow may be performed on the vehicle, and in particular on the vehicle during on-road driving. The method can be performed by a sampling apparatus that is mounted on the vehicle, with a sampling probe positioned in the vehicle exhaust pipe to separate the sample flow from the exhaust gas flow. Accordingly, the sample flow can be representative of real- life, on-road driving, with the associated unpredictability and varying conditions, while the flow restrictor maintains proportionality between the sample flow and the exhaust gas flow despite the transiency of the exhaust gas flow.

[0087] In some examples, the restricted sample flow may be diluted as described above.

[0088] In examples, the method may further comprise measuring and recording a flow rate of the exhaust gas flow. The flow rate may be a volumetric flow rate or a mass flow rate. The method may also comprise measuring and recording an integrated volume of the sample flow passing through the integrated sampler. The measured exhaust has flow can be used to determine a flow rate of the sample flow through the integrated sampler (due to the substantially constant split ratio), and so the measured amounts of constituents in the integrated sampler can be used to determine the flow rate of that constituent in the sample flow and in the exhaust gas flow.

[0089] In examples, the integrated sampler may be configured to retain one or more constituents of the sample flow. The one or more constituents may comprise a gaseous and/or particulate constituent. In examples, the one or more constituents may comprise one or more pollutants. In various examples, the one or more constituents may comprise various inorganic and organic pollutants, for example one or more of: carbon dioxide, carbon monoxide, nitrogen oxides, nitrous oxide, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons, sulfur dioxide, and/or ammonia.

[0090] In examples, the method may further comprise detecting one or more real-time characteristics of the sample flow. In particular, the sample flow may be directed through a sensing enclosure comprising one or more sensors configured to detect a real-time characteristic of the sample flow. The sample flow may be directed through the sensing enclosure and not through the integrated sampler. [0091] In examples, the method may further comprise testing the sample collected in integrated sampler. For example, the testing may comprise Gas Chromatography (GC) or Gas Chromatography Mass Spectrometry (GC-MS). As explained above, by measuring the amount of the constituent retained in the integrated sampler, and using the measured exhaust gas flow rate and sample flow rate, a (mass or volumetric) flow rate can be determined for the constituent in the exhaust gas flow.

[0092] The method may further comprise directing the sample flow into a first integrated sampler or into a second integrated sampler based on a variable parameter. The variable parameter may be as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

FIG. 1 schematically illustrates a sampling apparatus connected to a vehicle exhaust tailpipe;

FIG. 2 illustrates a sample collection unit of the sampling apparatus;

FIG. 3 shows a perspective view of an example sample collection unit;

FIG. 4 shows a side view of the sample collection unit of FIG. 3;

FIG. 5 is a graph showing the exhaust flow rate for a real driving exhaust flow;

FIG. 6 is a graph illustrating a correlation between exhaust flow rate and upstream pressure at the flow restrictor of the sampling apparatus of FIGS. 1 to 4;

FIG. 7 is a graph illustrating a correlation between exhaust flow rate and a sample flow rate during use of the apparatus of FIGS. 1 to 4; and

FIG. 8 illustrates geofencing as a variable parameter for collecting different samples during use of the apparatus of FIGS. 1 to 4.

DETAILED DESCRIPTION

[0094] The sampling apparatus 1 described hereinafter is for collecting an integrated sample of an exhaust gas for analysis, for example using gas chromatography. The sampling apparatus 1 may additionally provide real-time analysis of a sample flow of the exhaust gas.

[0095] As described below, the sampling apparatus 1 separates a sample flow from an exhaust gas flow and a sampling unit having one or more integrated samplers to collect an integrated sample of the sample flow. The integrated sample can be analysed to determine a mass flow of one or more constituents of the exhaust gas flow, for example gaseous and/or particulate pollutants.

[0096] Advantageously, the sampling unit may have a plurality of integrated samplers and the sample flow can be directed into different integrated samplers based on a variable parameter, such as the location of the vehicle or an engine operating parameter. This allows for different integrated samples to be collected as the variable parameter changes.

[0097] In examples, the sample flow that is separated from the exhaust gas flow may be restricted in such a way that the flow rate of the sample flow is directly proportional to the flow rate of the exhaust gas flow. In this way, the integrated sample can be analysed to determine the mass flow rates of the pollutants in the exhaust gas.

[0098] As used herein, the term “flow rate” may refer to a volumetric flow rate or a mass flow rate. Volumetric flow rate can be directly detected, for example using a flow rate meter, or may be estimated or calculated based on other factors as set out herein. Mass flow rate can be calculated based on the density of the flow and the volumetric flow rate, or a mass flow meter may be used to detect the mass flow rate. As will be appreciated, volumetric flow rate can be converted to mass flow rate, and vice versa, by knowledge of the density of the flow. The density of the flow can be determined based on at least the temperature and pressure of the flow, which may be measured (by one or more sensors) or estimated based on known parameters. In addition, the density may additionally be determined based on the composition of the flow, which may be assumed or measured or detected.

[0099] In addition, the restricted sample flow can be diluted to maintain a substantially constant flow rate into the sampling unit despite variations in the flow rate of the exhaust gas flow. This helps to ensure that the collected integrated sample is representative of a transient exhaust gas flow, allowing analysis of the collected sample to determine the mass flow rates of the pollutants in the exhaust gas.

[00100] The sampling apparatus 1 described hereinafter is particularly advantageous for sampling an exhaust gas of a vehicle (e.g., a petrol or diesel combustion engine) during on-road driving conditions, i.e., driving around different locations with acceleration, braking, and idling, etc .... Such on-road driving generates transient exhaust gas flow, with varying flow rate and varying mass flows of exhaust gas constituents, including pollutants. By collecting different integrated samples based on a variable parameter, for example a vehicle location, variations in the pollutant emission rates of the vehicle can be determined based on real-life driving conditions. In addition, by diluting the sample flow to maintain a substantially constant flow rate into the integrated sampler, the collected integrated sample can be used to accurately determine the mass flow of pollutants in the vehicle exhaust gas flow.

[00101] Additionally or alternatively, the sampling apparatus 1 may be used on exhaust gas flows generated by other combustion equipment, such as a stationary combustion engine (e.g., of a power generator or pump), or on other domestic or industrial installations such as heating boilers, furnaces, or similar. Different integrated samples may be collected based on a variable parameter, for example such as time or an operating parameter of the combustion equipment, allowing the emissions rates of the exhaust gas flows to be determined based on different conditions. In addition, such combustion equipment may generate transient exhaust gas flows. Restriction of the sample flow such that the flow rate of the sample flow is directly proportional to the flow rate of the exhaust gas flow provides for analysis of the integrated sample to determine the mass flow rates of the pollutants. The sample flow can be diluted to maintain a substantially constant flow rate into the integrated sampler.

[00102] As shown in FIG. 1, the sampling apparatus 1 includes a sampling probe 4 that is connected to an exhaust pipe 2 and separates a sample flow from the exhaust gas flow 3 in the exhaust pipe 2. In the illustrated examples the exhaust pipe 2 is a tailpipe of a road vehicle, but in other examples the exhaust pipe 2 may be an exhaust pipe of another combustion engine, or a flue or stack of other combustion equipment such as a boiler or furnace, for example.

[00103] The sample probe 4 comprises an open ended tube or pipe arranged such that the open end is directed towards the oncoming exhaust gas flow 3 within the exhaust pipe 2. A positive pressure of the exhaust gas flow 3 drives a proportion of the exhaust gas flow 3 into the sample probe 4 and into the sample collector unit 12 described below. Accordingly, a proportion of the exhaust gas flow 3 enters the sampling apparatus 1 via the sampling probe 4. The exhaust gas flow 3 that enters the sample probe 4 is a sample flow. [00104] In examples, the sample flow may comprise between 1% and 5% of the exhaust gas flow, for example about 2%. The ratio of the flow rate of the sample flow to the flow rate of the exhaust gas flow 3 is the split ratio, which is preferably substantially constant as described below.

[00105] The sample transfer line 6 transfers the sample flow to a flow control device 8 and a dilution unit 7. The size (e.g., diameter) of the sample probe 4 and sample transfer line 6 can be selected to provide a minimal pressure drop.

[00106] In addition, the size (e.g., diameter and length) of the sample probe 4 and the sample transfer line 6 can also be changed to reduce or increase the gas-transit time between the sample probe 4 and the dilution unit 7.

[00107] A water trap 5 is provided between the sample probe 4 and the flow control device 8 and dilution unit 7, to remove liquid water from the sample flow.

[00108] The flow control device 8 is arranged to control a flow rate of the sample flow. The flow control device 8 is configured to restrict the flow rate of the sample flow so that it is directly proportional to the flow rate of the exhaust gas flow 3. Without the flow control device 8 the flow rate of the sample flow will vary in a non-linear relationship to the flow rate of the exhaust gas flow 3.

[00109] FIG. 5 illustrates an example flow rate of the exhaust gas flow 3 (Y-axis) over a time period (X-axis) corresponding to on-road driving. In particular, FIG. 5 shows the flow rate of a Euro 5 1998cc diesel passenger car during a period of on-road driving.

As shown, the exhaust gas flow rate is transient and can vary largely over time. Accordingly, the flow rate of the sample flow will also change over time.

[00110] In particular, as shown in FIG. 6 the pressure of the sample flow at a position upstream of the flow restrictor 8 shown on the Y-axis, is correlated to the exhaust gas flow rate, shown on the X-axis. The data for FIG. 6 was obtained using a Pitot tube to determine a differential pressure measurement. Note that the scatter is mostly associated with the time response differences between the two pressure sensor signals.

[00111] As shown in FIG. 6, the relationship between the exhaust gas flow rate and the sample flow pressure is non-linear. The relationship between the exhaust gas flow rate and the sample flow pressure is-depends on the size and configuration of the sample probe 4 and sample transfer line 6, which define the pressure drop through this part of the sampling apparatus 1. [00112] The flow restrictor 8 is configured to linearize the sample flow rate to the flow rate of the exhaust gas flow 3, as shown in FIG. 7, such that the flow rate of the sample flow that passes through the flow restrictor 8 is directly proportional to the flow rate of the exhaust gas flow 3 in the exhaust pipe 2. Accordingly, as the flow rate of the exhaust gas flow 3 in the exhaust pipe 2 increases, the flow rate of the sample flow increases proportionally. The flow restrictor 8 is configured to create a sample flow having a flow rate that is directly proportional to the flow rate of the exhaust gas flow 3.

[00113] In the example shown in FIG. 7 the correlation coefficient between the sample flow rate and the exhaust gas flow rate is 0.9983, which is significantly higher than laws and regulations require (typically >0.95). The calculated slope also determines the flow rate of the sample flow as a fraction of the exhaust flow (split ratio). This demonstrates the direct proportionality between these two signals. In this example, the split ratio is 0.0253 or 2.53%.

[00114] The flow restrictor 8 is a mechanical flow restrictor, for example a critical flow orifice, or a plurality of capillaries. The flow restrictor 8 has no moving parts - it defines one or more fixed, restricted paths for the sample flow. The flow restrictor 8 comprises an orifice configured to linearize the flow rate of the sample flow to the flow rate of the exhaust gas flow 3. The orifice is configured to provide a non-linear relationship between the flow rate of the exhaust gas flow 3 and the pressure of the sample flow at the upstream side of the flow restrictor 8, such that the flow rate of the sample flow is directly proportional to the flow rate of the exhaust gas flow 3. The flow restrictor, i.e., the size of the orifice(s) of the flow restrictor 8, is configured according to the dimensions of the sample probe 4 and sample transfer line 6 that define the pressure drop between the exhaust gas flow 3 and the flow restrictor 8.

[00115] The flow restrictor 8 may comprise a plurality of orifices or capillaries having the same or different diameters. In one example, the flow restrictor 8 comprises at least two orifices having different diameters, or at least two capillaries having different lengths and/or diameters. An orifice will tend to restrict flow passing though the device in a manner that approximates to a square root relationship to pressure. In contrast, a capillary will provide a more linear response. The length of a capillary also changes the response. In particular, short capillaries have a small second order pressure coefficient.

[00116] The sample flow control device 8 is connected to a dilution chamber 9 of the dilution unit 7 such that the restricted sample flow passes into the dilution chamber 9. A dilution gas inlet 10 provides dilution gas to the dilution chamber 9 where it mixes with the sample flow to provide a diluted sample flow. [00117] In the dilution chamber 9 the sample flow passing through the flow restrictor 8 is diluted. The dilution gas provided to the dilution chamber 9 via the dilution gas inlet 10 may comprise air, for example filtered air. The filtered air may be passed through a HEPA filter upstream of the dilution gas inlet 10. Additionally or alternatively, the dilution gas provided to the dilution chamber 9 via the dilution gas inlet 10 may comprise an inert gas, such as nitrogen. The dilution gas may be provided to the dilution chamber 9 via the dilution gas inlet 10 at a constant flow rate.

[00118] The dilution gas inlet 10 comprises an overflow 43 from which the dilution fluid is drawn into the dilution chamber 9. The diluted sample flow is drawn from the dilution chamber 9 into the sample collector unit 12 by a pump (see FIG. 2). The pump is controlled to maintain a substantially constant flow rate of the diluted sample flow entering the sample collector unit 12. Accordingly, the restricted sample flow, which varies linearly according to the flow rate of the exhaust gas flow 3, is diluted with a varying proportion of dilution gas to provide a substantially constant flow rate of diluted sample flow into the sample collector unit 12.

[00119] By diluting the sample flow with the dilution gas, the dewpoint of the diluted sample flow is reduced which may help to prevent condensation downstream of the dilution chamber 7. In addition, dilution reduces the concentrations of the various pollutants in the sample flow, which may help to prevent overloading the integrated samplers (described hereinafter).

[00120] A further sample transfer line 11 transfers the diluted sample flow from the dilution unit 7 to a sample collector unit 12. As explained further hereinafter, the sample collector unit 12 includes one or more integrated samplers through which the diluted sample flow passes. Each integrated sampler is configured to retain one or more constituents of the sample flow, for example one or more gaseous or particulate pollutants. As explained further hereinafter, the sample collector unit 12 may additionally or alternatively include one or more sensors for real-time analysis of the diluted sample flow.

[00121] The transfer line 6 and/or further transfer line 11 may be insulated and/or heated, in particular electrically heated, to maintain or increase the temperature of the sample flow and diluted sample flow, respectively. In particular, the transfer line 6 and/or further transfer line 11 may be heated to evaporate water in the sample flow and/or prevent condensation of water in the sample flow. The transfer line 6 and/or further transfer line 11 may be heated to prevent condensation of semi-volatile compounds in the sample flow. In examples, the transfer line 6 and/or further transfer line 11 may be heated to a temperature of above about 100 degrees Celsius, for example about 190 degrees Celsius.

[00122] As illustrated, an exhaust gas flow meter 13 is provided in the exhaust pipe 2 for measuring a flow rate of the exhaust gas flow 3. As shown, the exhaust gas flow meter 13 is disposed downstream of the sampling probe 4 in the exhaust pipe 2, but may alternatively be located upstream of the sampling probe 4 in the exhaust pipe 2. In some examples, an exhaust gas flow meter 13 is disposed downstream of the sampling probe 4 in the exhaust pipe 2 and a further exhaust flow meter is located upstream of the sampling probe 4 in the exhaust pipe 2. The or each exhaust gas flow meter 13 provides the measured flow rate of the exhaust gas flow 3 to a controller 14. From the measured flow rate of the exhaust gas flow 3 the controller 14 (or subsequent processor) is able to determine the amount of sample flow that enters the sample collector unit 12, and so during analysis of the collected integrated sample it is possible to extrapolate the pollutant flow rates in the exhaust gas flow 3.

[00123] In alternative examples, the flow rate of the exhaust gas flow 3 may be determined based on an operating condition of the combustion engine, for example a fuel consumption rate and/or air intake rate and/or engine operating speed. A diagnostics system, for example a vehicle’s Onboard Diagnostics (OBD) 16 system may communicate this data to the controller 14.

[00124] As shown in FIG. 1, the controller 14 is further connected to the sample collector unit 12 for exchange of data and/or control, as described further hereinafter.

[00125] As shown in FIG. 1, the controller 14 is further configured to receive information from other inputs. For example, the controller 14 is further configured to receive inputs from a location unit, in particular a GPS unit 15, and/or an Onboard Diagnostics (OBD) system 16 of the vehicle, and/or one or more further inputs 17. As explained above, the controller 14 may receive information on the exhaust gas flow rate from the OBD system 16, or may determine the exhaust gas flow rate from data received from the OBD system 16.

[00126] In examples, the controller 14 may be configured to store data relating to all of the received information in a database. In some examples, the controller 14 may be configured to determine one or more parameters from the data received. The stored information may be a log used in the analysis of the integrated sample to determine the flow rate of the constituents in the exhaust gas, for example a mass or volume flow rate of one or more pollutants in the exhaust gas. [00127] In examples, the controller 14 is configured to log the flow rate of the exhaust gas flow 3, which may be volumetric or mass flow rate. From the flow rate of the exhaust gas flow 3 the controller 14 may determine the flow rate of the sample flow extracted from the exhaust gas flow 3 by the split ratio, which is fixed according to the flow restrictor 8. As explained further below, the controller 14 may additionally be configured to log a time that the diluted sample flow is provided to the sample collector unit 12, and in particular the time that the diluted sample flow is provided to an integrated sampler of the sample collector unit 12. In addition, the controller 14 may be configured to log a location, for example a location of the vehicle, as determined or received for example from GPS unit 15. The controller 13 may additionally be configured to log OBD data received from the OBD unit 16, for example vehicle speed, engine RPM, engine temperature, etc .... In examples, the controller 14 may additionally receive and log in particular temperature and pressure of the sample flow and diluted sample flow, and ambient conditions such as temperature, pressure and (relative) humidity, as received from one or more sensors.

[00128] As shown in FIG. 2, the further sample transfer line 11 is connected to the sample collector unit 12 by a quick-release connector 19. The further sample transfer line 11 is connected to an inlet manifold 20. The illustrated inlet manifold 20 comprises four sampler connections 21a, 21b, 21c, 21d and a bypass connection 22.

[00129] Each of the sampler connections 21a, 21b, 21c, 21d is connected to an integrated sampler. In this example, each integrated sampler is a sorbent tube 23a,

23b, 23c, 23d.

[00130] In the example illustrated in FIG. 2 the sample collection unit 12 includes four sorbent tubes 23a, 23b, 23c, 23d, but in various examples the sample collection unit 12 may comprise two or more sorbent tubes 23, for example two, three, five, six or more sorbent tubes 23. Similar numbers of other integrated samplers may be provided. Accordingly, the sample collection unit 12 comprises a plurality of integrated samplers.

[00131] The sample flow passes through each of the sorbent tubes 23a, 23b, 23c,

23d. Each sorbent tube 23a, 23b, 23c, 23d is packed with a sorbent material configured to retain or capture one or more constituents of the sample flow as the sample flow passes through the sorbent tube 23a, 23b, 23c, 23d. In examples, each sorbent tube 23a, 23b, 23c, 23d may comprise a single or multicomponent solid or liquid absorbent configured to absorb one or more constituents of the sample flow, in particular one or more pollutants. [00132] An outlet side of each sorbent tube 23a, 23b, 23c, 23d is connected to an outlet manifold 28 and an exhaust outlet 24 in turn.

[00133] A bypass connection 22 is connected between the inlet manifold 20 and the exhaust outlet 24 and bypasses the sorbent tubes 23a, 23b, 23c, 23d.

[00134] The sample collector unit 12 also includes one or more valves and/or pumps arranged to control flow of the sample flow through each of the sorbent tubes 23a, 23b, 23c, 23d and/or through the bypass connection 22. The one or more valves and/or pumps are configured to independently control through the sorbent tubes 23a, 23b,

23c, 23d so that one or more sorbent tubes 23a, 23b, 23c, 23d can be used at any time.

[00135] As illustrated, the sample collector unit 12 comprises a plurality of valves 27a, 27b, 27c, 27d. Each valve 27a, 27b, 27c, 27d is associated with a sorbent tube 23a, 23b, 23c, 23d and is operable to control flow of the sample flow from the inlet manifold 20 through the respective sorbent tube 23a, 23b, 23c, 23d.

[00136] The valves 27a, 27b, 27c, 27d are controlled by the controller 14. The valves 27a, 27b, 27c, 27d may be solenoid valves. The controller 14 can therefore control flow of the sample flow through the each of the sorbent tubes 23a, 23b, 23c, 23d independently.

[00137] A pump 30 is provided in the flow path passing through the sorbent tubes 23a, 23b, 23c, 23d. The pump 30 is operable to draw the sample flow through the or each sorbent tube 23a, 23b, 23c, 23d. In this example the pump 30 is a suction pump arranged downstream of the sorbent tubes 23a, 23b, 23c, 23d and downstream of the outlet manifold 28, but alternatively a positive pressure pump may be located upstream of the sorbent tubes 23a, 23b, 23c, 23d and/or inlet manifold 20 to drive flow through the sorbent tubes 23a, 23b, 23c, 23d.

[00138] A flow sensor 29 is provided to detect the flow rate of the sample flow passing through the sorbent tubes 23a, 23b, 23c, 23d.

[00139] The pump 30 is a suction pump. The pump 30 is operable to draw the sample flow through the sorbent tubes 23a, 23b, 23c, 23d in a sampling mode of the sample collection unit 12. When the pump 30 is operated the sample flow is drawn through the sorbent tubes 23a, 23b, 23c, 23d and to the outlet 24. The pump 30 is controlled by the controller 14. The controller 14 controls the pump 30 to maintain a substantially constant flow rate of diluted sample flow through the sorbent tubes 23a, 23b, 23c, 23d. In particular, the controller 14 controls the pump 30 based on the flow rate measured by flow sensor 29. As explained above, this draws the sample flow and an amount of dilution gas into the sample collector unit 12 to maintain a substantially constant flow rate of diluted sample flow entering the sample collector unit 12.

[00140] The bypass connection 22 also has a pump 31 and flow sensor 32. The pump 31 is operable to draw the sample flow through the bypass connection 22 in preference to the sorbent tubes 23a, 23b, 23c, 23d. The pump 31 is controlled by the controller 14 and is operated when the pump 30 is not operated, i.e., when the sample collection unit 12 is not in a sampling mode. The pump 31 is controlled by the controller 14. The controller 14 controls the pump 31 to maintain a substantially constant flow rate of diluted sample flow through the bypass connector 22. In particular, the controller 14 controls the pump 31 based on the flow rate measured by flow sensor 32. As explained above, this draws the sample flow and an amount of dilution gas into the sample collector unit 12 and through the bypass connection 22 to maintain a substantially constant flow rate of diluted sample flow entering the sample collector unit 12.

[00141] In another example, a single pump may be provided with a three-way valve that can be controlled to change between a sampling mode, in which the sample flow is directed through the sorbent tubes 23a, 23b, 23c, 23d, and a bypass mode, in which the sample flow is directed through the bypass connection 22.

[00142] The sample collector unit 12 also has a sensing enclosure 25 through which the sample flow passes before the exhaust outlet 24. The sensing enclosure 25 receives the sample flow from the outlet manifold 28 and from the bypass connection 22. The sensing enclosure 25 includes one or more sensors 26a, 26b, 26c. The sensors 26a, 26b, 26c may be gas sensors. The sensors 26a, 26b, 26c are configured to detect one or more real-time characteristics of the sample flow passing through the sensor enclosure 25. The sensors 26a, 26b, 26c may form a Portable Emission Measurement System (PEMS). The sensors 26a, 26b, 26c may include pressure and temperature sensors, and sensors to detect one or more pollutants such carbon dioxide, carbon monoxide, nitrogen oxide, total hydrocarbon emissions (THC), and particulates. Data provided by the sensors 26a, 26b, 26c may be used to validate one or more other measured parameters, for example the flow rate of the exhaust gas flow.

[00143] As shown in FIG. 2, the sorbent tubes 23a, 23b, 23c, 23d may be mounted within a sample collector module 33 within the sample collector unit 12. The sample collector module 33 may be removable from the sample collector unit 12.

[00144] FIGS. 3 and 4 illustrate an example of the sample collector module 33. In the example of FIGS. 3 and 4, sorbent tubes are arranged in groups, each group forming an integrated sampler 23a, 23b, 23c, 23d. That is, in the example of FIGS. 3 and 4 each integrated sampler 23a, 23b, 23c, 23d comprises a plurality of individual integrated samplers, for example sorbent tubes. In this example, each integrated sampler 23a, 23b, 23c, 23d comprises four sorbent tubes 23a-1 to 23d-4.

[00145] As shown in FIG. 3, the sample collector module 33 comprises an inlet plate 34 in which a plurality of inlet manifolds 20 are formed, and an outlet plate 35 in which a plurality of outlet manifolds 28 are formed.

[00146] The plurality of integrated samplers 23a, 23b, 23c, 23d are arranged to extend between the inlet plate 34 and the outlet plate 35. In this example, each integrated sampler 23a, 23b, 23c, 23d comprises four sorbent tubes 23a-1 to 23d-4. In particular, the first integrated sampler 23a has four sorbent tubes 23a-1 to 23a-4, a second integrated sampler 23b has four sorbent tubes 23b-1 to 23b-4, a third integrated sampler 23c has four sorbent tubes 23c-1 to 23c-4, and a fourth integrated sampler 23d has four sorbent tubes 23d-1 to 23d-4.

[00147] The inlet plate 34 includes an inlet manifold 20 for each of the integrated samplers 23a, 23b, 23c, 23d, where each of the sorbent tubes of each integrated sampler 23a, 23b, 23c, 23d is connected to a respective inlet manifold in the inlet plate 34. That is, the inlet plate 34 has a first inlet manifold 20a for the four sorbent tubes 23a-1 to 23a-4 of the first integrated sampler 23a, a second inlet manifold 20b for the four sorbent tubes 23b-1 to 23b-4 of the second integrated sampler 23b, a third inlet manifold 20c for the four sorbent tubes 23c-1 to 23c-4 of the third integrated sampler 23c, and a fourth inlet manifold 20d for the four sorbent tubes 23d-1 to 23d-4 of the fourth integrated sampler 23d.

[00148] Each inlet manifold 20a to 20d has an inlet connector 36a, 36b, 36c, 36d for inlet of the sample flow from the dilution chamber (9, see FIG. 1). For example, each of the inlet connectors 36a, 36b, 36c, 36d can be connected to the further sample transfer line (11, see FIGS. 1 and 2), for example by a quick release connector 19 as shown in FIG. 2.

[00149] Similarly, the outlet plate 35 includes an outlet manifold 28 for each of the integrated samplers 23a, 23b, 23c, 23d. That is, the outlet plate 35 has a first outlet manifold 28a for the four sorbent tubes 23a-1 to 23a-4 of the first integrated sampler 23a, a second outlet manifold 28b for the four sorbent tubes 23b-1 to 23b-4 of the second integrated sampler 23b, a third outlet manifold 28c for the four sorbent tubes 23c-1 to 23c-4 of the third integrated sampler 23c, and a fourth outlet manifold 28d for the four sorbent tubes 23d-1 to 23d-4 of the fourth integrated sampler 23d. [00150] Each outlet manifold 28a, 28b, 28c, 28d has an outlet connector 37a, 37b,

37c, 37d for outlet of the sample flow from the sample collector module 33 towards the exhaust outlet (24, see FIG. 2). In particular, each of the outlet connectors 37a, 37b, 37c, 37d can be connected to the pump 30 and sensing enclosure 25 as illustrated in FIG. 2.

[00151] The valves (27a to 27d, see FIG. 2) control flow of the sample flow through the sample collector module 33. In particular, the valves (27a to 27d, see FIG. 2) independently control flow of the sample flow through each of the integrated samplers 23a-23d. The valves (27a to 27d, see FIG. 2) may be attached to the inlet connectors 36a-36d or the outlet connectors 37a-37d. Accordingly, at any time the sample flow can be directed through at least one the first integrated sampler 23a, second integrated sampler 23b, third integrated sampler 23c, and/or fourth integrated sampler 23d and the respective sorbent tubes.

[00152] FIG. 4 shows a cross-section through the sample collector module 33, particularly through the first integrated sampler 23a formed of four sorbent tubes 23a-1 to 23a-4. As shown, the inlet plate 34 includes a first inlet manifold 20a that connects the first inlet connector 36a to each of the sorbent tubes 23a-1 to 23a-4 of the first integrated sampler 23a. Similarly, the outlet plate 35 includes a first outlet manifold 28a that connects each of the sorbent tubes 23a-1 to 23a-4 of the first integrated sampler 23a to the first outlet connector 37a.

[00153] Each of the second to fourth integrated samplers 23b to 23d has a similar arrangement. Accordingly, the sample collector module 33 has sixteen sorbent tubes 23a-1 to 23d-4 and flow can be directed through one or more of the integrated samplers 23a, 23b, 23c, 23d.

[00154] As shown in FIG. 4, each sorbent tube 23a-1 to 23a-4 of the first integrated sampler 23a is connected to the inlet plate 34 and the first inlet manifold 20a via an inlet connector 38a-1 to 38a-4. The inlet connectors 38a-1 to 38a-4 provide a removable attachment between the sorbent tubes 23a-1 to 23a-4 and the inlet plate 34. The inlet connectors 38a-1 to 38a-4 also define an orifice between the first inlet manifold 20a and the respective sorbent tube 23a-1 to 23a-4 that restricts flow into the sorbent tube 23a-1 to 23a-4.

[00155] Also shown in FIG. 4, each of the sorbent tubes 23a-1 to 23a-4 of the first integrated sampler 23a is connected to the outlet plate 35 and the first outlet manifold 28a via an outlet connector 39a-1 to 39a-4. The outlet connectors 39a-1 to 39a-4 provide a removable attachment between the sorbent tubes 23a-1 to 23a-4 and the outlet plate 35. The outlet connectors 39a-1 to 39a-4 also define an orifice between the sorbent tubes 23a-1 to 23a-4 and the first outlet manifold 28a that restricts flow through the sorbent tubes 23a-1 to 23a-4. The orifices of the outlet connectors 39a-1 to 39a-4 may be more restricted than the orifices of the corresponding inlet connectors 38a-1 to 38a-4 such that the orifices of the outlet connectors 39a-1 to 39a-4 are control orifices for defining a flow rate through the sorbent tubes 23a-1 to 23a-4.

[00156] In some examples, each of the sorbent tubes 23 within each integrated sampler 23a to 23d has a different packing material, so are configured to capture different constituents of the sample flow.

[00157] In some examples, one or more of the inlet connectors 38a to 38d and/or outlet connectors 39a-1 to 39a-4 of each integrated sampler 23a to 23d may have a different size orifice so that the flow rate of the sample flow passing through the sorbent tubes 23a-1 to 23a-4 is different. For example, a first sorbent tube 23a-1 of the first integrated sampler 23a may have a first packing material and the outlet connector 39a- 1 may have an orifice sized to provide a first flow rate through the first sorbent tube 23a-1 , and a second sorbent tube 23a-2 of the first integrated sampler 23a may have a second packing material and the outlet connector 39a-2 may have an orifice sized to provide a second flow rate through the second sorbent tube 23a-2. The first and second packing materials may be the same or different, and the first flow and second flow rates may be the same or different.

[00158] After use, each of the sorbent tubes 23 can be detached from the inlet plate 34 and outlet plate 35, sealed with a plug, and sent for analysis. On detachment of the sorbent tubes 23 from the inlet plate 34 and the outlet plate 35 the ends of the sorbent tubes 23 can be plugged or sealed.

[00159] Analysis of the constituents retained within the sorbent tubes 23 may comprise flushing the constituents out of the sorbent tubes 23 and into an analysis system, for example a gas chromatography system. In some examples, the sorbent tubes 23a-1 to 23a-4 are thermal desorption tubes and the constituents may be flushed from the sorbent tubes 23 by heating and passing a carrier fluid through the sorbent tubes 23. In other examples, the sorbent tubes 23a-1 to 23a-4 may be solvent desorption tubes and the constituents may be extracted by passing a solvent through the solvent desorption tubes.

[00160] Referring to FIGS. 1 and 2, during operation of the sampling apparatus 1, a first mode is a real-time sensing mode in which pump 30 is not operated and pump 31 is operated such that the sample flow passes from the inlet 11 through the bypass connection 22 to the sensing enclosure 25, and does not pass through the integrated samplers 23a to 23d. In this mode, the valves 27a to 27d may be closed. From the sensing enclosure 25 the sample flow is output via outlet 24. Within the sensing enclosure 25 one or more sensors 26a, 26b, 26c are provided to detect one or more real-time characteristics of the sample flow. Data provided by the sensors 26a, 26b,

26c may be used to validate one or more other measured parameters, for example the flow rate of the exhaust gas flow.

[00161] During operation of the sampling apparatus 1, a second mode is a sampling mode. In the sampling mode the pump 30 is operated to draw the sample flow through the sampling module 33, in particular through one or more of the integrated samplers 23a to 23d. Pump 31 is not operated so the sample flow does not pass through the bypass connection 22.

[00162] In the sampling mode the controller 14 is configured to operate the valves 27a to 27d to control flow of the sample flow through one or more of the integrated samplers 23a to 23d based on a variable parameter.

[00163] For example, if the variable parameter has a first value or is within a first range, the controller 14 is configured open valve 27a and close valves 27b to 27d such that the sample flow passes through the first integrated sampler 23a. If the variable parameter has a second value or is within a second range, the controller 14 is configured open valve 27b and close valves 27a, 27c and 27d such that the sample flow passes through the second integrated sampler 23b. Accordingly, different samples can be collected in different integrated samplers 23a to 23d based on the variable parameter.

[00164] In some examples, the variable parameter may be time. For example, during a first period of time the controller 14 may be configured to direct the sample flow through the first integrated sampler 23a and not through the second to fourth integrated samplers 23b to 23d, and during a second period of time the controller 14 may be configured to direct the sample flow through the second integrated sampler 23b and not through the first, third or fourth integrated samplers 23a, 23, 23d. Accordingly, different integrated samples can be collected at different times during operation of the combustion equipment.

[00165] In some examples, a first sample may be collected in the first integrated sampler 23a from start-up of the vehicle combustion engine for a first period of time. Such an integrated sample may be analysed to ascertain the pollutant mass flows when the vehicle combustion engine is first started. A second integrated sample may then be collected in the second integrated sampler 23b for a subsequent period of time, and so on.

[00166] In some examples, the variable parameter may be a location, for example a location of the vehicle to which the sampling apparatus 1 is mounted. The location may be determined by a location or navigation system, for example GPS. In other examples, location may be determined by RFID or WiFi.

[00167] In one example, when the sampling apparatus 1 is at a first location the controller 14 may be configured to direct the sample flow through the first integrated sampler 23a and not through the second to fourth integrated samplers 23b to 23d, and when the sampling apparatus is at a second location the controller 14 may be configured to direct the sample flow through the second integrated sampler 23b and not through the first, third or fourth integrated samplers 23a, 23, 23d.

[00168] FIG. 8 shows an example geofencing variable parameter that uses location as the variable parameter. A first geofencing area 40 is different to a second geofencing area 41 and a third geofencing area 42, and the sample is directed through different integrated samplers 23a to 23d when the location is within the different geofencing areas 40 to 42.

[00169] Accordingly, different integrated samples can be collected for operation of the vehicle combustion engine in different areas, which may be indicative of different driving conditions. For example, the first geofencing area 40 may be one or more small urban streets, the second geofencing area 41 may be a main thoroughfare, and the third geofencing area 42 may be a main thoroughfare through an urban area.

[00170] In some examples, the variable parameter may be an operating characteristic of the vehicle and/or the vehicle combustion engine (or other combustion equipment) generating the exhaust gas flow. For example, the variable parameter may be an operating temperature of the combustion engine, an operating pressure of the combustion engine, a throttle position of the combustion engine, a velocity of the vehicle, an acceleration of the combustion engine, a torque of the combustion engine, a power of the combustion engine, or other operating parameter of the combustion engine.

[00171] In some examples, the variable parameter may be a parameter of the sample flow. For example, the variable parameter may be a temperature of the sample flow, pressure of the sample flow, a flow rate of the sample flow, and/or integrated volume of the sample flow. [00172] In some examples, the sample flow is directed to a first integrated sampler 23a until the integrated volume of the sample flow passing through the first integrated sampler 23a approaches or reaches a threshold of the first integrated sampler 23a, and then the sample flow may be directed to a second integrated sampler 23b or to the exhaust outlet. Accordingly, saturation of the integrated samplers 23a to 23d can be avoided.

[00173] In some examples, the variable parameter comprises a variable parameter of the exhaust gas flow. For example, the variable parameter may be a temperature of the exhaust gas flow, a pressure of the exhaust gas flow, a flow rate of the exhaust gas flow, and/or integrated volume of the exhaust gas flow.

[00174] In some examples, the variable parameter comprises an aftertreatment system parameter. For example, the vehicle may have an aftertreatment system such as a heat exchanger, turbocharger, and/or catalytic converter. In examples, the variable parameter may be an operating temperature of the aftertreatment system, and/or a gas flow rate through the aftertreatment system.

[00175] In some examples, the variable parameter may be an operator input. For example, an operator input may be received through an operator interface (e.g., switch or computing device) and the controller 14 may direct the sample flow through one or more of the integrated samplers 23a to 23d based on the operator input.

[00176] It will be appreciated that the sample apparatus 1 may include one or more sensors to detect the variable parameter, such as one or more temperature sensors, pressure sensors, gas flow rate sensors, location sensors (e.g., GPS unit) and the like. Additionally to alternatively, the controller 14 of the sampling apparatus 1 may receive operating data for the combustion equipment from an external source, such as an Onboard Diagnostics (OBD) system of a vehicle or other control unit of the combustion equipment.

[00177] In various examples, the sampling apparatus 1 may detect or receive a plurality of variable parameters and direct the sample flow onto one or more integrated samplers based on one or a combination of the detected or received plurality of variable parameters. For example, during a first time period the sampling apparatus 1 may direct the sample flow through the first integrated sampler 23a or the second integrated sampler 23b based on the location of the vehicle (e.g., using the geofencing areas 40, 41, 42 illustrated in FIG. 8). Then, in a subsequent second time period the sampling apparatus 1 may direct the sample flow through the third integrated sampler 23c or the fourth integrated sampler 23d based on the location of the vehicle (e.g., using the geofencing areas 40, 41, 42 illustrated in FIG. 8). Accordingly, the sampling apparatus 1 may utilise a plurality of variable parameters in determining which of the integrated samplers 23a-23d to use.

[00178] In some examples the sampling apparatus 1 described herein can be mounted to a vehicle for sampling the exhaust gas flow of the vehicle. The sampling apparatus 1 may include a power source, for example a battery, or a connector for an external power source (e.g., vehicle power source).

[00179] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[00180] Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.