MICRO-PSS Particulate sampling system for on-road tests · The MICRO-PSS is based on the same technology (partial flow exhaust dilution and filter ... Page 5 CONTROL SISTEM S.r. l..-via

CONTROL SISTEM S.r.l. .-via Collegno, 29 int. - 10044 PIANEZZA (TORINO) P. I. 04791930011 – C.C.I.A.A. N. 660139

TEL.011/967.20.72 – 967.20.73 – FAX 011/967.20.44 - E-mail [email protected] - Sito internet www.controlsistem.it

MOD.01

MICRO-PSS

Particulate sampling system for on-road tests

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MOD.01

INTRODUCTION Control Sistem developed throughout the last 15 years the PSS-20 (Particulate Sampling System with 20 m

3/h of sampling volume) which is in accordance with EC directives and

international standard ISO 16183. The Directives 1999/96/EC 2005/55/EC and 2005/78/EC require the in-use conformity checking for heavy-duty vehicles to be effective from the Euro 4 stage. For several reasons it is impractical to apply an “in-use conformity checking scheme” for heavy-duty vehicles, which require disassembly of engines to compare pollutant emissions against legislative limits. Therefore Directorates General for Enterprise (DG ENTR) has proposed to develop a protocol for “in-use conformity checking” of heavy-duty vehicles based on the use of PEMS (Portable Emission Measurement System). DG ENTR and the Joint Research Centre (DG JRC) of the European Commission, the European heavy-duty vehicle industry (ACEA - Association des Constructeurs Européens d'Automobiles) and manufacturers of portable emission measuring systems (PEMS) had agreed to carry out a co-operative testing program in order to develop a standard testing protocol for the use of PEMS as an “in-use conformity checking procedure” for heavy-duty vehicles. The basis of the European project was the work already conducted in the United States by various organisations and industries and being formalised by the US EPA as test procedures under Part 1065 of the Code of Federal Regulations. However, a significant amount of work has been carried out to assess the capability of portable emission measuring systems before progressing to road trials and the development of standard protocols for the use of such systems. Control Sistem as a manufacturer of a standard partial flow Particulate Sampling System (PSS-20) and member of this “EU working group” offers a “Portable Particulate Sampling System” (MICRO-PSS) for “in-use conformity checking procedure”. The MICRO-PSS is based on the same technology (partial flow exhaust dilution and filter collection) used for the standard homologation system. The MICRO-PSS is assembled in a portable trolley having a total weight of about 39 kg and can be controlled by any kind of Laptop PCs with a standard TCP/IP (Ethernet) connection interface.

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SYSTEM DESCRIPTION

The system was designed according to the specifications of the ISO 16183 procedure with some modifications in order to simplify the rig and reduce the weight.

Fig. 1

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The MICRO-PSS is controlled by a Laptop PC trough a simple TCT/IP (Ethernet) connection and it needs only external 24V 15A power supply. All parts in contact with the sample, are made of stainless-steel. The dilution tunnel has 45 mm internal diameter and 250 mm length. At the inlet of the dilution-tunnel a gas sampling probe is installed. It has to be connected to the exhaust pipe of the engine. Sample inlet Dilution tunnel Dilution air in Filter holder Diluted gas out

Fig. 2 The connection between the mini-tunnel and exhaust pipe can be done in two different ways:

1) Direct connection through a heated sampling line (standard)

This type of connection (fig 3) is recommended if the system can be installed near the vehicle exhaust pipe and if the total length of the line is less than 2 meters.

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Fig 3

2) Connection through an auxiliary transfer pump (Option 3).

This type of connection (fig 4) is used when the location of the MICRO-PSS is far from the vehicle exhaust pipe (up to 5-6 meters) and allows to avoid the long response time due to a long sampling line. With this sampling a big amount of exhaust gas (about 6000 l/h) is transferred from the tailpipe to the sampling point near the minitunnel in a very short time; the sampling probe is short (less than 300 mm) and the response time is fast (transformation time < 100 ms).

Fig 4

EXHAUST

EXHAUST TRANSFER LINE

DILUTION AIR

DILUTED GAS

FILTER

VENT

EXHAUST

SAMPLE TRANSFER LINE

DILUTION AIR

DILUTED GAS

FILTER

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All parts, both of the dilution and the sampling system from the exhaust pipe, up to the filter-holder which are in contact with raw and diluted exhaust gas, are designed to minimise deposition or alteration of the particulate. All parts are made of electrically conductive materials, which do not react with the exhaust gas and are electrically grounded to prevent from electrostatic effects. The temperature is measured both near the inlet pipe and the filter holder. The dilution air is generated by a variable speed volumetric pump and measured by a high-precision volumetric flow meter which allows the system to have a very fast response time (transformation time lower than 0.20 sec). Dilution air is filtered, so that the particulate measurement cannot be altered by solid particles which are already present in the air. (Inlet air filter according HEPA specifications, 99.97% efficiency). A dilution air heating system allows to maintain the filter temperature at 47 ± 5 ºC (according USA 1065 and NRTC cycles). Temperature and pressure are also measured. The filter holder assembly includes a filter holder with cartridge for 47 mm filters. The cartridge can contain one or two (primary and back-up) filters. This is in accordance with the EC directive which states that diluted exhaust gas is sampled by two filters placed in series (one primary and one back-up filter) during the test sequence. A gas extraction tube is connected, downstream of the filters, to a second volumetric pump and to a second precision volumetric flow meter.

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Fig. 3

The gas flow-rate can be set according to the cycle's need and taking into account the specification for the filter’s face velocity; the common setting is from 1000 to 2000 nl/h of diluted gas. The system provides for maintaining a constant flow even when the filters get progressively clogged. This is done by automatically changing the aspiration pump speed. The MICRO-PSS is equipped with PLC for data acquisition and flow control. This PLC is connected to the laptop PC where the main software is installed. The equipment provides all pressure and temperature sensors in accordance with the current directives.

NEW REAL TIME PARTICULATE

DETECTOR

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MICRO-PSS BENEFITS

• Tanks to the high stability of the flow meters, the MICRO-PSS doesn’t need to be calibrated before running the test.

(See ISO procedure 16183 [Par. 7.3.2.3 -Pre-test check-])

• No compressed air or water is required.

• No appreciable maintenance of the system is required.

• No limitation regarding the type of trial and/or the size of the engine.

• The mechanical flow-meters are equipped with optical encoders in order to have high accuracy on flow rate measurement and low response time (Transformation Time is less than 0.20 sec).

• All functions can be controlled by an Host Computer. The Communication is done with AK protocol on RS 232 C serial line or TCP/IP.

• The test sequence can be controlled on the basis of "sampled gas volume" or "time" measurements.

• The unit is easily transportable (approximate weight about 39 kg).

• Only 24V DC power supply is required (external batteries or direct connection to the vehicle).

• Easy handling of the filter holders.

• Transient capability for test cycles in real vehicle driving conditions.

TECHNICAL DATA

Maximum flow of the dilution air pump: 4.000 nl/h Maximum flow of the diluted gas pump: 4.000 nl/h Maximum pressure drop after the filters: 300 mbar Diameter of mini-tunnel: 45 mm Length of mini-tunnel: 250 mm Diameter of filters: 47 mm Stability of flow rate regulation: ± 0.1 % Weight: approximately 39 kg

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OPTIONS: 1- Auxiliary exhaust transfer pump.

This sample-rig is made of a variable speed pump, a sampling volume and connection pipes. The gas is taken from the vehicle tailpipe to the sampling volume using a transfer line up to 5 meters. The exhaust gas is then sampled using a standard hatted probe.

2- Integrated PC

A mini-PC integrated in the Micro-PSS equipped with wireless connection; this option allows to reduce the space required for the installation avoiding the use of the laptop that can be used as a remote controller by means of the wireless network.

3- Real time particulate detector

The real time particle sensor operates by electrostatic charging particles passing through the sensor and then measuring the current caused by the charged particles leaving the sensor. Once integrated and corrected with gravimetric measurement this signal can be used to determine the quantity of particulate collected on the filter second per second. The detector is connected to the minitunnel after the dilution section, and the sampled flow is sent back to the main flow, thus allowing a correct sampling on the filter.

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4 - Exhaust gas flow measuring system. SEMTECH EFM-HS is a Pitot based flow meters for on-road applications. With a sampling rate of up to 2500 Hz and four, dual stage differential pressure transducers, the EFM-HS accurately measures every forward and reverse flow pulsation from idle to maximum flow rate, and properly accounts for these pulsations in the exhaust flow determination. This is a tremendous advantage over low speed exhaust flow meters which are susceptible to measurement error from high frequency pulsations. Mass flow rate accuracy and linearity of the SEMTECH EFM-HS exceeds the US and European performance standards over a 50:1 turndown ratio.

5- Standard External Unit for Flow Calibration It consists of a Laminar Flow Element installed in a box; it can be put in series with the MICRO-PSS flow meters in order to calibrate them by a SW automatic procedure. The LFE is NIST traceable.

6- Micro balance with conditioning box

Micro balance for 47mm filter weighting with certified 0.1µm resolution and 2.1g full scale range. The balance is placed in a conditioning box that allow to keep the temperature and the humidity in regulation range (20±1°C and 50±5%); moreover the box allows to prevent from dust contamination of the filters. The supply includes an electronic discharger and an antivibration table in order to obtain the maximum accuracy from the weighting procedure.

7- Additional Sampling Probe with its fitting. 8- Additional cartridge for 47 mm filters (one or two filters)

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MICRO-PSS Particulate sampling system for on-road tests · The MICRO-PSS is based on the same technology (partial flow exhaust dilution and filter ... Page 5 CONTROL SISTEM S.r. l..-via