WLTP DTP PMPN Regeneration small group
Title
Discussion Document on Experimental Protocol for PM/PN
emissions of Periodically Regenerating Exhaust After-treatment
Devices over the Validation Phase 2
Working Paper WLTP-DTP-PM/PN-10-02
Number
Authors
Christos Dardiotis, Massimo Carriero
Contents
1
INTRODUCTION
3
2
TEST SPECIFICATIONS
3
2.1
Testing Environment
3
2.2
Vehicle Specifications
3
2.3
Lubricating Oil
3
2.4
Lubricant Flush and Fill
3
2.5
Test Fuel
3
2.6
Test Cycles-repetitions
3
2.7
Test Order and System Preconditioning
4
3
MEASUREMENT AND SAMPLING SYSTEM FOR GASEOUS EMISSIONS
4
4
MEASUREMENT AND SAMPLING SYSTEM FOR PARTICULATES
4
5
PARTICLE NUMBER MEASUREMENT SYSTEM
4
6
TEST PROCEDURES
4
7
6.1
Dynamometer Preparation
6
6.2
Preparation of the Vehicle
6
6.3
Test Protocols
6
6.3.1
Emission test just after regeneration
6
6.3.2
Loading of the after-treatment device
6
6.3.3
Emission test just before regeneration
7
6.3.4
Regeneration emission test and subsequent hot start cycle(s)
7
LIST OF SPECIAL TERMS AND ABBREVIATIONS
APPENDIX 1: FILL AND FLUSH PROCEDURE
References
2
8
9
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1 INTRODUCTION
This document has been prepared in response to a request from Worldwide Harmonized
Light-duty Test Procedures (WLTP) PM/PN subgroup. The purpose of the document is to
specify the testing guidelines and protocol for an experimental investigation of Particulate
Matter (PM) and Particle Number (PN) emissions during exhaust after-treatment device
regeneration.
2 TEST SPECIFICATIONS
2.1 Testing Environment
The participating laboratories shall provide facilities and resources required to perform light
duty vehicle emissions tests according to the Regulation 83, plus additional capability required
for particle measurements as defined in this document.
2.2 Vehicle Specifications
Diesel-fuelled vehicles should be tested, at least one Euro 5 and if possible one Euro 6
certified.
May 2014: Euro 6 with NOx control aftertreatment device preference
2.3 Lubricating Oil
The lubrication oil shall meet the specifications of the engine manufacturer and preferably
contain the maximum allowed sulphur content oil.
2.4 Lubricant Flush and Fill
A defined flush and fill procedure will be employed upon arrival of the vehicle at the test
laboratory. The flush and fill procedure is presented in Appendix 1.
2.5 Test Fuel
Each vehicle should be tested on commercially available diesel fuel, compliant with Annex 2 of
the Directive 2009/30/EC [1].
2.6 Test Cycles-repetitions
All vehicles shall be tested according to the WLTP procedures, defined by the relevant WLTP
subgroup. At least two repetitions of the complete test protocol defined below (section 5) shall
be performed for each vehicle and each Particle Concentration Reduction Factor (PCRF)
setting in the PMP systems (2 PCRF values in total). This results in at least four in total
repetitions for each vehicle, as described below, in section 5.
May 2014: One repetition with a high PCRF is acceptable in order to gain info regarding
emission levels
3
2.7 Test Order and System Preconditioning
In the case where more than one vehicles are tested the same day in a laboratory, the test
order shall consider the possibility of contamination of test results by a previously tested
vehicle. The test order and the entire transfer and dilution system should be preconditioned
according to the specifications of the WLTP procedures.
3 MEASUREMENT AND
GASEOUS EMISSIONS
SAMPLING
SYSTEM
FOR
The mass of gaseous emissions shall be measured during all emission tests in accordance
with the WLTP procedures, defined by the relevant WLTP subgroup. Engine out and if
possible raw tailpipe gaseous emissions shall be measured on a continuous basis throughout
the test sequence.
4 MEASUREMENT
PARTICULATES
AND
SAMPLING
SYSTEM
FOR
The mass of particulate emissions shall be measured during all emission tests in accordance
with the WLTP procedures, defined by the relevant WLTP subgroup.
5 PARTICLE NUMBER MEASUREMENT SYSTEM
The number of particles emitted shall be measured during the test sequence in accordance
with the WLTP procedures, defined by the relevant WLTP subgroup. The Constant Volume
Sampler (CVS) flow rate should be set to the minimum allowable value according to WLTP
procedures. In order to investigate a potential cross interference of volatile particles emitted
during regeneration in the Particle Measurement Programme (PMP) PN results, it is required
that two PMP compliant systems shall be employed in parallel operating at different Particle
Concentration Reduction Factor (PCRF) values. The first should run on the minimum PCRF
value according to the manufacturer’s specifications (i.e. 100 or 250), while the second should
run at a PCRF value of 2000. The set-point temperature of the VPR should be documented.
May 2014: Wall temperature 350C. Desirable to have two systems, but not required. One with
PCRF around 2000 required (primary dilution >100)
6 TEST PROCEDURES
Figure 1 presents a flow chart of the experimental protocols should be followed for the scope
of these measurements. The different portions of the test protocol are described in the
subsequent sections.
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Figure 1 – Flow chart of the proposed experimental protocol for measuring PM/PN emissions during
periodic regeneration.
5
6.1 Dynamometer Preparation
The chassis dynamometer controller shall be adjusted to simulate the inertia of the test
vehicle. The inertia shall be set according to the generic inertia classes given in the WLTP
procedures, with corresponding coefficients for the road load curve.
6.2 Preparation of the Vehicle
The vehicle shall be conditioned prior to each test in accordance with the WLTP procedures.
The fuel and lube oil used shall be as specified in section 2 of this document.
Before testing the vehicle, it is crucial that the manufacturer provides information concerning:

A switch/procedure to prevent active regeneration (e.g. to deactivate post injection)

Data concerning the interval of the active regeneration in terms of kilometres of driving
in loading mode.
In order to ensure identical conditions of the after-treatment device at each test sequence, a
regeneration event of the after-treatment must be completed prior to the start of the campaign.
During this particular regeneration event the vehicle should be driven on a chassis
dynamometer on consecutive WLTP cycles or, alternatively, over a high load engine mode in
accordance to the recommendations of the manufacturer.
Operational parameters such as the HC and/or CO engine out emissions, or the EGR rate, or
the state of post injection (on/off) or any other parameter specified by the manufacturer should
be monitored in order to identify the regeneration event.
After the completeness of the regeneration event the vehicle should stop. It is not necessary to
measure the Particle Number and PM emissions during this phase.
If technically feasible, thermocouples should be used to measure the exhaust gas temperature
upstream and downstream of the after-treatment device. The temperatures should be
monitored during each test (i.e. loading, regeneration).
6.3 Test Protocols
6.3.1 Emission test just after regeneration
Each emission test is described by a preconditioning procedure, a soak time and a cold start
WLTP cycle, all defined by the WLTP procedure. After the preparation of the vehicle an
emission test should follow. The switch to prevent regeneration should be activated and
measurements of the emissions of the vehicle should take place.
6.3.2 Loading of the after-treatment device
The loading of the after-treatment device should be conducted by two alternative methods:
Either by dismantling the after-treatment system of the vehicle and conducting a fast loading
procedure on an engine chassis dynamometer, or by driving the vehicle on the chassis
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dynamometer over consecutive WLTP cycles, not necessary cold start. In the case where the
second method is employed, the vehicle should be driven for so many cycles required to load
the after-treatment device effectively, in order to ensure the initiation of the regeneration and in
accordance with the recommendations of the vehicle’s manufacturer (e.g. specific
distance/duration of driving). The switch to prevent regeneration should be enabled during the
loading protocol. PM and PN emissions should be measured for each WLTP cycle during
loading. All the other setting of the vehicle (e.g. Exhaust Gas Recirculation (EGR), should be
according to the ones prescribed by the vehicle’s manufacturer.
May 2014: Loading with WLTP cycles is the preferred method. Loading with other cycles,
engines can also be investigated.
6.3.3 Emission test just before regeneration
After the loading of the after-treatment device an emission test should be carried out
(preconditioning, soak time and cold start WLTP cycle). The device to prevent regeneration
should be activated and measurement of the emissions of the vehicle should be conducted.
6.3.4 Regeneration emission test and subsequent hot start cycle(s)
The regeneration emission test consists of a preconditioning, a soak period and a cold start
WLTP cycle, in accordance with the WLTP procedures. The switch to prevent regeneration
should be enabled during the preconditioning, but after the completion of the preconditioning
should be disabled and remain disabled during the cold start WLPT cycle. If the regeneration
will not be completed during the cycle, subsequent WLTP cycle(s) shall be driver immediately
until complete regeneration has been achieved (each cycle shall be completed). The time
necessary to set up a new test should be as short as possible (e.g. particular matter filter
change, analysis of bag gaseous emissions). The engine shall run on idle mode during this
period without switched off. Emission measurements should be conducted during all the
regeneration cycles.
If the regeneration will not initiate over this emission test, the emission test should be repeated
(preconditioning with the switch to prevent regeneration enabled, soak time and cold start
WLTP cycle with disabled the switch to prevent regeneration), until the regeneration be
achieved.
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7 LIST OF SPECIAL TERMS AND ABBREVIATIONS
CVS
Constant Volume Sampler
ECU
Engine Control Unit
EGR
Exhaust Gas Recirculation
PCRF
Particle Concentration Reduction Factor
PM
Particulate Matter
PMP
Particle Measurement Programme
PN
Particle Number
WLTP
Worldwide Harmonized Light-duty Test Procedures
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APPENDIX 1: FILL AND FLUSH PROCEDURE
1. Warm the oil by 10 minutes low load driving.
2. Install vehicle on elevated rump.
3. Release sump plug and drain oil.
4. Drain oil filter and refit.
5. Lower ramp, add the specified by the manufacturer quantity of fresh test oil to the
engine.
6. Start engine and idle for a fixed period (40 min), sufficient to reach operating
temperature.
7. Install vehicle on elevated rump. Drain oil again.
8. Remove oil filter and discard.
9. Fill engine with the specified by the manufacturer quantity of test oil.
10. Switch ignition off and allow to settle for 5 min. Check dipstick to ensure correct level.
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References
1
Directive 2009/30/EC of the European Parliament and of the Council of 23 April 2009,
“Amending Directive 98/70/EC as regards the specification of petrol, diesel and gas-oil and introducing a
mechanism to monitor and reduce greenhouse gas emissions and amending Council Directive
1999/32/EC as regards the specification of the fuel used by inland waterway vessels and repealing
Directive 93/12/EEC
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