INVESTIGATIONS OF DIESEL
PARTICULATE FILTERS IN THE
PERIODIC TECHNICAL INSPECTION
Gerrit Kadijk
Symposium Vehicle Emissions
November 3, 2016
BACKGROUND
The Dutch Ministry of Infrastructure and The Environment
registers and monitors the total PM10 emission of road
vehicles.
About 5-7% of Dutch diesel passenger cars have a
damaged or removed* Diesel Particulate Filter (DPF).
Are current Periodic Technical Inspections (PTI) suitable
for detection of defect particulate filters?
* TNO report TNO2015 R 10307v2
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OBJECTIVES
Development of a PTI test protocol in order to judge
the performance of Diesel Particulate Filters.
Euro 1,2,3,4: determination of the quality of the combustion; smoke
numbers are suitable (k = 0,3 – 2,5 m-1 on a measuring scale of 0 – 10 m-1 ).
Euro 5,6: Determination of the filtration efficiency of the DPF; smoke
numbers are extremely low (k = 0,00 – 0,05 m-1).
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REFERENCE TEST METHODS
Vehicle Type Approval PM & PN
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Engine Type Approval smoke
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EMISSION LIMIT VALUES
Emission class
Euro 1 – 1993
Euro 2 – 1996
Euro 3 – 2000
Euro 4 – 2005
Euro 5a – 2009
Euro 5b – 2011
Euro 6 – 2015
2018
Type approval,
chassis dynamometer
Type Approval & PTI
NEDC test 11 km
Free acceleration
test
PM limit value
[mg/km]
140
80
50
25
5
4.5
4.5
PN limit value
[#/km]
6 * 1011
6 * 1011
Smoke (Opacity)
k [m-1]
3.0
2.5
1.5
0.7
PM & PN limit values in TA-tests do not correlate with smoke emission limit
values in the PTI
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A DPF IS EXTREMELY EFFECTIVE
Tail pipe
covered with
black soot
DPF not OK, PM = 2-100 mg/km
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Tail pipe clean
DPF OK, PM < 2 mg/km
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IMPRESSION OF A DPF FAILURE
Euro 5a diesel @ 160.000 km
Backside DPF with
some cracks
NEDC PM emission 5 mg/km, PTI smoke 0.32 m-1
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IMPRESSION: EMISSIONS OF EURO 5/6
DIESEL VEHICLE
Unit
Test
Limit
value
Pre DPF
Post DPF
OK
PM
[mg/km]
NEDC
4,5
25 - 50
<1
PN
[#/km]
NEDC
6*1011
6*1013
6*109
[m-1]
PTI - FA
0.7
0.5 - 3
<0.01
PN
[#/cm3]
PTI - FA
-
250,000,000
100
PN
[#/cm3]
PTI - LI
-
5,000,000
10
Smoke
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INVESTIGATION OF A NEW PTI TEST
How can the performance of a DPF be measured in a PTI
test, which must be reliable, fast and cheap?
Which parameter?
Opacity (smoke)
Particulate Matter (PM)
Particulate Number (PN)
Which test and limit values?
Free acceleration
Low idle speed
High idle speed
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POTENTIAL DPF TEST METHODS IN A PTI
PTI: Visual
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Opacity
PN
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TNO PROJECT OF PTI EMISSIONS
Samples: Euro 5 and 6 LD diesel vehicles
All 213 vehicles have a DPF
Tailpipe swipe tests
Smoke emissions in free acceleration tests
PN-emission tests at low idle speed
Tissue test at low idle speed
Mobile test street
Fixed test team in this research project
10 test days at 7 different locations
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MILEAGES OF 213 VEHICLES
156 vehicles (73%) have run more than 100,000 km
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TEST RESULTS:
FIRST IMPRESSION SWIPE TESTS
21% of the tested vehicles have a (deep) black tail pipe.
Swipe test results are a first impression but cannot be
applied for PTI test purposes!
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PN EMISSIONS @ LOW IDLE SPEED
‘10% high
emitters’
24% elevated PN-emission
52 vehicles (24%) have an elevated PN emission (> 5000 #/cm3)
Screening performance of PN measurements is good.
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STANDARD OPACITY FREE ACCELERATION TESTS
1.4% high emitters are based on standard opacity readings, k ≥ 0.20
Screening performance is very low
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IMPROVED OPACITY FREE ACCELERATION TESTS
5.6 % high emitters are based on improved opacity readings, k ≥ 0.10
Screening performance seems low
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POTENTIAL SCREENING PERFORMANCE
OF DIFFERENT PTI TEST METHODS
Swipe
PN
Opacity
Swipe test cannot be applied for PTI purposes!
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CONCLUSIONS (1)
Current PTI test procedure is not suitable for detection of damaged Diesel
Particulate Filters because the screening performance is too low.
Improved smoke meters with an accuracy of +/- 0.01 in the range of
k = 0.00 – 0.20 are needed to continue current test procedures. Electronic
filtering of these measuring signals must be further investigated. Then a fixed
opacity limit value (k) for all diesel vehicles might be possible (0.10 or 0.15 or
0.20).
The sensitivity and stability of this test procedure must be validated in field
tests.
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CONCLUSIONS (2)
Particulate Number measurements at low idle operation are very suitable for
judgement of the DPF condition because the screening performance and the
accuracy are good and a limit value of 250,000 #/cm3 at low idle speed (@
hot engine) seems suitable. The total costs per PTI are expected to be
somewhat higher than current cost level.
Dedicated cheap PN testers for PTI purposes must be developed.
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NEXT STEPS
Further research, expected activities
Investigation of specifications of improved opacity meters
Investigation of smoke @ PN-emissions pre and post DPF
Detailed Opacity @ PN-test program
Planning: Next report: Q2-2017
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