Presentations text content in Diesel Engine Emissions Primer
Slide1
Diesel Engine Emissions Primer
Everything you need to know about why the world’s largest auto OEM (in 2015) will drop to # 3 in 2016
Slide2ASE-IEA PRESENTATION
JULY 26, 2016 Concord, NC
Sean Bennett
Cengage Learning
Slide3Perfect Combustion of Diesel
H is oxidized to form H
2
O
HC (fuel) is reacted with air
Carbon is oxidized to form CO2
Nitrogen remains unaffected by combustion reaction in cylinder
Slide4‘Perfect’ combustion seldom occurs …
… stoichiometry is generally unachievable in lean burn diesel engine cylinders
… in modern low emission diesels, cylinder temperatures have to be precisely managed
Slide5Combustion mixture rich or temperatures low:
Carbon component of the HC fuel is not properly oxidized in the cylinder…
… resulting in:
CO
VOCs (vaporized HC)
PM
Slide6Combustion mixture lean or temps too high:
… nitrogen ceases to be inert and is oxidized to form various compounds of nitrogen which we know as NOx
…
NOx
is gaseous … therefore not observable to the eye
Slide7PHOTOCHEMICAL SMOG
NOx and HC are primary constituents of photochemical smog
NO
2
is key to the formation of ozone and acid rain
Slide8How photochemical smog forms
HC (in liquid, solid, or gaseous states)
+
NOx
+
Sunlight
+
Time
=
Photochemical smog
Slide9Perfect conditions for photochemical smog formation:
LA … 2
nd
largest conurbation in NA
Abundant year-round sunshine
Per capita auto ownership is highest in the world
Ports of LA and Long Beach are diesel intense zones: shipping, drayage, trucking
San Gabriel mountains stall and wall in emissions
Slide10GHGs
Water vapor
Methane
Ozone
C02
Slide11CO2
2007: Massachusetts versus Supreme Court produced a ruling that CO2 was not just a GHG but also a pollutant
The ruling resulted in the current Administrations drive to set CO2 dump to a set of standards to begin implementation in 2017
Combusting 1 gallon of diesel fuel produces 22
lbs
of CO2
Slide12NEW TECHNOLOGY
DIESEL ENGINE (NTDE)
NTDE term was coined by Health Effects Institute
NTDEs are defined by HEI as diesels meeting EPA 2010 or later standards
HEI NTDE effects testing was undertaken on rats
Tests suggest that no animal respiratory or organic damage was sustained by animals after long term exposure to NTDE exhaust
Slide13EPA 2010 Standards and History
Slide14NTDE Features
Precise management of combustion
Exhaust gas recirculation (EGR)
Diesel oxidation catalysts (DOCs) (catalytic afterburning)
Diesel particulate filters (DPFs)
Selective catalytic reduction (SCR)
Slide15Slide16EGR
Exhaust discharge is the most convenient source of ‘dead’ (unreactive) gas
It dilutes the intake charge (of oxygen) and lowers combustion temperatures
It can be cooled and may be ‘cleaned’ (Cat CGI) sourced downstream DPF
EGR cut-percentage is ECM controlled
Slide17DOC
Diesel oxidation catalyst
Uses platinum and palladium catalysts
Used for a generation in diesel engines and is located upstream from DPF
Reaction temps range from 800-1000 C
Slide18SCR
NOx reduction agent used in gasoline fueled engines (rhodium) only functions as a catalyst when stoichiometry is <15:1
SCR uses ECM-managed DEF (aqueous urea) injection to reduce NOx compounds back to elemental O2 and N2
DEF is a consumable that must be replenished: levels are ECM-monitored and are EPA-required to progressively cripple the engine if refill alerts are ignored
Slide19SCR operation
Slide20DPF
A soot trap for emission solids known as
particulate matter (PM)
PM is entrapped by filters and collected
When soot reaches a threshold value, the DPF must be
regenerated
Regen reduces soot to unreactive ash
Slide21DPF Entrapment Principle
Slide22DPF regeneration modes
Passive
: set to occur when soot build-up has reached a threshold and engine exhaust temps are high enough
Engine is usually under load and the vehicle is running at highway speeds
Exhaust gas heat (600 C plus) is used to burn-off soot to unreactive ash
Ash is then collected
Slide23DPF regeneration modes
Active:
occurs when DPF soot levels exceed a threshold value
ECM-controlled when vehicle operating conditions permit
Or ECM-diagnostic software generated
May require fuel to be injected into the exhaust gas and spark-assist ignition
Slide24DPF Maintenance
Regeneration results in ash residues: ash build-up requires DPF to be cleaned using specialized equipment.
Federal law requires this to be no more frequent than once a year or 150,000 miles during ‘normal’ operation of the vehicle.
The minimum mileage thresholds are set to increase for MY 2017
Slide25Aftertreatment
status alerts
Slide26Heading toward 2017 and 2018: the “Freight Efficient” truck
Slide27Emissions Tampering
Current EPA penalty for ANY tampering with a diesel emission control device or programming is
$37,500
PER infraction
Attempting to bring a vehicle back into compliance that fails:
Fine $$$
Servicing vehicle engine and ignoring a CEL or HD-OBD alert:
Fine $$$
Slide28NO STATUTE OF LIMITATIONS!
Every vehicle from 1989 to current MY is covered
Every facility servicing commercial diesel engines should have a clearly stated shop policy for handling any emissions-related problem
Shops and technicians are liable!!!
Slide29VW and the damage done to the optics of owning any diesel engine – and to the environment
VW had 70% of the light vehicle diesel market from 2010 to Oct 2015
Within those years VW sold 490,000 non-compliant engines in the U.S.
The company sold another 10 million ‘non-compliant’ diesels worldwide.
Slide30How were they caught???
PEM (portable emissions measurement) tests at the West Virginia University’s Center for Alternative Fuels, Engines and Emissions (CAFEE) detected up to 35 times the permitted NOx dump in VW TDI engines - ALL of which easily passed CARB and EPA tests.
CAFEE reported their findings to CARB and EPA: PEM testing confirmed CAFEE
Slide31How did VW Fool CARB/EPA
VW had Bosch write an algorithm for TDI ECMs that detected CARB-EPA test drive cycles (absence of steering input and TPS angle inputs) – during which lean burn operation was disabled using the defeat programming
When non-test operation was detected, lean burn was activated increasing power and fuel economy – and NOx dump!
Slide32Consequences
Some math: $37,500 X 490,000 =
+
$18 B
VW have settled with EPA for
+
$13 B – good deal?
Next comes individual states lead by NY for criminal ‘damage to the environment
VW, Audi and Porsche diesel sales ban
Slide33Discussion
Thanks
Sean Bennett Cengage Learning
email@seanbennett.org
Diesel Engine Emissions Primer
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