Advance Science. Applied Technology
Achates Magnum OP Engine
Low NOX
Engine-Aftertreatment System
Christopher Sharp - SwRI
Samrat Patil, Ahmad Ghazi, Fabien Redon, John Headly - Achates Power
ASME Fall ICE – Achates OP Engine Symposium
November 7, 2018
• Ozone nonattainment areas across the United States continue to grow
– Growth in population
– Continued tightening of ozone standard
• 2015 EPA rulemaking changed NAAQS for ozone to 70 ppb
• CARB Inventory shows on-road heavy-duty trucks are ~20% of all NOX emissions
• California requires more reduction in NOX emissions to meet the current NAAQS for ozone and PM
– The current 0.20 g/bhp-hr NOX standard isn’t enough
Motivation
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Comparing 0.2g/hp-hr and 0.02 g/hp-hr
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Cold-FTP Hot-FTP
Aftertreatment NOX Conversion Efficiency, %
Test ConfigFTP Transient
RMC-SET WHTCCold Hot Composite
Baseline 75% 98.5% 95% 97% 97%
Low NOX 98% 99.7% 99.5% 99.3% 99.4%
SAE 2017-01-0958
Assumes ~ 3 g/hp-hr Engine-Out NOX
~0.06 g/hp-hr~0.01 g/hp-hr
Final Stage 1 ARB Low NOX Configuration
▪ All catalysts are coated on 13” diameter substrates
▪ SCRF is 13” X 12” on high porosity filter substrate
▪ Remaining catalysts are 13” X 6” on “thin wall, low thermal mass substrates”
▪ All sensors shown are production-type
NOX Levels with Development Aged Parts, g/hp-hr
Cold-FTP Hot-FTP Composite RMC-SET
Engine-Out 2.8 3.0 3.0 2.1
Tailpipe 0.06 0.008 0.016 0.015
2014 Volvo
MD13TC
Euro VI
4
Questions from Stage 1 Demonstration
▪With a more favorable engine platform, is a less
complicated aftertreatment system possible ?
– Primary goal = removal of supplemental heat
▪With a more favorable engine platform, can the GHG
impact be reduced or eliminated ?
▪Achates Magnum OP engine platform provides
potential to address both of these concerns...
5
Current Achates OP Engine Test Platform
▪ Engine mode investigations on 4.9L 3-cyl OP engine platform
▪ Results scaled to planned 10.6L 3-cyl platform size for AT
system simulations and planning
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Displacement 4.9L
Arrangement Inline 3-cyl OP
Bore 98.4 mm
Total Stroke 215.9 mm
Stroke-to-Bore Ratio 2.2
Compression Ratio 15.4 : 1
Nominal Power (kw@ rpm)
205 @ 2200
Max. Torque (Nm@rpm)
1100 @ 1200
Achates OP Engine Catalyst Light-Off Mode
▪ OP Engine has greater
flexibility to modify
scavenging and trapped
residuals while maintaining
stable combustion
▪ Enables CLO mode to target
very high exhaust enthalpy
and low engine-out NOX
▪ Fuel economy advantage
compromised for a limited
time period
– released to normal mode
after ~ 400 seconds
– overall cold-FTP BSFC still
< conventional engine
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0
50
100
150
200
250
300
350
400
0 200 400 600 800 1000 1200
Exh
aust
Te
mp
era
ture
, d
egC
Time, sec
Achates OPS ARB Low NOx - Final
ARB Low NOx - Baseline
Achates Magnum OP EngineCold-Start FTP Exhaust Temperatures
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>200°C at 37 seconds
SAE 2018-01-1378
CLO Mode Normal Mode
Achates Magnum OP EngineCold-Start FTP Engine-Out NOX
9
< 0.04 g/hp-hr before
LO-SCR light-off
SAE 2018-01-1378
13x4.5
Planned Magnum OP Engine Low NOX AT System
▪ Primary approach to Low NOX = close-coupled light-off SCR (LO-SCR)
– Requires dual dosing
– Gaseous NH3 (ASDS) used upstream for demonstration program
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SCR
ASC
CSF
LO-
SCR
SCR
= NOX Sensor = DEF Dosing = NH3 Sensor = NH3Dosing = Temp Sensor
DOC
Gaseous MixerDEF Mixer
Close-Coupled Unit (under-hood) Downstream Unit (under-floor)
13x6 13x5 13x8 13x4.5
13x4.5
Alternate AT System Choices
▪ Reduced thermal inertia – zoned CSF instead of DOC/DPF
▪ Higher deNOX performance – SCRoF instead of DPF (if needed)
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SCR
ASCZoned-
CSFLO-
SCR
SCR
Gaseous MixerDEF Mixer
ASC
SCRoF
LO-
SCR
SCR
DOC
Gaseous MixerDEF Mixer
Simulation Results
▪ Simulation results indicate potential to reach Low NOX
– Basic dosing strategy used for initial simulations
▪ * Improved dosing strategy for hot-start FTP should result in hot-FTP ~ 0.01g/hp-hr
– This will bring composite FTP < 0.02 g/hp-hr
▪ Engine mode test results indicate improved BSFC compared to conventional diesel platform
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* *
Advanced Model-Based SCR Controller with Mid-Bed
NH3 Sensor Feedback
• Primary controls challenge is repeatable hot-start/warmed-up NOX < 0.01 g/hp-hr
• Separate coverage observer models for downstream SCR bricks (7 cells each)
• LO-SCR will use same approach but without NH3 sensor feedback
• Primary calibration parameters are controller gains and coverage targets
TIn
ṁexh
NOX
NO2/NOX
NH3
TIn
ṁexh
NOX
NO2/NOX
NH3
SCR Model Cell
Thermal Model
Kinetic Model
Twall
SCR Model Cell
Thermal Model
Kinetic Model
Twall
TIn
ṁexh
NOX
NO2/NOX
NH3
SCR Model Cell
Thermal Model
Kinetic Model
Twall
TIn
ṁexh
NOX
NO2/NOX
NH3
θ1 θ2 θ3
Magnum OP Engine ccLO-SCR Package
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13in X 6in LO-SCR
▪ Magnum OP engine profile allows for easier packaging of close-coupled LO-SCR package
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Magnum OP Engine ccLO-SCR Package
Demonstration Vehicle Plans
▪ Achates Magnum OP Engine with Low NOX Aftertreatment
system will be operating in demonstration vehicles in Southern
California by end of 2019
▪ Timeline
– Aftertreatment Controls for integration in Q1 2019
– Engine Dynamometer integration and calibration Q2/Q3 2019
– Vehicle integration Q4 2019
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