Meeting Future Fuel Efficiency and Emissions Regulations with the Opposed-Piston Engine John Koszewnik Chief Technical Officer April 24, 2013
Jan 19, 2015
Meeting Future Fuel Efficiency and Emissions Regulations with the Opposed-Piston Engine
John KoszewnikChief Technical Officer
April 24, 2013
2©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
3©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
4©2013 Achates Power, Inc. All rights reserved.
Achates Power
A company formed to design and develop clean, more efficient, lower cost engines Founded in 2004
Well supported, technically and financially
Design and development of multiple variations of opposed-piston, two-stroke diesel engines
Demonstrated, validated results, 4,000+ test hours on several engine generations
State-of-the-art facilities and analytical tools
Highly capable team
An intellectual property company We rely on existing OEMs to produce our engines for their
vehicles.
Our revenue comes from a combination of professional services and royalties.
5©2013 Achates Power, Inc. All rights reserved.
Modernizing an Old Idea
“The simplicity and compactness of the OP
engine, combined with its potential for brake
fuel efficiency in excess of 45%, and low
emissions suggest this is a power unit that
needs re-evaluation.”
“Weight and cost comparisons indicate that
the two-stroke OP engine could be
approximately 34% lighter than the equivalent
performance four-stroke and cost 12% less.
Source:
JP Pirault, M. Flint, Opposed Piston Engines – Evolution, Use, andFuture Applications; SAE International 2009
6©2013 Achates Power, Inc. All rights reserved.
Opposed-Piston, Two-Stroke Engine Operation
Source: JP Pirault, M. Flint, Opposed Piston Engine: Evolution, Use, and Future Applications, SAE International 2009
7©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
8©2013 Achates Power, Inc. All rights reserved.
Engine Architectures with Comparable Friction
IVC IPC
IPC
Engine 4S
Cylinders 6
Trapped Volume/Cylinder 1.0 L
Bore 102.6 mm
Total Stroke 112.9 mm
Stroke per Piston 112.9 mm
Stroke/Bore Ratio 1.1
Trapped Comp. Ratio 15:1
Intake Valve Closure 180 bTDC
Engine OP2S
Cylinders 3
Trapped Volume/Cylinder 1.6 L
Bore 102.6 mm
Total Stroke 224.2 mm
Stroke per Piston 112.9 mm
Stroke/Bore Ratio 2.2
Trapped Comp. Ratio 15:1
Intake Port Closure 120 bTDC
Opposed-Piston, Two-Stroke (OP2S) Engine
Four-Stroke(4S) Engine
9©2013 Achates Power, Inc. All rights reserved.
Quantifying the Surface Area / Volume Ratio Advantage
IVC IPC
IPC
Surface Area (mm2) 4.05*104
Volume (TDC) (mm3) 1.43*105
Surface area / Volume(mm-1) 0.28
Opposed-Piston, Two-Stroke (OP2S) Engine
Four-Stroke(4S) Engine
Surface Area (mm2) 2.07*104
Volume (TDC) (mm3) 1.14*105
Surface area / Volume(mm-1) 0.18
-49%-20%-36%
This surface area-to-volume advantage minimizes heat losses…i.e., more energy goes into work and improves fuel efficiency.
This comparison is conservative as the cylinder head of a four-stroke typically runs 80-100o C less than the cylinder liner.
10©2013 Achates Power, Inc. All rights reserved.
Fuel Injection System Unique and proprietary injector nozzle design and spray pattern
provides interdigitated fuel plumes with larger λ=1 isosurfaces Dual injectors per cylinder provide multiple injection events,
appropriate flow rates and mid-cylinder penetration
Patented Achates Power Combustion System
Port and Manifold Design Port design is optimized to provide optimal blow down, uniflow
scavenging, supercharging and swirl characteristics
Piston Bowl Shape Proprietary piston crown designs combine swirl with tumble
motion during compression Provides excellent mixing, air utilization and charge motion for
rapid diffusion and flame propagation Ellipsoidal shape of combustion chamber guarantees air
entrainment into spray of plumes coming from two sides into center of cylinder
Minimal flame-wall interaction during combustion
Result: Short burn duration, earlier auto-ignition timing, minimal heat transfer losses
11©2013 Achates Power, Inc. All rights reserved.
Heat Release Rates
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
0
100
200
300
400
500
600
700
800
900
1000
Mas
s Bu
rnt F
racti
on
Hea
t Rel
ease
Rat
e
Crank Angle
Typical 4S Engine
Measured OP2S Engine
12©2013 Achates Power, Inc. All rights reserved.
Why Is an OP2S Diesel More Fuel Efficient?
Versus four-stroke engines 30+% lower surface area-to-volume ratio No heat losses to cylinder head Shorter burn duration Earlier combustion phasing without
exceeding peak cylinder pressure Leaner combustion -- i.e., favorable
specific heat of air/fuel mixture Reduced pumping losses at low loads
leads to flat fuel map – can leave residuals in reducing pumping work
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 2 4 6 8 10 12 14 16
Surf
ace
to V
olum
e Ra
tio a
t TD
C [1
/mm
]
4-Stroke Engine Displacement [L]
API OP6 2-stroke diesel
4-stroke diesel
30% lower
13©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
14©2013 Achates Power, Inc. All rights reserved.
Why Does an OP2S Diesel Have Superior Emissions?
• By selecting an appropriate power density, the OP2S diesel has lower peak cylinder pressures and lower peak temperatures and, therefore, can meet more stringent NOx emissions limits without significant calibration trade-offs
• In addition, our OP2S diesel has a very high Exhaust Gas Recirculation (EGR) tolerance. EGR also reduces peak temperatures and thereby reduces NOx.
3 3.5 4 4.5 5 5.5 6 6.5 70
5
10
15
20
25
4-Stroke BMEP
4-Stroke Disp.
BMEP/Displacement Trade-OffComparison to 4-Stroke Engine at Rated
Power
Displacement (L)
BM
EP
(b
ar)
™
Source: Kaario O., Antila E. and Larmi M. Applying soot phi‐T maps for engineering CFD applications in diesel engines, SAE 2005‐01‐3856, 2005
15©2013 Achates Power, Inc. All rights reserved.
Fuel Injection System
Piston Bowl Shape
Why Does an OP2S Diesel Have Superior Emissions?
By selecting the appropriate injection strategy (hole size, spray pattern, fuel rail pressure, start of injection and duration timing) coupled with the appropriate piston
bowl shape, the opposed injection sprays can avoid impinging upon one another and can avoid contact with the piston crown. This results in low particulate matter.
16©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
17©2013 Achates Power, Inc. All rights reserved.
1.6L Single-Cylinder Measured Data
0
0.25
0.5
0.75
1
0
20
40
60
80
100
120
140
160
180
200
220
240
-30 0 30 60 90
nA
MF
B (
-)
AH
RR
(J/d
eg)
Crank Angle (deg aMV)
1.6L Single CylinderINDICATED RESULTS SUMMARY
OPERATING CONDITIONS HEAT RELEASE ANALYSISSpeed 1203 (rpm) CA10 -3.4 (deg aMV)
Delivered Air Flow 141.3 (kg/hr) CA50 2.0 (deg aMV)Fuel Mass 62.7 (mg/rev) CA90 14.4 (deg aMV)
SOI -6.0 (deg aMV) Burn Duration (10-90) 17.8 (deg aMV)Injection Duration 6.7 (deg) Energy Released 2701.1 (J)Injection Pressure 1200 (bar)
CALCULATED OUTPUTSAVERAGE GAS TEMPERATURES
IMEP 8.8 (bar)
Intake Manifold Inlet 324.5 (K) Indicated Thermal Efficiency 53.2 (%)Intake Manifold 323.3 (K) Indicated Power 28.9 (kW)
Exhaust Manifold 588.8 (K) Indicated Torque 229.1 (N-m)Exhaust Manifold Outlet 566.0 (K) Peak Pressure 142.0 (bar)
Loc. of Peak Pressure 5.0 (deg aMV)AVERAGE GAS PRESSURES MPRR 8.4 (bar/deg)
Intake Manifold 2.10 (bar) Loc. of MPRR -1.0 (deg aMV)Exhaust Manifold 2.01 (bar) ISFC 156.8 (g/ikW-hr)
ISCO2 497.0 (g/ikW-hr)EMISSIONS-BASED CALCULATIONS ISCO 0.08 (g/ikW-hr)
Delivered AF 28.4 (-) ISNOX 3.772 (g/ikW-hr)ISHC 0.211 (g/ikW-hr)
Combustion Efficiency 99.9 (%)EGR Rate 30.4 (%) ISSoot 0.005 (g/ikW-hr)
Cyl
inde
r P
ress
ure
(Bar
)
18©2013 Achates Power, Inc. All rights reserved.
Out of 100% fuel energy, the single-cylinder test results cover heat losses and the air flow enthalpies.
Indicated thermal efficiency doesn’t take into account pumping and friction.
Pumping losses for a multi-cylinder includes Supercharger, Turbocharger, Charge Air Cooler and
Exhaust Aftertreatment System. Brake thermal efficiency is indicated efficiency minus pumping minus
friction losses.
0
20
40
60
80
100
Exhaust-Intake
Enthalpy
HeatTransfer
IndicatedThermal
Efficiency
PumpingLoss:
SC, TC, CAC, EATS
Friction
BrakeThermal
Efficiency
Per
cen
t F
uel
En
erg
y
Single-CylinderMeasurement
Multi-CylinderPrediction
Data Generation Process
From Indicated to Brake-Specific Values
19©2013 Achates Power, Inc. All rights reserved.
Multi-Cylinder Interface Model Input Data
Input data into GT-Power model are a combination of test cell data and a set of application-specific assumptions.
The multi-cylinder model also considers wave dynamics and tuning effects.
Geometry Data: stroke/bore
displacementnumber of cylinderscompression ratio
Air Charge System: scaled TC,SC maps,
EGR system
Engine Cooling System:
CAC and EGR cooler performance,
coolant temperatures
Aftertreatment System:
backpressure representative of full
aftertreatment
Multi Cylinder Performance Model
Single Cylinder Test Data:
speed, fuel & air mass, pressures &
temperatures
Performance Report:Brake-specific data:BSFC, BMEP, BSNOx, BSPM, etc.
Friction:Chen-Flynn model
parameterized according internal correlated model
Combustion System:
rate of heat release, excess air ratio
EGR rate
Test Data
Assumptions
Legend:
Data Generation Process
Scavenging Characteristics:measured with high-
speed sampling
20©2013 Achates Power, Inc. All rights reserved.
OP Engine Performance Advantage
Comparison of optimized OP2S engine vs. conventional, state-of-the-art medium-duty engine
15% “best point” advantage 22% cycle-average advantage (20.8% at equivalent engine-out NOx)
Best Point 48.5% BTE
Best Point 40.9% BTE
OP2S
21©2013 Achates Power, Inc. All rights reserved.
Engine Speed (RPM)
To
rqu
e (
n/m
)
BSFC Map HD 2016
800 1000 1200 1400 1600 1800 2000 2200 2400
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
BS
FC
(g/
kW-h
r)
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
Projected Heavy-duty OP2S BSFC Map
11 Liter, 3-cylinder
2000-2500 Nm Max Torque
400-500hp Max Power
Best Point 51.5% BTE
22©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
23©2013 Achates Power, Inc. All rights reserved.
Practical ConsiderationsPackaging
Wrist Pin Durability
-600000
-500000
-400000
-300000
-200000
-100000
0
100000
200000
-160000
-140000
-120000
-100000
-80000
-60000
-40000
-20000
0
20000
40000
60000
0 120 240 360 480 600 720
Forc
e in
Wri
stp
in (
N)
Crank Angle (deg)
Wristpin loads for typical 4-Stroke vs 2-Stroke
4-stroke2-stroke
0
Co
mp
ressiv
eTe
nsile
Oil Consumption Versus Power Cylinder Durability
Fuel specific oil consumption
Piston Thermal Mgmt.
24©2013 Achates Power, Inc. All rights reserved.
Oil Control Design Parameters
Liner temperature Bore texture, form after honing, form at
operating temperature Oil ring tension Scraper element conformability Ring end gaps, end chamfers and land
chamfers Groove tilt, pinch, keystone angle, texture
and flatness Ring side clearance, cross sealing and
side sealing Volume behind ring, volume between rings
25©2013 Achates Power, Inc. All rights reserved.
Da Vinci Lubricant Oil Consumption (DALOC™)
Oil Measurement System
Measures piston/ring/liner and turbocharger lubricant losses
Measurement principle: Sulfur free fuel (< 2 ppm)
Oil with known sulfur (~3500 ppm)
Excite SO2 in exhaust with ultraviolet light
Quantify fluorescence
Technology benefits: Real-time resolution
Sensitivity: <0.1 g/hr. minimum detection limit
Repeatability: <2% test-to-test
Accuracy: <10% from other methods
Non-intrusive, non-destructive
Insensitive to air, fuel or soot dilution in the lubricant oil
26©2013 Achates Power, Inc. All rights reserved.
OP2S Oil Consumption Results
Weighted cycle-average
Average of three runs.
Conclusion:
The OP2S engine achieved weighted, cycle-average, fuel-specific oil consumption of 0.11% with all points in the operating map < 0.18%. This beats the best two-stroke results published in the literature and is within the range of state-of-the-art, heavy-duty, four-stroke engines.
Best two-stroke in literature
Modern heavy-duty four-stroke
Best in class
27©2013 Achates Power, Inc. All rights reserved.
-600000
-500000
-400000
-300000
-200000
-100000
0
100000
200000
-160000
-140000
-120000
-100000
-80000
-60000
-40000
-20000
0
20000
40000
60000
0 120 240 360 480 600 720
Forc
e in
Wri
stpi
n (N
)
Crank Angle (deg)
Wristpin loads for typical 4-Stroke vs 2-Stroke
4-stroke2-stroke
Wrist Pin
0
Com
pre
ssiv
eTe
nsile
28©2013 Achates Power, Inc. All rights reserved.
Biaxial Wrist Pin Bearing
Ladder-type bearing and corresponding biaxial bearing
29©2013 Achates Power, Inc. All rights reserved.
Biaxial Bearing Analysis Tool
The bearing parameters (clearance, axis spacing, etc.) are optimized to provide adequate MOFT, filling, film density and film pressure.
30©2013 Achates Power, Inc. All rights reserved.
Piston Thermal Management Countermeasures
Management of the “hot side” – that is, combustion strategy: Piston bowl geometry Injection – i.e., spray pattern, number of holes, hole size Calibration – start of injection, duration, air/fuel ratio Liner & manifold – port-to-port balance, swirl
Management of the “cold side” Cooling gallery – geometry and fill ratio Oil jets – number and flow rate Oil flow through the connecting rod
Material selections Crown and skirt Anti-oxidation coatings
Appropriate power densities Etc.
31©2013 Achates Power, Inc. All rights reserved.
Detailed CFD Results: Baseline vs. Best Candidate
Genetic Algorithms
Best
32©2013 Achates Power, Inc. All rights reserved.
5
Thermocouple Measurement / FEA Extrapolation
Bowl<520°C
Pin<180°CRin
gs<
285°
C
Und
ercr
own<
285°
C
Surface Temperature Limits
1 & 36 & 7
Templug
Model includes:
1. Temperature-dependent material properties
2. Epoxy thermal conductivity
3. Hot-side zones (flame contact)
4. Cold-side zones (impingement, gallery shaking)
33©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
34©2013 Achates Power, Inc. All rights reserved.
0% 1% 2% 3% 4% 5% 6% 7%0
200
400
600
800
1,000
1,200
1,400
1,600
Conventional Engine Efficiency Technology Roadmap
Waste heat recovery
Improved fuel injection system
$ p
er %
Fu
el C
on
sum
pti
on
Imp
rove
men
t
Friction reduction - engine
Variable displacement
pumpAccessory electrification
Improved turbocharger
Sources: TIAX, National Academy of Engineering, Achates Power, Inc.
% Fuel Consumption Improvement
Increase cylinder pressure
Friction reduction - accessories
35©2013 Achates Power, Inc. All rights reserved.
Key Questions To Be Addressed Today
Who is Achates Power?
Why can an opposed-piston, two-stroke diesel engine be more fuel efficient than a four-stroke diesel?
Why can an opposed-piston, two-stroke diesel engine have superior emissions performance?
What has been demonstrated via dynamometer testing?
How are the historical challenges of opposed-piston, two-stroke diesels addressed?
How does this compare with four-stroke fuel efficiency and emission improvement actions?
How should you validate a game-changing, disruptive technology?
36©2013 Achates Power, Inc. All rights reserved.
How To Validate a Game-Changing Technology
The opposed-piston, two-stroke engine
Provides a step-function efficiency improvement
Meets emissions requirements
Has fewer parts, less mass, lower costs
Demonstrated, enduring advantages……a game changer.
Key validation steps
Sound thermodynamic and combustion basis for claims
Published and peer-reviewed data backing up those claims
No unsolvable implementation issues
25 Companies to Watch in Energy Tech
For More InformationContact:[email protected]
+1 858.535.9920, ext. 301
Visit:www.achatespower.com