calstart webinar series: achates power on opposed piston two stroke engines 4-24-2013

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?


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.


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


Opposed-Piston, Two-Stroke Engine Operation

Source: JP Pirault, M. Flint, Opposed Piston Engine: Evolution, Use, and Future Applications, SAE International 2009


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


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.


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


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


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


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


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.


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

)


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


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


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


OP2S


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



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.


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


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


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


-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


Biaxial Wrist Pin Bearing

Ladder-type bearing and corresponding biaxial bearing


Biaxial Bearing Analysis Tool

The bearing parameters (clearance, axis spacing, etc.) are optimized to provide adequate MOFT, filling, film density and film pressure.


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.


Detailed CFD Results: Baseline vs. Best Candidate

Genetic Algorithms

Best


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)


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


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

calstart webinar series: achates power on opposed piston two stroke engines 4-24-2013

Automotive

stroke diesel engines

stroke engine operationsource

stroke op engine

mmtotal stroke

stroke fuel efficiency

engine architectures

engine generations

achates powera company