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Spark-Assisted HCCI Residential CHP
Achieve 40% electrical efficiency at 1 kWe by
transforming small internal combustion (IC) engine
efficiency through a systematic reduction of losses
Project Goal
Fed. funding: $2.6M
Length 36 mo.
Demonstrated over 34% brake thermal efficiency at 1 KW with
concept 1 configuration surpassing year 2 target of 33%
Current Technical Status
Dr. Rolf Reitz, Dr. David
Wickman, and Chris Wright
Wisconsin Engine Research Consultants (WERC)
(Lead and Engine Modeling)
Dr. Sage Kokjohn and Mike
Andrie
University of Wisconsin – Madison Engine Research
Center (Performance Testing and Air Handling)
Doug Shears and David
Procknow
Briggs & Stratton (Manufacturing and
Tech-to-Market)
Lloyd Kamo Adiabatics, Inc. (Coatings)
Technical Details and Data Approach
Key Technology Role in Reducing Losses
Compact combustion chamber with
high compression ratio
Improved expansion stroke energy
extraction
Long stroke and small bore Reduced heat transfer losses
Cooled EGR Reduced heat transfer and NOx
Advanced boosting Increased load to decrease role of friction
Advanced thermal barrier coatings Reduced heat transfer
Stoichiometric operation Enables low cost aftertreatment
Technology combination results in reductions in all major loss categories!
1
Technical Details and Data
• Analysis driven development approach (validated 1-D and 3-D
simulation) used to identify optimal design configurations
• Initial engine concepts designed • Concept 1 uses many production engine components to accelerate
engine testing with an engine close to the design study specifications
• Concept 3 is a clean sheet engine design based on the design study
• Both engines have optimized bore/stroke (<<1) and high compression ratio
• Concept 3 features increased tumble and optimized piston design to
reduce incomplete combustion
• Stoichiometric operation to enable use of three way catalyst
Concept 1 Concept 3
Displacement (cc) 71 70
Bore (mm) 39.5 40
Stroke (mm) 57.9 56
Bore/Stroke Ratio (-) 0.68 0.71
CR 17 18
Testing Status Complete Future
System Level
Developments
2
Technical Details and Data
• Engine testing of concept 1 configuration at 1 kW demonstrated
34% brake thermal efficiency
• 𝜆 = 1 operation (closed loop) with TWC installed
System Level
Developments
Concept 1 Engine
2400 rev/min
𝜆 = 1
MBT Spark Timing
3
Technical Details and Data
• Validated simulations show pathway to reach program targets
continue targeted loss reduction with concept 3 engine
System Level
Developments
Validation
Concept 3 Configuration
4
Technical Details and Data
• Operation at peak efficiency (maximum brake torque (MBT)) spark
timing possible over methane numbers from 65 to 100
System Level
Developments
Spark Timing
Margin
5
Technical Details and Data Concept 3 Engine
Development
6
Technical Details and Data
Engine Control Unit (ECU)
Low flow rate boosting system to
enable increased EGR
• Developed and tested pressure wave
supercharger (PWS) shows ability to achieve
over 1.3 bar abs. intake pressure at target
conditions
• Current engine testing shows
potential for minimal boost
requirement <1.15 bar abs.
passive devices may be possible
• Currently developing membrane
based charger
• Custom engine control unit developed by Woodward®
• Closed loop combustion phasing and AFR control
• EGR feedback based on intake/exhaust O2 sensors
Component Level
Developments
7
Technical Details and Data
Improved Thermal Barrier Coatings with Very Low Thermal Conductivity and
Heat Capacitance with Minimum Porosity
0.94
0.67
0.28
0
0.2
0.4
0.6
0.8
1
Plasma20YSZ
ToyotaSiRPA
RCCoating
Thermal Cond (W/m-K)
2630
1540
500
0
500
1000
1500
2000
2500
3000
Plasma20YSZ
ToyotaSiRPA
RCCoating
Heat Capacity (kJ/m3-K) @ 300°C
Coating after 476 hrs
of Engine Testing
Exhaust Valve Cylinder Head Piston
Component Level
Developments
• Compared to Yttria-stabilized zirconia
current coating has
‒ a factor of 5 reduction in heat
capacity
‒ a factor of 3 reduction in thermal
conductivity
• On engine durability testing has
completed over 400 hours with no
noticeable degradation
8
Tech-to-Market Strategy
mCHP Prime Mover PoC
GENSETS Project
Demonstrated 𝜂𝑒 ≥ 32%
Projected Cost ≤ $1000@10k/y
Projected Life ≥ 40,000 hrs
Yes
No
Exploit
component
technologies in
collateral markets
Continue
Development
for Production
Intent Design
Design,
Construct, and
Test
Proof-of-
Concept mCHP
Appliance
Dissolve
Project
Team
Pitch Concept
to potential
OEM partners. B&S activities
Evaluate
B&S as OEM
Lab
Reliability
Testing
Phase 2
mCHP
Development
Phase
3 Proto
Build
Pilot
Field
Deploy
Seek
Funding
Limited
Market
Intro
2018 2019 2020 2022
• Q8-Q12 testing supporting cost and efficiency tradeoff analysis
• Proceed to development of resCHP appliance with favorable results
Current program results have been favorable enough to ensure efforts
will continue to develop and exploit component technologies. 9
Details on Envisioned Product Offering
*Assumes 96% efficient generator and 3% thermoelectric recovery
per project FOA
Metric Program Target Current Status
(Prime Mover)
Target Product
(resCHP Appliance)
Power (kWe) 1 1 1
Fuel-to-Elec Eff. (%) 40 35.7* >33
Thermal (kWt/kWe) >1 TBD >1.25
Capacity factor (%) 99.9 TBD 99.9
System Cost ($) 3,000 CBI <1,000
System Life (years) ≥10 by design 10
Exhaust Emissions CARB Std TBD CARB Std
Sound (dB(A) @ 3 ft) ≤55 TBD ≤55
Methane Number Tol. >70 demonstrated ≤70
Maint. Interval (#/yr) ≤1 by design ≤1
O&M cost ($/kWh) ≤0.005 TBD ≤0.015
Maint. Labor (hr) ≤1 by design ≤1
System Mass (kg) ≤150 <50 ≤100
10
Current Challenges / Focus Areas
Key Focus Areas for 2018 Emissions Control (methane, CO, and NOx targets are very low)
Approach: Overall program has focused on stoichiometric operation to
enable use of a three-way catalyst. After treatment effort is evaluating catalyst
formulations for methane reduction. Control strategy will require dithering to
enable simultaneous reduction of methane, NOx (𝜆 < 1), and CO (𝜆 > 1)
Efficiency - Cost Tradeoff
Approach: Systematic quantification of efficiency cost tradeoff of individual
components (boost system, EGR, ultra-high CR, feedback control, etc…) to
enable detailed techno-economic analysis
System Integration and Endurance
Approach:
• Integration of thermal barrier coatings and passive boosting concept
• Endurance testing of concept 3 engine
Future: Technology extension to plug-in hybrid electric vehicles (range
extender) appears to be a natural transition
11