1 Engine Research Center, 2016 Reactivity Controlled Compression Ignition (RCCI) for high-efficiency clean IC engines Prof. Rolf D. Reitz Engine Research Center, University of Wisconsin-Madison Aurel Stodola Lecture Department of Mechanical and Process Engineering of ETH Zurich Wednesday, November 9 th , 2016 Acknowledgements : Industry Partners: Direct-injection Engine Research Consortium members, Caterpillar, Ford, General Motors. Sandia, Argonne, Oak Ridge National Labs, ARO, DOE, NASA, ONR, Princeton CEFRC. - ERC faculty, staff and students
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1 Engine Research Center, 2016
Reactivity Controlled Compression Ignition (RCCI)
for high-efficiency clean IC engines
Prof. Rolf D. Reitz
Engine Research Center,
University of Wisconsin-Madison
Aurel Stodola Lecture
Department of Mechanical and Process Engineering of ETH Zurich
Wednesday, November 9th, 2016
Acknowledgements:
Industry Partners:
Direct-injection Engine Research Consortium members,
Caterpillar, Ford, General Motors.
Sandia, Argonne, Oak Ridge National Labs,
ARO, DOE, NASA, ONR, Princeton CEFRC.
- ERC faculty, staff and students
UW-Madison
Founded in 1848 (land-grant institution). 42,600 students; 2,000 facultyRanked No. 2 US public university
~ $1 billion/year in research funding
Engine Research CenterLargest academic research center focusing
- pathway to high-efficiency clean combustion using in-cylinder
blending of fuels with different auto-ignition characteristics
• Performance of RCCI combustion
• Limits and practical applications of RCCI
• New concepts
• Conclusions and future research directions
Why research IC engine efficiency?
5 Engine Research Center, 2016
Internal combustion (IC) engines are the work horses of transportation and
power generation
70% of all crude oil consumed is used to fuel IC engines
Improvements in engine efficiency can have a major impact on fossil fuel
consumption and green house gas (GHG) emissions on a global scale
IC engines are expected to be the dominant (>90%) prime mover for
transportation applications well into the future1,2,3
Many open questions:4
- what combustion process should future IC engines utilize?
- what fuels are best suited for high efficiency combustion?
- how can renewable and alternative fuel sources be utilized most
effectively?
1Quadrennial Technology Review, DOE 20112Review of the Research Program of the FreedomCAR and Fuel Partnership: 3rd
Report, NRC 2010 3Energy Information Agency, Annual Energy Outlook 2012, June 2012. 4Reitz, R.D., “Directions in Internal Combustion Engine Research,” CNF, 160, 2013.
Engine Research Center, 20166
Boyd T (1950) Pathfinding in Fuels and
Engines. SAE 500175, 4(2) 182-195.
Fuel ignitability affects engine efficiency - limits compression ratio (CR).
Early Spark Ignition (SI) engines were plagued by “spark knock”, CR ~ 4:1.
Cylinder pressure measurements by Midgley and Kettering at DELCO/GM
showed different fuels had different knock tendency
e.g., kerosene worse than gasoline
Volatility differences were thought to be the explanation.
Guided by the “Mayflower,” they added a red dye (iodine) to kerosene
and knock tendency was greatly reduced!
Unfortunately, tests with other red dyes did
not inhibit knock, disproving the theory.
But, finding powerful antiknock additives was
a major serendipitous discovery!
Mayflower – Trailing Arbutus Jane
in early spring
Lessons from history (1910-20) – “the Mayflower”1/11 CR
Engine Research Center, 20167
Research after WW-I was motivated by national security - Improved fuel efficiency with higher CRs made possible the first
non-stop airplane flight from New York to San Diego in the 1920’s.
GM and US Army studied hundreds of additives and found aromatic
amines to be effective knock suppressors.
1920 experimental GM car driven on gasoline with toluidine with CR ~7:1 - 40% better fuel consumption than 4:1.
Engine exhaust plagued by unpleasant odors
Lessons from history (1920-30) – the Amines and TEL
Reitz, Front. Mech. Eng. 1:1, 2015
Much research was devoted to find acceptable additives, - finally leading to tetraethyl lead (TEL)
But, TEL caused solid deposits, damaged exhaust valves and spark plugs.
Scavenger additives with bromine and chlorine corrected the problem.- Partnership with Ethyl-Dow and DuPont to extract compounds from sea water
- 10 tons of sea water needed to provide 1 lb of bromine!
- “the goat”!
WW-II aviation engines used iso-heptane (triptane: 2,2,3-trimethyl butane) - allowed CR as high as 16:1.
Engine Research Center, 20168
Lead poisoning was an early concern - In 1926 US Surgeon General determined that TEL poses no health hazards.
- Use of lead in automotive fuels has been called “The mistake of the 20th century”
1950: Dr. Arie Haagen-Smit - cause of smog in LA to be HC/NO - Cars were the largest source of UHC/NOx
1950: Eugene Houdry - developed catalytic converter for auto exhaust. - But, lead was found to poison catalytic converters.
20 years later: US EPA announces gas stations must offer "unleaded" gasoline,
- Based accumulated evidence of negative effects of lead on human health.
- Leaded gasoline was still tolerated in certain applications (e.g., aircraft),
but was permanently banned in the US in 1996, in Europe since 2000
Lessons from history (1930-70) –TEL and the future
Reitz, Front. Mech. Eng. 1:1, 2015
World Wars & national security played a major role to define automotive fuels.
Today’s engines and their fuels would not have been developed without
close collaboration between engine OEMs, energy and chemical companies!
A consequence of collaboration between “big” engine and “big” oil is that
transformative changes in transportation systems will not occur easily.
A new concept engine must be able to use available fuels,
Temperature contours near CA50, Crank = 6.1 deg ATDC
Comparison of conv. diesel and RCCI combustion
• High temperature in conventional diesel next to piston bowl surface
• Highest temperature for RCCI in center of chamber (adiabatic core)
• Region near liner has similar temperatures
– heat transfer differences are at piston bowl surface
30 Engine Research Center, 2016
RCCI
(800 bar)
High-EGR
Diesel
(1800 bar)
Ringing (MW/m2) 3.8 2.8
Max PRR (bar/deg) 10.3 8.9
Gross Indicate TE (%) 54.3 48.5
Combustion Loss (%) 1.3 0.7
ISNOx (g/kW-hr) 0.006 0.97
ISsoot (g/kW-hr) 0.01 0.1
48.557.9
19.2 10.9
31.641.5 33.4 38.1
61.954.3
0
10
20
30
40
50
60
70
80
90
100
With HT Adiabatic With HT Adiabatic
High-EGR Diesel RCCI
Fu
el E
nerg
y [
%]
Comb. LossExhaustHeat LossGIE
Comparison of conv. diesel and RCCI - KIVA CFD
RCCI:
- Similar pressure rise rates
- Significantly lower NOx and soot
- 16% higher thermal efficiency
- Reduced heat losses (~50%)
- Improved end-of-combustion phasing
SOI -12o
-10 -5 0 5 10 15 20 25
39
42
45
48
51
54
57
RCCI
High EGR Diesel Pinj 800 bar
High EGR Diesel Pinj 1800 bar
RCCI Combustion
SOI -20ATDC
CA50 [ATDC]
Gro
ss In
dica
ted
Eff
icie
ncy
[%]
7% of
fuel energy
Pancake 18.7:1 piston design
~1.2 less surface area
GT-Power heat transfer HX tuned to
match data
- 14.9:1 piston required HX = 0.4
- 18.7:1 required HX = 0.3
- without oil cooling, HX = 0.2
GTE
(%)
IMEPg
(bar)
NTE
(%)
IMEPn
(bar)
Experiment 59.1 6.82 55.0 6.27
Model, HX =0
100% comb. η62.4 7.12 58.5 6.85
Model, HX =0
100% comb.η,
0% EGR
63.4 7.23 61.0 6.95
94% of maximum theoretical cycle efficiency achieved !
-40 -30 -20 -10 0 10 20 30 40-15
0
15
30
45
60
75
90
105
120
135
150
E85 / 3% EHN+91 PON RCCI
43C intake, 42% EGR,
6.3 bar IMEPn
EXP, Squirter off, 43% EGR, Oil Matrix Point 83
GTPower, HX=0, 100% comb. , 43% EGR
GTPower, HX=0, 100% comb. , 0% EGR
Pre
ss
ure
(b
ar)
Crank Angle (CA ATDC)
0
150
300
450
600
750
AH
RR
(J
/ C
A)
Splitter et al. “RCCI Engine Operation Towards 60% Thermal Efficiency”, SAE 2013-01-0279
31 Engine Research Center, 2016
Ultra high efficiency, dual fuel RCCI combustion
DI: 3%EHN+91ON
PFI: E85
TIVC = 43 C
EGR = 42%
16.1
14.918.7
32 Engine Research Center, 2016
GM 1.9L Engine Specifications
Multi-cylinder RCCI - transient operation, open/closed loop control
Engine Type EURO IV Diesel
Bore 82 mm
Stroke 90.4 mm
Displacement 1.9 liters
Cylinder
Configuration
Inline 4
4 valves per cylinder
Swirl Ratio Variable (2.2-5.6)
Compression
Ratio 17.5
EGR SystemHybrid High/Low
Pressure, Cooled
ECU (OEM) Bosch EDC16
ECU (new) Drivven
Common Rail
Injectors
Bosch CRIP2-MI
148° Included Angle
7 holes,
440 flow number.
Port Fuel
Injectors
Delphi
2.27 g/s steady flow
400 kPa fuel pressure
UW RCCI Hybrid Vehicle
SAE 2015-01-0837
Highway Fuel Economy Testing of an RCCI Series Hybrid VehicleReed Hanson, Shawn Spannbauer, Christopher Gross, Rolf D. Reitz, University of Wisconsin; Scott Curran, John Storey, Shean Huff, ORNL
Made possible by advances in fuel injectors and computer control
RCCI GTEs in the 58-60% range achieved within ~94% of theoretical cycle.
Inconvenience of two fuels already accepted by diesel industry (diesel/DEF)
RCCI is cost effective and offers fuel flexibility: - low cost port-injected less reactive fuel (e.g., gasoline, E85, “wet” EtOH, C/LNG) with
optimized* low pressure DI of more-reactive fuel (e.g., diesel/additized gas) - reduced after-treatment needed - meet NOx and PM emission mandates in-cylinder- diesel or SI (w/spark plug) operation can be retained (e.g., mixed mode, limp home).
Improved transient control:- proportions of low and high reactivity fuels can be changed dynamically, with same/next-
cycle combustion feedback control
Direct injection of both fuels allows more control of heat release:- reduced noise, reduced cyclic variability, no efficiency penalty, move waste heat to exhaust