HCCI in a Variable Compression Ratio Engine: … in a Variable Compression Ratio Engine: Effects of...
Transcript of HCCI in a Variable Compression Ratio Engine: … in a Variable Compression Ratio Engine: Effects of...
HCCI in a Variable Compression Ratio Engine:Effects of Engine Variables
HCCI in a Variable Compression Ratio Engine:Effects of Engine Variables
Thomas RyanSouthwest Research Institute
HCCI NOx Reduction Base Engine w LPL EGR
BSNOx = 1.6 g/hp-hr, hot-start transient cycle
0%10%20%30%40%50%60%70%80%90%
100%
0 20 40 60 80 100Load Threshold for HCCI, % of Max Power
Perc
ent T
rans
ient
Cyc
le N
Ox
Red
uctio
n
Fixed HCCI NOx Level Varied HCCI NOx Level
Prediction of HD FTP NOx with Various Levels of HCCIPrediction of HD FTP NOx with Various Levels of HCCI
Outline of PresentationOutline of Presentation
BackgroundDescription of Experimental MatrixExperimental ProceduresGraphical AnalysisConclusions
Background - SwRI HCCI ProgramBackground - SwRI HCCI Program
Fifth in the Series of HCCI PresentationsPrediction of the Start of ReactionControl of the Start of ReactionHCCI Fuel RequirementsEngine Heat ReleaseInteraction of Engine and Fuels
Practical Full Time HCCI Operation Will Require Specific HCCI Fuel
Low Octane gasoline
Experimental VariablesExperimental Variables
Engine VariablesIntake Manifold Temperature and PressureExhaust Gas Recirculation LevelCompression Ratio
Fuel Variables (Selection)Boiling Point DistributionCetane/Octane NumberComposition
Test Engine SpecificationsTest Engine Specifications
Bore 96.8 mmStroke 95.3 mmRod Length 166.5 mmDisplacement 702 ccCompression Ratio 7.5:1 to 16.5:1Swirl Ratio Less Than 0.7CombustionChamber
Shallow Dish
Combustion Chamber DesignCombustion Chamber Design
Bowl In PistonShallow DishSquish Area of 51%
Two Valve HeadLow Swirl Ratio
0.7 Swirl NumberIntake Port Fuel Injection
Air Assist Swirl Atomizer
1
10
100
100 1000Pressure (kPa)
Sauter MeanDiameter(µm)D[v,0.9]
D[v,0.1]
D[v,0.5]
Combustion Chamber PhotoCombustion Chamber Photo
Test FuelsTest Fuels
Diesel Fuel (Typical US)Gasoline (Pump Grade 87 RON)Fischer Tropsch NaphthaBlends of Gasoline and Diesel Fuel
Test Fuel PropertiesTest Fuel Properties
PROPERTY FT NAPHATHA DIESEL FUEL GASOLINEHeat of Combustion,
MJ/kgNet 44.3 42.5 32.9*
Gross 47.7 45.3 45.4*Sulfur, mass % 0.0 0.039 .023Specific Gravity 0.7095 0.8485 .7436
IBP, oC 61 187 2950% 141 263 10595% 186 328 188FBP 194 339 201
Carbon, mass % 83.98 86.83 86.74*Hydrogen mass % 15.92 13.24 13.22*
Cetane Number (IQT) 51 43 13
Test MatrixTest Matrix
CR 8 to 16.5:1EGR 0 to 50%A/F 12.5 to 75:1MAT 28 to 220oCMAP 1 to 2.1 BarSpeed 600 to 2000
Test ProcedureTest Procedure
Full Factorial or DOE was not PossibleEngine Warmed UpSpeed SelectedCR FixedVaried A/F, EGR, MAT, and MAPMapped Region of HCCI Operation
Zero Soot (BSN)Less than 25 ppm NOx (revised Recently down to 15 ppm NOx)
NOx Emissions versus A/FNOx Emissions versus A/F
Air Fuel Ratio10 20 30 40 50 60 70 80
NO
x (p
pm)
0
5
10
15
20
25
Definition of TermsDefinition of Terms
Diesel Fuel
CA (Degrees)140 160 180 200
Hea
t Rel
ease
Rat
e (J
/deg
)
-200
20406080
100120140160
Pre-Reaction
Main Reaction
Phasing
Pre-Reaction Start
Main Reaction Start
Diesel Fuel - Gasoline TestsDiesel Fuel - Gasoline Tests
Gasoline Added to Diesel to Affect the Volatility and IgnitionTests at Zero EGR and 14:1 CR
Gasoline Required 16:1 CR
Delay Decreases with Compression Temp
Pre-Reaction Delay versus Compression T
Compression T (K)900 950 1000 1050 1100
Pre-
Rea
ctio
n D
elay
(ms)
0.81.01.21.41.61.82.02.22.42.6
Pre-Reaction Delay - 20% GasolinePre-Reaction Delay - 20% Gasoline
Linear Relationship -Exponential Curve FitRelationships for Other Blends are Similar
Pre-Reaction Delay versus Compression T20% Gasoline in Diesel Fuel
Compression T (K)900 920 940 960 980 1000 1020 1040 1060 1080
Pre-
Rea
ctio
n D
elay
(ms)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
td = -2.4988 + 20.2548 exp-0.0016*T)
Phasing - 20% Gasoline Blend Phasing - 20% Gasoline Blend
Phasing Linearly Related to the Magnitude of the Pre-ReactionAll Blends Demonstrated the Same Trends
Phasing versus Pre-Reaction Heat Release20% Gasoline in Diesel Fuel
Pre-Reaction Heat Release (kJ)1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
Phas
ing
(ms)
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
Pre-Reaction Delay - Curve FitsDiesel Fuel-Gasoline BlendsPre-Reaction Delay - Curve FitsDiesel Fuel-Gasoline Blends
Blends all Demonstrated the Same TrendsReactions Appear to be Dominated by the Diesel Fuel
Pre-Reaction Delay versus Compression T
Compression T (K)850 900 950 1000 1050 1100 1150
Pre-
Rea
ctio
n D
elay
(ms)
0.81.01.21.41.61.82.02.22.42.6
20% Blend 40% Blend60% Blend80% Blend
Phasing - Curve FitsDiesel Fuel-Gasoline BlendsPhasing - Curve FitsDiesel Fuel-Gasoline Blends
Phasing versus Pre-Reaction Heat Release
Pre-reaction Heat release (kJ)0.000 0.005 0.010 0.015 0.020 0.025
Phas
ing
(ms)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
20% Blend 40% Blend60% Blend 80% Blend
All Blends Demonstrated Exactly the Same RelationshipsPre-Reaction Delay and Phasing for these Blends Again Demonstrate the Problem with CN
FT Naphtha - HHR ComparisonFT Naphtha - HHR Comparison
Heat Release Rate versus CA FT Naphtha and Diesel Fuel
CA (Degrees)100 120 140 160 180 200
Hea
t Rel
ease
Rat
e (J
/deg
)
-20
0
20
40
60
80
100
120
140
FT has much Larger Pre-Reaction StageFT Pre-Reaction Delay is LongerPhasing is Much ShorterCN of FT is 51 Compared to 43 for DF - CN Problem
FT Naphtha - Delay and PhasingFT Naphtha - Delay and Phasing
Excellent Correlations for Pre-Reaction Delay and PhasingLarge Pre-Reaction and Long Delay Likely to due to Highly Paraffinic Composition of FT
Pre-Reaction Delay versus Compression TFT Naphtha
Compression T (K)700 750 800 850 900 950 1000
Pre-
Rea
ctio
n D
elay
(ms)
0.5
1.0
1.5
2.0
2.5
3.0
td = -4.0435 + 15.8922 EXP(0.0012*t)
Phasing versus Pre-Reaction Heat ReleaseFT Naphtha
Pre-Reaction Heat Release (kJ)0.03 0.04 0.05 0.06 0.07
Phas
ing
(ms)
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Phasing = 2.0719 -14.98*Heat Release
Impact of Pre-ReactionImpact of Pre-Reaction
FTN Demonstrates very Significant Pre-ReactionGasoline Demonstrates Some Pre-ReactionDiesel Fuel Fall Between the FTN and GasolineMethane Demonstrates No Pre-Reaction
How do the Different Fuels Interact in Blends?
Effect of HRR TimingEffect of HRR Timing
Actual Heat Release too EarlyChanged the Start of the Main ReactionHeld Pre-Reaction Magnitude and Phasing Constant
CA Degree300 320 340 360 380 400
Hea
t Rel
ease
Rat
e
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Indicated Thermal Efficiency
CA of Main HRR Peak350 360 370 380
Indi
cate
d Th
erm
al E
ffici
ency
26
28
30
32
34
36
38
40
ITE=3108.7-32.927CA+0.11CA2-0.0001CA3
Early SOR and Low EfficiencyITE = 27%
Pre-Reaction DelayPre-Reaction DelayAll Fuels
Pre-Reaction Delay versus Compression T at TDCPRD=7.292-5.49E-03*TPRD=9.136-7.68E-03*TPRD=8.261-6.996E-03*TPRD=7.988-6.303E-03*TPRD=8.388-6.675E-03*TPRD=8.238-6.431E-03*TPRD=8.398-6.673E-03*T
Compression T (K)600 700 800 900 1000 1100 1200
Pre-
Rea
ctio
n D
elay
(ms)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
20% Gasoline40% Gasoline60% Gasoline80% Gasoline0% Gasoline100% Gasoline (16:1 CR)FT Naphtha
Gasoline, Diesel Fuel and BlendsPre-Reaction Delay versus Compression T at TDC
PRD=7.292-5.49E-03*TPRD=9.136-7.68E-03*T
PRD=7.988-6.303E-03*TPRD=8.388-6.675E-03*TPRD=8.238-6.431E-03*TPRD=8.398-6.673E-03*T
Compression T (K)900 950 1000 1050 1100 1150
Pre-
Rea
ctio
n D
elay
(ms)
0.60.81.01.21.41.61.82.02.22.42.6
20% Gasoline40% Gasoline60% Gasoline80% Gasoline0% Gasoline100% Gasoline (16:1 CR)
Pre-Reaction DelayPre-Reaction DelayAll Fuels
Pre-Reaction Delay versus Compression T at TDCPRD=7.292-5.49E-03*TPRD=9.136-7.68E-03*TPRD=8.261-6.996E-03*TPRD=7.988-6.303E-03*TPRD=8.388-6.675E-03*TPRD=8.238-6.431E-03*TPRD=8.398-6.673E-03*T
Compression T (K)600 700 800 900 1000 1100 1200
Pre-
Rea
ctio
n D
elay
(ms)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
20% Gasoline40% Gasoline60% Gasoline80% Gasoline0% Gasoline100% Gasoline (16:1 CR)FT Naphtha
Gasoline, Diesel Fuel and BlendsPre-Reaction Delay versus Compression T at TDC
PRD=7.292-5.49E-03*TPRD=9.136-7.68E-03*T
PRD=7.988-6.303E-03*TPRD=8.388-6.675E-03*TPRD=8.238-6.431E-03*TPRD=8.398-6.673E-03*T
Compression T (K)900 950 1000 1050 1100 1150
Pre-
Rea
ctio
n D
elay
(ms)
0.60.81.01.21.41.61.82.02.22.42.6
20% Gasoline40% Gasoline60% Gasoline80% Gasoline0% Gasoline100% Gasoline (16:1 CR)
Gasoline
Diesel Fuel
20% Gasoline80% of Difference FTN
More Like DF But Shorter Delays
Pre-Reaction RatioPre-Reaction Ratio
Pre-Reaction Ratio Defined as the Ratio of the Pre to the Total Heat Release
Pre-Reaction Ratio Increases with Increased Pre-Reaction Delay
All Gasoline and Diesel Fuel BlendsPre-Reaction Ratio versus Pre-Reaction Delay
Pre-Reaction Delay (ms)0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
Pre-
Rea
ctio
n R
atio
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
All Gasoline and Diesel Fuel BlendsPre-Reaction Ratio versus Pre-Reaction Delay
Pre-Reaction Delay (ms)0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Pre-
Rea
ctio
n R
atio
0.00
0.05
0.10
0.15
0.20
0.25
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% GasolineFT Naphtha
Pre-Reaction RatioPre-Reaction Ratio
All Gasoline and Diesel Fuel BlendsPre-Reaction Ratio versus Pre-Reaction Delay
Pre-Reaction Delay (ms)0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
Pre-
Rea
ctio
n R
atio
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
Diesel Fuel
Gasoline
20% Gasoline
All Gasoline and Diesel Fuel BlendsPre-Reaction Ratio versus Pre-Reaction Delay
Pre-Reaction Delay (ms)0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Pre-
Rea
ctio
n R
atio
0.00
0.05
0.10
0.15
0.20
0.25
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% GasolineFT Naphtha
FTNPre-Reaction Ratio
4 to 6 X all Other Fuels
Pre-Reaction Ratio Increases with Increased Pre-Reaction Delay
Pre-Reaction Ratio Defined as the Ratio of the Pre to the Total Heat Release
PhasingPhasing
Phasing Related to the Pre-Reaction Heat Release
Larger Pre-Reaction Means Shorter Phasing
All Gasoline and Diesel Fuel BlendsPhasing versus Pre-Reaction Delay
Pre-Reaction Heat Release0.006 0.008 0.010 0.012 0.014 0.016 0.018 0.020 0.022
Phas
ing
(ms)
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
All Gasoline and Diesel Fuel Blends and FT NaphthaPhasing versus Pre-Reaction Heat Release
Pre-Reaction Heat Release0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07
Phas
ing
(ms)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
FT Naphtha0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
PhasingPhasing
All Gasoline and Diesel Fuel Blends and FT NaphthaPhasing versus Pre-Reaction Heat Release
Pre-Reaction Heat Release0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07
Phas
ing
(ms)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
FT Naphtha0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
FTN 33% LessThan Gasoline and 65% Less
Than Diesel
All Gasoline and Diesel Fuel BlendsPhasing versus Pre-Reaction Delay
Pre-Reaction Heat Release0.006 0.008 0.010 0.012 0.014 0.016 0.018 0.020 0.022
Phas
ing
(ms)
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0% Gasoline20% Gasoline40% Gasoline60% Gasoline80% Gasoline100% Gasoline
Diesel Fuel
Gasoline
20% Gasoline75% of Difference
Larger Pre-Reaction Means Shorter Phasing
Phasing Related to the Pre-Reaction Heat Release
SummarySummary
Pre-Reaction Delay, Pre-Reaction Ratio (Pre-Reaction Heat Release), and Phasing are all ImportantDiesel Fuel Pre-Reaction Delay (PRD) Shorter than Gasoline
Adding 20% Gasoline Increases PRD by 80% of DifferencesFTN Shortest, but Follows Trend of Diesel Fuel
Summary (continued)Summary (continued)
Diesel Fuel Pre-Reaction Ratio (PRR) Larger than Gasoline
Adding 20% Gasoline Reduced the PRR by 75% of the DifferenceFTN has the Largest PRR by 4-6X
Diesel Fuel Phasing Longer than GasolineAdding 20% Gasoline Reduced the Phasing by 80% of the DifferenceFTN has the Shortest Phasing
33% Less than Gasoline and 65% Less than Diesel Fuel
Summary (continued)Summary (continued)
FTN, Diesel Fuel, and Gasoline all Exhibit Pre-Reaction Heat Release
On Average, 4-6 X Diesel Fuel and GasolineDiesel Fuel PRR is Larger than Gasoline
Methane Doesn’t Exhibit Pre-Reaction Heat ReleaseSwRI Used Methane and FTN in a Multi-Cylinder Test Engine (SAE 2001-01-1897)
Multi-Cylinder Engine TestMulti-Cylinder Engine Test
-20
0
20
40
60
80
100
120
140
-40 -30 -20 -10 0 10 20 30 40
Multi-Cylinder Engine on Two FuelsH
eat R
elea
se R
ate
(Arb
itrar
y U
nits
)
Crank Angle Degrees
1000 RPM (approx.)97 kPa MAPConstant Amount of Reactive FuelIncreasing Non-Reactive Fuel
Straight Reactive Fuel
Increasing Non-Reactive Fuel
PRD and PRR not Affected by the Presence of the Methane, but Main HRR Delayed by Methane
HypothesisHypothesis
Gasoline -FTN Blends will Provide Options for Control of the Ignition and Reaction Processes
FTN is the Reactive Component Gasoline will Affect the PRD, the PRR, and the Phasing of the Blend20/80 Blend of FTN in Gasoline is Proposed
Gasoline will Inhibit the PRD of the FTNLarge PRR of FTN will Decrease the Phasing of the Gasoline
Why 20/80 BlendWhy 20/80 Blend
Alamo_Engine (SwRI Cycle Simulation Code) used to Compute the Compression Temperature History in the Test Engine Operating at Equivalent Diesel Full Load Conditions:
25:1 Air-Fuel Ratio3 Bar Boost10% EGR
Baseline Engine ResultBaseline Engine Result
Parameter ValueMAP (kPa) 300
Fuel Flow Rate(kg/s)
0.00114
Fresh Air FlowRate (kg/s)
0.0292
Torque (N-m) 108.7Indicated Power
(kW)21.76
Indicated ThermalEfficiency
44.2
BSFC ((g/kW-hr) 195.1
Computed TDC Compression T = 860K
Performance Prediction 20/80 BlendPerformance Prediction 20/80 Blend
Used the Relationships Shown AboveAt 860K
PRD – FTN = 2.24– Gasoline = 2.57
PRR– FTN = 0.154– Gasoline = 0.048
Phasing– FTN = 1.79 ms– Gasoline = 1.61 ms
Assumed Gasoline Affects FTN Same as Diesel Fuel, at 1800 rpm, 3 Bar MAP, 95% Combustion Efficiency
Pre SOR at 19o BTDC, Main SOR at 1.1o BTDC, Pre Heat Release = 0.334kJ and Main = 2.76 kJ
Heat Release Rate
0.00
0.50
1.00
1.50
2.00
2.50
3.00
-20 -15 -10 -5 0 5 10CAD (deg aTDC)
HR
R (k
J/C
AD)
Thermal Efficiency = 40%
Thank You.Thank You.