University of Wisconsin Engine Research Center Experimental Facilities Objective Injection Timing...
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University of Wisconsin Engine Research Center Experimental Facilities Objective Injection Timing Effects Conclusions Effects at Varied Equivalence Ratios Effects at Varied Fueling Rates Level of Fuel Unmixedness Engine Test Cell Setup Fuel Unmixedness Effects in a Gasoline HCCI Engine Fuel Unmixedness Effects in a Gasoline HCCI Engine Students: R.E. Herold, R.J. Iverson (MS, 2004) Faculty: D.E. Foster, J.B. Ghandhi • Quantify the effect fuel unmixedness has on gasoline HCCI combustion. Surge Tank 2 Surge Tank 1 Inline Heater EGR AIR Port Fuel Injection Point Exhaust Premixed Fuel Injection Point Engine To Engine Dichroic Mirror Pellin-Broca Prism f = 1000 mm Plano- Convex Spherical Lens f = -500 mm Plano- Concave Cylindrical Lens 90° Turning Prism Beam Stop UG5 Schott Glass Filter Engine Properties CR 10.95 Bore 86 mm Strok e 94.6 mm EVO 131 aTDC IVO 350 aTDC EVC 375 aTDC IVC 595 aTDC Vaporized Fuel 2.3 mm ID Tube Inta ke Valv e Heated Air + EGR Port, Prevaporized Fuel Injector Cylinder Head Quartz Cylind er Window Optical Engine Sapphire Piston Window Bowditch Piston Extentio n Drop-down Liner Imaging Mirror Optical Setup for PLIF Experiments Nd:YAG Laser • Level of fuel unmixedness created when using the port, prevaporized fuel injection was investigated optically using fuel tracer planar laser-induced fluorescence (PLIF). • Injection crank angle locations (detailed below) corresponded to those detailed in metal engine experiments. 829° 724° 469° 364° 361° 256° 196° 140° 301° 245° IVC (855°) IVO (358°) IVC (135°) = Intake Valve Open 720° (TDC – Previous Cycle) 360° (TDC Exhaust) 180° (BDC) 0° (TDC – Cycle of Interest) Crank Angle (° bTDC) • A significant level of unmixedness is created with prevaporized port fueling. • Fuel unmixedness increases with retarded injection timings except for the EoPI = 256° bTDC injection timing, which is less unmixed than the EoPI = 364° bTDC injection timing. • For the most retarded injection timing, regions exist in the cylinder with equivalence ratios that differ from the mean by +/- 50%. 25 20 15 10 5 0 PDF 2.0 1.5 1.0 0.5 0.0 0 6 4 2 0 H om ogeneous Unm ixed 724°bTD C 364°bTD C 256°bTD C 196°bTD C 140°bTD C 4000 3500 3000 2500 2000 Peak Pressure (kPa) 15 10 5 0 C A50 (° aTD C ) 99 98 97 96 95 94 C om bustion Efficiency Prem ixed 724° bTD C 364° bTD C 256° bTD C 196° bTD C 140° bTD C • Variations with respect to intake charge temperature due to heat transfer in intake port. • All combustion metrics investigation (i.e., peak pressure, combustion efficiency) show that at a given combustion phasing (CA50) premixed and prevaporized port injection are indistinguishable. • NO x emissions increase with fuel unmixedness, resulting from regions richer than the mean which burn hotter after autoignition. • CO emissions show a slight increase with fuel unmixedness, possibly a result of regions richer than stoichiometric or quenching in regions leaner than the mean. 4000 3500 3000 2500 2000 Peak Pressure (kPa) 15 10 5 0 C A50 (°aTD C ) 100 95 90 85 C om bustion Efficiency 10 m g/cycle 7 m g/cycle 5 m g/cycle O pen = Port C losed = Prem ixed 200 150 100 50 0 EIC O (g/kg) 15 10 5 0 C A50 (° aTD C ) 8 6 4 2 0 EIN O x (g/kg) 10 8 6 4 2 0 EIN O x (g/kg) 15 10 5 0 C A50 (° aTD C ) 30 25 20 15 10 5 0 EIC O (g/kg) • No changes in combustion observed between premixed and port fueling. • Significant NO x emissions increases only observed in 10 mg/cycle fueling. NO x emissions were near zero for the 7 and 5 mg/cycle fueling conditions due to high EGR. • The difference in CO emissions between premixed and port fueling increases with decreasing fueling rate. 2800 2600 2400 2200 2000 1800 Peak Pressure (kPa) 15 10 5 0 C A50 (°aTD C ) 100 95 90 85 80 C om bustion Efficiency = 0.75 = 0.6 = 0.5 O pen = Port C losed = Prem ixed • No changes in combustion observed between premixed and port fueling. • NO x emissions were near zero for all conditions because of high EGR rate at the 5 mg/cycle fueling condition • Decreasing the equivalence ratio (increasing air flow, decreasing EGR at constant fueling rate) leads to an increase in CO emissions but a decrease in the difference in CO emissions between premixed and port fueling. • Fuel unmixedness in the absence of thermal and residual unmixedness had no effect on the HCCI combustion. • Small changes in CO and NO x emissions were observed for the port fueling, which were attributed to the regions in the charge that were either locally richer or leaner than the mean equivalence ratio. • At a given operating condition the CO and NO x emissions are the lowest for a fully homogeneous fuel distribution. Regions locally richer and leaner than the mean equivalence ratio lead to increases in NO x and CO and therefore should be avoiding in an HCCI engine. • Fuel unmixedness in the absence of thermal and residual unmixedness does not appear to be a viable method for gasoline HCCI combustion control. 4000 3500 3000 2500 2000 Peak Pressure (kPa) 330 320 310 300 Intake C harge Tem perature (°C ) 4000 3500 3000 2500 2000 1500 Peak Pressure (kPa) 375 350 325 300 Intake C harge Tem perature (°C ) 250 200 150 100 50 0 EIC O (g/kg) 15 10 5 0 C A50 (° aTD C ) 2800 2600 2400 2200 2000 1800 Peak Pressure (kPa) 375 350 325 Intake C harge Tem perature (°C )
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Transcript of University of Wisconsin Engine Research Center Experimental Facilities Objective Injection Timing...
University of Wisconsin Engine Research Center
Experimental Facilities
Objective
Injection Timing Effects
Conclusions
Effects at Varied Equivalence Ratios
Effects at Varied Fueling RatesLevel of Fuel Unmixedness
Engine Test Cell Setup
Fuel Unmixedness Effects in a Gasoline HCCI EngineFuel Unmixedness Effects in a Gasoline HCCI EngineStudents: R.E. Herold, R.J. Iverson (MS, 2004) Faculty: D.E. Foster, J.B. Ghandhi
• Quantify the effect fuel unmixedness has on gasoline HCCI combustion.
SurgeTank 2
SurgeTank 1
Inline Heater
EGR
AIR
Port Fuel Injection
Point
Exhaust
Premixed Fuel Injection
Point
Engine
To Engine
Dichroic Mirror
Pellin-Broca Prism
f = 1000 mm Plano-Convex Spherical Lens
f = -500 mm Plano-Concave
Cylindrical Lens
90° Turning Prism
Beam Stop
UG5 Schott Glass Filter
Engine Properties
CR 10.95
Bore 86 mm
Stroke 94.6 mm
EVO 131 aTDC
IVO 350 aTDC
EVC 375 aTDC
IVC 595 aTDC
Vaporized Fuel
2.3 mm ID Tube
Intake Valve Heated
Air + EGR
Port, Prevaporized Fuel Injector
Cylinder Head
Quartz Cylinder Window
Optical Engine
Sapphire Piston
Window Bowditch
Piston Extention Drop-down
Liner
Imaging Mirror
Optical Setup for PLIF Experiments
Nd:YAG Laser
• Level of fuel unmixedness created when using the port, prevaporized fuel injection was investigated optically using fuel tracer planar laser-induced fluorescence (PLIF).
• Injection crank angle locations (detailed below) corresponded to those detailed in metal engine experiments.
829° 724°
469° 364°
361° 256°
196°
140°
301°
245°IVC (855°)
IVO (358°)
IVC (135°)
= Intake Valve Open
720° (TDC – Previous Cycle)
360° (TDC Exhaust)
180° (BDC)
0° (TDC – Cycle of Interest)
Crank Angle (° bTDC)
• A significant level of unmixedness is created with prevaporized port fueling.
• Fuel unmixedness increases with retarded injection timings except for the EoPI = 256° bTDC injection timing, which is less unmixed than the EoPI = 364° bTDC injection timing.
• For the most retarded injection timing, regions exist in the cylinder with equivalence ratios that differ from the mean by +/- 50%.
25
20
15
10
5
0
PD
F
2.01.51.00.50.00
6
4
2
0
Homogeneous
Unmixed
724° bTDC 364° bTDC 256° bTDC 196° bTDC 140° bTDC
4000
3500
3000
2500
2000
Pe
ak
Pre
ssu
re (
kPa
)
151050
CA50 (° aTDC)
99
98
97
96
95
94Co
mb
ust
ion
Effi
cie
ncy
Premixed 724° bTDC 364° bTDC 256° bTDC 196° bTDC 140° bTDC
• Variations with respect to intake charge temperature due to heat transfer in intake port.• All combustion metrics investigation (i.e., peak pressure, combustion efficiency) show that
at a given combustion phasing (CA50) premixed and prevaporized port injection are indistinguishable.
• NOx emissions increase with fuel unmixedness, resulting from regions richer than the mean which burn hotter after autoignition.
• CO emissions show a slight increase with fuel unmixedness, possibly a result of regions richer than stoichiometric or quenching in regions leaner than the mean.
4000
3500
3000
2500
2000Pe
ak
Pre
ssu
re (
kPa
)
151050
CA50 (° aTDC)
100
95
90
85
Co
mb
ust
ion
Effi
cie
ncy
10 mg/cycle 7 mg/cycle 5 mg/cycle
Open = PortClosed = Premixed
200
150
100
50
0
EIC
O (
g/k
g)
151050
CA50 (° aTDC)
8
6
4
2
0
EIN
Ox
(g/k
g)
10
8
6
4
2
0
EIN
Ox
(g/k
g)
151050
CA50 (° aTDC)
30
25
20
15
10
5
0
EIC
O (
g/k
g)
• No changes in combustion observed between premixed and port fueling.• Significant NOx emissions increases only observed in 10 mg/cycle fueling. NOx
emissions were near zero for the 7 and 5 mg/cycle fueling conditions due to high EGR.• The difference in CO emissions between premixed and port fueling increases with
decreasing fueling rate.
2800
2600
2400
2200
2000
1800
Pe
ak
Pre
ssu
re (
kPa
)
151050
CA50 (° aTDC)
100
95
90
85
80Co
mb
ust
ion
Effi
cie
ncy
= 0.75 = 0.6 = 0.5
Open = PortClosed = Premixed
• No changes in combustion observed between premixed and port fueling.• NOx emissions were near zero for all conditions because of high EGR rate at the 5
mg/cycle fueling condition• Decreasing the equivalence ratio (increasing air flow, decreasing EGR at constant fueling
rate) leads to an increase in CO emissions but a decrease in the difference in CO emissions between premixed and port fueling.
• Fuel unmixedness in the absence of thermal and residual unmixedness had no effect on the HCCI combustion.
• Small changes in CO and NOx emissions were observed for the port fueling, which were attributed to the regions in the charge that were either locally richer or leaner than the mean equivalence ratio.
• At a given operating condition the CO and NOx emissions are the lowest for a fully homogeneous fuel distribution. Regions locally richer and leaner than the mean equivalence ratio lead to increases in NOx and CO and therefore should be avoiding in an HCCI engine.
• Fuel unmixedness in the absence of thermal and residual unmixedness does not appear to be a viable method for gasoline HCCI combustion control.
4000
3500
3000
2500
2000
Pe
ak
Pre
ssu
re (
kPa
)
330320310300
Intake Charge Temperature (°C)
4000
3500
3000
2500
2000
1500
Pe
ak
Pre
ssu
re (
kPa
)
375350325300
Intake Charge Temperature (°C)
250
200
150
100
50
0
EIC
O (
g/k
g)
151050
CA50 (° aTDC)
2800
2600
2400
2200
2000
1800
Pe
ak
Pre
ssu
re (
kPa
)
375350325
Intake Charge Temperature (°C)
