Author Contributions
Conceptualization, S.-H.M. and H.-K.S.; methodology, S.-H.M.; software, S.-H.M.; validation, S.-H.M.; formal analysis, S.-H.M. and H.-K.S.; investigation, S.-H.M.; resources, H.-K.S.; data curation, S.-H.M. and H.-K.S.; writing—original draft preparation, S.-H.M.; writing—review and editing, S.-H.M. and H.-K.S.; visualization, S.-H.M.; supervision, H.-K.S.; project administration, H.-K.S.; funding acquisition, H.-K.S. All authors have read and agreed to the published version of the manuscript.
Figure 1.
The schematics of RCCI engine experimental setup.
Figure 1.
The schematics of RCCI engine experimental setup.
Figure 2.
The lower heating value of diesel and ethanol according to the injection mass.
Figure 2.
The lower heating value of diesel and ethanol according to the injection mass.
Figure 3.
Validation results of combustion and exhaust emission characteristics (line and column: numerical results, symbol: experimental results). (a) Validation results of combustion characteristics; (b) validation results of exhaust emission characteristics.
Figure 3.
Validation results of combustion and exhaust emission characteristics (line and column: numerical results, symbol: experimental results). (a) Validation results of combustion characteristics; (b) validation results of exhaust emission characteristics.
Figure 4.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the peak cylinder pressure under RCCI combustion (Pinj = 100 MPa, LHVnet = 595 J, teng = BTDC 12 deg, 1800 rpm).
Figure 4.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the peak cylinder pressure under RCCI combustion (Pinj = 100 MPa, LHVnet = 595 J, teng = BTDC 12 deg, 1800 rpm).
Figure 5.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ignition delay under RCCI combustion (Pinj = 100 Mpa, LHVnet = 595 J, 1800 rpm).
Figure 5.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ignition delay under RCCI combustion (Pinj = 100 Mpa, LHVnet = 595 J, 1800 rpm).
Figure 6.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the equivalence ratio distribution characteristics (symbol and contour mean SMD and NO mass fraction) (Pinj = 100 Mpa, LHVtotal = 595 J, tASOI = 3 deg, 1800 rpm).
Figure 6.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the equivalence ratio distribution characteristics (symbol and contour mean SMD and NO mass fraction) (Pinj = 100 Mpa, LHVtotal = 595 J, tASOI = 3 deg, 1800 rpm).
Figure 7.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the IMEP characteristics (Pinj = 100 Mpa, LHVnet = 595 J, 1800 rpm).
Figure 7.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the IMEP characteristics (Pinj = 100 Mpa, LHVnet = 595 J, 1800 rpm).
Figure 8.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the IMEP characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm). (a) teng = BTDC 30 deg; (b) teng = BTDC 12 deg.
Figure 8.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the IMEP characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm). (a) teng = BTDC 30 deg; (b) teng = BTDC 12 deg.
Figure 9.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ISNO characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 9.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ISNO characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 10.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the cylinder temperature characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm). (a) teng = BTDC 30 deg; (b) teng = BTDC 21 deg; (c) teng = BTDC 12 deg.
Figure 10.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the cylinder temperature characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm). (a) teng = BTDC 30 deg; (b) teng = BTDC 21 deg; (c) teng = BTDC 12 deg.
Figure 11.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the NO mass fraction distribution characteristics (contour means NO mass fraction) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 11.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the NO mass fraction distribution characteristics (contour means NO mass fraction) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 12.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the cylinder temperature distribution characteristics (contour means cylinder temperature) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 12.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the cylinder temperature distribution characteristics (contour means cylinder temperature) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 13.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ISCO characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 13.
The effect of premixed ethanol ratio based on the same total LHV in-cylinder on the ISCO characteristics (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 14.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the CO mass fraction distribution characteristics (contour means CO mass fraction) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 14.
The effect of the premixed ethanol ratio based on the same total LHV in-cylinder on the CO mass fraction distribution characteristics (contour means CO mass fraction) (Pinj = 100 MPa, LHVtotal = 595 J, 1800 rpm).
Figure 15.
Comparison of ISNO and ISCO according to the start of energizing timing to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 15.
Comparison of ISNO and ISCO according to the start of energizing timing to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 16.
Comparison of ISNO and ISCO according to the premixed ethanol ratio based on total heating value in-cylinder to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 16.
Comparison of ISNO and ISCO according to the premixed ethanol ratio based on total heating value in-cylinder to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 17.
Comparison of ISNO and ISCO according to the IMEP characteristics to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Figure 17.
Comparison of ISNO and ISCO according to the IMEP characteristics to find optimal operating conditions (Pinj = 100 MPa, LHVnet = 595 J, 1800 rpm).
Table 1.
Detailed specifications of test engine.
Table 1.
Detailed specifications of test engine.
Item | Specification |
---|
Engine | Displacement [cc] | 498 |
Bore × Stroke [mm] | 83 × 92 |
Compression ratio [-] | 17.7 |
Injector | Number of nozzle holes [ea] | 5 |
Hole diameter [mm] | 0.168 |
Inclined spray angle [deg] | 154 |
Table 2.
Detailed measurement methods and specifications of PEMS.
Table 2.
Detailed measurement methods and specifications of PEMS.
Emission | Method | Range | Span |
---|
NOX | CLD (CLA-150) | 0~5000 ppm | NO/N2-bal 1494 ppm |
CO | NDIR (AIA-110) | 0~3000 ppm | CO/N2-bal 7404 ppm |
Table 3.
Properties of test fuels [
16].
Table 3.
Properties of test fuels [
16].
Item | Diesel | Ethanol |
---|
LHV; Lower Heating Value [MJ/kg] | 42.5 | 26.8 |
Latent heat of Evaporation [kJ/kg] | 250 | 846 |
Density@20 °C [kg/m3] | 838.2 | 789.4 |
Carbon Content [% mass] | 86.7 | 52.14 |
Hydrogen content [% mass] | 12.71 | 13.13 |
Sulfur content [% mass] | 0.041 | - |
Oxygen content [% mass] | - | 34.73 |
Flash point [°C] | 67 | 13 |
Kinematic viscosity@40 °C [mm2/s] | 2.8271 | 1.056 |
Typical formula | C14.09H24.78 | C2H6O |
Cetane number | 42.6 | 8.5 |
Lubricity, HFRR@60 °C [μm] | Max. 520 | Max. 605 |
Table 4.
Initial air composition in the cylinder according to the heating value ratio of diesel and ethanol.
Table 4.
Initial air composition in the cylinder according to the heating value ratio of diesel and ethanol.
Fuel Injection Ratio [Main/Premixed] | Fuel Amount [mg] | Heating Value [J] | O2 Mass Fraction [-] | N2 Mass Fraction [-] | Ethanol Mass Fraction [-] |
---|
D100/E0 | 14/0 | 595/0 | 0.23200 | 0.76800 | 0.00000 |
D90/E10 | 12.6/2.2 | 535.5/59.5 | 0.23081 | 0.76407 | 0.00512 |
D80/E20 | 11.2/4.4 | 476/119 | 0.22984 | 0.76084 | 0.00932 |
D70/E30 | 9.8/6.7 | 416.5/178.5 | 0.22876 | 0.75273 | 0.01396 |
D60/E40 | 8.4/8.9 | 357/238 | 0.22781 | 0.75413 | 0.01806 |
Table 5.
Sub-model for numerical analysis [
17,
18,
19].
Table 5.
Sub-model for numerical analysis [
17,
18,
19].
Phenomenon | Model |
---|
Turbulence | k-zeta-f |
Break-up | Wave |
Evaporation | Dukowicz |
Wall interaction | Mundo Tropea Sommerfeld |
Combustion | ECFM-3Z |
NO | Extended Zel’dovich |
Soot | Kennedy-Hiroyasu-Magnussen |
Table 6.
Detailed experimental and numerical analysis conditions.
Table 6.
Detailed experimental and numerical analysis conditions.
Contents | Experiment and Numerical Analysis |
---|
RPM | 1800 |
Injection pressure [MPa] | Diesel: 100, Ethanol: 10 |
Total heating value [J] | 595 |
Start of energizing timing [ATDC deg] | −30~−12 |
Heating value ratio of diesel and ethanol | D100/E0, D90/E10, D80/E20, D70/E30, D60/E40 |