1 Introduction
2 Setup
2.1 Properties of OME fuel
Tab.1 OME fuel composition |
Molecule | Content/wt.% |
---|---|
OME1 | 0.01 |
OME2 | < 0.01 |
OME3 | 57.90 |
OME4 | 28.87 |
OME5 | 10.07 |
OME6 | 1.91 |
Tab.2 Fuel properties of OME mixture |
Property | Unit | Value |
---|---|---|
Density | kg/m3 (t = 15 °C) | 1057.10 |
Viscosity | mm2/s (t = 40 °C) | 1.08 |
Cetane number | – | 68.6 |
Lubricity | µm | 320 |
Flash point | °C | 65 |
Lower heating value | MJ/kg | 19.26 |
Initial boiling point | °C | 144.40 |
Final boiling point | °C | 242.40 |
Total contaminations | mg/kg | < 1 |
Carbon content | wt.% | 43 |
Hydrogen content | wt.% | 8.53 |
Oxygen content | wt.% | 46.4 |
(A/F)st at 21% of O2 | – | 5.89:1 |
(A/F)st at 15% of O2 | – | 8.18:1 |
2.2 Development of the new OME oxidation mechanism
2.2.1 Experimental procedure of JSR
2.2.2 Mechanism modification and validation
Tab.3 Mechanism modification |
No. | Reaction | Modification |
---|---|---|
295 | OME3 + HO2 = OME3RX1 + H2O2 | A295 → 3A295 |
313 | CH3OCH2OCH2OCHO + OH = HOCHO + CO + CH3OCH2 + H2O | A313 → 4A313 |
314 | CH3OCH2OCH2OCHO + OH = 2CH2O + CH3O + CO + H2O | A314 → 6A314 |
311 | OME3X1OOHX3OO = OME3XKET1X3 + OH | A311 → 0.5A311 |
336 | OME4X1OOHX3OO = OME4XKET1X3 + OH | A336 → 0.1A336 |
361 | OME5X1OOHX3OO = OME5XKET1X3 + OH | A361 → 0.1A361 |
386 | OME6X1OOHX3OO = OME6XKET1X3 + OH | A386 → 0.1A386 |
2.3 Operating points
Tab.4 Operating points |
Label | Ambient temperature: TCC/K | Ambient pressure: pCC/bar | Ambient Density: ρCC/(kg·m−3) | Inj. temperature: Tinj/K | Inj. pressure: pinj/bar | Inj. Duration: tinj/ms | O2-content/vol.% |
---|---|---|---|---|---|---|---|
OP1 | 800 | 54 | 22.8 | 363 | 1500 | 1.5 | 15 |
OP2 | 900 | 61 | 22.8 | 363 | 1500 | 1.5 | 15 |
OP3 | 1000 | 68 | 22.8 | 363 | 1500 | 1.5 | 15 |
OP4 | 900 | 61 | 22.8 | 363 | 1500 | 0.3/0.5/1.2 | 15 |
OP5 | 900 | 60 | 22.8 | 363 | 1500 | 1.5 | 21 |
2.4 Experimental setup
2.5 Injectors
Tab.5 Injector properties |
Property | Conti3L | SprayA3 |
---|---|---|
Orifice exit diameter/µm | 115 | 97 |
Contraction coefficient (CA) | 0.98 | 0.98 |
Number of holes | 3 | 1 |
Elevation angle/(° ) | 45 | 0 |
2.6 Numerical setup
2.6.1 Mesh
Tab.6 Mesh refinement |
Refinement | L/mm | R1/mm | R2/mm | Cell size/mm |
---|---|---|---|---|
0 (base mesh) | 120 | 30 | 30 | 1.000 |
1 | 80 | 5 | 10 | 0.500 |
2 | 50 | 3 | 5 | 0.250 |
3 | 25 | 2 | 3 | 0.125 |
2.6.2 Submodels
Tab.7 Summary of numerical submodels |
Injection type | Blob [21] | |
---|---|---|
Liquid spray models | Breakup | KHRT [21,22] |
Turbulent dispersion | O’Rourke & Bracco [25] | |
Evaporation | Brenn et al. (multi-component) [23] | |
Drag Law | Schiller-Naumann [26] | |
Gaseous phase models | Temporal discretization | 0.5 µs (during injection); 1.0 µs (after injection) |
Turbulence modeling | RANS approach; k-ζ-f model [19] | |
Wall treatment | Compound (hybrid) [20] | |
Pressure-correction | SIMPLE (1st) / PISO (2nd) |