1. Prologue
Combustion Properties of Alternative Liquid Fuels 21 JULY 211 Cheng Tung Chong, Simone Hochgreb
Content 1. Introduction 2. What s biodiesels 3. Burner design and experimental 4. Results - Flame structure - Spectroscopy - Spray droplets - Flow field - Emissions 5. Conclusion and summary
2. Biodiesel
Transesterification process - Vegetable oil+methanol Methyl esters+glycerol Biodiesels are mixtures of methyl esters (ME). ME are long-chain esters. O Example : H 3 C O CH 3 Methyl palmitate (C 17 H 34 O 2 ) (carbon: Composition (%) Fatty acids bond) Rapeseed Soybean Jatropha Palm Lauric (C12:) -.1 -.2 Myristic (C14:) 1..1.1.8 Palmitic (C16:) 3.5 1.2 15.6 39.5 Stearic (C18:).9 3.7 1.5 5.1 Oleic (C18:1) 64.1 22.8 42.1 43.1 Linoleic (C18:2) 22.5 53.7 3.9 1.4 Linolenic (C18:3) 8. 8.6.2.1 Others -.8.6.8
- Difference between biodiesels and conventional fuels Jet-A1 Palm methyl esters () Rapeseed methyl esters () Gas chromatography
Fuel properties Properties Jet-A1 Approx. formula C 11 H 21 C 16 H 34 C 19 H 36 O 2 C 19 H 36 O 2 H/C ratio* 1.98 1.9 1.89 1.89 C/O ratio* - - 9.83 1.6 Boiling range ( o C) 166-266 19-36 >215 >2 Spec. grav. 15 o C.81.85.88.88 Pour point ( o C) - -2-18 -1 Flash point ( o C) 38 6-72 174 17 Viscosity (cst) 4 o C - 2.6 4.5 4.83 LHV (kj/kg) 4315 439 3677 368 Cetane number - 52 62.6 51
- Yes, the FUEL properties are different, so HOW do we test the fundamental combustion properties? - What kind of experiment and under what conditions? Objectives - Investigation of the combustion properties of biodiesels under a gas turbine type combustor - Develop a methodology to test alternative fuels WHY gas turbine-type combustor?? Swirling spray flame - Potential to be used in Gas turbines - Spray flame present in many applications - Obtain an experimental database for modelling
Experimental Spray combustion Non-reacting flow Reacting flow System Setup Burner design + System Setup PDA PDA Emissions Chemiluminescence & spectroscopy PIV
3. Swirl burner configurations 1 Quartz tube 18 19.2 38.4 Rope heater 39 In mm 55 Air inlet Atomizing air inlet Fuel inlet Air heater Schematic of the (a) swirl burner and (b) Setup for liquid spray flame measurement
Burner geometry and flow delivery (a) 18 Swirler y x 38.4 1 Quartz tube Atomizer 19.2 (b) 9.6 19.2 1.73 13.8 In mm Main air Fuel line Atomizing air Total vane = 8 @ 45 o Vane thickness =1.5 mm Geometry description of the swirl (a) burner and the (b) swirler
Injector Plain-jet airblast type 4 o 1.35.5 1.73 1.1 Atomizing air inlet Fuel passage Air swirl slot In mm Fuel inlet Schematic of the internal geometry of plain-jet airblast atomizer
Burner and flow delivery Quartz tube Thermocouple Swirler Fuel Fuel line Plenum Pump MFC Heated and insulated Heater MFC MFC Air Atomizing air Schematic of the single swirl flame burner Man in love with his burner
Swirling spray flame Operating conditions Fuel φ AFR Air (g/s) Fuel (g/s) Power (kw).47 31.8 4.43.14 6. Jet-A1.47 31.42 4.37.14 6..47 26.75 4.37.16 6..47 26.75 4.36.16 6. Can you guess what fuel is used?
4. Experimental Spray combustion Non-reacting flow Reacting flow System Setup Burner design + System Setup PDA PDA Emissions Chemiluminescence & spectroscopy PIV
Flame imaging Jet-A1
CH* Chemiluminescence imaging Jet-A1
Long Band pass >55 nm Jet-A1
Flame spectroscopy Intensity count 2.5 x 14 2 1.5 1.5 Jet-A1 388 (CN*) 31 (OH*) 47 (C 2 *) 432 (CH*) 515 (C 2 *) 588 Intensity count 2.5 x 14 2 515 (C 2 *) 1.5 47 (C 2 *) 1 432 (CH*) 388 (CN*).5 31 (OH*) 5% /diesel 2% /diesel 588 2 35 5 65 8 Wavelength(nm) Flame emission spectroscopy measurements of four fuels 2 35 5 65 8 Wavelength(nm) Flame emission spectroscopy of diesel,, blends of 2% and 5% with diesel
Experimental Spray combustion Non-reacting flow Reacting flow System Setup Burner design + System Setup PDA PDA Emissions Chemiluminescence & spectroscopy PIV
PDA setup for reacting flow Beam transmitter y x Measurement locations 2 mm 15 mm 1 mm Main air at 623 K Atomizing air Fuel Receiving optics PDA setup and measurement locations 56 o Table 3: PDA optical setting Transmitting optics Wavelength Power Beam spacing Beam width Focal Length Number of fringes Width of measurement vol. Length of measurement vol. Receiving Optics Focal length Scattering angle 514.5 nm.8 W 45 mm 2.2 mm 5 mm 26.149 mm 3.312 mm 31 mm 56 o
PDA Setup for Reacting Flow Receiving optic Beam transmitter Traverse Burner Air heater Setup for PDA measurements
Droplet velocity and SMD Mean axial velocity (m/s) 8 6 4 2 (a) 1 mm Mean axial velocity (m/s) 8 6 4 2 (b) 15 mm Mean axial velocity (m/s) 8 6 4 2 (c) 2 mm 3 24 5 1 15 2 Radial position (mm) (d) 1 mm 3 24 5 1 15 2 Radial position (mm) (e) 15 mm 3 24 5 1 15 2 Radial position (mm) (f) 2 mm SMD (μm) 18 12 6 5 1 15 2 Radial position (mm) SMD (μm) 18 12 6 5 1 15 2 Radial position (mm) SMD (μm) 18 12 6 5 1 15 2 Radial position (mm) Droplet profiles at axial distance 1, 15, 2 mm from the atomizer tip
Droplet concentration and volume flux Droplets density (#/cm 2 /s) 12 9 6 3 x 1 4 (a) 15 mm Droplets density (#/cm 2 /s) 12 9 6 3 (b) 15 mm Droplets density (#/cm 2 /s) 2 15 1 5 (c) 2 mm Volume flux (cm 3 /cm 2 /s) 5 1 15 2 Radial position (mm) 12 x 1-3 (d) 1 mm 8 4 5 1 15 2 Radial position (mm) Volume flux (cm 3 /cm 2 /s) 12 8 4 5 1 15 2 Radial position (mm) x 1-3 (e) 15 mm 5 1 15 2 Radial position (mm) Volume flux (cm 3 /cm 2 /s) 5 x 1-3 (f) 4 3 2 1 5 1 15 2 Radial position (mm) 2 mm 5 1 15 2 Radial position (mm) Droplet number density and volume flux at axial distance 1, 15, 2 mm from the atomizer tip
Droplet distribution in flame Droplet distribution in (a) Jet-A1 and (b) flame
Experimental Spray combustion Non-reacting flow Reacting flow System Setup Burner design + System Setup PDA PDA Emissions Chemiluminescence & spectroscopy PIV
Particle imaging velocimetry Laser Quartz tube CCD camera Thermocouple Seeding air MFC Seeder Fuel line Heated and Insulated Heater MFC Air Fuel Pump MFC MFC Atomizing air Schematic of the flow delivery single swirl flame burner
Non-reacting flow PIV measurement Axial position (mm) 75 6 45 3 15 Axial position (mm) 6 45 3 15 (c) T=2 o C -4-2 2 4 Radial position (mm) Non-reacting flow at open air -4-2 2 4 Radial position (mm) Main flow + spray at open air
Flow field in enclosure Burner centerline 45 45 Axial position (mm) 35 25 15 Axial position (mm) 35 25 15 5 5-5 -4-3 -2-1 Radial position (mm) Cold spray + main air + spray + enclosure -5-4 -3-2 -1 Radial position (mm) Reacting spray flame with enclosure
Flow field and droplet distribution in flame flame + flow field + flame reaction zone
Experimental Spray combustion Non-reacting flow Reacting flow System Setup Burner design + System Setup PDA PDA Emissions Chemiluminescence & spectroscopy PIV
Emission measurement - Measure the emission across the burner outlet. - Average the spatial values. -NO, NO 2, CO, O 2 and CO 2 are measured Emissions (mg.m -3 /kg fuel.s -1 ) 1.8.6.4.2 (b) x5 NO NO2 CO Jet-A1 x1 Emissions under the same power output condition
Emission measurement (i) NO (mg.m -3 /kg fuel.s -1 ) 1.6 1.2.8.4 (a).25.4.55.7.85 Equivalence ratio φ NO 2 (mg.m -3 /kg fuel.s -1 ).8.6.4.2 (b).25.4.55.7.85 Equivalence ratio φ CO (mg.m -3 /kg fuel.s -1 ).8.6.4.2 (c).25.4.55.7.85 Equivalence ratio φ CO 2 (%) 16 12 (d) 8 4.25.4.55.7.85 Equivalence ratio φ Emissions as a function of equivalence ratio
Emission measurement (ii) NO (mg.m -3 /kg fuel.s -1 ) CO (mg.m -3 /kg fuel.s -1 ) 1.2.9.6.3.2.15.1.5 (a) Jet-A1 5% /Jet-A1 5% /Jet-A1 2 2.2 2.4 2.6 2.8 Air/liquid mass ratio (ALR) (c) 5% /Jet-A1 5% /Jet-A1 2 2.2 2.4 2.6 2.8 Air/liquid mass ratio (ALR) NO 2 (mg.m -3 /kg fuel.s -1 ) CO 2 (%).1.8.6.4.2 2 15 1 5 (b) 5% /Jet-A1 5% /Jet-A1 2 2.2 2.4 2.6 2.8 Air/liquid mass ratio (ALR) (d) Jet-A1 5% /Jet-A1 5% /Jet-A1 2 2.2 2.4 2.6 2.8 Air/liquid mass ratio (ALR) Emissions as a function of air-liquid-mass ratio
Emission measurement (iii) NO (mg.m -3 /kg fuel.s -1 ) 1.6 1.2.8.4 (a) Jet-A1 5% / 5% / 4 6 8 1 Power (kw) NO 2 (mg.m -3 /kg fuel.s -1 ).5.4.3.2.1 (b) Jet-A1 5% / 5% / 4 6 8 1 Power (kw) CO (mg.m -3 /kg fuel.s -1 ).1.8.6.4.2 (c) 5% / 5% / 4 6 8 1 Power (kw) CO 2 (%) 2 15 1 5 (d) Jet-A1 5% / 5% / 4 6 8 1 Power (kw) Emissions as a function of burner power output
5. Summary and conclusion Combustion properties of alternative fuel can be significantly different. A methodology is developed to systematically measure the combustion properties of alternative fuels. Advanced modelling of fuel and combustion requires experimental data.
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