GCEP Optimization of the Molecular Structure of Low-Greenhouse-Gas-Emission Synthetic Oxygenated Fuels for Improved Combustion and Pollutant Emission Characteristics of Diesel Engines C. T. Bowman, R. K. Hanson, H. Pitsch, D. M. Golden Department of Mechanical Engineering R. Malhotra SRI International 1
GCEP Optimization of the Molecular Structure of Synthetic Oxygenated Fuels for Diesel Engine Applications C. T. Bowman, R. K. Hanson, H. Pitsch, D. M. Golden Department of Mechanical Engineering R. Malhotra SRI International 2
GCEP Optimization of Synthetic Oxygenated Fuels (a.k.a The Oxyfuels Project) C. T. Bowman, R. K. Hanson, H. Pitsch, D. M. Golden Department of Mechanical Engineering R. Malhotra SRI International 3
GCEP Presentation Outline Background and Motivation Why Oxyfuels? Project Goals Research Tasks and Approach Results 4
U. S. Combustion-Generated CO 2 Emissions Total = 1631 x 10 9 kg C/yr (2005) GCEP Residential 6% Commercial 4% Ship 3% Electric Power Generation - 39% Transportation 33% Industrial 18% Heavy Duty Truck and Rail - 23% Aircraft 12% Automobile and Light Truck 62% EIA 2006 5
GCEP U.S. Energy Consumption 2004 Total = 100.3 quads Renewables = 6.1 quads Natural gas, 23% Coal, 23% Biomass, 47% Hydroelectric, 45% Nuclear, 8% Petroleum, 40% Renewables, 6% Geothermal, 5% Wind, 2% Solar, 1% EIA, 2005 6
GCEP Fossil fuels will be a dominant energy carrier in the 21 st century. 7
GCEP Projected Growth in Bio-Transportation Fuels Percent of Transportation Fuels 20 15 10 5 0 U. S. DOE, 2005 US DOE, 2005 1/1/1900 1/2/1900 1/3/1900 1/4/1900 2005 2010 2020 2030 Year Biomass may become an increasingly important energy carrier. 8
Automotive Engine/Fuel Performance Projected Growth in Bio-Transportation Fuels NiMH Battery Electric FC (PEM) Hybrid - hydrogen FC (PEM) Hybrid - methanol 10 9 8 Total Energy Use - MJ/km 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 GCEP FC (PEM) Hybrid - gasoline SI Hybrid - CNG 7 6 Ad. CI Hybrid - diesel fuel Ad. SI Hybrid - gasoline 5 4 Advanced CI - diesel fuel 3 Advanced SI - gasoline Current SI -gasoline MIT Energy Lab, 2000 MIT Energy Lab, 2000 2 1 0 10 20 30 40 50 60 70 80 Carbon Emissions - gc/km 9
GCEP 10
GCEP Mitigation of GHG emissions from transportation sources will require implementation of a variety of strategies: improvements in overall efficiency of vehicle/fuel systems, such as hybrid and new high-efficiency diesel engines use of synthetic or renewable fuels to replace or supplement petroleum-based fuels or as performanceimproving additives 11
GCEP An attractive class of synthetic fuels is oxygenated liquid fuels that may be synthesized from a variety of feedstocks. Oxygenated fuels are especially attractive for use in advanced diesel engines and diesel-hybrids because of the inherently high thermal efficiencies of these engines. In addition, these fuels offer significant potential for reduction in particulate emissions from diesel engines. 12
GCEP Westbrook and Pitz, 2005 How well an oxygenated fuel works to reduce soot depends on its molecular structure. 13
GCEP Project Goals Explore the impact of oxygenated fuel structure on combustion and emissions performance under diesel combustion conditions - determine fuel structures that will minimize pollutant emissions (especially soot) and provide suitable ignition properties - identify processing strategies to produce synthetic oxygenated hydrocarbons from various feedstocks on a refinery scale 14
GCEP Research Tasks Task 1a: Experimentally investigate the combustion and emissions characteristics of oxygenated fuels using two high-pressure combustion facilities shock tube and flow reactor. Task 1b: Develop and validate detailed chemical kinetics models for these fuels to provide insight into the mechanisms by which fuel structure impacts combustion behavior. 15
GCEP Research Tasks Task 2: Use advanced CFD models to examine effects of fuel structure and in-cylinder processes on soot and NO x formation and ignition in diesel engine environments. Task 3: Identify functionalities most suitable for cleanburning diesel fuels. Task 4: Explore strategies for production of candidate oxygenated fuels on a large-scale basis from a variety of feedstocks. 16
Task 1 GCEP Screening Structures for Effectiveness in Soot Suppression Compound C H O N MW MW/O Alcohols 1 Methanol 1 4 1 0 32 32 2 Ethanol 2 6 1 0 46 46 3 Butanol 4 10 1 0 74 74 4 Hexanol 6 14 1 0 102 102 5 Octanol 8 18 1 0 130 130 Ethers 6 Dimethyl ether 2 6 1 0 46 46 7 Diethyl ether 4 10 1 0 74 74 8 Dimethoxymethane 3 8 2 0 76 38 9 2,2-Dimethoxy propane 5 12 2 0 104 52 10 Ethyleneglycol dimethyl ether 4 10 2 0 90 45 11 Diethyleneglycol methyl ether 5 12 3 0 120 40 12 Triehtyleneglycol methyl ether 7 16 4 0 164 41 Esters 13 Methyl acteate 3 6 2 0 74 37 14 Methyl propanoate 4 8 2 0 88 44 15 Ethyl propanoate 5 10 2 0 102 51 16 Methyl butanoate 5 10 2 0 102 51 17 Ethyl butanoate 6 12 2 0 116 58 18 Diethyl carbonoate 5 10 3 0 118 39.7 19 Methyl soyate Compound C H O N MW MW/O Ketones 20 Acetone 3 6 1 0 58 58 21 3-Pentanone 5 10 1 0 86 86 22 2-Pentanone 5 10 1 0 86 86 23 Acetophenone 8 8 1 0 120 120 Aldehydes 24 Butanal 4 8 1 0 72 72 25 Pentanal 5 10 1 0 86 86 26 Hexanal 6 12 1 0 100 100 Misc. 27 2-Ethylhexyl nitrate 8 17 3 1 161 53.7 28 Di-t-butyl peroxide 8 18 2 0 146 73 29 2-Nitropentane 5 11 2 1 103 51.5 30 Amyl nitrate 5 11 3 1 119 39. 7 31 Amyl nitrite 5 11 2 1 103 51.5 17
Task 1 GCEP Screening Structures for Effectiveness in Soot Suppression Methanol 50.0 Ethanol Butanol 45.0 Hexanol EthyleneglycolDME 40.0 Methyl acetate Diethyl ether Neat fuel Smoke Height mm* 35.0 30.0 25.0 20.0 15.0 10.0 Data from Kirby and Boehman, Penn State Fuels Lab Dimethoxymethane Dimethoxypropane Methyl propanoate Ethyl propanoate Methyl butanoate Ethyl butanoate Diethyl carbonoate Acetone 2 Pentanone 3-Pentanone Ethyl acetate 5.0 DiethyleneglycolDME Butanal 0.0 0 5 10 15 20 25 Wt% Oxygen * ASTM D1322 Pentanal Hexanal 18
Task 1 GCEP Screening Structures for Effectiveness in Soot Suppression Effectiveness of soot suppressing additives depends on the mass of oxygen in the fuel blend and on molecular structure 19
Task 1 GCEP Screening Structures for Effectiveness in Soot Suppression Effectiveness of soot suppressing additives depends on the mass of oxygen in the fuel blend and on molecular structure The smoke point tests indicate that: - for a given oxygen functionality the effectiveness increases with chain length 20
Task 1 GCEP Screening Structures for Effectiveness in Soot Suppression Effectiveness of soot suppressing additives depends on the mass of oxygen in the fuel blend and on molecular structure The smoke point tests indicate that: - for a given oxygen functionality the effectiveness increases with chain length - effectiveness scales as aldehydes >> ketones > ethers esters > alcohols 21
Task 1 GCEP Ignition Behavior of DME and DME-Heptane mixtures φ = 2 φ = 1 1% DME in Ar/O 2 P = 1.8 atm Scaled as P -0.66 φ = 0.5 1% Total fuel in Ar/O 2 φ = 1 P scaled to 1.5 atm (P -0.68 ) 1000 1000 τ ign [µs] 100 Stanford data (current study) Model, Curran, et al (2000) Stanford data (current study) Model, Curran, et al (2000) Stanford data (current study) Model, Curran, et al (2000) 0.64 0.66 0.68 0.70 0.72 0.74 0.76 0.78 0.80 0.82 1000/T [1/K] τ ign [µs] 100 1% DME Data 1% DME Model.75% DME/.25% Heptane Data.75% DME/.25% Heptane Model.5% DME/.5% Heptane Data.5% DME/.5% Heptane Model.25% DME/.75% Heptane Data.25% DME/.75% Heptane Model 0.68 0.70 0.72 0.74 0.76 0.78 0.80 0.82 0.84 1000/T [1/K] 22
Task 1 GCEP Sooting Characteristics of Heptane and DME-Heptane Mixtures Soot Induction Times 23
Task 1 GCEP Sooting Characteristics of Heptane and DME-Heptane Mixtures Fraction of Fuel Carbon Converted to Soot 24
General Objectives Task 2 TSD GCEP CFD Modeling of Diesel Engine Combustion Assess effect of fuel structure on emissions in Diesel engine combustion and examine fuel optimization Required computational capabilities LES and RANS Immersed boundary method for complex geometry Surrogate fuels Advanced combustion models Advanced soot models 25
Strategy for New Code Task 2 TSD GCEP CFD Modeling of Diesel Engine Combustion Strategy Based on existing LES codes Required accuracy and numerical methods Multi-phase models in place Strategy for moving and complex geometry Moving meshes for moving piston Immersed boundary for valves and possibly piston bowl 26
Present Work Task 2 TSD GCEP CFD Modeling of Diesel Engine Combustion Current Work Interfacing IB implementation with STL files STereoLithography: Industry standard for geometry representation Finalize compressible solver More test cases: Realistic engine simulations 27
Present Work Task 2 TSD CFD Modeling of Diesel Engine Combustion GCEP 28
GCEP Posters Effect of Pressure on the Oxidation of Hydrocarbon Fuels under Flameless Oxidation Conditions Walters and Bowman: #9 Shock Tube Studies of Soot Formation in Heptane-Air and Heptane-DME-Air Mixtures - Hong, Davidson and Hanson: #2 Ignition Delay Times of DME/O 2 /Ar and DME/Heptane/O 2 /Ar Mixtures Cook, Davidson and Hanson: #1 Advanced Modeling and Optimization of Diesel Engines Shashank, Wang, Iyengar and Pitsch: #10 29
GCEP "The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in the course of time as important as the petroleum and coal tar products of the present time" Rudolph Diesel, 1912 30
Projected Generic Growth RTL in Synfuels Bio-Transportation Process Fuels GCEP 31
Estimated Recoverable Coal Reserves (1,000 billion tons) GCEP South Africa 5% Poland 2% ROW 9% USA 27% Australia 9% India 10% BP Global 2005 China 13% FSU 25% 32