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Comparing Combustion Energies of Petroleum Diesel and Biodiesel Fuels By Bomb Calorimetry Penn State University, Department of Chemistry, CHEM 457, Section 1, Fall 2013 By: Tim Haggerty, Arjun Plakkat, Kelly Helfrich, Kristen Woznick
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Motivation
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Holmes, Frank. "World Running Low on Its "Energy Drink" - U.S. Global Investors - September 21, 2011." World Running Low on Its "Energy Drink" - U.S. Global Investors - September 21, 2011. US Global Investors, 2013. Web. 10 Dec. 2013.
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Matt. "Half of Oil Burnable in 2000-2050 to Keep Us within 2 Degrees Warming Has Been Used up as We Hit 400 Ppm." Half of Oil Burnable in 2000-2050 to Keep Us within 2 Degrees Warming Has Been Used up as We Hit 400 Ppm. Crude Oil Peak, 16 May 2013. Web. 10 Dec. 2013.
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Introduction Combustion for Average Diesel Molecule Combustion for Average Biodiesel Molecule Ciolkosz, Daniel, Joseph Perez, Dennis Buffington, and Glen Cauffman. "Renewable and Alternate Energy Fact Sheet." Penn State College of Agricultural Science, 2009. Web. 1 Dec. 2013.. Krol, Walter J. "Comparative Fuel Characteristics." Biodiesel Fuel. The Connecticut Agricultural Experiment Station, n.d. Web. 4 Dec. 2013.. Graboski, Michael S., and Robert L. McCormick. "Combustion of Fat and Vegetable Oil Derived Fuels in Diesel Engines." Progress in Energy and Combustion Science 24.2 (1998): 125- 64. ScienceDirect. Web. 30 Nov. 2013.. Patzek, Tad. "A First Law Thermodynamic Analysis of Biodiesel Production From Soybean." Texas A&M Department of Petroleum and Geosystems Engineering, 13 Apr. 2009. Web. 29 Nov. 2013.. Biodiesel Labs. "Combustion of a Renewable and Fossil Fuel: Teacher Manual." Loyola University of Chicago, n.d. Web. 7 Dec. 2013. Dunn, Bruce. "Liquid Fuels." Liquid Fuels. NASA, n.d. Web. 07 Dec. 2013.
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Parr Bomb Calorimetry ∆U = Q + W First Law of Thermodynamics ∆H v =∆U + ∆n(g)RT Chem 345. "Bomb Calorimetry." Bomb Calorimetry. Hope University, n.d. Web. 09 Dec. 2013. Milosavljevic, Bratoljub H. Lab Packet for CHEM 457 Experimental Physical Chemistry.
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Parr Bomb Calorimetry Chem 345. "Bomb Calorimetry." Bomb Calorimetry. Hope University, n.d. Web. 09 Dec. 2013. Milosavljevic, Bratoljub H. Lab Packet for CHEM 457 Experimental Physical Chemistry.
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EXPERIMENTAL Bomb Calorimeter Motor For Stirrer Ignition Box
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EXPERIMENTAL Bomb: Samples Placed In Here Specifications: 5 Diesel Samples 5 Biodiesel Samples 10 cm of Wire 30 atm Oxygen 2 L Water Bath Milosavljevic, Bratoljub H. Lab Packet for CHEM 457 Experimental Physical Chemistry.
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Results Trial Parameters
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Trial parameters- Day 1 Δ Wire Mass (±0.0008 g) Sample Mass (±0.0004 g) Δ T ( o C) Benzoic Acid0.01021.0044 2.577 ± 0.007 Biodiesel 10.00840.5877 2.39 ± 0.01 Diesel 10.00490.5768 1.981 ± 0.002 Biodiesel 20.00610.6039 2.497 ± 0.004 Diesel 20.01040.5467 2.5947±0.0009 Biodiesel 30.00920.57412.389 ± 0.005
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Trial parameters- Day 2 Δ Wire Mass ( ± 0.0008 g) Sample Mass ( ± 0.0004 g) Δ T ( o C) Benzoic Acid0.14570.9701 2.470 ± 0.020 Diesel 30.00790.5259 2.156 ± 0.002 Biodiesel 40.00530.5126 2.395 ± 0.008 Diesel 40.01020.5625 2.579 ± 0.001 Biodiesel 50.00450.5379 2.397 ± 0.001 Diesel 50.0080.5728 2.492 ± 0.001
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Results Bomb Calorimetry Data- Average Temperature Profiles
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T 60% =24.33 °C t 60% =6.62 min.
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Data Analysis Instantaneous T f and T i determined from T 60% and t 60% Regression slopes of pre-/post- ignition lines due to stirrer work and heat transfer to surroundings Calorimeter heat capacity determined from benzoic acid combustion First diesel run excluded as per Q- test Milosavljevic, Bratoljub H. Lab Packet for CHEM 457 Experimental Physical Chemistry.
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T 60% =23.23 °C t 60% =6.89 min.
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T 60% =24.56 °C t 60% =6.81 min.
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Results Bomb Calorimetry Data- ΔH comb
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Final Results BiodieselDiesel Δn(mol)-15-6 Experimental ΔH comb (kJ/mol) -11,700 ± 60-8,070 ± 60 (kJ/g) -43.3 ± 0.2 -47.9 ± 0.4 (kJ/L) -36,600 ± 200-39,900 ± 300 Literature ΔH comb (kJ/mol) -10963-7202 Deviation between Exp. and Lit. Values 7%12% Theoretical ΔH comb (kJ/mol) -11616-7538 Deviation between Exp. and Theo. Values 0.72%11.51% Krol, Walter J. "Comparative Fuel Characteristics." Biodiesel Fuel. The Connecticut Agricultural Experiment Station, n.d. Web. 4 Dec. 2013.. Graboski, Michael S., and Robert L. McCormick. "Combustion of Fat and Vegetable Oil Derived Fuels in Diesel Engines." Progress in Energy and Combustion Science 24.2 (1998): 125-64. ScienceDirect. Web. 30 Nov. 2013..
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Discussion
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Controlling for accurate data Measured temperature difference largest source ◦Same calorimeter used each day ◦Same volume of water used in each trial ◦Increasing by 0.01 K -> 4% change in ΔH comb Purged bomb with 30 atm O 2 to prevent NO x formation Milosavljevic, Bratoljub H. Lab Packet for CHEM 457 Experimental Physical Chemistry.
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Why is biodiesel’s value higher? ◦Biodiesel structure has more C-C bonds (C17) ◦Diesel structure has no ester group (C12) Biodiesel Labs. "Combustion of a Renewable and Fossil Fuel: Teacher Manual." Loyola University of Chicago, n.d. Web. 7 Dec. 2013.
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Sources of error Ideal gas behavior assumed ◦Assumption holds best at 1 atm ◦SRK or PR EOS better choice to model thermodynamics Puncturing capsule with fuse wire ◦Contained liquid sample beforehand ◦Might be mitigated with larger capsules Uncertainty change in temperature
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Conclusion
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Experimental objective achieved Liquid biodiesel ◦ΔH comb =- 11700 ± 60 kJ/mol 7% difference from lit. value ◦ΔH comb =-36,600±200 kJ/L ◦ΔH comb =-43.3±0.2 kJ/g Liquid diesel ◦Δh comb =- 8070 ± 60 kJ/mol 12% difference from lit. value ◦ΔH comb =-39,900 ± 300 kJ/L ◦ΔH comb =-47.9 ± 0.4 kJ/g
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Questions?
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